• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.142-142
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• 2012

다양한 In/Si (111) 표면에 PTCDA분자를 흡착하여 일어나는 현상에 대해 STM을 이용하여 실험하였다. PTCDA분자가 $\sqrt{31}{\times}\sqrt{31}$ 표면에서는 강한 표면-분자 상호작용 때문에 배열되지 않고 고립된 분자로 흡착되며 $\sqrt{7}{\times}\sqrt{3}$-hex표면에서는 표면-분자 상호작용이 약하여 분자와 분자 사이의 상호작용으로 수소결합을 통한 2차원 herringbone 구조를 형성한다. 하지만 $4{\times}1$ 표면에서는 수소결합 없이 준 1차원 배열을 형성하며 지금까지 연구된 다른 모든 표면에서 수소결합에 의하여 분자배열을 이루는 것과 대조된다. 이는 $4{\times}1$ 표면에서 표면-분자 사이의 상호작용에 의해 분자배열이 결정되기 때문이다. 또한, Si (111)$-7{\times}7$면 위에 서로 다른 덮힘양의 In 원자를 포함하는$\sqrt{3}{\times}\sqrt{3}$, $2{\times}2$, 그리고 $\sqrt{7}{\times}\sqrt{3}$-hex상이 같이 있는 표면에 PTCDA분자를 흡착할 경우, PTCDA분자의 흡착이 In층 안에서 In 원자를 이동시키면서 국소적으로 in의 덮힘양이 많은 상으로 변화시키는 것을 관찰하였다. PTCDA분자가 In원자를 이동시키는 이유는 상대적으로 약한 In층과의 결합보다는 더 강한 Si (111)표면과의 결합을 위한 것으로 해석된다.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.342-342
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• 2011

방사광을 이용한 흡수스펙트럼으로부터 그래핀 표면 위 TCPP(Tetra(4-carboxyphenyl)porphine) 유기 분자의 흡착구조에 대하여 연구하였다. 순수한 그래핀 표면의 비활성도는 소자응용 분야에 있어 그 영역을 제한할 수 있는 하나의 걸림돌이 되고 있다. 이를 극복하기 위해 유기분자막의 초기 흡착을 이용한 다양한 방법이 시도되어왔다. 그 중 TCPP 분자막을 이용한 그래핀 표면의 기능성 및 그 우수성을 이미 보고한 바 있다. 그러나 그 분자의 흡착구조에 대해 밝혀진 바 없다. 그래핀 표면과 분자간의 흡착 메커니즘 및 분자 상호간의 역학관계는 그 흡착구조의 규명으로부터 얻어질 수 있는데, 본 연구에서는 C 1s K-edge에 대한 NEXAFS 스펙트럼을 이용하여 TCPP 분자가 그래핀과 평행한 방향으로 흡착됨을 알 수 있었다. 이는 또한 분자흡착량의 증가에 따른 AFM 이미지와 일관됨을 알 수 있었다.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.8 no.3
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• pp.474-477
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• 1998

We discuss the surface diffusion process of an adsorbed gas molecules by the method of Markoff probability process and give a relationship between the surface diffusion length and the surface coverage of an adsorbed molecule.

• Journal of the Korean Chemical Society
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• v.8 no.3
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• pp.121-124
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• 1964

Considering the molecular orientation on the first surface layer and applying the significant structure theory of liquid water proposed by the authors in the previous paper, the surface tension of liquid water is calculated for various temperatures which agree well with the observed values.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.41 no.6
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• pp.429-434
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• 2017

A molecular-continuum hybrid method was developed to simulate microscale and nanoscale fluids where continuum fluidics cannot be used to predict Couette flow. Molecular dynamics simulation is used near the solid surface where the flow cannot be predicted by continuum fluidics, and Navier-Stokes equations are used in the other regions. Numerical simulation of Couette flow was performed using the hybrid method to investigate the effect of solid-liquid interaction and surface roughness in a nanochannel. It was found that the solid-liquid interaction and surface roughness influence the boundary condition. When the surface energy is low, slippage occurs near the solid surface, and the magnitude of slippage decreases with increase in surface energy. When the surface energy is high, a locking boundary condition is formed. The roughness disturbs slippage near the solid surface and promotes the locking boundary condition.

• Journal of the Korean Vacuum Society
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• v.17 no.5
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• pp.375-380
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• 2008

We have investigated the low-dimensional nanostructures produced by adsorption of triangular Co coplexed dipyrromethane(DPM-trimer, Fig. 1) on graphite surface by using scanning tunneling microscope. DPM-trimer deposition on the graphite surface leads to the formation of long 1-D molecular wires and 2-D hexagonal patterns. We analyzed the heights and structures of 1-D molecular wires and 2-D hexagonal patterns. The 1-D molecular wires were formed 'edge-on' alignments on graphite surface result of continuos $\pi-\pi$ stacking interactions. The other case of 2-D hexagonal patterns were formed 'face-on' alignments on graphite surface.

• Polymer(Korea)
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• v.28 no.1
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• pp.77-85
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• 2004

It has been widely used ultra high molecular weight polyethylene (UHMWPE) for the biomaterials due to its excellent mechanical properties and biocompatibility. In the case of blend of UHMPE with another polymeric biomaterials, however, UHMWPE might have low blend compatibility due to surface inertness. In this study, in order to improve the mechanical properties of poly(methyl methacrylate) (PMMA) bone cement by means of the impregnation of UHMWPE powder, we developed the novel surface modification method by the mixture of methyl methacrylate (MMA) and xylene. We investigated the variation of composition of MMA/xylene. It was confirmed by the analysis of Fourier transform infrared-attenuated total reflectance, scanning electron microscope, universal transverse mercator, and digital thermometer. The maximum mechanical strength of surface modified UHMWPE powder impregnated PMMA bone cement compound was observed the ratio of 1 : 1 (v/v％) MMA/xylene. Also its curing temperature decreased from 103 $^{\circ}C$ to 58 ∼ 73 $^{\circ}C$ The mechanism of surface modification of UHMWPE powder by the mixture of MMA/xylene has been proposed.

• The KIPS Transactions:PartA
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• v.19A no.2
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• pp.73-76
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• 2012

In this paper, we propose an efficient method to extract surface atoms from a protein molecule. Surface atoms are defined as a set of atoms who can contact given probe solvent $P$, where $P$ does not collide with the molecule. The atoms contained in the molecule are represented as a set of spheres with van der Waals radii. The probe solvent also is represented as a sphere. We propose a method to extract the surface atoms by computing the offset surface of the molecule with respect to the radius of $P$. For efficient computation of the offset surface of a molecule, a voxel map is constructed for the offset surfaces of the spheres. Based on GPU (graphic processor unit) acceleration, a data parallel algorithm is used to extract the surface atoms in 42.87 milliseconds for the molecule containing up to 6,412 atoms.

• The Journal of the Korea Contents Association
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• v.19 no.2
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• pp.277-283
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• 2019

In this study, low molecular weight chitosan (LC) was added to dental cement liquid at 0, 0.5, 1.0, and 2.0 wt% by weight for surface properties and oral bacteria adhesive of dental cement. The evaluated by net setting time and surface properties of surface energy on the surface roughness. The degree of oral bacterial adhesion was assessed using two strains of oral bacteria, S. mutans and E.coli. The results showed that the setting time at the LC0.5 group increased no statistically difference was observed (p<0.05). The surface roughness statically significant LC2.0 group and oral bacteria adhesion experiment results in contrast to the control group LC0, LC-added experimental group showed a somewhat lower adherent surface statistically significant difference was observed (p<0.05). It seems that this LC proved that surface properties and oral bacteria adhesion effect was demonstrated. Therefore, it was suggest that the additional effects of LC and research on a wide range of substances.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2007.04a
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• pp.35-36
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• 2007

고분자는 다양한 산업 분야에 응용되고 있으며, 표면의 기능화 처리로 그 응용 분야를 넓히는 것이 가능하다. 본 연구에서는 고분자 (PC, PET) 표면에 N - (2 - aminoethyl) 3 -aminopropyl trimethoxysilane (AEAPS) 분자막을 Thermal CVD법에 의해 형성시키고, XPS와 수적접 촉각을 이용하여 표면 상태를 측정하였다. 또한, AEAPS 분자막에 Carboxy acid과 Pd 이온의 흡착 실험을 통해 고분자 표면에서의 amino기 작용에 대한 연구를 하였다.