• 한국전기전자재료학회논문지
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• 제14권2호
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• pp.130-132
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• 2001

The mechanisms of pretilt angle generation in nematic liquid crystal (NLC) with negative dielectric anisotropy on a rubbed polyimide (PI) surface for homeotropic alignment were studied. The pretilt angle of negative type NLC was smaller than that of the positive type NLC for all rubbing strength regions on the rubbed PI surface. The pretilt angle generated in NLC does not attributable to steric interaction between the fluorine moiety of NLC and the polymer surface on the rubbed PI surface. Consequently, the mechanism of the pretilt angle generation for homeotropic alignment is different from the one for homogeneous alignment.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2005년도 International Meeting on Information Displayvol.I
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• pp.768-773
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• 2005

We present an overview of our new method of liquid crystal (LC) alignment based on the anisotropic etching of the alignment layers with a directed plasma flux. The method is realized by the use of anode layer source of "race track" geometry generating two "sheets" of accelerated plasma. These sheets are directed obliquely to the treated substrates. The static and dynamic irradiation regimes have been explored. The optimized processing conditions and materials are discussed. The technique yields an excellent uniformity of liquid crystal alignment of planar, tilted and vertical types. It is shown that the new method can be easily adapted for the alignment treatment of large area substrates used in the modern LCD manufacturing process.

• 한국위성정보통신학회논문지
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• 제10권1호
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• pp.67-70
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• 2015

본 연구에서는 폴리이미드 박막위에서의 수직 및 수평배향에서 혼합액정의 배향 특성에 대해서 연구하였다. 혼합액정은 러빙을 이용하여 배향처리하였으며, 러빙에 사용된 폴리이미드 박막은 알킬기를 Side Chain으로 가진 수직배향용 배향막과 그렇지 배향막으로 나누어서 프리틸트각 특성을 측정하였다. 실험결과 혼합액정을 사용하여 양호한 배향상태를 얻을 수 있었으며, 고온에서의 열안 정성에서도 우수한 특성을 보이는 것을 알 수 있었다. 또한 프리틸트각의 발생 원리를 이해하기 위해서 접촉각 측정을 실시하였으며, 이 둘이 밀접한 상관관계를 갖고 있음을 알 수 있었다.

• Transactions on Electrical and Electronic Materials
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• 제17권2호
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• pp.109-112
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• 2016

We demonstrated an alternative electrically controlled birefringence liquid crystal (ECB-LC) system with ion beam (IB)-irradiated yttrium gallium oxide (YGaO) alignment films using a sol-gel process. The surface roughness of the films was dependent on the annealing temperature; aggregated particles on surface were observed at lower annealing temperatures, whereas a smooth surface could be obtained with higher annealing temperatures. Higher transmittance in the visible region was observed at higher annealing temperatures. The film had an amorphous crystallographic state irrespective of the annealing temperature. Furthermore, ECB-LC cell with our IB-irradiated YGaO film yielded faster response time when compared to ECB-LC cell with rubbed polyimide. Considering the fast response time and high transmittance, the IB-irradiated YGaO-base LC system is a powerful alternative application for the liquid crystal display industry.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2000년도 추계학술대회논문집
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• pp.133-136
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• 2000

We investigated the improvement of viewing angle using a patterned double twisted (PDT) vertical-alignment (VA) cell mode on a homeotropic alignment layer. Good voltage-transmittance curves for negative dielectric anisotropic nematic liquid crystal (NLC) using the PDT-VA cell without a negative compensation film were obtained. The viewing angle of the PDT-VA cell without a negative compensation film was wider than that of a conventional VA cell.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 추계학술대회 논문집
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• pp.133-136
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• 2000

We investigated the improvement of viewing angle using a patterned double twisted (PDT) vertical-alignment (VA) cell mode on a homeotropic alignment layer. Good voltage-transmittance curves for negative dielectric anisotropic nematic liquid crystal (NLC) using the PDT-VA cell without a negative compensation film were obtained. The viewing angle of the PDT-VA cell without a negative compensation film was wider than that of a conventional VA cell.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.1
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• pp.199-202
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• 2003

We have investigated the generation of pretilt angle for a nematic liquid crystal (NLC) alignment with rubbing alignment method on two kinds of polyimide (PI) surfaces using thin plastic substrates. The generated NLC pretilt angles on the pre-imidized type PI are about $3.8^{\circ}$ by the rubbing alignment method with thin plastic substrates, However, the pretilt angle measured at about $2.8^{\circ}$ lower on the polyamic acid type PI than by pre-imidized type PI surface with thin polymer film. The tilt angle increases as increasing curring temperature for making polyimide layer using polyamic acid type PI. It was concluded that pretilt angle in the polyimide surface is attributable to the increasing of imide rato.

• 한국전기전자재료학회논문지
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• 제26권11호
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• pp.821-825
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• 2013

Effect of multi-stacked layer (MSL), 0.1 mol (M) and 0.3 mol (M) hafnium oxide ($HfO_2$) alignment layers were fabricated via a solution-process for LCs orientation. The solutions were spin-coated and annealed in a furnace. MSL consists of three sub-layers using 0.1 M solution, mono-layer (ML) is composed of 0.3 M $HfO_2$ solution. Then ion-beam irradiation was treated with 1.8 keV for 2 min. $HfO_2$-based LC cells were investigated through photographs, pre-tilt angle using crystal rotation method, X-ray photoelectron spectroscopy (XPS) measurement, and surface roughness using atomic force microscopy(AFM) for their characteristic research. Good LC orientation characteristics were observed on MSL $HfO_2$ surface. The LC alignment mechanism on MSL $HfO_2$ and ML $HfO_2$ surfaces was attributed to van der Waals (VDW) interaction between the LC molecular and substrate surface.

• 폴리머
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• 제27권5호
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• pp.484-492
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• 2003

러빙에 의해 유도된 네마틱 액정의 배향 특성과 그 안정성이 액정-폴리이미드 계면 특성과 어떠한 관계가 있는지를 조사하였다. 합성된 5 종류의 폴리이미드 특성을 분석하고 폴리이미드 배향막에서의 액정 배향의 균일성, 선경사각, 정착 에너지, 그리고 열 안정성을 측정 조사하였다. 러빙된 폴리이미드는 강한 정착의 액정 배향을 유도하고 액정 배향의 특성과 안정성은 배향막 표면에서의 액정과 폴리이미드 간의 분자 차원의 상호작용에 의해 결정된다는 것을 확인하였다. 폴리이미드의 유연성의 증가는 이미드화를 촉진시키며 액정의 선경사각과 배향 안정성을 증대시킨다. 반면에, 폴리이미드의 플루오르화는 액정의 배향성 및 배향 안정성을 감소시키는 것으로 나타났다. 폴리이미드의 방향족과 지방족 고리 이무수물 구조에 따른 액정 배향의 특성과 안정성에는 뚜렷한 차이가 나타나지 않았다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 추계학술대회 논문집 Vol.15
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• pp.526-529
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• 2002

We studied the nematic liquid crystal (NLC) aligning capabilities by the UV alignment method on a diamond like carbon (DLC) thin film surface. A good LC alignment by UV exposure on the DLC thin film surface at $200\AA$ of layer thickness was achieved. Also, a good LC alignment by the UV alignment method on the DLC thin film surface was observed at annealing temperature of $180^{\circ}C$. However, the alignment defect of the NLC was observed above annealing temperature of $200^{\circ}C$. Consequently, the good thermal stability of LC alignment by the UV alignment method on the DLC thin film surface can be achieved.