• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.456-456
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• 2011

최근 차세대 디스플레이, 터치스크린, 전자파 차폐 및 흡수 등의 다양한 응용분야에 적합한 소재를 개발하기 위한 연구가 진행되고 있다. 현재 주로 사용되는 ITO박막은 희소원소인 인듐의 매장량 한계와 높은 비용이 문제시 되고 있기 때문에, 대체 재료의 개발이 시급하게 요구되고 있다. 탄소나노튜브(CNT)는 금속을 능가하는 이론적인 전기전도도를 갖고 있으며 높은 탄성등의 우수한 기계적 성질을 갖고 있어 다양한 차세대 응용에 있어서 최적의 재료로 주목을 받고 있다. 특히, CNT 기반의 투명전도막은 기존의 ITO 박막 보다 우수한 유연성이 기대되어 더욱 기대를 모으고 있다. 본 연구에서는, 최종 고순도 재료를 얻기까지 합성 및 정제에 많은 공정과 시간이 요구되는 고가의 단층벽 나노튜브(SWNT)를 이용하지 않고, 웨이퍼 기판 위에 수직배향 합성한 상태의 다층벽 나노튜브(MWNT)를 별도의 정제과정 없이 초음파 분산한 뒤, 스프레이 코팅법을 이용하여 고분자 기판 위에 투명전도막을 제작하였고, 이때 각기 다른 길이의 수직배향 MWNT를 이용하여 유연성 투명전도막의 전기적 특성에 미치는 MWNT 길이의 영향에 대해 알아보았다. MWNT는 아세틸렌가스를 이용하여 열CVD법으로 합성하였고, 합성시간을 제어함으로써 길이가 다른 MWNT를 얻을 수 있었다. 투명전도막 제조공정의 단순화를 위하여 이용한 MWNT의 초음파 분산 결과, $500{\mu}m$ 이하 길이의 MWNT에서 분산성이 현저히 빨라지는 것을 확인하였다. 한편, 제작한 MWNT 기반의 유연성 투명전도막은 원자간힘현미경 및 면저항 측정기를 이용하여 막 두께에 따른 면저항 특성을 조사하였다. 그 결과 응용 가능한 면저항을 갖는 MWNT 투명전도막의 두께는 최소 50 nm 이상이어야 함을 알았고, 특히 MWNT등의 접촉점(node) 수에 따른 접촉저항 및 전기전도경로(electric conductivity path)를 고려했을 때 최적의 MWNT 길이가 존재하는 것을 확인하였다.

• Applied Chemistry for Engineering
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• v.22 no.2
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• pp.230-234
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• 2011

In this work, the primary material for a single layered hardmask which can afford a spin-on process was prepared by the minture of organic and inorganic sources. The preparation of hybrid polymer was attempted by esterification from silanol terminated siloxane compounds and acetonide-2,2-bis(methoxy)propionic acid. The optical, thermal and morphological properties of the test hardmask film was examined in terms of cross-linking agent and additives. In addition, the etch rate of hardmask film and photo resist layer were compared. The hybrid polymer prepared from organic and inorganic materials was found to be useful for hardmask film to form the nano-patterns.

• Journal of the Korean Vacuum Society
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• v.22 no.5
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• pp.270-275
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• 2013

Single-layer graphene layers have been synthesized by using chemical vapor deposition, subsequently transferred on 300 nm $SiO_2/Si$ and quartz substrates, and doped with $AuCl_3$ by spin coating for various doping concentrations ($n_D$) from 1 to 10 mM. Based on the $n_D$-dependent variations of Raman frequencies/peak-intensity ratios, sheet resistance, work function, and Dirac point, measured by structural, optical, and electrical analysis techniques, the p-type nature of graphene is shown to be strengthened with increasing $n_D$. Especially, as estimated from the drain current-gate voltage curves of graphene field effect transistors, the hole mobility is very little varied with increasing $n_D$, in strong contrast with the $n_D$-dependent large variation of electron mobility. These results suggest that $AuCl_3$ is one of the best p-type dopants for graphene and is promising for device applications of the doped graphene.

• Polymer(Korea)
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• v.27 no.5
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• pp.397-404
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• 2003

The interaction of cell adhesive protein and polypeptide with bone marrow stromal stem cells (BMSCs) grown in tissue engineered films and scaffolds were examined. Several proteins or polypeptide known as cell-adhesive were coated adsorption on poly(lactide-co-glycolide) (PLGA) films and scaffolds and adhesion and proliferation behavior of BMSC on those surfaces were compared. The protein and polypeptide used include collagen IV, fibrinogen, laminin, gelatin, fibronectin, and poly(L-lysine). The protein and polypeptide were adsorbed on the PLGA film surfaces with almost monolayer coverage except poly(L-lysine). BMSCs were cultured for 1, 2, and 4 days on the protein- or polypeptide-adsorbed PLGA films and scaffolds. The cell adhesion and proliferation behaviors were assessed by sulforho damine B assay. It was observed that the protein- or polypeptide-adsorbed surfaces showed better cell adhesion and proliferation than the control.

• Journal of the Korean Geosynthetics Society
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• v.17 no.4
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• pp.169-177
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• 2018

Glass fiber reinforced polyester (GFRP) composites are widely used as structural materials in harsh environment such as underground pipes, tanks and boat hulls, which requires long-term water resistance. Especially, these materials might be damaged due to delamination between gelcoat and composites through an osmotic process when they are immersed in water. In this study, GFRP laminates were prepared by surface treatment of UPE (unsaturated polyester) gelcoat by vacuum infusion process to improve the durability of composite materials used in underground pipes. The composite surface coated with gelcoat was examined for surface defects, cracking, and hardness change characteristics in water-immersion environments (different temperatures of $60^{\circ}C$, $75^{\circ}C$, and $85^{\circ}C$). The penetration depth of cracks was investigated by micro CT imaging according to water immersion temperature. It was confirmed that cracks developed into the composites material at $75^{\circ}C$ and $85^{\circ}C$ causing loss of durability of the materials. The point at which the initial crack initiated was defined as the failure time and the life expectancy at $23^{\circ}C$ was measured using the Arrhenius equation. The results from this study is expected to be applied to reliability evaluation of various industrial fields where gelcoat is applied such as civil engineering, construction, and marine industry.