1/t pressure and fermion behaviour of water in two dimensions (2009)
Ha, Taekyun, Chung, Sukmin, Choi, M. Y.
A variety of metal vacuum systems display the celebrated 1/t pressure, namely power-law dependence on time t, with the exponent close to unity, the origin of which has been a long-standing...
Jeon, Gun Sang, Lee, Sung Jong, Kim, Bongsoo, Choi, M. Y.
Equilibrium and non-equilibrium relaxation behaviors of two-dimensional superconducting arrays are investigated via numerical simulations at low temperatures in the presence of incommensurate...
Lee, Keumsook, Jung, Woo-Sung, Park, Jong Soo, Choi, M. Y.
The Metropolitan Seoul Subway system, consisting of 380 stations, provides the major transportation mode in the metropolitan Seoul area. Focusing on the network structure, we analyze statistical...
Jeong, Daun, Choi, M. Y., Jung, YounJoon, Kim, Hyung J.
To understand the non-exponential relaxation associated with solvation dynamics in the ionic liquid 1-ethyl-3-methylimidazolium hexafluorophosphate, we study power spectra of the fluctuating...
LETTER TO THE EDITOR Entropic sampling and natural selection in biological (2007)
M Y Choi, H Y Lee, D Kim, S H Park
Abstract. With a view to connecting random mutation on the molecular level to punctuated equilibrium behaviour on the phenotype level, we propose a new model for biological evolution, which...
Construction of equilibrium networks with an energy function (2007)
Jeong, Daun, Choi, M. Y., Park, Hyunggyu
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...
Quantum Dissipative Dynamics of Entanglement in the Spin-Boson Model (2006)
Lim, Jong Soo, Choi, Mahn-Soo, Choi, M. Y.
We study quantum dissipative dynamics of entanglement in the spin-boson model, described by the generalized master equation. We consider the two opposite limits of pure-dephasing and relaxation...
Um, Jaegon, Kim, Beom Jun, Minnhagen, Petter, Choi, M. Y., Lee, Sung-Ik
We numerically investigate dynamic critical behaviors of two-dimensional (2D) Josephson-junction arrays with positional disorder in the scheme of the resistively shunted junction dynamics....
Kondo Effects in Carbon Nanotubes: From SU(4) to SU(2) symmetry (2006)
Lim, Jong Soo, Choi, Mahn-Soo, Choi, M. Y., Lopez, Rosa, Aguado, Ramon
We study the Kondo effect in a single-electron transistor device realized in a single-wall carbon nanotube. The K-K' double orbital degeneracy of a nanotube, which originates from the peculiar...
Defect Motion and Lattice Pinning Barrier in Josephson-Junction Ladders (2005)
Kang, H., Lim, Jong Soo, Choi, J., Choi, M. Y.
We study motion of domain wall defects in a fully frustrated Josephson-unction ladder system, driven by small applied currents. For small system sizes, the energy barrier E_B to the defect motion is...
Glucose metabolism and oscillatory behavior of pancreatic islets (2005)
Kang, H., Jo, J., Kim, H. J., Choi, M. Y., Rhee, S. W., Koh, D. S.
A variety of oscillations are observed in pancreatic islets.We establish a model, incorporating two oscillatory systems of different time scales: One is the well-known bursting model in pancreatic...
How Noise and Coupling Induce Bursting Action Potentials in Pancreatic beta-cells (2005)
Jo, J., Kang, H., Choi, M. Y., Koh, D. S.
Unlike isolated beta-cells, which usually produce continuous spikes or fast and irregular bursts, electrically coupled beta-cells are apt to exhibit robust bursting action potentials. We consider the...
Dynamic model for failures in biological systems (2005)
A dynamic model for failures in biological organisms is proposed and studied both analytically and numerically. Each cell in the organism becomes dead under sufficiently strong stress, and is then...
Network Marketing on a Small-World Network (2005)
Kim, Beom Jun, Jun, Tackseung, Kim, Jeong-Yoo, Choi, M. Y.
We investigate a dynamic model of network marketing in a small-world network structure artificially constructed similarly to the Watts-Strogatz network model. Different from the traditional...
Stability of thermodynamic and dynamical order in a system of globally coupled rotors (2005)
A system of globally coupled rotors is studied in a unified framework of microcanonical and canonical ensembles. We consider the Fokker-Planck equation governing the time evolution of the system, and...
1/f spectrum in the information transfer model for mass extinction (2005)
We study the information transfer model for biological evolution with several kinds of fitness function. The system is stimulated to volve into a stationary state, depending on the fitness function...
Critical currents for vortex defect motion in superconducting arrays (2005)
Lim, Jong Soo, Choi, M. Y., Kim, Beom Jun, Choi, J.
We study numerically the motion of vortices in two-dimensional arrays of resistively shunted Josephson junctions. An extra vortex is created in the ground states by introducing novel boundary...
Entropic sampling dynamics of the globally-coupled kinetic Ising model (2005)
The entropic sampling dynamics based on the reversible information transfer to and from the environment is applied to the globally coupled Ising model in the presence of an oscillating magnetic...
Shim, Y., Choi, M. Y., Kim, Hyung J.
Solvation in 1-ethyl-3-methylmidazolium chloride and in 1-ethyl-3-methylimidazolium hexafluorophosphate near equilibrium is investigated via molecular dynamics computer simulations with diatomic and...
Shim, Y., Choi, M. Y., Kim, H. J.
The molecular dynamics (MD) simulation study of solvation structure and free energetics in 1-ethyl-3-methylimidazolium chloride and 1-ethyl-3-methylimidazolium hexafluorophosphate using a probe...
Jeong, Daun, Choi, M. Y., Park, Hyunggyu
We consider the Ising model on a small-world network, where the long-range interaction strength $J_2$ is in general different from the local interaction strength $J_1$, and examine its relaxation...
Scale-free dynamics emerging from information transfer (2004)
Choi, M. Y., Kim, B. J., Park, H.
The dynamics based on information transfer is proposed as an underlying mechanism for the scale-invariant dynamic critical behavior observed in a variety of systems. We apply the dynamics to the...
Dynamic transition and Shapiro-step melting in a frustrated Josephson-junction array (2004)
Lim, J. S., Choi, M. Y., Choi, J., Kim, B. J.
We consider a two-dimensional fully frustrated Josephson-junction array driven by combined direct and alternating currents. Interplay between the mode locking phenomenon, manifested by giant Shapiro...
Hong, H., Park, Hyunggyu, Choi, M. Y.
We study collective behavior of locally coupled limit-cycle oscillators with random intrinsic frequencies, spatially extended over $d$-dimensional hypercubic lattices. Phase synchronization as well...
Dynamic model of fiber bundles (2004)
A realistic continuous-time dynamics for fiber bundles is introduced and studied both analytically and numerically. The equation of motion reproduces known stationary-state results in the...
Factors that predict better synchronizability on complex networks (2004)
Hong, H., Kim, Beom Jun, Choi, M. Y., Park, Hyunggyu
While shorter characteristic path length has in general been believed to enhance synchronizability of a coupled oscillator system on a complex network,the suppressing tendency of the heterogeneity of...
Phase Transitions in Models for Coupled Charge-Density Waves (2004)
Lee, Minchul, Kim, Eun-Ah, Lim, Jong Soo, Choi, M. Y.
Various phase transitions in models for coupled charge-density waves are investigated by means of the $\epsilon$-expansion, mean-field theory, and Monte Carlo simulations. At zero temperature the...
Stiles, P. L., Choi, M. Y, Miller, R. E.
Author Institution: Department of Chemistry, The University of North Carolina at Chapel Hill
Collective phase synchronization in locally-coupled limit-cycle oscillators (2003)
Hong, H., Park, Hyunggyu, Choi, M. Y.
We study collective behavior of locally-coupled limit-cycle oscillators with scattered intrinsic frequencies on $d$-dimensional lattices. A linear analysis shows that the system should be always...
Correspondences and Quantum Description of Aharonov-Bohm and Aharonov-Casher Effects (2003)
We establish systematic consolidation of the Aharonov-Bohm and Aharonov-Casher effects including their scalar counterparts. Their formal correspondences in acquiring topological phases are revealed...
Stability and ensemble inequivalence in a globally coupled system (2003)
We consider a system of globally coupled rotors, described by a set of Langevin equations, and examine stability of the incoherent phase. The corresponding Fokker-Planck equation, providing a unified...
Quantum and classical diffusion in small-world networks (2003)
Kim, Beom Jun, Hong, H., Choi, M. Y.
We study numerically quantum diffusion of a particle on small-world networks by integrating the time-dependent Schr\"odinger equation with a localized initial state. The participation ratio, which...
Jeong, Daun, Hong, H., Kim, Beom Jun, Choi, M. Y.
We study the collective behavior of an Ising system on a small-world network with the interaction $J(r) \propto r^{-\alpha}$, where $r$ represents the Euclidean distance between two nodes. In the...
Frequency resonance in Josephson-junction arrays under strong driving (2003)
Lim, Jong Soo, Choi, M. Y., Kim, Beom Jun
We study resonance behavior of a two-dimensional fully frustrated Josephson-junction array driven by high alternating currents. The signal-to-noise ratio (SNR) is examined as the frequency of the...
Netons: Vibrations of Complex Networks (2003)
Kim, Beom Jun, Hong, H., Choi, M. Y.
We consider atoms interacting each other through the topological structure of a complex network and investigate lattice vibrations of the system, the quanta of which we call {\em netons} for...
Quantum Phase Transitions and Persistent Currents in Josephson-Junction Ladders (2003)
Lee, Minchul, Choi, Mahn-Soo, Choi, M. Y.
In this work we study quantum phase transitions and persistent currents in capacitively coupled one-dimensional Josephson-junction arrays. We will focus particularly on the roles of exciton-like...
Optimal Size of a Complex Network (2003)
Hong, H., Kim, Beom Jun, Choi, M. Y.
We investigate the response behavior of an Ising system, driven by an oscillating field, on a small-world network, with particular attention to the effects of the system size. The responses of the...
Relaxation and Coarsening Dynamics in Superconducting Arrays (2002)
Jeon, Gun Sang, Lee, Sung Jong, Choi, M. Y.
We investigate the nonequilibrium coarsening dynamics in two-dimensional overdamped superconducting arrays under zero external current, where ohmic dissipation occurs on junctions between...
Autonomous stochastic resonance in fully frustrated Josephson-junction ladders (2002)
We investigate autonomous stochastic resonance in fully frustrated Josephson-junction ladders, which are driven by uniform constant currents. At zero temperature large currents induce oscillations...
Kim, Beom Jun, Trusina, Ala, Holme, Petter, Minnhagen, Petter, Chung, Jean S., Choi, M. Y.
A two-dimensional small-world type network, subject to spatial prisoners' dilemma dynamics and containing an influential node defined as a special node with a finite density of directed random links...
Lee, Minchul, Jeon, Gun Sang, Choi, M. Y.
We consider interacting electrons in a two-dimensional quantum Coulomb glass and investigate by means of the Hartree-Fock approximation the combined effects of the electron-electron interaction and...
Dynamic transition and resonance in current-driven arrays of Josephson junctions (2002)
Jeon, Gun Sang, Lim, Jong Soo, Kim, Hyun Jin, Choi, M. Y.
We consider a two-dimensional fully frustrated Josephson-junction array, which is driven uniformly by oscillating currents. As the temperature is lowered, there emerges a dynamic phase transition to...
Stochastic resonance in the driven Ising model on small-world networks (2002)
Hong, H., Kim, Beom Jun, Choi, M. Y.
We investigate the stochastic resonance phenomena in the field-driven Ising model on small-world networks. The response of the magnetization to an oscillating magnetic field is examined by means of...
Jeon, Gun Sang, Kim, Hyun Jin, Choi, M. Y., Kim, Beom Jun, Minnhagen, Petter
We investigate dynamic transitions and stochastic resonance phenomena in two-dimensional fully frustrated Josephson-junction arrays driven by staggered oscillating magnetic fields. As the temperature...
Comment on "Ising model on a small world network" (2002)
Hong, H., Kim, Beom Jun, Choi, M. Y.
In the recent study of the Ising model on a small-world network by A. P\c{e}kalski [Phys. Rev. E {\bf 64}, 057104 (2001)], a surprisingly small value of the critical exponent $\beta \approx 0.0001$...
Phase ordering on small-world networks with nearest-neighbor edges (2002)
Hong, H., Choi, M. Y., Kim, Beom Jun
We investigate global phase coherence in a system of coupled oscillators on a small-world networks constructed from a ring with nearest-neighbor edges. The effects of both thermal noise and quenched...
Spontaneous phase oscillation induced by inertia and time delay (2001)
Hong, H., Jeon, Gun Sang, Choi, M. Y.
We consider a system of coupled oscillators with finite inertia and time-delayed interaction, and investigate the interplay between inertia and delay both analytically and numerically. The phase...
Synchronization on small-world networks (2001)
Hong, H., Choi, M. Y., Kim, Beom Jun
We investigate collective synchronization in a system of coupled oscillators on small-world networks. The order parameters which measure synchronization of phases and frequencies are introduced and...
XY model in small-world networks (2001)
Kim, Beom Jun, Hong, H., Holme, Petter, Jeon, Gun Sang, Minnhagen, Petter, Choi, M. Y.
The phase transition in the XY model on one-dimensional small-world networks is investigated by means of Monte-Carlo simulations. It is found that long-range order is present at finite temperatures,...
Double stochastic resonance peaks in systems with dynamic phase transitions (2001)
Kim, Beom Jun, Minnhagen, Petter, Kim, Hyun Jin, Choi, M. Y., Jeon, Gun Sang
To probe the connection between the dynamic phase transition and stochastic resonance, we study the mean-field kinetic Ising model and the two-dimensional Josephson-junction array in the presence of...
Topological interpretation of subharmonic mode locking in coupled oscillators with inertia (2001)
A topological argument is constructed and applied to explain subharmonic mode locking in a system of coupled oscillators with inertia. Via a series of transformations, the system is shown to be...
Topological quantization and degeneracy in Josephson-junction arrays (2001)
We consider the conductivity quantization in two-dimensional arrays of mesoscopic Josephson junctions, and examine the associated degeneracy in various regimes of the system. The filling factor of...
Spatiotemporal Stochastic Resonance in Fully Frustrated Josephson Ladders (2000)
Kim, Beom Jun, Choi, Mahn-Soo, Minnhagen, Petter, Jeon, Gun Sang, Kim, H. J., Choi, M. Y.
We consider a Josephson-junction ladder in an external magnetic field with half flux quantum per plaquette. When driven by external currents, periodic in time and staggered in space, such a fully...
Renormalization-group study of gate charge effects in Josephson-junction chains (2000)
Choi, M. Y., Rhee, Sung Wu, Lee, Minchul, Choi, J.
We study the quantum phase transition in a chain of superconducting grains, coupled by Josephson junctions, with emphasis on the effects of gate charges induced on the grains. At zero temperature the...
Intrinsic finite-size effects in the two-dimensional XY model with irrational frustration (2000)
Park, Sung Yong, Choi, M. Y., Kim, Beom Jun, Jeon, Gun Sang, Chung, Jean S.
This study investigates in detail the finite-size scaling of the two-dimensional irrationally frustrated XY model. By means of Monte Carlo simulations with entropic sampling, we examine the size...
Phase synchronization and noise-induced resonance in systems of coupled oscillators (2000)
We study synchronization and noise-induced resonance phenomena in systems of globally coupled oscillators, each possessing finite inertia. The behavior of the order parameter, which measures...
Boundary Effects on Dynamic Behavior of Josephson-Junction Arrays (2000)
Choi, M. Y., Jeon, Gun Sang, Yoon, Mina
The boundary effects on the current-voltage characteristics in two-dimensional arrays of resistively shunted Josephson junctions are examined. In particular, we consider both the conventional...
Lattice effects on the current-voltage characteristics of superconducting arrays (1999)
Yoon, Mina, Choi, M. Y., Kim, Beom Jun
The lattice effects on the current-voltage characteristics of two-dimensional arrays of resistively shunted Josephson junctions are investigated. The lattice potential energies due to the discrete...
Synchronization in a System of Globally Coupled Oscillators with Time Delay (1999)
Choi, M. Y., Kim, H. J., Kim, D., Hong, H.
We study the synchronization phenomena in a system of globally coupled oscillators with time delay in the coupling. The self-consistency equations for the order parameter are derived, which depend...
Synchronization and resonance in a driven system of coupled oscillators (1999)
Hong, H., Choi, M. Y., Park, K.
We study the noise effects in a driven system of globally coupled oscillators, with particular attention to the interplay between driving and noise. The self-consistency equation for the order...
Charge Frustration Effects in Capacitively Coupled Two-Dimensional Josephson-Junction Arrays (1999)
Lee, Minchul, Choi, Mahn-Soo, Choi, M. Y.
We investigate the quantum phase transitions in two capacitively coupled two-dimensional Josephson-junction arrays with charge frustration. The system is mapped onto the S=1 and $S=1/2$ anisotropic...
Phase Transition in the Two-Dimensional Gauge Glass (1999)
The two-dimensional XY gauge glass, which describes disordered superconducting grains in strong magnetic fields, is investigated, with regard to the possibility of a glass transition. We compute the...
Park, Sung Yong, Lee, Ji-Woo, Cha, Min-Chul, Choi, M. Y., Kim, B. J., Kim, Doochul
We study the zero-temperature phase transitions of a two-dimensional disordered boson Hubbard model at incommensurate boson densities. Via matrix diagonalization and quantum Monte Carlo simulations,...
Quantum phase transitions in superconducting arrays under external magnetic fields (1998)
Kim, Beom Jun, Jeon, Gun Sang, Choi, M. Y.
We study the zero-temperature phase transitions of two-dimensional superconducting arrays with both the self- and the junction capacitances in the presence of external magnetic fields. We consider...
Current responses and voltage fluctuations in Josephson-junction systems (1998)
Choi, Mahn-Soo, Choi, M. Y., Lee, Sung-Ik
We consider arrays of Josephson junctions as well as single junctions in both the classical and quantum-mechanical regimes, and examine the generalized (frequency-dependent) resistance, which...
Choi, Mahn-Soo, Choi, M. Y., Choi, Taeseung, Lee, Sung-Ik
We investigate the quantum phase transitions in two capacitively coupled chains of ultra-small Josephson-junctions, with emphasis on the external charge effects. The particle-hole symmetry of the...
Woo, J. C., Kim, W. S., Ko, H. S., Leem, Y. A., Kim, Y. S., Kim, D. S., ...
In Zeeman spectra of a GaAs-AlGaAs quantum wire array with superlattice period lp, the zero-field shift is found to increase in steps of (2 pi hbar/ e)lp^{-2} at the cyclotron radius Rc ~lp, lp/2,...
Choi, Mahn-Soo, Choi, M. Y., Lee, Sung-Ik
We consider two chains of ultrasmall Josephson junctions, coupled capacitively with each other, and investigate the transport of particle-hole pairs and the quantum phase transitions at zero...
Genetic Polymorphism in Evolving Population (1998)
Lee, H. Y., Kim, D., Choi, M. Y.
We present a model for evolving population which maintains genetic polymorphism. By introducing random mutation in the model population at a constant rate, we observe that the population does not...
Quantum Phase Transitions in Josephson Junction Chains (1997)
Choi, Mahn-Soo, Yi, J., Choi, M. Y., Choi, J.
We investigate the quantum phase transition in a one-dimensional chain of ultra-small superconducting grains, considering both the self- and junction capacitances. At zero temperature, the system is...
Dissipative Dynamics of Quantum Vortices in Superconducting Arrays (1997)
Choi, Mahn-Soo, Lee, Sung-Ik, Choi, M. Y.
We consider a two-dimensional array of ultra-small superconducting grains, weakly coupled by Josephson junctions with large charging energy. We start from an effective action based on a microscopic...
Anomalous Relaxation in the XY Gauge Glass (1997)
Kim, Beom Jun, Choi, M. Y., Ryu, S., Stroud, D.
To study relaxation dynamics of the two-dimensional XY gauge glass, we integrate directly the equations of motion and investigate the energy function. As usual, it decays exponentially at high...
Quantum Phase Transitions in Superconducting Arrays with General Capacitance Matrices (1997)
Kim, Beom Jun, Kim, Jeenu, Park, Sung Yong, Choi, M. Y.
We investigate quantum phase transitions in two-dimensional superconducting arrays with general capacitance matrices and discrete charge states. We use the perturbation theory together with the...
Coulomb Gaps in One-Dimensional Spin-Polarized Electron Systems (1996)
Jeon, Gun Sang, Choi, M. Y., Yang, S. -R. Eric
We investigate the density of states (DOS) near the Fermi energy of one-dimensional spin-polarized electron systems in the quantum regime where the localization length is comparable to or larger than...
Entropic Sampling and Natural Selection in Biological Evolution (1996)
Choi, M. Y., Lee, H. Y., Kim, D., Park, S. H.
With a view to connecting random mutation on the molecular level to punctuated equilibrium behavior on the phenotype level, we propose a new model for biological evolution, which incorporates random...
Optimal storage capacity of neural networks at finite temperatures (1993)
Shimi, G. M., Kim, D., Choi, M. Y.
Gardner's analysis of the optimal storage capacity of neural networks is extended to study finite-temperature effects. The typical volume of the space of interactions is calculated for...
Choi, M. Y., Park, I. K., Yu, Y. S.
BACKGROUND/AIMS—A longitudinal study of premature infants was conducted to examine changes in refractive status and their relation with age and factors influencing the occurrence and degree of...
Effect of ADCON-L on adjustable strabismus surgery in rabbits
Choi, M. Y., Auh, S., Choi, D. G., Chang, B. L.
BACKGROUND/AIMS—In search of a way to prevent postoperative adhesion after strabismus surgery, an animal study was performed to assess the effect of a gel consisting of a polyglycan ester in a...
Choi, M. Y., Lee, K., Hwang, J., Choi, D. G., Lee, D. S., Park, K. H., ...
AIMS—To assess calcarine activation with functional magnetic resonance imaging (fMRI) in patients with anisometropic and strabismic amblyopia. METHODS—14 amblyopes (eight anisometropic and six...