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³í¹®
NUMBER  
AUTHOR  Park, Hyunggyu,Um, Jaegon,Lee, Sang Hoon 
TITLE  Nonuniversality of heatengine efficiency at maximum power 
ARCHIVE  
FILE  
JOURNAL  PHYSICAL REVIEW E, 2018 
ABSTRACT  We study the efficiency of a simple quantum dot heat engine at maximum power. In contrast to the quasistatically operated Carnot engine whose efficiency reaches the theoretical maximum, recent research on more realistic engines operated in a finite time has revealed other classes of efficiencies such as the CurzonAhlborn efficiency maximizing the power. Such a powermaximizing efficiency has been argued to be always half of the maximum efficiency up to the linear order near equilibrium under the tightcoupling condition between thermodynamic fluxes. We show, however, that this universality may break down for the quantum dot heat engine, depending on the constraint imposed on the engine control parameters (local optimization), even though the tightcoupling condition remains satisfied. It is shown that this deviation is critically related to the applicability of the linear irreversible thermodynamics. 

³í¹®
NUMBER  P18104 
AUTHOR  Park, Hyunggyu,Rahbari, S. H. E. 
TITLE  Characterizing the nature of the rigidity transition 
ARCHIVE  https://journals.aps.org/pre/pdf/10.1103/PhysRevE. 
FILE  
JOURNAL  PHYSICAL REVIEW E, 2018 
ABSTRACT  Particulate matter, such as foams, emulsions, and granular materials, attain rigidity in a dense regime: the rigid phase can yield when a threshold force is applied. The rigidity transition in particulate matter exhibits bona fide scaling behavior near the transition point. However, a precise determination of exponents describing the rigidity transition has raised much controversy. Here we pinpoint the causes of the controversies. We then establish a conceptual framework to quantify the critical nature of the rigidity transition. Our results demonstrate that there is a spectrum of possible values for the critical exponents for which, without a robust framework, one cannot distinguish the genuine values of the exponents. Our approach is twofold: (1) a precise determination of the transition density using rheological measurements and (2) a matching rule that selects the critical exponents and rules out all other possibilities from the spectrum. This enables us to determine exponents with unprecedented accuracy and resolve the longstanding controversy over exponents of jamming The generality of the approach paves the way to quantify the critical nature of many other types of rheological phase transitions such as those in oscillatory shearing. 

³í¹®
NUMBER  Q18009 
AUTHOR  Park, Hyunggyu,Lee, Jae Sung 
TITLE  Stochastic thermodynamics and hierarchy of fluctuation theorems with multiple reservoirs 
ARCHIVE  
FILE  
JOURNAL  NEW JOURNAL OF PHYSICS, 2018 
ABSTRACT  We reformulate stochastic thermodynamics in terms of noise realizations for Langevin systems in contact with multiple reservoirs and investigate the structure of the second laws of thermodynamics. We derive a hierarchy of fluctuation theorems when one degree of freedom of the system is affected by multiple reservoirs simultaneously, that is, when noisemixing occurs. These theorems and the associated second laws of thermodynamics put stricter bounds on the thermodynamics of Langevin systems. We apply our results to a stochastic machine in noisemixing environments and demonstrate that our new bounds play a crucial role in determining the potential function and performance of the machine. 

³í¹®
NUMBER  Q17062 
AUTHOR  Park, Hyunggyu,Lee, Jae Sung 
TITLE  Additivity of multiple heat reservoirs in the Langevin equation 
ARCHIVE  arXiv:1712.00972 
FILE  
JOURNAL  PHYSICAL REVIEW E, 2018 
ABSTRACT  The Langevin equation greatly simplifies the mathematical expression of the effects of thermal noise by using only two terms, a dissipation term, and a randomnoise term. The Langevin description was originally applied to a system in contact with a single heat reservoir; however, many recent studies have also adopted a Langevin description for systems connected to multiple heat reservoirs. This is accomplished through the introduction of a simple summation for the dissipation and randomnoise terms associated with each reservoir. However, the validity of this simple addition has been the focus of only limited discussion and has raised several criticisms. Moreover, this additive description has never been either experimentally or numerically verified, rendering its validity is still an open question. Here we perform molecular dynamics simulations for a Brownian system in simultaneous contact with multiple heat reservoirs to check the validity of this additive approach. Our simulation results confirm that the effect of multiple heat reservoirs is additive in general. A very small deviation in the total amount of dissipation and associated noise is found but seems not significant within statistical errors. We find that the steadystate properties satisfy the additivity perfectly and are not affected by this deviation. 

³í¹®
NUMBER  
AUTHOR  Park, Hyunggyu 
TITLE  Entropy and Thermodynamic Second Laws: New Perspective  Stochastic Thermodynamics and Fluctuation Theorems 
ARCHIVE  
FILE  
JOURNAL  JOURNAL OF THE KOREAN PHYSICAL SOCIETY, 2018 
ABSTRACT  Recently, there has been a considerable progress on the issue of the thermodynamic second law, which is known as the law of entropy increase or irreversibility. In particular, a novel symmetry known as the GallavottiCohen symmetry is found in nonequilibrium (NEQ) fluctuations, which leads to socalled fluctuation theorems. The thermodynamic second law is a simple corollary of fluctuation theorems, from which one can predict quantitatively how often NEQ processes violate the law of entropy increase. Violations disappear in the thermodynamic limit, but can be observed reasonably well in small systems. In this article, we will briefly introduce the stochastic thermodynamics and derive various fluctuation theorems, including the total entropy production (EP), the workfreeenergy relation, the excess and housekeeping EP, and the information entropy. 

³í¹®
NUMBER  Q17027 
AUTHOR  Park, Hyunggyu,Lee, Jae Sung 
TITLE  Carnot efficiency is reachable in an irreversible process 
ARCHIVE  arXiv:1611.07665 
FILE  
JOURNAL  SCIENTIFIC REPORTS, 2017 
ABSTRACT  In thermodynamics, there exists a conventional belief that the Carnot efficiency is reachable only in the reversible ( zero entropy production) limit of nearly reversible processes. However, there is no theorem proving that the Carnot efficiency is unattainable in an irreversible process. Here, we show that the Carnot efficiency is reachable in an irreversible process through investigation of the FeynmanSmoluchowski ratchet (FSR). We also show that it is possible to enhance the efficiency by increasing the irreversibility. Our result opens a new possibility of designing an efficient heat engine in a highly irreversible process and also answers the longstanding question of whether the FSR can operate with the Carnot efficiency. 

³í¹®
NUMBER  
AUTHOR  Park, Hyunggyu,Lahiri, Sourabh 
TITLE  Nonequilibrium steady states in Langevin thermal systems 
ARCHIVE  
FILE  
JOURNAL  PHYSICAL REVIEW E, 2017 
ABSTRACT  Equilibrium is characterized by its fundamental properties, such as the detailed balance, the fluctuationdissipation relation, and no heat dissipation. Based on the stochastic thermodynamics, we show that these three properties are equivalent to each other in conventional Langevin thermal systems with microscopic reversibility. Thus, a conventional steady state has either all three properties (equilibrium) or none of them (nonequilibrium). In contrast, with velocitydependent forces breaking the microscopic reversibility, we prove that the detailed balance and the fluctuationdissipation relation mutually exclude each other, and no equivalence relation is possible between any two of the three properties. This implies that a steady state of Langevin systems with velocitydependent forces may maintain some equilibrium properties but not all of them. Our results are illustrated with a few example systems. 

³í¹®
NUMBER  P17027 
AUTHOR  Park, Hyunggyu,Rahbari, S. H. E. 
TITLE  Characterizing rare fluctuations in soft particulate flows 
ARCHIVE  
FILE  
JOURNAL  NATURE COMMUNICATIONS, 2017 
ABSTRACT  Soft particulate media include a wide range of systems involving athermal dissipative particles both in nonliving and biological materials. Characterization of flows of particulate media is of great practical and theoretical importance. A fascinating feature of these systems is the existence of a critical rigidity transition in the dense regime dominated by highly intermittent fluctuations that severely affects the flow properties. Here, we unveil the underlying mechanisms of rare fluctuations in soft particulate flows. We find that rare fluctuations have different origins above and below the critical jamming density and become suppressed near the jamming transition. We then conjecture a timeindependent local fluctuation relation, which we verify numerically, and that gives rise to an effective temperature. We discuss similarities and differences between our proposed effective temperature with the conventional kinetic temperature in the system by means of a universal scaling collapse. 

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NUMBER  
AUTHOR  Park, Hyunggyu,Um, Jaegon,Kwon, Chulan 
TITLE  Information thermodynamics for a multifeedback process with time delay 
ARCHIVE  
FILE  
JOURNAL  EPL, 2017 
ABSTRACT  We investigate a measurementfeedback process of repeated operations with time delay. During a finitetime interval, measurement on the system is performed and the feedback protocol derived from the measurement outcome is applied with time delay. This protocol is maintained into the next interval until a new protocol from the next measurement is applied. Unlike a feedback process without delay, both memories associated with previous and present measurement outcomes are involved in the system dynamics, which naturally brings forth a joint system described by a system state and two memory states. The thermodynamic second law provides a lower bound for heat flow into a thermal reservoir by the (3state) Shannon entropy change of the joint system. However, as the feedback protocol depends on memory states sequentially, we can deduce a tighter bound for heat flow by integrating out irrelevant memory states during dynamics. As a simple example, we consider the socalled cold damping feedback process where the velocity of a particle is measured and a dissipative feedback protocol is applied to decelerate the particle. We confirm that the heat flow is well above the tightest bound. We also examine the longtime limit of this feedback process, which turns out to exhibit an interesting instability transition as well as heating by controlling parameters such as measurement errors, time interval, protocol strength, and time delay length. We discuss the underlying mechanism for instability and heating, which might be unavoidable in reality. Copyright (C) EPLA, 2017 

³í¹®
NUMBER  
AUTHOR  Park, Hyunggyu 
TITLE  Unconventional entropy production in the presence of momentumdependent forces 
ARCHIVE  
FILE  
JOURNAL  JOURNAL OF THE KOREAN PHYSICAL SOCIETY, 2016 
ABSTRACT  We investigate the unconventional nature of entropy production (EP) in nonequilibrium systems with oddparity variables that change signs under time reversal. We consider the Brownian motion of a particle in contact with a heat reservoir, where the particles momentum is an oddparity variable. In the presence of an external momentumdependent force, the EP transferred to the environment is found to be not equivalent to the usual reservoir entropy change due to heat transfer. An additional unconventional contribution to the EP, which is crucial for maintaining the nonnegativity of the (average) total EP enforced by the second law of thermodynamics, appears. A few examples are considered to elucidate the novel nature of the EP. We also discuss detailed balance conditions with a momentumdependent force. 

³í¹®
NUMBER  
AUTHOR  Park, Hyunggyu,Durang, Xavier 
TITLE  Overdamped limit and inversefriction expansion for Brownian motion in an inhomogeneous medium 
ARCHIVE  
FILE  
JOURNAL  PHYSICAL REVIEW E, 2015 
ABSTRACT  We revisit the problem of the overdamped (largefriction) limit of the Brownian dynamics in an inhomogeneous medium characterized by a positiondependent friction coefficient and a multiplicative noise (local temperature) in onedimensional space. Starting from the Kramers equation and analyzing it through the expansion in terms of eigenfunctions of a quantum harmonic oscillator, we derive analytically the corresponding FokkerPlanck equation in the overdamped limit. The result is fully consistent with the previous finding by Sancho, San Miguel, and Durr [J. Stat. Phys. 28, 291 (1982)]. Our method allows us to generalize the Brinkmans hierarchy, and thus it would be straightforward to obtain higherorder corrections in a systematic inversefriction expansion without any assumption. Our results are confirmed by numerical simulations for simple examples. 

³í¹®
NUMBER  
AUTHOR  Park, Hyunggyu,Um, Jaegon 
TITLE  Total cost of operating an information engine 
ARCHIVE  
FILE  
JOURNAL  NEW JOURNAL OF PHYSICS, 2015 
ABSTRACT  We study a twolevel system controlled in a discrete feedback loop, modeling both the system and the controller in terms of stochastic Markov processes. We find that the extracted work, which is known to be bounded from above by the mutual information acquired during measurement, has to be compensated by an additional energy supply during the measurement process itself, which is bounded by the same mutual information from below. Our results confirm that the total cost of operating an information engine is in full agreement with the conventional second law of thermodynamics. We also consider the efficiency of the information engine as a function of the cycle time and discuss the operating condition for maximal power generation. Moreover, we find that the entropy production of our information engine is maximal for maximal efficiency, in sharp contrast to conventional reversible heat engines. 

³í¹®
NUMBER  
AUTHOR  Park, Hyunggyu 
TITLE  Finitesize scaling, dynamic fluctuations, and hyperscaling relation in the Kuramoto model 
ARCHIVE  
FILE  
JOURNAL  PHYSICAL REVIEW E, 2015 
ABSTRACT  We revisit the Kuramoto model to explore the finitesize scaling (FSS) of the order parameter and its dynamic fluctuations near the onset of the synchronization transition, paying particular attention to effects induced by the randomness of the intrinsic frequencies of oscillators. For a population of size N, we study two ways of sampling the intrinsic frequencies according to the same given unimodal distribution g(omega). In the random case, frequencies are generated independently in accordance with g(omega), which gives rise to oscillator number fluctuation within any given frequency interval. In the regular case, the N frequencies are generated in a deterministic manner that minimizes the oscillator number fluctuations, leading to quasiuniformly spaced frequencies in the population. We find that the two samplings yield substantially different finitesize properties with clearly distinct scaling exponents. Moreover, the hyperscaling relation between the order parameter and its fluctuations is valid in the regular case, but it is violated in the random case. In this last case, a selfconsistent meanfield theory that completely ignores dynamic fluctuations correctly predicts the FSS exponent of the order parameter but not its critical amplitude. 

³í¹®
NUMBER  
AUTHOR  Park, Hyunggyu,Kim, Kwangmoo 
TITLE  Heat fluctuations and initial ensembles 
ARCHIVE  
FILE  
JOURNAL  PHYSICAL REVIEW E, 2014 
ABSTRACT  Timeintegrated quantities such as work and heat increase incessantly in time during nonequilibrium processes near steady states. In the longtime limit, the average values of work and heat become asymptotically equivalent to each other, since they only differ by a finite energy change in average. However, the fluctuation theorem (FT) for the heat is found not to hold with the equilibrium initial ensemble, while the FT for the work holds. This reveals an intriguing effect of everlasting initial memory stored in rare events. We revisit the problem of a Brownian particle in a harmonic potential dragged with a constant velocity, which is in contact with a thermal reservoir. The heat and work fluctuations are investigated with initial Boltzmann ensembles at temperatures generally different from the reservoir temperature. We find that, in the infinitetime limit, the FT for the work is fully recovered for arbitrary initial temperatures, while the heat fluctuations significantly deviate from the FT characteristics except for the infinite initialtemperature limit (a uniform initial ensemble). Furthermore, we succeed in calculating finitetime corrections to the heat and work distributions analytically, using the modified saddle point integral method recently developed by us. Interestingly, we find noncommutativity between the infinitetime limit and the infiniteinitialtemperature limit for the probability distribution function (PDF) of the heat. 

³í¹®
NUMBER  
AUTHOR  Park, Hyunggyu,Durang, Xavier 
TITLE  The statistical mechanics of the coagulationdiffusion process with a stochastic reset 
ARCHIVE  
FILE  
JOURNAL  JOURNAL OF PHYSICS AMATHEMATICAL AND THEORETICAL, 2014 
ABSTRACT  The effects of a stochastic reset, to its initial configuration, is studied in the exactly solvable onedimensional coagulationdiffusion process. A finite resetting rate leads to a modified nonequilibrium stationary state. If, in addition, the input of particles at a fixed given rate is admitted, then a competition between the resetting and the input rates leads to a nontrivial behaviour of the particledensity in the stationary state. From the exact interparticle probability distribution, a simple physical picture emerges: the reset mainly changes the behaviour at larger distance scales, while at smaller length scales, the nontrivial correlation of the model without a reset dominate. 

³í¹®
NUMBER  
AUTHOR  Um, Jaegon,Park, Hyunggyu 
TITLE  Nature of synchronization transitions in random networks of coupled oscillators 
ARCHIVE  
FILE  
JOURNAL  PHYSICAL REVIEW E, 2014 
ABSTRACT  We consider a system of phase oscillators with random intrinsic frequencies coupled through sparse random networks and investigate how the connectivity disorder affects the nature of collective synchronization transitions. Various distribution types of intrinsic frequencies are considered: uniform, unimodal, and bimodal distribution. We employ a heterogeneous meanfield approximation based on the annealed networks and also perform numerical simulations on the quenched ErdosRenyi networks. We find that the connectivity disorder drastically changes the nature of the synchronization transitions. In particular, the quenched randomness completely wipes away the diversity of the transition nature, and only a continuous transition appears with the same meanfield exponent for all types of frequency distributions. The physical origin of this unexpected result is discussed. 

³í¹®
NUMBER  
AUTHOR  Noh, Jae Dong,Park, Hyunggyu 
TITLE  Work fluctuations in a timedependent harmonic potential: Rigorous results beyond the overdamped limit 
ARCHIVE  
FILE  
JOURNAL  PHYSICAL REVIEW E, 2013 
ABSTRACT  We investigate the stochastic motion of a Brownian particle in the harmonic potential with a timedependent force constant. It may describe the motion of a colloidal particle in an optical trap where the potential well is formed by a timedependent field. We use the path integral formalism to solve the Langevin equation and the associated FokkerPlanck (Kramers) equation. Rigorous relations are derived to generate the probability density function for the timedependent nonequilibrium work production beyond the overdamped limit. We find that the work distribution exhibits an exponential tail with a powerlaw prefactor, accompanied by an interesting oscillatory feature (multiple pseudolockingunlocking transitions) due to the inertial effect. Some exactly solvable cases are discussed in the overdamped limit. 

³í¹®
NUMBER  Q17037 
AUTHOR  Park, Hyunggyu,Lee, Jae Sung 
TITLE  Modified saddlepoint integral near a singularity for the large deviation function 
ARCHIVE  
FILE  
JOURNAL  JOURNAL OF STATISTICAL MECHANICSTHEORY AND EXPERIMENT, 2013 
ABSTRACT  Longtimeintegrated quantities in stochastic processes, in or out of equilibrium, usually exhibit rare but huge fluctuations. Work or heat production is such a quantity, for which the probability distribution function displays an exponential decay characterized by the large deviation function (LDF). The LDF is often deduced from the cumulant generating function through the inverse Fourier transformation. The saddlepoint integration method is a powerful technique to obtain the asymptotic results in the Fourier integral, but special care should be taken when the saddle point is located near a singularity of the integrand. In this paper, we present a modified saddlepoint method to handle such a difficulty efficiently. We investigate the dissipated and injected heat production in equilibration processes with various initial conditions, for example, where the generating functions contain branchcut singularities as well as powerlaw ones. Exploiting the new modified saddlepoint integrations, we obtain the leading finitetime corrections for the LDFs, which are confirmed by numerical results. 

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NUMBER  
AUTHOR  Noh, Jae Dong,Park, Hyunggyu 
TITLE  Multiple Dynamic Transitions in Nonequilibrium Work Fluctuations 
ARCHIVE  
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JOURNAL  PHYSICAL REVIEW LETTERS, 2013 
ABSTRACT  The timedependent work probability distribution function P(W) is investigated analytically for a diffusing particle trapped by an anisotropic harmonic potential and driven by a nonconservative drift force in two dimensions. We find that the exponential tail shape of P(W) characterizing rareevent probabilities undergoes a sequence of dynamic transitions in time. These remarkable lockingunlocking type transitions result from an intricate interplay between a rotational mode induced by the nonconservative force and an anisotropic decaying mode due to the conservative attractive force. We expect that most of the highdimensional dynamical systems should exhibit similar multiple dynamic transitions. 

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NUMBER  
AUTHOR  Um, Jaegon,Park, Hyunggyu 
TITLE  Linkdisorder fluctuation effects on synchronization in random networks 
ARCHIVE  
FILE  
JOURNAL  PHYSICAL REVIEW E, 2013 
ABSTRACT  We consider one typical system of oscillators coupled through disordered link configurations in networks, i.e., a finite population of coupled phase oscillators with distributed intrinsic frequencies on a random network. We investigate the collective synchronization behavior, paying particular attention to linkdisorder fluctuation effects on the synchronization transition and its finitesize scaling (FSS). Extensive numerical simulations as well as the meanfield analysis have been performed. We find that linkdisorder fluctuations effectively induce uncorrelated random fluctuations in frequency, resulting in the FSS exponent (nu) over tilde = 5/2, which is identical to that in the globally coupled case (no link disorder) with frequencydisorder fluctuations. DOI: 10.1103/PhysRevE.87.042105 

³í¹®
NUMBER  Q17038 
AUTHOR  Park, Hyunggyu,Lee, J. S. 
TITLE  Everlasting initial memory threshold for rare events in equilibration processes 
ARCHIVE  
FILE  
JOURNAL  PHYSICAL REVIEW E, 2013 
ABSTRACT  Conventional wisdom indicates that initial memory should decay away exponentially in time for general (noncritial) equilibration processes. In particular, timeintegrated quantities such as heat are presumed to lose initial memory in a sufficiently longtime limit. However, we show that the large deviation function of timeintegrated quantities may exhibit initial memory effect even in the infinitetime limit, if the system is initially prepared sufficiently far away from equilibrium. For a Brownian particle dynamics, as an example, we found a sharp finite threshold rigorously, beyond which the corresponding large deviation function contains everlasting initial memory. The physical origin for this phenomenon is explored with an intuitive argument and also from a toy model analysis. Our results can be applied to general nonequilibrium relaxation processes reaching (non)equilibrium steady states. DOI: 10.1103/PhysRevE.87.020104 

³í¹®
NUMBER  
AUTHOR  Park, Hyunggyu 
TITLE  Fluctuation Theorems and Entropy Production with OddParity Variables 
ARCHIVE  
FILE  
JOURNAL  PHYSICAL REVIEW LETTERS, 2013 
ABSTRACT  We show that the total entropy production in stochastic processes with oddparity variables (under time reversal) is separated into three parts, only two of which satisfy the integral fluctuation theorems in general. One is the usual excess contribution that can appear only transiently and is called nonadiabatic. Another one is attributed solely to the breakage of detailed balance. The last part that does not satisfy the fluctuation theorem comes from the steadystate distribution asymmetry for oddparity variables that is activated in a nontransient manner. The latter two parts combine together as the housekeeping (adiabatic) contribution, whose positivity is not guaranteed except when the excess contribution completely vanishes. Our finding reveals that the equilibrium requires the steadystate distribution symmetry for oddparity variables independently, in addition to the usual detailed balance. DOI: 10.1103/PhysRevLett.110.050602 

³í¹®
NUMBER  
AUTHOR  Um, Jaegon,Park, Hyunggyu 
TITLE  Entanglement versus mutual information in quantum spin chains 
ARCHIVE  
FILE  
JOURNAL  JOURNAL OF STATISTICAL MECHANICSTHEORY AND EXPERIMENT, 2012 
ABSTRACT  The quantum entanglement E of a bipartite quantum Ising chain is compared with the mutual information I between the two parts after a local measurement of the classical spin configuration. As the model is conformally invariant, the entanglement measured in its ground state at the critical point is known to obey a certain scaling form. Surprisingly, the mutual information of classical spin configurations is found to obey the same scaling form, although with a different prefactor. Moreover, we find that mutual information and the entanglement obey the inequality I <= E in the ground state as well as in a dynamically evolving situation. This inequality holds for general bipartite systems in a pure state and can be proved using similar techniques as for Holevos bound. 

³í¹®
NUMBER  P11020 
AUTHOR  Park, Hyunggyu,Um, Jaegon 
TITLE  Rectification of Spatial Disorder 
ARCHIVE  1104.4831 
FILE  
JOURNAL  PHYSICAL REVIEW LETTERS, 2012 
ABSTRACT  We demonstrate that a large ensemble of noiseless globally coupledpinned oscillators is capable of rectifying spatial disorder with spontaneous current activated through a dynamical phase transition mechanism, either of first or second order, depending on the profile of the pinning potential. In the presence of an external weak drive, the same collective mechanism can result in an absolute negative mobility, which, though not immediately related to symmetry breaking, is most prominent at the phase transition. Our results apply to a tugofwar by competing molecular motors for bidirectional cargo transport. 

³í¹®
NUMBER  P11019 
AUTHOR  Park, Hyunggyu 
TITLE  Continuity of the explosive percolation transition 
ARCHIVE  1103.4439 
FILE  
JOURNAL  PHYSICAL REVIEW E, 2011 
ABSTRACT  The explosive percolation problem on the complete graph is investigated via extensive numerical simulations. We obtain the clustersize distribution at the moment when the cluster size heterogeneity becomes maximum. The distribution is found to be well described by the powerlaw form with the decay exponent tau = 2.06(2), followed by a hump. We then use the finitesize scaling method to make all the distributions at various system sizes up to N = 2(37) collapse perfectly onto a scaling curve characterized solely by the single exponent tau. We also observe that the instant of that collapse converges to a welldefined percolation threshold from below as N > infinity. Based on these observations, we show that the explosive percolation transition in the model should be continuous, contrary to the widely spread belief of its discontinuity. 

³í¹®
NUMBER  P11029 
AUTHOR  Noh, Jae Dong,Park, Hyunggyu 
TITLE  Scaling of cluster heterogeneity in percolation transitions 
ARCHIVE  arXiv:1106.0354 
FILE  
JOURNAL  PHYSICAL REVIEW E, 2011 
ABSTRACT  We investigate a critical scaling law for the cluster heterogeneity H in site and bond percolations in ddimensional lattices with d = 2,...,6. The cluster heterogeneity is defined as the number of distinct cluster sizes. As an occupation probability p increases, the cluster size distribution evolves from a monodisperse distribution to a polydisperse one in the subcritical phase, and back to a monodisperse one in the supercritical phase. We show analytically that H diverges algebraically, approaching the percolation critical point p(c) as H similar to vertical bar p  p(c)vertical bar(1/sigma) with the critical exponent sigma associated with the characteristic cluster size. Interestingly, its finitesizescaling behavior is governed by a new exponent v(H) = (1 + d(f)/d)v, where d(f) is the fractal dimension of the critical percolating cluster and v is the correlation length exponent. The corresponding scaling variable defines a singular path to the critical point. All results are confirmed by numerical simulations. 

³í¹®
NUMBER  P11018 
AUTHOR  Noh, Jae Dong,Park, Hyunggyu 
TITLE  Nonequilibrium fluctuations for linear diffusion dynamics 
ARCHIVE  1102.2973 
FILE  
JOURNAL  PHYSICAL REVIEW E, 2011 
ABSTRACT  We present the theoretical study on nonequilibrium (NEQ) fluctuations for diffusion dynamics in high dimensions driven by a linear drift force. We consider a general situation in which NEQ is caused by two conditions: (i) drift force not derivable from a potential function, and (ii) diffusion matrix not proportional to the unit matrix, implying nonidentical and correlated multidimensional noise. The former is a wellknown NEQ source and the latter can be realized in the presence of multiple heat reservoirs or multiple noise sources. We develop a statistical mechanical theory based on generalized thermodynamic quantities such as energy, work, and heat. The NEQ fluctuation theorems are reproduced successfully. We also find the timedependent probability distribution function exactly as well as the NEQ work production distribution P(W) in terms of solutions of nonlinear differential equations. In addition, we compute loworder cumulants of the NEQ work production explicitly. In two dimensions, we carry out numerical simulations to check out our analytic results and also to get P(W). We find an interesting dynamic phase transition in the exponential tail shape of P(W), associated with a singularity found in solutions of the nonlinear differential equation. Finally, we discuss possible realizations in experiments. 

³í¹®
NUMBER  P10008 
AUTHOR  Park, Hyunggyu,Lee, Hyun Keun,Jo, HangHyun 
TITLE  Collective helping and bystander effects in coevolving helping networks 
ARCHIVE  1003.5023 
FILE  
JOURNAL  PHYSICAL REVIEW E, 2010 
ABSTRACT  We study collective helping behavior and bystander effects in a coevolving helping network model. A node and a link of the network represents an agent who renders or receives help and a friendly relation between agents, respectively. A helping trial of an agent depends on relations with other involved agents and its result (success or failure) updates the relation between the helper and the recipient. We study the network link dynamics and its steady states analytically and numerically. The full phase diagram is presented with various kinds of active and inactive phases and the nature of phase transitions are explored. We find various interesting bystander effects, consistent with the field study results, of which the underlying mechanism is proposed. 

³í¹®
NUMBER  P09059 
AUTHOR  Park, Hyunggyu 
TITLE  Critical behavior of the Ising model in annealed scalefree networks 
ARCHIVE  0909.1597 
FILE  
JOURNAL  PHYSICAL REVIEW E, 2009 
ABSTRACT  We study the critical behavior of the Ising model in annealed scalefree (SF) networks of finite system size with forced upper cutoff in degree. By mapping the model onto the weighted fully connected Ising model, we derive analytic results for the finitesize scaling (FSS) near the phase transition, characterized by the cutoffdependent twoparameter scaling with four distinct scaling regimes, in highly heterogeneous networks. These results are essentially the same as those found for the nonequilibrium contact process in annealed SF networks, except for an additional complication due to the trivial critical point shift in finite systems. The discrepancy of the FSS theories between annealed and quenched SF networks still remains in the equilibrium Ising model, like some other nonequilibrium models. All of our analytic results are confirmed reasonably well by numerical simulations. 

³í¹®
NUMBER  P09058 
AUTHOR  Park, Hyunggyu 
TITLE  Relaxation dynamics of an elastic string in random media 
ARCHIVE  0908.4154 
FILE  
JOURNAL  PHYSICAL REVIEW E, 2009 
ABSTRACT  We investigate numerically the relaxation dynamics of an elastic string in twodimensional random media by thermal fluctuations starting from a flat configuration. Measuring spatial fluctuations of its mean position, we find that the correlation length grows in time asymptotically as xi similar to(ln t)(1/chi approximate to). This implies that the relaxation dynamics is driven by thermal activations over random energy barriers which scale as EB(l)similar to l(chi approximate to) with a length scale l. Numerical data strongly suggest that the energy barrier exponent chi approximate to is identical to the energy fluctuation exponent chi=1/3. We also find that there exists a long transient regime, where the correlation length follows a powerlaw dynamics as xi similar to t(1/z) with a nonuniversal dynamic exponent z. The origin of the transient scaling behavior is discussed in the context of the relaxation dynamics on finite ramified clusters of disorder. 

³í¹®
NUMBER  P09004 
AUTHOR  Park, Hyunggyu 
TITLE  Critical behavior of the contact process in annealed scalefree networks 
ARCHIVE  0811.4199 
FILE  
JOURNAL  PHYSICAL REVIEW E, 2009 
ABSTRACT  The critical behavior of the contact process is studied in annealed scalefree networks by mapping it on the randomwalk problem. We obtain the analytic results for the critical scaling using the eventdriven dynamics approach. These results are confirmed by numerical simulations. The disorder fluctuation induced by the sampling disorder in annealed networks is also explored. Finally, we discuss over a possible discrepancy of the finitesizescaling theory in annealed and quenched networks in spirit of the droplet size scale and the linking disorder fluctuation. 

³í¹®
NUMBER  P09013 
AUTHOR  Park, Hyunggyu 
TITLE  Crossover from the parityconserving pair contact process with diffusion to other universality classes 
ARCHIVE  0903.4222 
FILE  
JOURNAL  PHYSICAL REVIEW E, 2009 
ABSTRACT  The pair contact process with diffusion (PCPD) with modulo 2 conservation (PCPD2) [2A > 4A, 2A > 0] is studied in one dimension, focused on the crossover to other well established universality classes: the directed Ising (DI) and the directed percolation (DP). First, we show that the PCPD2 shares the critical behaviors with the PCPD, both with and without directional bias. Second, the crossover from the PCPD2 to the DI is studied by including a parityconserving singleparticle process (A > 3A). We find the crossover exponent 1/phi(1)=0.57(3), which is argued to be identical to that of the PCPDtoDP crossover by adding A > 2A. This suggests that the PCPD universality class has a welldefined fixed point distinct from the DP. Third, we study the crossover from a hybridtype reactiondiffusion process belonging to the DP [3A > 5A, 2A > 0] to the DI by adding A > 3A. We find 1/phi(2)=0.73(4) for the DPtoDI crossover. The inequality of phi(1) and phi(2) further supports the nonDP nature of the PCPD scaling. Finally, we introduce a symmetrybreaking field in the dual spin language to study the crossover from the PCPD2 to the DP. We find 1/phi(3)=1.23(10), which is associated with a new independent route from the PCPD to the DP. 

³í¹®
NUMBER  P09003 
AUTHOR  Dutta, Sreedhar B.,Park, Hyunggyu 
TITLE  Kinetics of a nonGlauberian Ising model: global observables and exact results 
ARCHIVE  0901.3428 
FILE  
JOURNAL  JOURNAL OF STATISTICAL MECHANICSTHEORY AND EXPERIMENT, 2009 
ABSTRACT  We analyse the spinflip dynamics in kinetic Ising chains with KimballDekerHaake transition rates, and evaluate exactly the evolution of global quantities like magnetization and its fluctuations, and the twotime susceptibilities and correlations of the global spin and the global 3spin. Information on the ageing behaviour after a quench to zero temperature is extracted. 

³í¹®
NUMBER  C09012 
AUTHOR  Park, Hyungju 
TITLE  EMBEDDINGS OF LINE IN THE PLANE AND ABHYANKARMOH EPIMORPHISM THEOREM 
ARCHIVE  
FILE  
JOURNAL  BULLETIN OF THE KOREAN MATHEMATICAL SOCIETY, 2009 
ABSTRACT  In this paper, we consider the parameter space of the rational plane curves with unibranched singularity. We show that such a parameter space is decomposable into irreducible components which are rational varieties. Rational parametrizations of the irreducible components are given in a constructive way, by a repeated use of AbhyankarMoh Epimorphism Theorem. We compute an enumerative invariant of this parameter space, and include explicit computational examples to recover some classicallyknown invariants. 

³í¹®
NUMBER  P08058 
AUTHOR  Park, Hyunggyu 
TITLE  Three different routes from the directed Ising to the directed percolation class 
ARCHIVE  0807.3450 
FILE  
JOURNAL  PHYSICAL REVIEW E, 2008 
ABSTRACT  The scaling nature of absorbing critical phenomena is well understood for the directed percolation (DP) and the directed Ising (DI) systems. However, a full analysis of the crossover behavior is still lacking, which is of our interest in this study. In one dimension, we find three different routes from the DI to the DP classes by introducing a symmetrybreaking field (SB), breaking a modulo 2 conservation (CB), or making channels connecting two equivalent absorbing states (CC). Each route can be characterized by a crossover exponent, which is found numerically as phi=2.1 +/ 0.1 (SB), 4.6 +/ 0.2 (CB), and 2.9 +/ 0.1 (CC), respectively. The difference between the SB and CB crossover can be understood easily in the domain wall language, while the CC crossover involves an additional critical singularity in the auxiliary field density with the memory effect to identify itself independent. 

³í¹®
NUMBER  P08004 
AUTHOR  Park, Hyunggyu 
TITLE  Nonequilibrium phase transitions into absorbing states 
ARCHIVE  0711.2197 
FILE  
JOURNAL  EUROPEAN PHYSICAL JOURNAL B, 2008 
ABSTRACT  Systems with absorbing (trapped) states may exhibit a nonequilibrium phase transition from a noisefree inactive phase into an everlasting active phase. We briefly review the absorbing critical phenomena and universality classes, and discuss over the controversial issues on the pair contact process with diffusion (PCPD). Two different approaches are proposed to clarify its universality issue, which unveil strong evidences that the PCPD belongs to a new universality class other than the directed percolation class. 

³í¹®
NUMBER  P08034 
AUTHOR  Park, Hyunggyu,Nagar, Apoorva 
TITLE  Boundaryinduced abrupt transition in the symmetric exclusion process 
ARCHIVE  0804.4212 
FILE  
JOURNAL  PHYSICAL REVIEW E, 2008 
ABSTRACT  We investigate the role of the boundary in the symmetric simple exclusion process with competing nonlocal and local hopping events. With open boundaries, the system undergoes a firstorder phase transition from a finite density phase to an empty road phase as the nonlocal hopping rate increases. Using a cluster stability analysis, we determine the location of such an abrupt nonequilibrium phase transition, which agrees well with numerical results. Our cluster analysis provides physical insight into the mechanism behind this transition. We also explain why the transition becomes discontinuous in contrast to the case with periodic boundary conditions, in which the continuous phase transition has been observed. 

³í¹®
NUMBER  P08003 
AUTHOR  Park, Hyunggyu 
TITLE  Finitesize scaling of synchronized oscillation on complex networks 
ARCHIVE  0710.1137 
FILE  
JOURNAL  PHYSICAL REVIEW E, 2007 
ABSTRACT  The onset of synchronization in a system of random frequency oscillators coupled through a random network is investigated. Using a meanfield approximation, we characterize sampletosample fluctuations for networks of finite size, and derive the corresponding scaling properties in the critical region. For scalefree networks with the degree distribution P(k) similar to k(gamma) at large k, we found that the finitesize exponent (nu) over bar takes on the value 5/2 when gamma > 5, the same as in the globally coupled Kuramoto model. For highly heterogeneous networks (3 

³í¹®
NUMBER  P07006 
AUTHOR  Park, Hyunggyu 
TITLE  Entrainment transition in populations of random frequency oscillators 
ARCHIVE  condmat/0701646 
FILE  
JOURNAL  PHYSICAL REVIEW LETTERS, 2007 
ABSTRACT  The entrainment transition of coupled random frequency oscillators is revisited. The Kuramoto model (global coupling) is shown to exhibit unusual sampledependent finitesize effects leading to a correlation size exponent (v) over bar = 5/2. Simulations of locally coupled oscillators in d dimensions reveal two types of frequency entrainment: meanfield behavior at d > 4 and aggregation of compact synchronized domains in three and four dimensions. In the latter case, scaling arguments yield a correlation length exponent v = 2/(d  2), in good agreement with numerical results. 

³í¹®
NUMBER  P07029 
AUTHOR  Park, Hyunggyu 
TITLE  Nontrivial critical crossover between directed percolation models: Effect of infinitely many absorbing states 
ARCHIVE  0706.2973 
FILE  
JOURNAL  PHYSICAL REVIEW E, 2007 
ABSTRACT  At nonequilibrium phase transitions into absorbing (trapped) states, it is well known that the directed percolation (DP) critical scaling is shared by two classes of models with a single (S) absorbing state and with infinitely many (IM) absorbing states. We study the crossover behavior in one dimension, arising from a considerable reduction of the number of absorbing states (typically from the IMtype to the Stype DP models) by following two different (excitatory or inhibitory) routes which make the auxiliary field density abruptly jump at the crossover. Along the excitatory route, the system becomes overly activated even for an infinitesimal perturbation and its crossover becomes discontinuous. Along the inhibitory route, we find a continuous crossover with universal crossover exponent phi similar or equal to 1.78(6), which is argued to be equal to nu(parallel to), the relaxation time exponent of the DP universality class on a general footing. This conjecture is also confirmed in the case of the directed Ising (parityconserving) class. Finally, we discuss the effect of diffusion on the IMtype models and suggest an argument why diffusive models with some hybridtype reactions should belong to the DP class. 

³í¹®
NUMBER  P07038 
AUTHOR  Choi, M. Y.,Park, Hyunggyu 
TITLE  Construction of equilibrium networks with an energy function 
ARCHIVE  0707.0531 
FILE  
JOURNAL  JOURNAL OF PHYSICS AMATHEMATICAL AND THEORETICAL, 2007 
ABSTRACT  We construct equilibrium networks by introducing an energy function depending on the degree of each node as well as the product of neighboring degrees. With this topological energy function, networks constitute a canonical ensemble, which follows the Boltzmann distribution for given temperature. It is observed that the system undergoes a topological phase transition from a random network to a star or a fully connected network as the temperature is lowered. Both meanfield analysis and numerical simulations reveal strong firstorder phase transitions at temperatures which decrease logarithmically with the system size. Quantitative discrepancies of the simulation results from the meanfield prediction are discussed in view of the strong firstorder nature. 

³í¹®
NUMBER  P06024 
AUTHOR  Park, Hyunggyu 
TITLE  Finitesize scaling in complex networks 
ARCHIVE  
FILE  
JOURNAL  PHYSICAL REVIEW LETTERS, 2007 
ABSTRACT  A finitesizescaling (FSS) theory is proposed for various models in complex networks. In particular, we focus on the FSS exponent, which plays a crucial role in analyzing numerical data for finitesize systems. Based on the dropletexcitation (hyperscaling) argument, we conjecture the values of the FSS exponents for the Ising model, the susceptibleinfectedsusceptible model, and the contact process, all of which are confirmed reasonably well in numerical simulations. 

³í¹®
NUMBER  P07030 
AUTHOR  Park, Hyunggyu 
TITLE  Dynamic instability transitions in onedimensional driven diffusive flow with nonlocal hopping 
ARCHIVE  condmat/0703604 
FILE  
JOURNAL  PHYSICAL REVIEW E, 2007 
ABSTRACT  Onedimensional directed driven stochastic flow with competing nonlocal and local hopping events has an instability threshold from a populated phase into an emptyroad (ER) phase. We implement this in the context of the asymmetric exclusion process. The nonlocal skids promote strong clustering in the stationary populated phase. Such clusters drive the dynamic phase transition and determine its scaling properties. We numerically establish that the instability transition into the ER phase is second order in the regime where the entry point reservoir controls the current and first order in the regime where the bulk is in control. The firstorder transition originates from a turnabout of the cluster drift velocity. At the critical line, the current remains analytic, the road density vanishes linearly, and fluctuations scale as uncorrelated noise. A selfconsistent cluster dynamics analysis explains why these scaling properties remain that simple. 

³í¹®
NUMBER  P06011 
AUTHOR  Ha, Meesoon,Park, Hyunggyu 
TITLE  Comment on NonMeanField behavior of the contact process on scalefree networks 
ARCHIVE  condmat/0603787 
FILE  
JOURNAL  PHYSICAL REVIEW LETTERS, 2007 
ABSTRACT  

³í¹®
NUMBER  P06052 
AUTHOR  Park, Hyunggyu 
TITLE  Anomalous binder cumulant and lack of selfaverageness in systems with quenched disorder 
ARCHIVE  condmat/0611509 
FILE  
JOURNAL  JOURNAL OF THE KOREAN PHYSICAL SOCIETY, 2006 
ABSTRACT  The Binder cumulant (BC) has been widely used for locating the phase transition point accurately in systems with thermal noise. In systems with quenched disorder, the BC may show subtle finitesize effects due to large sampletosample fluctuations. We study the globally coupled Kuramoto model of interacting limitcycle oscillators with random natural frequencies and find an anomalous dip in the BC near the transition. We show that the dip is related to nonselfaverageness of the order parameter at the transition. Alternative definitions of the BC, which do not show any anomalous behavior regardless of the existence of nonselfaverageness, are proposed. 

³í¹®
NUMBER  P06032 
AUTHOR  Park, Hyunggyu,Lee, H. K. 
TITLE  Equivalence of operatorsplitting schemes for the integration of the Langevin equation 
ARCHIVE  condmat/0607596 
FILE  
JOURNAL  JOURNAL OF STATISTICAL MECHANICSTHEORY AND EXPERIMENT, 2006 
ABSTRACT  We investigate the equivalence of different operatorsplitting schemes for the integration of the Langevin equation. We consider a specific problem, the so called directed percolation process, which can be extended to a wider class of problems. We first give a compact mathematical description of the operatorsplitting method and introduce two typical splitting schemes that will be useful in numerical studies. We show that the two schemes are essentially equivalent through the map that turns out to be an automorphism. An associated equivalent class of operatorsplitting integrations is also defined by generalizing the specified equivalence. 

³í¹®
NUMBER  P05074 
AUTHOR  Park, SC,Park, H 
TITLE  Crossover from the pair contact process with diffusion to directed percolation 
ARCHIVE  condmat/0512076 
FILE  
JOURNAL  PHYSICAL REVIEW E, 2006 
ABSTRACT  Crossover behaviors from the pair contact process with diffusion (PCPD) and the driven PCPD (DPCPD) to the directed percolation (DP) are studied in one dimension by introducing a single particle annihilation and/or branching dynamics. The crossover exponents phi are estimated numerically as 1/phi similar or equal to 0.58 +/ 0.03 for the PCPD and 1/phi similar or equal to 0.49 +/ 0.02 for the DPCPD. Nontriviality of the PCPD crossover exponent strongly supports the nonDP nature of the PCPD critical scaling, which is further evidenced by the anomalous critical amplitude scaling near the PCPD point. In addition, we find that the DPCPD crossover is consistent with the mean field prediction of the tricritical DP class as expected. 

³í¹®
NUMBER  
AUTHOR  Park, H 
TITLE  Proceedings of the 13(th) Workshop on Statistical Physics  August 810, 2005  Suwon, Korea 
ARCHIVE  
FILE  
JOURNAL  JOURNAL OF THE KOREAN PHYSICAL SOCIETY, 2006 
ABSTRACT  

³í¹®
NUMBER  P05022 
AUTHOR  Park, SC,Park, H 
TITLE  Generating function for particlenumber probability distribution in directed percolation 
ARCHIVE  condmat/0502667 
FILE  
JOURNAL  JOURNAL OF PHYSICS AMATHEMATICAL AND GENERAL, 2005 
ABSTRACT  We derive a generic expression for the generating function (GF) of the particlenumber probability distribution (PNPD) for a simple reaction diffusion model that belongs to the directed percolation universality class. Starting with a single particle on a lattice, we show that the GF of the PNPD can be written as an infinite series of cumulants taken at zero momentum. This series can be summed up into a complete form at the level of a meanfield approximation. Using the renormalization group techniques, we determine logarithmic corrections for the GF at the upper critical dimension. We also find the critical scaling form for the PNPD and check its universality numerically in one dimension. The critical scaling function is found to be universal up to two nonuniversal metric factors. 

³í¹®
NUMBER  P04032 
AUTHOR  Hong, H,Park, H,Choi, MY 
TITLE  Collective synchronization in spatially extended systems of coupled oscillators with random frequencies 
ARCHIVE  condmat/0408553 
FILE  
JOURNAL  PHYSICAL REVIEW E, 2005 
ABSTRACT  We study collective behavior of locally coupled limitcycle oscillators with random intrinsic frequencies, spatially extended over ddimensional hypercubic lattices. Phase synchronization as well as frequency entrainment are explored analytically in the linear (strongcoupling) regime and numerically in the nonlinear (weakcoupling) regime. Our analysis shows that the oscillator phases are always desynchronized up to d=4, which implies the lower critical dimension d(l)(P)=4 for phase synchronization. On the other hand, the oscillators behave collectively in frequency (phase velocity) even in three dimensions (d=3), indicating that the lower critical dimension for frequency entrainment is d(l)(F)=2. Nonlinear effects due to the periodic nature of limitcycle oscillators are found to become significant in the weakcoupling regime: Socalled runaway oscillators destroy the synchronized (ordered) phase and there emerges a fully random (disordered) phase. Critical behavior near the synchronization transition into the fully random phase is unveiled via numerical investigation. Collective behavior of globally coupled oscillators is also examined and compared with that of locally coupled oscillators. 

³í¹®
NUMBER  P05004 
AUTHOR  Park, H 
TITLE  Asymmetrically coupled directed percolation systems 
ARCHIVE  condmat/0501542 
FILE  
JOURNAL  PHYSICAL REVIEW LETTERS, 2005 
ABSTRACT  We introduce a dynamical model of coupled directed percolation systems with two particle species. The two species A and B are coupled asymmetrically in that A particles branch B particles, whereas B particles prey on A particles. This model may describe epidemic spreading controlled by reactive immunization agents. We study nonequilibrium phase transitions with attention focused on the multicritical point where both species undergo the absorbing phase transition simultaneously. In one dimension, we find that the inhibitory coupling from B to A is irrelevant and the model belongs to the unidirectionally coupled directed percolation class. On the contrary, a meanfield analysis predicts that the inhibitory coupling is relevant and a new universality appears with a variable dynamic exponent. Numerical simulations on smallworld networks confirm our predictions. 

³í¹®
NUMBER  P05002 
AUTHOR  Choi, MY,Park, H 
TITLE  Slow relaxation in the Ising model on a smallworld network with strong longrange interactions 
ARCHIVE  condmat/0501099 
FILE  
JOURNAL  PHYSICAL REVIEW E, 2005 
ABSTRACT  We consider the Ising model on a smallworld network, where the longrange interaction strength J(2) is in general different from the local interaction strength J(1), and examine its relaxation behaviors as well as phase transitions. As J(2)/J(1) is raised from zero, the critical temperature also increases, manifesting contributions of longrange interactions to ordering. However, it becomes saturated eventually at large values of J(2)/J(1) and the system is found to display very slow relaxation, revealing that ordering dynamics is inhibited rather than facilitated by strong longrange interactions. To circumvent this problem, we propose a modified updating algorithm in Monte Carlo simulations, assisting the system to reach equilibrium quickly. 

³í¹®
NUMBER  P04026 
AUTHOR  Park, SC,Park, H 
TITLE  Driven pair contact process with diffusion 
ARCHIVE  condmat/0406606 
FILE  
JOURNAL  PHYSICAL REVIEW LETTERS, 2005 
ABSTRACT  The pair contact process with diffusion (PCPD) has been recently investigated extensively, but its critical behavior is not yet clearly established. By introducing biased diffusion, we show that the external driving is relevant and the driven PCPD exhibits a meanfieldtype critical behavior even in one dimension. In systems which can be described by a singlespecies bosonic field theory, the Galilean invariance guarantees that the driving is irrelevant. The wellestablished directed percolation (DP) and parityconserving (PC) classes are such examples. This leads us to conclude that the PCPD universality class should be distinct from the DP or the PC class. Moreover, it implies that the PCPD is generically a multispecies model and a field theory of two species is suitable for proper description. 

³í¹®
NUMBER  P04048 
AUTHOR  Choi, MY,Park, H 
TITLE  Scalefree dynamics emerging from information transfer 
ARCHIVE  condmat/0412156 
FILE  
JOURNAL  EUROPHYSICS LETTERS, 2005 
ABSTRACT  The dynamics based on information transfer is proposed as an underlying mechanism for the scaleinvariant dynamic critical behavior observed in a variety of systems. We apply the dynamics to the globally coupled Ising model, which is a,analytically tractable, mid show that dynamic criticality is indeed attained. Such emergence of criticality is confirmed numerically in the twodimensional Ising model as well as the globally coupled one and in a biological evolution model. Although criticality is precise only when information transfer is reversible, it may also be observed even in the irreversible case, during the practical time scale shorter than the relaxation time. 

³í¹®
NUMBER  P04034 
AUTHOR  Park, SC,Park, H 
TITLE  Cluster meanfield approximations with the coherentanomalymethod analysis for the driven pair contact process with diffusion 
ARCHIVE  condmat/0409115 
FILE  
JOURNAL  PHYSICAL REVIEW E, 2005 
ABSTRACT  The cluster meanfield approximations are performed, up to 13 cluster sizes, to study the critical behavior of the driven pair contact process with diffusion (DPCPD) and its precedent, the PCPD in one dimension. Critical points are estimated by extrapolating our data to the infinite cluster size limit, which are in good accordance with recent simulation results. Within the cluster meanfield approximation scheme, the PCPD and the DPCPD share the same meanfield critical behavior. The application of the coherent anomaly method, however, shows that the two models develop different coherent anomalies, which lead to different true critical scaling. The values of the critical exponents for the particle density, the pair density, the correlation length, and the relaxation time are fairly well estimated for the DPCPD. These results support and complement our recent simulation results for the DPCPD. 

³í¹®
NUMBER  P03093 
AUTHOR  Hong, H,Park, H,Choi, MY 
TITLE  Collective phase synchronization in locally coupled limitcycle oscillators 
ARCHIVE  condmat/0312599 
FILE  
JOURNAL  PHYSICAL REVIEW E, 2004 
ABSTRACT  We study collective behavior of locally coupled limitcycle oscillators with scattered intrinsic frequencies on ddimensional lattices. A linear analysis shows that the system should always be desynchronized up to d=4. On the other hand, numerical investigation for d=5 and d=6 reveals the emergence of the synchronized (ordered) phase via a continuous transition from the fully random desynchronized phase. This demonstrates that the lower critical dimension for the phase synchronization in this system is d(l)=4. 

³í¹®
NUMBER  P04020 
AUTHOR  Park, H 
TITLE  Stability of vacuum in coupled directed percolation processes 
ARCHIVE  condmat/0403730 
FILE  
JOURNAL  PHYSICAL REVIEW E, 2004 
ABSTRACT  We study the absorbing phase transitions in coupled directed percolation (DP) processes with Nspecies particles in one dimension. The interspecies coupling is linear, bidirectional, and excitatory. We find that the presence of a spontaneous annihilation process A>0 is essential in stabilizing the absorbing phase (vacuum). In the coupled contact processes, the vacuum is stable and the system exhibits DP type transitions, regardless of the coupling strength, for all N. However, in the coupled branching annihilation random walks with one offspring (BAW), where particle annihilations occur only through binary diffusion processes A+A>0, the vacuum becomes unstable with respect to an arbitrarily small branching rate in a sufficiently strong coupling regime for Ngreater than or equal to3. The N=2 BAW exhibits the DP type transition for any coupling strength, but the inclusion of interspecies hard core (HC) interaction makes the vacuum unstable again and the system is always active in a strong coupling regime. Critical behavior near the zero branching point is characterized by the meanfield scaling exponents, beta=nu(perpendicular to)=1/2 and nu(parallel to)=1, regardless of the presence of HC interaction. We also discuss the effects of the asymmetric coupling. 

³í¹®
NUMBER  P02084 
AUTHOR  Park, H 
TITLE  Universality class of absorbing transitions with continuously varying critical exponents 
ARCHIVE  condmat/0109516 
FILE  
JOURNAL  PHYSICAL REVIEW E, 2004 
ABSTRACT  The wellestablished universality classes of absorbing critical phenomena are directed percolation (DP) and directed Ising (DI) classes. Recently, the pair contact process with diffusion (PCPD) has been investigated extensively and claimed to exhibit a different type of critical phenomenon distinct from both DP and DI classes. Noticing that the PCPD possesses a longterm memory effect, we introduce a generalized version of the PCPD (GPCPD) with a parameter controlling the memory strength. The GPCPD connects the DP fixed point to the PCPD point continuously. Monte Carlo simulations strongly suggest that the GPCPD displays, to our knowledge, novel critical phenomena which are characterized by continuously varying critical exponents. The same critical behaviors are also observed in models where two species of particles are coupled cyclically. We present one possible scenario that the longterm memory may serve as a marginal perturbation to the ordinary DP fixed point. 

³í¹®
NUMBER  P03024 
AUTHOR  Park, H 
TITLE  Comment on Restricted curvature model with suppression of extremal height 
ARCHIVE  condmat/0303301 
FILE  
JOURNAL  PHYSICAL REVIEW E, 2003 
ABSTRACT  Recently Jeong and Kim [Phys. Rev. E 66, 051605 (2002)] investigated the scaling properties of equilibrium selfflattening surfaces subject to a restricted curvature constraint. In one dimension (1D), they found numerically that the stationary roughness exponent alphaapproximate to0.561 and the window exponent deltaapproximate to0.423. We present an analytic argument for general selfflattening surfaces in D dimensions, leading to alpha=Dalpha(0)/(D+alpha(0)) and delta=D/(D+alpha(0)), where alpha(0) is the roughness exponent for equilibrium surfaces without the selfflattening mechanism. In case of surfaces subject to a restricted curvature constraint, it is known exactly that alpha(0)=3/2 in 1D, which leads to alpha=3/5 and delta=2/5. Small discrepancies between our analytic values and their numerical values may be attributed to finite size effects. 

³í¹®
NUMBER  P02082 
AUTHOR  Park, H 
TITLE  Fluctuations of selfflattening surfaces 
ARCHIVE  condmat/0209576 
FILE  
JOURNAL  PHYSICAL REVIEW E, 2002 
ABSTRACT  We study the scaling properties of selfflattening surfaces under global suppression on surface fluctuations. Evolution of selfflattening surfaces is described by restricted solidonsolid type monomer depositionevaporation model with reduced deposition (evaporation) at the globally highest (lowest) site. We find numerically that equilibrium surface fluctuations are anomalous with roughness exponent alphasimilar or equal to1/3 and dynamic exponent z(W)similar or equal to3/2 in one dimension (1D) and alpha=0 (log) and z(W)similar or equal to5/2 in 2D. Stationary roughness can be understood analytically by relating our model to the static selfattracting random walk model and the dissociative dimertype depositionevaporation model. In case of nonequilibrium growingeroding surfaces, selfflattening dynamics turns out to be irrelevant and the normal KardarParisiZhang universality is recovered in all dimensions. 

³í¹®
NUMBER  P02083 
AUTHOR  Park, H 
TITLE  Dynamical surface structures in multiparticlecorrelated surface growths 
ARCHIVE  condmat/0205427 
FILE  
JOURNAL  PHYSICAL REVIEW E, 2002 
ABSTRACT  We investigate the scaling properties of the interface fluctuation width for the Qmer and Qparticlecorrelated depositionevaporation models. These models are constrained with a global conservation law that the particle number at each height is conserved modulo Q. In equilibrium, the stationary roughness is anomalous but universal with the roughness exponent alpha = 1/3, while the early time evolution shows nonuniversal behavior with the growth exponent beta varying with models and Q. Nonequilibrium surfaces display diverse growing and stationary behaviors. The Qmer model shows a faceted structure, while the Qparticlecorrelated model shows a macroscopically grooved structure. 


³í¹®
NUMBER  
AUTHOR  Lee, Jae Sung; Park, Hyunggyu 
TITLE  Stochastic thermodynamics and hierarchy of fluctuation theorems with multiple reservoirs 
ARCHIVE  
FILE  
JOURNAL  NEW JOURNAL OF PHYSICS, v.20, 83010, 2018 
ABSTRACT  We reformulate stochastic thermodynamics in terms of noise realizations for Langevin systems in contact with multiple reservoirs and investigate the structure of the second laws of thermodynamics. We derive a hierarchy of fluctuation theorems when one degree of freedom of the system is affected by multiple reservoirs simultaneously, that is, when noisemixing occurs. These theorems and the associated second laws of thermodynamics put stricter bounds on the thermodynamics of Langevin systems. We apply our results to a stochastic machine in noisemixing environments and demonstrate that our new bounds play a crucial role in determining the potential function and performance of the machine.


³í¹®
NUMBER  
AUTHOR  Lee, Sang Hoon; Um, Jaegon; Park, Hyunggyu 
TITLE  Nonuniversality of heatengine efficiency at maximum power 
ARCHIVE  
FILE  
JOURNAL  PHYSICAL REVIEW E, 98(5), 52137, 2018 
ABSTRACT  We study the efficiency of a simple quantum dot heat engine at maximum power. In contrast to the quasistatically operated Carnot engine whose efficiency reaches the theoretical maximum, recent research on more realistic engines operated in a finite time has revealed other classes of efficiencies such as the CurzonAhlborn efficiency maximizing the power. Such a powermaximizing efficiency has been argued to be always half of the maximum efficiency up to the linear order near equilibrium under the tightcoupling condition between thermodynamic fluxes. We show, however, that this universality may break down for the quantum dot heat engine, depending on the constraint imposed on the engine control parameters (local optimization), even though the tightcoupling condition remains satisfied. It is shown that this deviation is critically related to the applicability of the linear irreversible thermodynamics.


³í¹®
NUMBER  
AUTHOR  Park, Hyunggyu 
TITLE  Entropy and Thermodynamic Second Laws: New Perspective  Stochastic Thermodynamics and Fluctuation Theorems 
ARCHIVE  
FILE  
JOURNAL  JOURNAL OF THE KOREAN PHYSICAL SOCIETY, 72(15), 14131420, 2018 
ABSTRACT  Recently, there has been a considerable progress on the issue of the thermodynamic second law, which is known as the law of entropy increase or irreversibility. In particular, a novel symmetry known as the GallavottiCohen symmetry is found in nonequilibrium (NEQ) fluctuations, which leads to socalled fluctuation theorems. The thermodynamic second law is a simple corollary of fluctuation theorems, from which one can predict quantitatively how often NEQ processes violate the law of entropy increase. Violations disappear in the thermodynamic limit, but can be observed reasonably well in small systems. In this article, we will briefly introduce the stochastic thermodynamics and derive various fluctuation theorems, including the total entropy production (EP), the workfreeenergy relation, the excess and housekeeping EP, and the information entropy.


³í¹®
NUMBER  
AUTHOR  Rahbari, S. H. E.; Vollmer, J.; Park, Hyunggyu 
TITLE  Characterizing the nature of the rigidity transition 
ARCHIVE  
FILE  
JOURNAL  PHYSICAL REVIEW E, 98(5), 52905, 2018 
ABSTRACT  Particulate matter, such as foams, emulsions, and granular materials, attain rigidity in a dense regime: the rigid phase can yield when a threshold force is applied. The rigidity transition in particulate matter exhibits bona fide scaling behavior near the transition point. However, a precise determination of exponents describing the rigidity transition has raised much controversy. Here we pinpoint the causes of the controversies. We then establish a conceptual framework to quantify the critical nature of the rigidity transition. Our results demonstrate that there is a spectrum of possible values for the critical exponents for which, without a robust framework, one cannot distinguish the genuine values of the exponents. Our approach is twofold: (1) a precise determination of the transition density using rheological measurements and (2) a matching rule that selects the critical exponents and rules out all other possibilities from the spectrum. This enables us to determine exponents with unprecedented accuracy and resolve the longstanding controversy over exponents of jamming The generality of the approach paves the way to quantify the critical nature of many other types of rheological phase transitions such as those in oscillatory shearing.


³í¹®
NUMBER  
AUTHOR  Lee, Jae Sung; Park, Hyunggyu 
TITLE  Additivity of multiple heat reservoirs in the Langevin equation 
ARCHIVE  
FILE  
JOURNAL  PHYSICAL REVIEW E, 97(6), 62135, 2018 
ABSTRACT  The Langevin equation greatly simplifies the mathematical expression of the effects of thermal noise by using only two terms, a dissipation term, and a randomnoise term. The Langevin description was originally applied to a system in contact with a single heat reservoir; however, many recent studies have also adopted a Langevin description for systems connected to multiple heat reservoirs. This is accomplished through the introduction of a simple summation for the dissipation and randomnoise terms associated with each reservoir. However, the validity of this simple addition has been the focus of only limited discussion and has raised several criticisms. Moreover, this additive description has never been either experimentally or numerically verified, rendering its validity is still an open question. Here we perform molecular dynamics simulations for a Brownian system in simultaneous contact with multiple heat reservoirs to check the validity of this additive approach. Our simulation results confirm that the effect of multiple heat reservoirs is additive in general. A very small deviation in the total amount of dissipation and associated noise is found but seems not significant within statistical errors. We find that the steadystate properties satisfy the additivity perfectly and are not affected by this deviation.


³í¹®
NUMBER  
AUTHOR  Kwon, Chulan; Um, Jaegon; Park, Hyunggyu 
TITLE  Information thermodynamics for a multifeedback process with time delay 
ARCHIVE  
FILE  
JOURNAL  EPL v.117(1), 10011. 2017 
ABSTRACT  

³í¹®
NUMBER  P17027 
AUTHOR  Rahbari, S. H. E.; Saberi, A. A.; Park, Hyunggyu; Vollmer, J. 
TITLE  Characterizing rare fluctuations in soft particulate flows 
ARCHIVE  
FILE  
JOURNAL  NATURE COMMUNICATIONS v.8, 11. 2017. 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  Lee, Hyun Keun; Lahiri, Sourabh; Park, Hyunggyu 
TITLE  Nonequilibrium steady states in Langevin thermal systems 
ARCHIVE  
FILE  
JOURNAL  PHYSICAL REVIEW E v.96(2), 022134. 2017. 
ABSTRACT  

³í¹®
NUMBER  Q17027 
AUTHOR  Lee, Jae Sung; Park, Hyunggyu 
TITLE  Carnot efficiency is reachable in an irreversible process 
ARCHIVE  
FILE  
JOURNAL  SCIENTIFIC REPORTS v.7, 10725. 2017. 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  Kwon, Chulan; Yeo, Joonhyun; Lee, Hyun Keun; Park, Hyunggyu 
TITLE  Unconventional entropy production in the presence of momentumdependent forces 
ARCHIVE  
FILE  
JOURNAL  JOURNAL OF THE KOREAN PHYSICAL SOCIETY v.68(5), 633638p. 2016. 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  Durang, X; Kwon, C; Park, H 
TITLE  Overdamped limit and inversefriction expansion for Brownian motion in an inhomogeneous medium 
ARCHIVE  
FILE  
JOURNAL  PHYSICAL REVIEW E, v.91 no.6 (2015) 062118 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  Um, J; Hinrichsen, H; Kwon, C; Park, H 
TITLE  Total cost of operating an information engine 
ARCHIVE  
FILE  
JOURNAL  NEW JOURNAL OF PHYSICS, v.17 (2015) 085001 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  Hong, H; Chate, H; Tang, LH; Park, H 
TITLE  Finitesize scaling, dynamic fluctuations, and hyperscaling relation in the Kuramoto model 
ARCHIVE  
FILE  
JOURNAL  PHYSICAL REVIEW E, v.92 no.2 (2015) 022122 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  Um, J; Hong, H; Park, H 
TITLE  Nature of synchronization transitions in random networks of coupled oscillators 
ARCHIVE  
FILE  
JOURNAL  PHYSICAL REVIEW E, v.89 no.1 (2014) 012810 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  Durang, X; Henkel, M; Park, H 
TITLE  The statistical mechanics of the coagulationdiffusion process with a stochastic reset 
ARCHIVE  
FILE  
JOURNAL  JOURNAL OF PHYSICS AMATHEMATICAL AND THEORETICAL, v.47 no.4 (2014) 045002 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  Kim, K; Kwon, C; Park, H 
TITLE  Heat fluctuations and initial ensembles 
ARCHIVE  
FILE  
JOURNAL  PHYSICAL REVIEW E, v.90 no.3 (2014) 032117 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  Lee, HK; Kwon, C; Park, H 
TITLE  Fluctuation Theorems and Entropy Production with OddParity Variables 
ARCHIVE  
FILE  
JOURNAL  PHYSICAL REVIEW LETTERS, v.110 no.5 (2013) 050602 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  Lee, JS; Kwon, C; Park, H 
TITLE  Everlasting initial memory threshold for rare events in equilibration processes 
ARCHIVE  
FILE  
JOURNAL  PHYSICAL REVIEW E, v.87 no.2 (2013) 020104 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  Hong, H; Um, J; Park, H 
TITLE  Linkdisorder fluctuation effects on synchronization in random networks 
ARCHIVE  
FILE  
JOURNAL  PHYSICAL REVIEW E, v.87 no.4 (2013) 042105 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  Noh, JD; Kwon, C; Park, H 
TITLE  Multiple Dynamic Transitions in Nonequilibrium Work Fluctuations 
ARCHIVE  
FILE  
JOURNAL  PHYSICAL REVIEW LETTERS, v.111 no.13 (2013) 130601 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  Lee, JS; Kwon, C; Park, H 
TITLE  Modified saddlepoint integral near a singularity for the large deviation function 
ARCHIVE  
FILE  
JOURNAL  JOURNAL OF STATISTICAL MECHANICSTHEORY AND EXPERIMENT (2013) P11002 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  Kwon, C; Noh, JD; Park, H 
TITLE  Work fluctuations in a timedependent harmonic potential: Rigorous results beyond the overdamped limit 
ARCHIVE  
FILE  
JOURNAL  PHYSICAL REVIEW E, v.88 no.6 (2013) 062102 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  Um, J; Park, H; Hinrichsen, H 
TITLE  Entanglement versus mutual information in quantum spin chains 
ARCHIVE  
FILE  
JOURNAL  JOURNAL OF STATISTICAL MECHANICSTHEORY AND EXPERIMENT (2012) P10026 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  Jaegon Um, Hyunsuk Hong, Fabio Marchesoni, and Hyunggyu Park 
TITLE  Rectification of spatial disorder 
ARCHIVE  arXiv:1104.4831 
FILE  
JOURNAL  PHYSICAL REVIEW LETTERS, v.108 no.6 (2012) 060601 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  Hyun Keun Lee, Beom Jun Kim, and Hyunggyu Park 
TITLE  Continuity of the explosive percolation transition 
ARCHIVE  
FILE  
JOURNAL  Physical Review E 84, 020101(R) (2011/8/3) 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  Jae Dong Noh, Hyun Keun Lee, and Hyunggyu Park 
TITLE  Scaling of cluster heterogeneity in percolation transitions 
ARCHIVE  
FILE  
JOURNAL  Physical Review E 84, 010101(R) (2011/7/20) 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  Chulan Kwon, Jae Dong Noh and Hyunggyu Park 
TITLE  Nonequilibrium fluctuations for linear diffusion dynamics 
ARCHIVE  
FILE  
JOURNAL  Physical Review E 83, 061145 (2011/6/24) 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  Hyunggyu Park 
TITLE  Collective helping and bystander effects in coevolving helping networks 
ARCHIVE  
FILE  
JOURNAL  Phys. Rev. E 81, 066108(2010) 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  Sreedhar B. Dutta, Malte Henkel and Hyunggyu Park 
TITLE  Kinetics of a nonglauberian Ising model: global observables and exact results 
ARCHIVE  
FILE  
JOURNAL  J. Stat. Mech. P03023 (2009) 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  SuChan Park and Hyunggyu Park 
TITLE  Crossover from the parityconserving pair contact process with diffusion to other universality classes 
ARCHIVE  
FILE  
JOURNAL  Phys. Rev. E 79, 051130 (2009) 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  Jae Dong Noh and Hyunggyu Park 
TITLE  Critical behavior of the contact process in annealed scalefree networks 
ARCHIVE  
FILE  
JOURNAL  Phys. Rev. E 78, 041128 (2009) 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  Jae Dong Noh and Hyunggyu Park 
TITLE  Relaxation dynamics of an elastic string in random media 
ARCHIVE  
FILE  
JOURNAL  Phys. Rev. E 80, 040102(R) (2009) 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  Sang Hoon Lee, Meesoon Ha, Hawoong Jeong, Jae Dong Noh, and Hyunggyu Park 
TITLE  Critical behavior of the Ising model in annealed scalefree networks 
ARCHIVE  
FILE  
JOURNAL  Phys. Rev. E 80, 051127 (2009) 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  Apoorva Nagar, Meesoon Ha, and Hyunggyu Park 
TITLE  Boundaryinduced abrupt transition in the symmetric exclusion process 
ARCHIVE  
FILE  
JOURNAL  Phys. Rev. E 77, 061118 (2008) 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  SuChan Park and Hyunggyu Park 
TITLE  Nonequilibrium phase transitions into absorbing states: Focused around the pair contact process with diffusion 
ARCHIVE  
FILE  
JOURNAL  Eur. Phy. J. B 64, 415 (2008) 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  SuChan Park and Hyunggyu Park 
TITLE  Three different routes from the directed Ising to the directed percolation class 
ARCHIVE  
FILE  
JOURNAL  Phys. Rev. E 78, 041128 (2008) 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  Meesoon Ha, H. Hong, and Hyunggyu Park 
TITLE  Comment on ¡° Nonmeanfield behavior of the contact process on scalefree networks¡± 
ARCHIVE  
FILE  
JOURNAL  Phys. Rev. Lett. 98, 029801 (2007) 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  Hyunsuk Hong, Meesoon Ha, and Hyunggyu Park 
TITLE  Finitesize scaling in complex networks 
ARCHIVE  
FILE  
JOURNAL  Phys. Rev. Lett. 98, 258701 (2007) 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  Meesoon Ha, Hyunggyu Park, and Marcel den Nijs 
TITLE  Dynamic instability transitions in 1D driven diffusive flow with nonlocal hopping 
ARCHIVE  
FILE  
JOURNAL  Phys. Rev. E 75, 061131 (2007) 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  Daun Jeong, M. Y. Choi, and Hyunggyu Park 
TITLE  Construction of equilibrium networks with an energy function 
ARCHIVE  
FILE  
JOURNAL  J. Phys. A 40, 9723 (2007) 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  Hyunsuk Hong, Hyunggyu Park, and LeiHan Tang 
TITLE  Entrainment transition in populations of random frequency oscillators 
ARCHIVE  
FILE  
JOURNAL  Phys. Rev. Lett. 99, 184101 (2007) 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  SuChan Park and Hyunggyu Park 
TITLE  Nontrivial critical crossover between directed percolation models: Effect of infinitely many absorbing states 
ARCHIVE  
FILE  
JOURNAL  Phys. Rev. E 76, 051123 (2007) 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  Hyunsuk Hong, Hyunggyu Park, and LeiHan Tang 
TITLE  Finitesize scaling of synchronized oscillation on complex networks 
ARCHIVE  
FILE  
JOURNAL  Phys. Rev. E 76, 066104 (2007) 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  SuChan Park and Hyunggyu Park 
TITLE  Crossover from the pair contact proces with diffusion to directed percolation 
ARCHIVE  
FILE  
JOURNAL  Phys. Rev. E 73, 025105(R) (2006) 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  H. K. Lee, C. Kwon, and Hyunggyu Park 
TITLE  Equivalence of operatorsplitting schemes for the integration of the Langevin equation 
ARCHIVE  
FILE  
JOURNAL  J. Stat. Mech. P08021 (2006) 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  Hyunsuk Hong, Hyunggyu Park, and LeiHan Tang 
TITLE  Anomalous Binder cumulant and lack of self averageness in systems with quenched disorder 
ARCHIVE  
FILE  
JOURNAL  J. Korean Phys. Soc. 49, L1885 (2006) 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  SuChan Park and Hyunggyu Park 
TITLE  Cluster mean field approximations with the coherent anomaly method analysis for the driven pair contact process with diffusion 
ARCHIVE  
FILE  
JOURNAL  Phys. Rev. E 71, 016137 (2005) 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  M. Y. Choi, Beom Jun Kim, B.G. Yoon, and Hyunggyu Park 
TITLE  Scalefree dynamics emerging from information transfer 
ARCHIVE  
FILE  
JOURNAL  Europhys. Lett. 69, 503 (2005) 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  SuChan Park and Hyunggyu Park 
TITLE  Driven pair contact process with diffusion 
ARCHIVE  
FILE  
JOURNAL  Phys. Rev. Lett. 94, 065701 (2005) 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  Daun Jeong, M. Y. Choi, and Hyunggyu Park 
TITLE  Slow relaxation in the Ising model on a smallworld network with strong longrange interactions 
ARCHIVE  
FILE  
JOURNAL  Phys. Rev. E 71, 036103 (2005) 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  Jae Dong Noh and Hyunggyu Park 
TITLE  Asymmetrically coupled directed percolation systems 
ARCHIVE  
FILE  
JOURNAL  Phys. Rev. Lett. 94, 145702 (2005) 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  Lucian Anton, Hyunggyu Park, and SuChan Park 
TITLE  Generating function for particlenumber probability distribution in directed percolation 
ARCHIVE  
FILE  
JOURNAL  J. Phys. A 38, 8187 (2005) 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  H. Hong, Hyunggyu Park, and M. Y. Choi 
TITLE  Collective synchronization in spatially extended systems of coupled oscillators with random frequencies 
ARCHIVE  
FILE  
JOURNAL  Phys. Rev. E 72, 036217 (2005) 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  Jae Dong Noh and Hyunggyu Park 
TITLE  Universality class of absorbing transitions with continuously varying exponents 
ARCHIVE  
FILE  
JOURNAL  Phys. Rev. E 69, 016122 (2004) 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  Sungchul Kwon and Hyunggyu Park 
TITLE  Stability of vacuum in coupled directed percolation processes 
ARCHIVE  
FILE  
JOURNAL  Phys. Rev. E 69, 066125 (2004) 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  H. Hong, Beom Jun Kim, M. Y. Choi, and Hyunggyu Park 
TITLE  Factors that predict better synchronizability on complex networks 
ARCHIVE  
FILE  
JOURNAL  Phys. Rev. E 69, 067105 (2004) 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  H. Hong, Hyunggyu Park, and M. Y. Choi 
TITLE  Collective phase synchronization in locallycoupled limitcycle oscillators 
ARCHIVE  
FILE  
JOURNAL  Phys. Rev. E 70, 045204(R) (2004) 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  Hyunggyu Park 
TITLE  Comment on ¡°Restricted curvature model with suppression of extremal height¡± 
ARCHIVE  
FILE  
JOURNAL  Phys. Rev. E 68, 053601 (2003) 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  Yup Kim, T. S. Kim, and Hyunggyu Park 
TITLE  Dynamic surface structures in multiparticlecorrelated surface growths 
ARCHIVE  
FILE  
JOURNAL  Phys. Rev. E 66, 046123 (2002) 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  Yup Kim, S. Y. Yoon, and Hyunggyu Park 
TITLE  Fluctuations of selfflattening surfaces 
ARCHIVE  
FILE  
JOURNAL  Phys. Rev. E 66, 040602(R) (2002) 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  Heung Sik Park and Hyunggyu Park 
TITLE  Relaxation of nonorder parameter field in directed Ising systems 
ARCHIVE  
FILE  
JOURNAL  J. Korean Phys. Soc. 38, 494 (2001) 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  Sungchul Kwon and Hyunggyu Park 
TITLE  Twospecies branching annihilating random walks with one offspring 
ARCHIVE  
FILE  
JOURNAL  J. Korean Phys. Soc. 38, 490 (2001) 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  Jae Dong Noh, Hyunggyu Park, Doochul Kim, and Marcel den Nijs 
TITLE  Anomalous roughness, localization, and globally constrained random walks 
ARCHIVE  
FILE  
JOURNAL  Phys. Rev. E 64, 046131 (2001) 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  Hyunggyu Park and Sungchul Kwon 
TITLE  Absorbingstate critical phenomena in interacting surface reaction models 
ARCHIVE  
FILE  
JOURNAL  Brazilian J. Phys. 30, 133 (2000) 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  Jae Dong Noh, Hyunggyu Park, and Marcel den Nijs 
TITLE  Anomalous roughness for dimer type surface growth 
ARCHIVE  
FILE  
JOURNAL  Phys. Rev. Lett. 84, 3891 (2000) 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  Sungchul Kwon, Jysoo Lee, and Hyunggyu Park 
TITLE  Does hard core interaction change absorbingtype critical phenomena? 
ARCHIVE  
FILE  
JOURNAL  Phys. Rev. Lett. 85, 1682 (2000) 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  Jae Dong Noh, Hyunggyu Park, and Marcel den Nijs 
TITLE  Directed Ising type dynamic preroughening transition in one dimensional interfaces 
ARCHIVE  
FILE  
JOURNAL  Phys. Rev. E 59, 194 (1999) 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  WonMuk Hwang and Hyunggyu Park 
TITLE  Interacting monomerdimer model with infinitely many absorbing states 
ARCHIVE  
FILE  
JOURNAL  Phys. Rev. E 59, 4683 (1999) 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  Sungchul Kwon, WonMuk Hwang, and Hyunggyu Park 
TITLE  Dynamic behavior of driven interfaces in models with two absorbing states 
ARCHIVE  
FILE  
JOURNAL  Phys. Rev. E 59, 4949 (1999) 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  ChunChung Chen, Hyunggyu Park, and Marcel den Nijs 
TITLE  Active width at a slanted active boundary in directed percolation 
ARCHIVE  
FILE  
JOURNAL  Phys. Rev. E 60, 2496 (1999) 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  Meesoon Ha, Hyunggyu Park, and Marcel den Nijs 
TITLE  Particle dynamics in a masscoalescence process 
ARCHIVE  
FILE  
JOURNAL  J. Phys. A 32, L495 (1999) 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  WonMuk Hwang, Sungchul Kwon, Heungwon Park, and Hyunggyu Park 
TITLE  Critical phenomena of nonequilibrium dynamical systems with two absorbing states 
ARCHIVE  
FILE  
JOURNAL  Phys. Rev. E 57, 6438 (1998) 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  Hyunggyu Park, Meesoon Ha, and Inmook Kim 
TITLE  Exact solutions of a restricted ballistic deposition model on a onedimensional staircase 
ARCHIVE  
FILE  
JOURNAL  Phys. Rev. E 51, 1047 (1995) 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  Heungwon Park, Mann Ho Kim, and Hyunggyu Park 
TITLE  Dynamic scaling behavior of an interacting monomerdimer model 
ARCHIVE  
FILE  
JOURNAL  Phys. Rev. E 52, 5664 (1995) 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  Hyunggyu Park and Heungwon Park 
TITLE  Critical behavior of an absorbing phase transition in an interacting monomerdimer model 
ARCHIVE  
FILE  
JOURNAL  Physica A 221, 97 (1995) 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  Sungchul Kwon and Hyunggyu Park 
TITLE  Reentrant phase diagram of branching annihilating random walks with one and two offsp 
ARCHIVE  
FILE  
JOURNAL  Phys. Rev. E 52, 5955 (1995) 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  Hyunggyu Park 
TITLE  Threestate Potts model on a triangular lattice 
ARCHIVE  
FILE  
JOURNAL  Phys. Rev. B 49, 12881 (1994) 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  Mann Ho Kim and Hyunggyu Park 
TITLE  Critical behavior of an interacting monomerdimer model 
ARCHIVE  
FILE  
JOURNAL  Phys. Rev. Lett. 73, 2579 (1994) 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  Hyunggyu Park, Joachim Koeler, Inmook Kim, Daniel benAvraham,and Sidney Redner 
TITLE  Excluded volume effect in heterogeneous catalysis: reactions between ¡®dollars¡¯ and ¡®dimes¡¯ 
ARCHIVE  
FILE  
JOURNAL  J. Phys. A 26, 2071 (1993) 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  Jun Zhuo, Sidney Redner, and Hyunggyu Park 
TITLE  Critical behavior of an interacting surface reaction model 
ARCHIVE  
FILE  
JOURNAL  J. Phys. A 26, 4197 (1993) 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  Mann Ho Kim and Hyunggyu Park 
TITLE  Critical behavior of surfacereaction models 
ARCHIVE  
FILE  
JOURNAL  J. Korean Phys. Soc. 26, S345 (1993) 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  Hyunggyu Park and Tong Chull Chey 
TITLE  The antiferromagnetic threestate Potts model on a triangular lattice 
ARCHIVE  
FILE  
JOURNAL  J. Korean Phys. Soc. 26, S399 (1993) 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  Inmook Kim, Hyunjoo Kim, and Hyunggyu Park 
TITLE  Dynamic scaling theory of A + B ¡æ surface reaction 
ARCHIVE  
FILE  
JOURNAL  J. Korean Phys. Soc. 26, S406 (1993) 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  Weixiong Lee, Hyunggyu Park, Michael Widom 
TITLE  Phase diagram of a random tiling quasicrystal 
ARCHIVE  
FILE  
JOURNAL  J. Stat. Phys. 66, 1 (1992) 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  Mann Ho Kim, Jysoo Lee, Hyunggyu Park, and Inmook Kim 
TITLE  Triviality of the critical exponents of directed selfavoiding walks on Sierpinsky carpets 
ARCHIVE  
FILE  
JOURNAL  J. Phys. A 25, L453 (1992) 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  Weixiong Lee and Hyunggyu Park 
TITLE  Logarithmic singularity in the surface free energy near commensurateincommensurate transitions 
ARCHIVE  
FILE  
JOURNAL  J. Phys. A 24, 257 (1991) 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  Hyunggyu Park, Astro Provata, and Sidney Redner 
TITLE  Interface growth with competing surface currents 
ARCHIVE  
FILE  
JOURNAL  J. Phys. A 24, L1391 (1991) 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  Hyunggyu Park and Michael Widom 
TITLE  Finitesizescaling amplitudes of the incommensurate phase 
ARCHIVE  
FILE  
JOURNAL  Phys. Rev. Lett. 64, 1076 (1990) 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  Hyunggyu Park 
TITLE  Universal finitesizescaling amplitudes on a torus for the triangular Ising lattice gas 
ARCHIVE  
FILE  
JOURNAL  J. Phys. A 23, 1789 (1990) 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  Weixiong Lee, Hyunggyu Park, and Michael Widom 
TITLE  Finitesizescaling amplitudes in a random tiling model 
ARCHIVE  
FILE  
JOURNAL  J. Phys. A 23, L573 (1990) 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  Hyunggyu Park and Michael Widom 
TITLE  Conformal invariance in incommensurate phases 
ARCHIVE  
FILE  
JOURNAL  J. Stat. Phys. 61, 51 (1990) 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  Hyunggyu Park and Marcel den Nijs 
TITLE  Universal finitesizescaling amplitudes of interfacial free energies in Monte Carlo simulations 
ARCHIVE  
FILE  
JOURNAL  J. Phys. A 22, 3663 (1989) 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  Hyunggyu Park and Michael Widom 
TITLE  Exact results on the antiferromagnetic three state Potts model 
ARCHIVE  
FILE  
JOURNAL  Phys. Rev. Lett. 63, 1193 (1989) 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  Hyunggyu Park and Marcel den Nijs 
TITLE  Universal finitesizescaling amplitudes of the Potts model on a torus 
ARCHIVE  
FILE  
JOURNAL  Phys. Rev. B 38, 565 (1988) 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  Hyunggyu Park, Eberhard K. Riedel, and Marcel den Nijs 
TITLE  Anisotropic honeycomb domain wall networks in uniaxial systems 
ARCHIVE  
FILE  
JOURNAL  Ann. Phys. 172, 419 (1986) 
ABSTRACT  

³í¹®
NUMBER  
AUTHOR  Hyunggyu Park and Doochul Kim 
TITLE  Large q expansion of the Potts model susceptibility and magnetization in two and three dimensions 
ARCHIVE  
FILE  
JOURNAL  J. Korean Phys. Soc. 15, 55 (1982) 
ABSTRACT  

 2010  Present : Review Board Member, National Research Foundation of Korea
 2009  2010 : Visiting Professor, Department of Physics, University of Washington
 2008  2009 : Vice President, KIAS
 2007 : Dean of Faculty, KIAS
 2007  2009 : Program Manager, Korea Research Foundation
 2006  2008 : Chair of Statistical Division of the Korean Physical Society
 2005  2006 : Chair of School of Physics, KIAS
 2003  2006 : Steering Committee Member of KIAS
 2002  Present : Professor, School of Physics, KIAS
 2001  2002 : Professor, Department of Physics, Inha University
 1999  2001 : Chair of Department of Physics, Inha University
 1998  1999 : Visiting Scientist, Department of Physics, University of Washington
 1996  2001 : Associate Professor, Department of Physics, Inha University
 1992  1996 : Assistant Professor, Department of Physics, Inha University
 1990  1992 : Research Associate, Department of Physics, Boston University
 1988  1990 : Postdoctoral Research Associate, Department of Physics, Carnegie Mellon University
 1983  1988 : Department of Physics, University of Washington, USA (PhD)
 1982  1983 : Department of Physics, University of California at Santa Cruz
 1979  1981 : Department of Physics, Seoul National University, Korea (MS)
 1975  1979 : Department of Physics, Seoul National University, Korea (BS)
 2008 : Haksul (Science) award from the Korean Physical Society
 1986 : Joseph H. Weis Prize at University of Washington
 Office:1315 / TEL) 8229583823 / FAX) 8229583786
 School of School of Physics, Korea Institute for Advanced Study
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