• Proceedings of the Computational Structural Engineering Institute Conference
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• 2007.04a
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• pp.427-432
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• 2007

In general, the response of bulk material is independent of its size when it comes to considering classical elasticity theory. Because the surface to bulk ratio of the large solids is very small, the influence of surface can be negligible. But the surface effect plays important role as the surface to bulk ratio becomes larger, that is, the contribution of the surface effect must be considered in nano-size elements such as thin film or beam structure. Molecular dynamics computation has been a conventional way to analyze these ultra-thin structures but this method is limited to simulate on the order of $10^6-10^8$ atoms for a few nanoseconds, and besides, very time consuming. Analysis of structures in submicro to micro range(thin-film, wire etc.) is difficult with classical molecular dynamics due to the restriction of computing resources and time. Therefore, in this paper, the continuum-based method is considered to simulate the overall physical and mechanical properties of the structures in nano-scale, especially, for the thin-film.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.1200-1203
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• 2004

We investigated the molecular aligning capability of a polymer layer containing ceramic nanoparticles which can be used as a gate insulator of organic thin-film transistors (OTFTs). Because of the enhanced dielectric properties arising from the nanoparticles and molecular aligning properties of the polymer, the composite layer provides excellent mobility characteristics of the OTFTs.

• Tribology and Lubricants
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• v.38 no.5
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• pp.199-204
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• 2022

This paper presents a numerical investigation of the influence of water molecule thickness on frictional behavior at the nanoscale using molecular dynamics simulation. Three different models, comprising water thin films of various thicknesses, were built, and indentation and sliding simulations were performed using the models. Various normal loads were applied by indenting the Si tip on the water film for the sliding simulation to evaluate the interplay between the water thin film thickness and the normal load. The results of the simulations showed that the friction force generally increased with respect to the normal load and thickness of the water thin film. The friction coefficient varied with respect to the normal load and the water film thickness. The friction coefficient was the smallest under a moderate normal force and increased with decreasing or increasing normal loads. As the water film became thicker, the contact area between the tip and water film became larger. Under well-lubricated conditions, the friction force was proportional to the contact area regardless of the water film thickness. As the normal force increased above a critical condition, the water molecules beneath the Si tip spread out; thus, the film could not provide lubrication. Consequently, the substrate was permanently deformed by direct contact with the Si tip, while the friction force and friction coefficient significantly increased. The results suggest that a thin water film can effectively reduce friction under relatively low normal load and contact pressure conditions. In addition, the contact area between the contacting surfaces dominates the friction force.

• Proceedings of the IEEK Conference
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• 2004.06b
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• pp.383-386
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• 2004

The one of important requisites for fabricating molecular electronic device is the single crystal direction of bottom substrate nowadays. [1,2]. We obtain the optimum SAM result when the Au crystal is <111> structure for Self-Assembled molecular. To get the <111> crystal Au, we generally repeat heating and cooling course after evaporating Au [3]. However, we can fabricate <111> crystal Av thin film except post treatment because we simultaneously evaporate and anneal using Effusion Cell. In this paper, we study on thin film growth of <111> crystal Au as bottom electrode which is essential for Self-Assembled molecular by Effusion Cell and analyze crystal structure, thickness, surface conductivity and so on as each process condition.

• Tribology and Lubricants
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• v.39 no.1
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• pp.8-12
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• 2023

This study presents a molecular simulation of adhesion control between carbon nanotube (CNT) and Ag thin film deposited on silicon substrate. Rough and flat Ag thin film models were prepared to investigate the effect of surface roughness on adhesion force. Heat treatment was applied to the models to modify the adhesion characteristics of the Ag/CNT interface based on thermal wetting. Simulation results showed that the heat treatment altered the Ag thin film morphology by thermal wetting, causing an increase in contact area of Ag/CNT interface and the adhesion force for both the flat and rough models changed. Despite the increase in contact area, the adhesion force of flat Ag/CNT interface decreased after the heat treatment because of plastic deformation of the Ag thin film. The result suggests that internal stress of the CNT induced by the substrate deformation contributes in reduction of adhesion. Contrarily, heat treatment to the rough model increases adhesion force because of the expanded contact area. The contact area is speculated to be more influential to the adhesion force rather than the internal stress of the CNT on the rough Ag thin film, because the CNT on the rough model contains internal stress regardless of the heat treatment. Therefore, as demonstrated by simulation results, the heat treatment can prevent delamination or wear of CNT coating on a rough metallic substrate by thermal wetting phenomena.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.333-333
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• 2006

We synthesized two novel polynorbornene derivatives, chiral poly(norbornene acid methyl ester) (C-PNME) and racemic poly(norbornene acid n-butyl ester) (R-PNME), which are potential low dielectric constant materials for applications in advanced microelectronic and display devices. Thin films of these polymers deposited on substrates were investigated by structural analyses using synchrotron grazing incidence X-ray scattering, specular reflectivity and ellipsometry. These analyses provided important information on the structure, electron density gradient across film thickness, chain orientation, refractive index and thermal expansion of the polymers in substrate-supported thin films. The structural characteristics and properties of the thin films were first dependent on the polymer chain' tacticity and further influenced by film thickness and thermal annealing.

• Proceedings of the KIEE Conference
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• 1989.11a
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• pp.98-100
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• 1989

Langmuir-Blodgett(LB) technique will be used to produce ultra thin film, and then characterization of the physical and electrical properties of LB ultra thin films, this study will be an investigation for the possibilities of the ultra thin films as an Molecular Electronic Device.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.298-298
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• 2006

There has been much interest in incorporating nanoscale voids into dielectric materials in order to reduce their k value, and thus in producing low-k porous interdielectric materials. One approach to the development of low-k dielectric materials is the templated polycondensation of organosilicate precursors in the presence of a thermally labile, organic polymeric porogen. The other is SiOCH films have low dielectric constant as well as good mechanical strength and high thermal stability through PECVD. In this article we explore the nanopore generation mechanism of organosilicate film using star-shape porogen and SiOCH film using bis-trimethylsilylmethane (BTMSM) precursor.

• Biotechnology and Bioprocess Engineering:BBE
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• v.9 no.4
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• pp.241-244
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• 2004

Protein A molecular thin film was fabricated as a platform of antibody-based biosensor. For the immobilization of the protein A thin film, a viologen multilayer was built up using the Langmuir-Blodgett (LB) technique, and then, protein A was adsorbed on the viologen LB film by an electrostatic interaction force, which was formed as a hetero-film structure. For the deposition of viologen, surface pressure area ($\pi$-A) isotherm was investigated. The fabricated protein A-viologen hetero LB film was investigated using atomic force microscopy (AFM). Using the developed molecular film, antibody immobilization and fluorescence measurement was carried out.

• Journal of the Korean Applied Science and Technology
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• v.31 no.3
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• pp.402-407
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• 2014

Herein, we describe the effect of the cooling-off condition of a solution-processed 6,13-bis(triisopropylsilylethynyl)-pentacene (TIPS-pentacene) film on its molecular distribution and the resultant electrical properties. Since the solvent in a TIPS-pentacene droplet gradually evaporates from the rim to the center exhibiting a radial form of solute, for a quenched case, domains of the TIPS-pentacene film are aboriginally spread showing original features of radial shape due to suppressed molecular rearrangement during the momentary cooling period. For the slowly cooled case, however, TIPS-pentacene molecules are randomly rearranged during the long cooling period. As a result, in the lopsided electrodes structure proposed in this work, the charge transport generates more effectively under the case for radial distribution induced by the quenching technique. It was found that the molecular redistribution during the cooling-period plays an important role on the magnitude of the mobility in a solution-processed organic transistor. This work provides at least a scientific basis between the molecular distribution and electrical properties in solution-processed organic devices.