분자 전산 모사의 van der Waals 인력 포텐셜

서숭혁 啓明大學校 産業技術硏究所 1996 産業技術硏究所 論文報告集 Vol.19 No.1

In this paper, we have shown that commonly used Lennard-Jones and Exp-6 potentials in molecular simulations failed to account for the high quality rare-gas data. It was found that a relatively simple potential based on the distance-buffered interaction accurately reproduced the rate-gas potentials over the wide range of interatomic separations. For the unlike pair potentials, the standard arithmetic and geometric mean combination rules performed poorly, and the alternative combination rule performed significantly via the cubic mean and HHG approximation for minimum energy separation R*ij and well depth ξij.

Li-X형 제올라이트에 흡착된 기체 분자의 Monte Carlo 전산 모사 연구

서숭혁,이윤태 啓明大學校 産業技術硏究所 1996 産業技術硏究所 論文報告集 Vol.19 No.1

In this paper, grand canonical ensemble Monte Carlo simulation have been carried out to investigate the adsorption and structural properties of nitrogen and oxygen molecule adsorbed in Li-X zeolite systems. The adsorption isotherm, energy distribution curves and mass density profiles are computed over a wide range of temperatures and bulk pressures. For bulk pressure conditions employed in this work, the adsorption capabilities of nitrogen is consistently greater than those of oxygen mainly due to the larger quadrupole moment on nitrogen interacted with lithium cations. Nitrogen molecules display considerable localization near the adsorption sites of lithium cations, while oxygen molecules diffuse throughout zeolite cavities. Separation factors are also calculated for the mixture compositions of N₂/O₂and the resulting values in the range 6 to 14 are found to be higher comparing with 3.0 to 3.5 for the systems of zeolite 5A or 13X.

경주산 규조토를 이용한 비실리카겔 흡습제에 관한 연구

서숭혁,이해룡 啓明大學校 産業技術硏究所 1993 産業技術硏究所 論文報告集 Vol.16 No.2

The water-vapor adsorption capacities of desiccants were investigated over a wide range of pre-calcined temperatures, screened particle-sizes, and relative humidities. Natural porous diatomites, currently produced in Kyungju, Kyungpook area, were used as moisture sorbents. Under all relative humidities conditions employed in this work, the moisture adsorption capacities of diatomite desiccants were shown to be better than those obtained from silica-gel desiccants. The silica-gel desiccants arrived at saturated equilibrium in relatively short time less than 10 hours, while the diatomite desiccants exhibited the continous moisture adsorption even after 40 hours due to the capillary condensation effects. The amount of adsorbed moistures were increased with increasing pre-calcined temperature up to 800˚C. Above this temperature, however, the structural change to cristobalite phase significantly led to the decrement of adsorption rate.

일차원적 연결 구형 세공에 관한 분자 전산 모사

서숭혁 啓明大學校 産業技術硏究所 1997 産業技術硏究所 論文報告集 Vol.20 No.-

Molecular dynamics simulations have been carried out to investigate the Knudsen diffusion properties for the non-adsorbed, collisionless molecules confined within the one-dimensional model pore system, namely, the sequentially linked spherical pore. Simulation results were used to evaluate various theoretical calculations appeared in the literature including the random walk approximation, the radiating disc method, and the molecular path tracing method. A latter theory, in comparison with simulation results, has proven to be successful to qualitatively and quantitatively predict the diffusion coefficient in the Knudsen regime over the entire ranges of the pore cross-sectional variations in such a model system.

Vectorization and Optimization of Molecular Dynamics Programs Using the Cray-2 Supercomputer

徐崇爀 계명대학교 산업기술연구소 1992 産業技術硏究所 論文報告集 Vol.15 No.2

The highly optimized and vectorized algorithm for molecular dynamics simulations recently proposed by Brode and Ahlrichs is applied to the systems interacting though the Lennard-Jones 12-6 pair potential. The Cray-2 vectorized version is shown to be efficient for the small system of less than 1,000 particles. For example, 45% reduction of the total CPU time is achieved for the system of 108 particles and 10% for 864 particles, respectively, by comparing with those obtained from the conventional vectorized codes on the same computer.

분무형 표면 보호 피막제 특성 연구

이해룡,서숭혁 啓明大學校 産業技術硏究所 1998 産業技術硏究所 論文報告集 Vol.21 No.2

The spray-type protective coating film has been developed and applied for alumina, glass, wooden, and metal structures to extend the protection against the elements that cause structural corrosion and degradation. We describe the characteristics of selecting and testing additives as well as sensitivities to variations in selecting the start formulation. The product formulation is obtained by blending the theoretical together with the practical in solvent-based applications. From a commercial view point, this durable film method can effectively provide the first line of defense for complex structural shape as a barrier to the effects of water, oxygen, pollutants and microorganisms.

Cu(100) 표면에 충격된 불활성 이온의 산란 특성에 관한 분자 전산 연구

민웅기,박상훈,서숭혁 한국화학공학회 2003 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.41 No.1

본 연구에서는 초기 충격에너지 100eV에서 1,600eV 범위의 He, Ne, Ar, Kr, Xe 등을 포함란 다양한 충돌원자 이온을 Cu(100)표면에 수직으로 주사시켜 산란 특성을 조사하는 분자 동력학적 잔산 모의실험을 수행하여 충돌 이온의 에너지 및 질량 변화에 따른 산란 이온의 에너지 변화, 방향성에 관한 분포 특성 등을 분자 차원에서 고찰하였다. 상대 질량이 작은 He와 Ne 이온들의 경우 주사 에너지에 대한 평균 산란 에너지비는 이원자 강체 충돌 효과에 근거한 이론식에 근접하는 것으로 나타났다. 반면, 상대 질량이 큰 Ar, Kr, Xe 이온들의 경우 초기 충돌 에너지가 작을 때 산란 특성은 첫 번째 및 두 번째 층의 Cu 원자와 다중 충돌 효과가 주된 충돌 특성임을 보였다. 초기 충돌 에너지 및 충격 이온의 질량이 증가할수록 산란 에너지 및 확률 분포는 보다 좁은 것으로 나타났다. 한편, 길이각 및 방위각에 따른 방향성 분포 특성은 상대 질량이 작은 경우 무관한 분포 특성을 나타내었으나 상대 질량이 큰 경우 길이 방향에 대하여 제한적인 방향성을 나타내었다. In this study, molecular dynamics simulations have been carried out to investigate the scattering properties of impacted ions on Cu(100) surfaces with the normal incident angle for various noble gas atoms including He, Ne, Ar, Kr and Xe. The initial kinetic energy of the projectile atoms was ranged from 100eV to 1,600eV. The simulation results are focused upon the scattering energy variations and angel dependencies according to the incident energy and the projectile mass. For light atoms(He and Ne), the ratio of the scattered to the incident projectile energy was in a good agreement with the theoretical prediction based on the binary collision approximation. However, in the low energy regime, the scattering trajectories of heavy atoms(Ar. Kr and Xe) were characterized by the multiple collisions with the top and the second layer surfaces. With increasing the initial kinetic energy and the projectile mass, the scattering energy and the probability distribution were shown to be sharp and narrow. The angle dependencies of both longitudinal and azimuthal directions were not significant for light projectiles, while the longitudinal angel dependencies on the scattering distribution were indicated for heavy progectiles.

" The Korean Journal of Chemical Engineering " 게재 논문 요약 : Thermodynamic and Structural Properties of Hard - Sphere Fluids Confined within a Spherical Hard Wall Pore

Soong Hyuck Suh,Heai Ku Park 한국화학공학회 1994 NICE Vol.12 No.5

N/A The grand canonical ensemble Monte Carlo simulation have been carried out to investigate he thermodynamic and structural properties of hard-sphere fluids confined within a spherical hard-wall pore. Equilibrium partition coefficients and pore density profiles are computed over a wide range of particle-to-pore size ratios and concentrations distributing between an external bulk phase and a pore phase. The simulation data for equilibrium partitioning are used bo assess the limitations and applicabilities of theoretical approximations including the virial expansion equation and the extended two-state prediction. The Monte Carlo results obtained in these studies, in conjunction with the theoretical models, provide the basis for a discussion on the steric effects in size-exclusion partitioning of such systems.

A Modified Enskog-Like Equation of Self-Diffusion Coefficients for Penetrable-Sphere Model Fluids

Soong-Hyuck Suh,Hong-Lai Liu 대한화학회 2011 Bulletin of the Korean Chemical Society Vol.32 No.4

Molecular dynamics simulations have been performed to investigate the transport properties of self-diffusion coefficients in the penetrable-sphere model system. The resulting simulation data for the product of the packing fraction and the self-diffusion coefficient exhibit a transition from an increasing function of density in lower repulsive systems, where the soft-type collisions are dominant, to a decreasing function in higher repulsive systems, where most particle collisions are the hard-type reflections due to the low-penetrability effects. A modified Enskog-like equation implemented by the effective packing fraction with the mean-field energy correction is also proposed, and this heuristic approximation yields a reasonably good result even in systems of high densities and high repulsive energy barriers.

Research Papers : Simulation Studies of Nearest-Neighbor Distribution Functions and Related Structural Properties for Hard-Sphere Systems

( Soong Hyuck Suh ),( Woong Ki Min ),( Viorel Chihaia ),( Jae Wook Lee ),( Soon Chul Kim ) 한국화학공학회 2000 Korean Journal of Chemical Engineering Vol.17 No.3