• Journal of Energy Engineering
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• v.23 no.2
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• pp.7-12
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• 2014

Molecular simulation was performed to evaluate the possibility of hydrogen storage of carbon nanotubes. The equilibrium state of hydrogen adsorbed on carbon nanotubes was simulated by grand canonical Monte Carlo method at constant temperature and pressure. The interaction energy between hydrogen molecule and carbon nanotube was calculated by Lennard-Jones potential model. According to the interaction energy calculated, more hydrogen molecules were adsorbed on the inside than the outside of nanotubes. Whereas the adsorption strength was higher outside than inside. Adsorption capacity was investigated for various temperature and pressure. The maximum capacity of carbon nanotube for hydrogen storage was 2.5wt% at 200 K and 200 bar.

• Journal of the Korean Magnetics Society
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• v.19 no.5
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• pp.161-164
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• 2009

The effect of periodic vacancies to the magnetism of the Fe monolayer was investigated by calculating the electronic structures using the full-potential linearized augmented plane wave method within the GGA approximation. We considered four types of vacancies, point defect, I type, + type, and H type which are consisted of one, three, five and seven vacant sites, respectively. We found that the Fe atoms nearest to the vacancy have the largest magnetic moment in each system, and the value of magnetic moment of the atom was increased as the number of vacancy site is increased. The value of the largest magnetic moment in the systems of point defect, I type, + type, and H type are 3.08, 3.09, 3.15, and 3.30 bohr magnetons, respectively.

• Journal of the Korean Chemical Society
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• v.23 no.5
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• pp.271-276
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• 1979

The EHT and CNDO/2 molecular orbital calculations were performed to determine relative stabilities of various conformers of inositol. Our EHT results agree with experimental findings, and correctly predict the destabilizing effect of 1,3-nonbonded interaction of O atoms. In addition, the EHT result show that attractive potential energies between hydroxyl hydrogens and neighboring oxygens are another major factor determining conformational preferences. The inability of CNDO/2 method in predicting correct destabilizing effect of lone pair interaction caused overestimation of stabilization energies for conformers which had 1,3-interactions. The EHT method is superior to the CNDO/2 method for conformational studies of inositols.

• Journal of the Korean Chemical Society
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• v.26 no.4
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• pp.211-217
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• 1982

Assuming krypton molecules adsorbed on the graphite surface as a two-dimensional (2D) gas, 4th virial coefficient of the virial equation is calculated by the use of cluster integrals. The Henry's law constant, and 2nd and 3rd virial coefficients are also calculated. Adsorption isotherms calculated from this virial equation agree very satisfactorily with experimental results. The interaction energy of Kr-graphite surface is calculated assuming the pairwise additivity of Lennard-Jones(12,6) potential, and parametars therein are taken as; ${\varepsilon}_{gs}$/k = 71.1 K, ${\varepsilon}_{gg}$/k = 170 K, ${\sigma}_{gs}$ = 354 pm, and ${\sigma}_{gg}$ = 368 pm.

• Proceeding of EDISON Challenge
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• 2016.03a
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• pp.15-22
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• 2016

분자의 진동(특히, 뒤틀림 운동)은 분자의 반응성과 동역학적 특성을 결정하는 중요한 요인이다. 특히, 분자내 메틸기의 뒤틀림 운동은 매우 흔히 관찰되지만, 이 운동을 분광학 실험으로 관찰하고 이론적으로 설명하는 것은 여전히 어려운 과제이다. 여러 양자화학 소프트웨어가 상용화되어 있지만, 뒤틀림 운동과 같은 주기적인 퍼텐셜 에너지를 갖는 운동을 기술하기 위해서는 뒤틀림 운동을 위한 양자화학 솔버가 필요하다. 따라서, 우리는 EDISON의 양자화학 솔버(1차원 슈레딩거 방정식(LagChem), 작은 유기 분자의 분광스펙트럼 분석을 위한 양자 소프트웨어(SGU-QASSO))들을 이용하여 $2-C_3H_5Br$의 ZEKE/MATI (J.Chem.Phys.119,12351(2003),Zero kinetic energy/mass-analyzed threshold ionization)스펙트럼을 이해하고 해석해보았다. $2-C_3H_5Br$ 분자는 메틸기의 강한 뒤틀림 운동을 관찰 할 수 있는 비교적 간단한 분자이기 때문에 뒤틀림 운동 분석을 위한 실험대상으로 적절하다(J.Chem.Phys.119,12352(2003)). $2-C_3H_5Br$ 분자의ZEKE/MATI스펙트럼의 결과는 EDISON양자화학 솔버를 통해 성공적으로 재현되었다. 각 진동 전이의 진동수와 세기는 실험 결과와 일치했으며, 진동 상태에 따른 파동 함수도 구할수 있었다. 이를 바탕으로 thietane 분자와 같은 고리분자의 ring-puckering운동에 대해 이해하려 한다.

• Journal of the Korean Magnetics Society
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• v.17 no.3
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• pp.109-113
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• 2007

We investigated the magnetic properties of VRu(001) surface by using the all electron full-potenial linearized augmented planewave (FLAPW) energy band method within the GGA. We consider two different configurations, V and Ru surface layers, respectively. The V atoms in surface layer was calculated to have large magnetic moment of $1.71_{{\mu}_B}$ while the Ru surface layer to have nearly nonmagnetic state. The calculated spin-polarized density of states. spin density contour, and charge density were discussed in relation to the magnetic properties of VRu(001) surface.

• Korean Journal of Optics and Photonics
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• v.32 no.3
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• pp.114-119
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• 2021

A large-area graphene sheet has been successfully grown on a copper-foil substrate by chemical vapor deposition (CVD) for industrial use. To screen out unsatisfactory graphene films as quickly as possible, noninvasive optical characterization in reflection geometry is necessary. Based on the optical conductivity of graphene, developed by the single-electron tight-binding method, we have investigated the optical-reflectance contrast. Depending on the four independent control parameters of layer number, chemical potential, hopping energy, and temperature, the optical-reflectance contrast can change dramatically enough to reveal the quality of the grown graphene sheet.

• Journal of the Korean Chemical Society
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• v.25 no.4
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• pp.246-252
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• 1981

Assuming krypton molecules adsorbed on graphite surface as 2D gas, the interaction energy of Kr-graphite and the Henry's constant are calculated analytically by the Fourier series expansion method. 2D virial cofficients, $B_{2D}$ and $C_{2D}$, are also calculated to obtain 2D equation of state, and hence adsorption isotherms. The isotherms so obtained are compared with experimental results reported by Putnam and Fort. The pairwise additivity of Lennard-Jones(12, 6) interaction energy is also assumed, and parameters therein are taken as; ${\varepsilon}_{gs}$/k = 70 K, ${\sigma}_{gs}$ = 0.35 nm, ${\varepsilon}_{gg}$/k = 170 K, and ${\sigma}_{gg}$ = 0.37 nm.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.40 no.3
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• pp.127-136
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• 2003

In this paper, we propose a robust object tracking algorithm based on model and edge, using deformed template and Level-Set theory. The proposed algorithm can track objects in case of background variation, object flexibility and occlusions. First we design a new potential difference energy function(PDEF) composed of two terms including inter-region distance and edge values. This function is utilized to estimate and refine the object shape. The first step is to approximately estimate the shape and location of template object based on the assumption that the object changes its shape according to the affine transform. The second step is a refinement of the object shape to fit into the real object accurately, by using the potential energy map and the modified Level-Set speed function. The experimental results show that the proposed algorithm can track non-rigid objects under various environments, such as largely flexible objects, objects with large variation in the backgrounds, and occluded objects.

• New Physics: Sae Mulli
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• v.68 no.11
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• pp.1183-1191
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• 2018

The plasmon behaviors in a superlattice of $GaAs/Al_xGa_{1-x}As$ multiple quantum wells with a half-parabolic confining potential due to different dielectric interfaces are studied under magnetic and electric fields perpendicular and parallel to the superlattice axis by using a previously published theoretical framework. From the density-density correlation functions by considering the intrasubband and the inter-subband transitions under the random phase approximation, we calculate the dispersion energies of the surface and the bulk states as functions of the composition of the multiple quantum well structure and of the magnetic field strength and the average electric field strength over the quantum well. The Raman intensities for various magnetic field strengths and average electric field strengths over the quantum well are also obtained as a function of the energy of the incoming light for these states.