Chi-Ok Hwang

Bio: Chi-Ok Hwang is an academic researcher from Gwangju Institute of Science and Technology. The author has contributed to research in topics: Monte Carlo method & Kinetic Monte Carlo. The author has an hindex of 13, co-authored 52 publications receiving 379 citations. Previous affiliations of Chi-Ok Hwang include Soongsil University & Inha University.

Six-state clock model on the square lattice: fisher zero approach with Wang-Landau sampling.

Abstract: We investigate the six-state clock model with nearest-neighbor interactions on the square lattice. We obtain the density of states of the finite systems up to $L=28$ using the Wang-Landau sampling. With the density of states and the Fisher zero approach, we successfully find two different critical temperatures 0.632(2) and 0.997(2) for the clock model. It seems that this study supports the recent results by [Lapilli et al.Phys. Rev. Lett. 96, 140603 (2006)] that the transitions are not of Kosterlitz and Thouless type.

First- and last-passage Monte Carlo algorithms for the charge density distribution on a conducting surface.

Abstract: Recent research shows that Monte Carlo diffusion methods are often the most efficient algorithms for solving certain elliptic boundary value problems. In this paper, we extend this research by providing two efficient algorithms based on the concept of "last-passage diffusion." These algorithms are qualitatively compared with each other (and with the best first-passage diffusion algorithm) in solving the classical problem of computing the charge distribution on a conducting disk held at unit voltage. All three algorithms show detailed agreement with the known analytic solution to this problem.

Electrical capacitance of the unit cube

Abstract: It is well known that there is no analytical expression for the electrical capacitance of a cube, even though it has been claimed that one can compute this capacitance numerically to high precision. However, there have been some disparities between reported numerical results of the capacitance of the unit cube. In this article, the “walk on planes” (WOP) algorithm [M. L. Mansfield, J. F. Douglas, and E. J. Garboczi, Phys. Rev. E 64, 061401 (2001)] is used to compute the capacitance of the unit cube. With WOP, we remove the error from the e-absorption layer commonly used in “walk on spheres” computations so that there is no inherent error introduced in these WOP computations except the intrinsic Monte Carlo sampling error of size O(N1/2). This WOP technique comes from the isomorphism, provided by probabilistic potential theory, between the electrostatic Dirichlet problem on a conducting surface, and the corresponding Brownian motion first-passage expectation. The numerical result we obtain with WOP, 0.660 ...

Lectures on Theoretical Physics

Abstract: Vorlesungen uber theoretische Physik Von Prof. Arnold Sommerfeld. Band 1: Mechanik. Vierte, neubearbeitete Auflage. Pp. xii + 276. 18 D. marks. Band 2: Mechanik der deformierbaren Medien. Pp. xv + 376 + 4 plates. 18 D. marks. Band 3: Elektrodynamik. Pp. xvi + 368. 18 D. marks. Band 6: Partielle Differentialgleichungen der Physik. Pp. xiii + 332. 18 D. marks. (Wiesbaden: Dieterich'sche Verlagsbuchhandlung, 1947–1949.)

Methods in membrane lipids

Abstract: Methods in Membrane Lipids: Table of Contents Introductory Chapters: 1 A glance at the structural and functional diversity of membrane lipids Alejandro M. Dopico and Gabor J. Tigyi 2 Membrane lipid polymorphism: relationship to bilayer properties and protein function Richard Epand Lipid distribution, membrane lipid structure, and lipid-lipid interactions: 3 Acrylodan-labeled intestinal fatty acid binding protein to measure concentrations of unbound fatty acids Jeffrey R. Simard, Frits Kamp, and James A. Hamilton 4 Measuring molecular order and orientation using Coherent-anti Stokes Raman scattering microscopy Hilde A. Rinia, George W.H. Wurpel, and Michiel Muller 5 Preparation of oriented, fully hydrated lipid samples for structure determination using X-ray scattering Stephanie Tristram-Nagle 6 Nuclear Magnetic Resonance investigation of oriented lipid membranes Olivier Soubias and Klaus Gawrisch 7 Molecular dynamics simulations as a complement to Nuclear Magnetic Resonance and X-ray diffraction measurements Scott Feller 8 Use of inverse theory algorithms in the analysis of biomembrane Nuclear Magnetic Resonance data Edward Sternin 9 Statistical thermodynamics via computer simulation to characterize phospholipid interactions in membranes Mihaly Mezei and Pal Jedlovszky 10 Fluorometric assay for detection of sterol oxidation in liposomal membranes Parkson L-G. Chong and Michelle Olsher 11 Fluorescence detection of signs of sterol superlattice formation in lipid membranes Parkson L-G. Chong, Berenice Venegas, and Michelle Olsher Characterization of lipid phases: 12 Differential scanning calorimetry in the study of lipid phase transitions in model and biological membranes: practical considerations Ruthven N. A. H. Lewis, David A. Mannock, and Ronald N. McElhaney 13 Pressure-perturbationcalorimetry Heiko Heerklotz 14 Fourier transform infrared spectroscopy in the study of lipid phase transitions in model and biological membranes: practical considerations Ruthven N. A. H.Lewis and Ronald McElhaney 15 Optical dynamometry to study phase transitions in lipid membranes Rumiana Dimova and Bernard Pouligny Lipid movements and diffusion: 16 Fluorescence assays for measuring fatty acid binding and transport through membranes Kellen Brunaldi, Jeffrey R. Simard, Frits Kamp, Charu Rewal, Tanong Asawakarn, Paul O'Shea, and James A. Hamilton 17 Measurement of lateral diffusion rates in membranes by Pulsed Magnetic Field Gradient, Magic Angle-Spinning Proton Nuclear Magnetic Resonance Klaus Gawrisch and Holly Gaede 18 Using Fluorescence Recovery After Photobleaching to measure diffusion in membranes Conrad W. Mullineaux and Helmut Kirchhoff 19 Single molecule fluorescence microscopy to determine phospholipid lateral diffusion Michael J. Murcia, Sumit Garg, and Christoph Naumann 20 Modeling two- and three-dimensional diffusion Michael Saxton 21 Measurement of water and solute permeability by stopped-flow fluorimetry John C. Mathai and Mark L. Zeidel Pressure between lipids, mono- and bilayer lipid curvature and stress: 22 Fluorescence microscopy to study pressure between lipids in giant unilamelar vesicles Anna Celli, Claudia Y.C. Lee, and Enrico Gratton 23 X-ray scattering and solid-state deuterium Nuclear Magnetic Resonance probes of structural fluctuations in lipid membranes Horia I. Petrache and Michael F. Brown 24 Determination of lipid spontaneous curvature from X-ray examinations of inverted hexagonal phases Michael Kozlov 25 Shape analysis of giant vesicles with fluid phase coexistence by laser scanning microscopy to determine curvature, bending elasticity and line tension Samuel T. Hess, M

The Capacitance of Pristine Ice Crystals and Aggregate Snowflakes

Abstract: A new method of accurately calculating the capacitance of realistic ice particles is described: such values are key to accurate estimates of deposition and evaporation (sublimation) rates in numerical weather models. The trajectories of diffusing water molecules are directly sampled, using random ‘walkers’. By counting how many of these trajectories intersect the surface of the ice particle (which may be any shape) and how many escape outside a spherical boundary far from the particle, the capacitance of a number of model ice particle habits have been estimated, including hexagonal columns and plates, ‘scalene’ columns and plates, bullets, bullet-rosettes, dendrites, and realistic aggregate snowflakes. For ice particles with sharp edges and corners this method is an efficient and straightforward way ofsolving Laplace’s equation for the capacitance. Provided that a large enough number of random walkers are used to sample the particle geometry (∼ 10 4 ) the authors expect the calculated capacitances to be accurate to within ∼ 1%. The capacitance for our modelled aggregate snowflakes (C/Dmax = 0.25, normalised by the maximum dimension Dmax) is shown to be in close agreement with recent aircraft measurements of snowflake sublimation rates. This result shows that the capacitance of a sphere (C/Dmax = 0.5) which is commonly used in numerical models, overestimates the evaporation rate of snowflakes by a factor of two. The effect of vapor ‘screening’ by crystals growing in the vicinity of one another has also been investigated. The results clearly show that neighbouring crystals growing on a filament in cloud chamber experiments can strongly constrict the vapor supply to each other, and the resulting growth rate measurements may severely underestimate the rate for a single crystal in isolation (by a factor of 3 in our model setup).