• Bulletin of the Korean Chemical Society
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• v.22 no.3
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• pp.253-254
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• 2001

• Journal of Mechanical Science and Technology
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• v.18 no.12
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• pp.2104-2113
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• 2004

Surface degreasing method with premixed flame is proposed as the removal method of adherent impurities on materials. Effects of adherent molecular thickness and surface potential energy on evaporation rate of adherent molecules and molecular evaporation mechanism were investigated and discussed in the present study. Evaporation processes of adherent molecules on surface molecules were simulated by the molecular dynamics method to understand thermal phenomena on evaporation processes of adherent molecules by using high temperature gas like burnt gas. The calculation system was composed of a high temperature gas region, an adherent molecular region and a surface molecular region. Both the thickness of adherent molecules and potential parameters affceted the evaporation rate of adherent molecules and evaporation mechanism in molecular scale.

• Bulletin of the Korean Chemical Society
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• v.24 no.1
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• pp.95-98
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• 2003

Enantioselectivity of the propranolol on β-cyclodextrin was simulated by molecular modeling. Monte Carlo (MC) docking and molecular dynamics (MD) simulations were applied to investigate the molecular mechanism of enantioselective difference of both enantiomeric complexes. An energetic analysis of MC docking simulations coupled to the MD simulations successfully explains the experimental elution order of propranolol enantiomers. Molecular dynamics simulations indicate that average energy difference between the enantiomeric complexes, frequently used as a measure of chiral recognition, depends on the length of the simulation time. We found that, only in case of much longer MD simulations, noticeable chiral separation was observed.

• International Journal of Automotive Technology
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• v.7 no.2
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• pp.121-128
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• 2006

The interaction between adherent molecules and gas molecules was modeled in the molecular scale and simulated by the molecular dynamics method in order to understand evaporation and removal processes of adherent molecules on metallic surface using high temperature gas flow. Methanol molecules were chosen as adherent molecules to investigate effects of adhesion quantity and gas molecular collisions because the industrial oil has too complex structures of fatty acid. Effects of adherent quantity, gas temperature, surface temperature and adhesion strength for the evaporation rate of adherent molecules and the molecular removal mechanism were investigated and discussed in the present study. Evaporation and removal rates of adherent molecules from metallic surface calculated by the molecular dynamics method showed the similar dependence on the surface temperature shown in the experimental results.

• Proceeding of EDISON Challenge
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• 2015.03a
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• pp.163-166
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• 2015

Intramolecular energy migration in a cyclic porphyrin array is spontaneous transfer of energy from one excited site to another. Since the efficiency of energy migration is inversely proportional to distance, the energy migration is occurred on their adjacent sites more often than distant ones. Therefore, the energy migration in the cyclic porphyrin array is largely dependent on their conformational characters. However, evaluation of conformational information by means of experimental tools is ambiguous since their limited resolution. In this work, we calculate the internal angle and distance distributions of cyclic porphyrin arrays using molecular dynamics simulations to obtain conformational information. To evaluate the angle and distance distributions respect to molecular size, we constructed molecules with n porphyrin dimers (n=1,3,7) in implicit solvent environment. Performing molecular dynamics simulations, we modulated alkyl groups to investigate additional conformational effects of the system.

• Journal of the Korean institute of surface engineering
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• v.39 no.2
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• pp.76-81
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• 2006

Molecular dynamics simulations were carried out to investigate physical sputtering of Fe(100) substrate due to energetic ion bombardments. Repulsive interatomic potentials at short internuclear distances were determined with ab initio calculations using the density functional theory. Bohr potentials were fitted to the ab initio results on diatomic pairs (Ar-Fe, Fe-Fe) and used as repulsive screened Coulombic potentials in sputtering simulations. The fitted-Bohr potentials improve the accuracy of the sputtering yields predicted by molecular dynamics for sputtering of Fe(100), whereas Moliere and ZBL potentials were found to be too repulsive and gave relatively high sputtering yields. In spite of assumptions and limitations in this simulation work, the sputtering yields predicted by the molecular dynamics method were in fairly good accordance with the obtainable experimental data in absolute values as well as in manner of the variation according to the Incident energy. Threshold energy for sputtering of Fe(100) substrate was found to be about 40 eV. Additionally, distributions of kinetic energies of sputtered atoms and their original depths could be obtained.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1928-1933
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• 2008

In this paper, elastic properties such as Young's modulus and Poisson's ratio of various transition metal nanofilms are calculated for the {100} and {110} surfaces by using molecular dynamics simulation. A new method using $3^{rd}$ order elastic constants and least square method is presented for the calculation of elastic constants. We also introduce analytical method of calculating elastic constants for EAM potential and it's results as the reference value to be compared with the simulation results.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.1139-1144
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• 2003

This paper addresses a theoretical study to calculate the amount of the stored energy due to vacancies during high-strain-rate deformation. The study concerns the role of excess vacancies, which can play an important role to increase the amount of stored energy. Molecular dynamics simulation using a 3D model is carried out and the result clearly shows that the excess vacancies are credited to generation of the stored energy.

• Proceedings of the Korean Society of Life Science Conference
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• 2006.09a
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• pp.29.2-29.2
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• 2006

• Transactions of Materials Processing
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• v.14 no.4 s.76
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• pp.319-326
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• 2005

In this study, the nano-deformation behavior of semi-solid Al-Si alloy was investigated using a molecular dynamics simulation as a part of the research on the surface crack behavior in thixoformed automobile parts. The microstructure of the grain-size controlled Al-Si alloy consists of primary and eutectic regions. In eutectic regions the crack initiation begins with initial fracture of the eutectic silicon particles and inside other intermetallic phases. Nano-deformation characteristics in the eutectic and primary phase of the grain-size controlled Al-Si alloy were investigated through the molecular dynamics simulation. The primary phase was assumed to be single crystal aluminum. It was shown that the vacancy occurred at the zone where silicon molecules were.