• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2005년도 International Meeting on Information Displayvol.I
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• pp.480-483
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• 2005

We report on studies of photoalignment of cholesteric liquid crystals on photosensitive phenylon-based polymer. We found that reflective and electro-optical characteristics of cholesteric cells strongly depend on UV exposure doze. The optimized UV treatment of the polymer allowed us to obtain the same quality of alignment on standard rubbed polyimide orientants. At the same time, the photosensitive orientant possesses evident advantage of the effective control of cholesteric textures

• 한국전기전자재료학회논문지
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• 제15권2호
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• pp.169-172
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• 2002

The voltage holding ratio(VHR) and the residual DC property in the in-plane switching (IPS) cells on a polyimide surface was studied. Several IPS cells which have different concentrations of cyano liquid crystals (LCs) were fabricated. We found that the VHR of the IPS cell was decreased with increasing concentration of cyano LCs. Also, the VHR of the IPS cell was increased with increasing specific resistivity of fluorine LCs. The residual DC voltage of the IPS cell by capacitance-voltage (C-V) hysteresis method was decreased with increasing concentration of cyano LCs. The residual DC property of the IPS cell on the rubbed PI surface can be improved by high polarity of cyano LC.

• Macromolecular Research
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• 제8권4호
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• pp.172-178
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• 2000

We synthesized polymethacrylate and polyurethane bearing a photosensitive azobenzene chromophore. Photo-induced birefringence of the thin film was observed under a linearly polarized light(λ = 532 nm). Dynamic behaviors of birefringence in two polymers were investigated in terms of the rate constants of growth and decay. An induced dichroism was observed from polarized UV-VIS absorption spectroscopy. Layers of two photosensitive polymers were used for aligning liquid crystal (LC) molecules instead of one of the rubbed polyimide layers in the conventional twisted nematic cell. For producing homogeneous alignment of a nematic LC molecule, a linearly polarized light was exposed to the films of two polymers. The stability of the LC alignment upon the linearly polarized light exposure was also studied.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 추계학술대회 논문집
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• pp.515-518
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• 2000

We studied the viewing angle characteristics of a negative dielectric anisotropy nematic liquid crystal (NLC) using the new vertical-alignment (VA)-1/6 cell on a rubbed polyimide (PI) surface. Good voltage-transmittance (V-T)characteristics using the new VA-1/6 cell without a negative compensation film were obtained. The iso-viewing angle characteristics using the new VA-1/6 cell without the negative compensation film can be achieved.

• Transactions on Electrical and Electronic Materials
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• 제14권2호
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• pp.82-85
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• 2013

This paper introduces 6,13-bis(triisopropylsilylethynyl) pentacene (TIPS pentacene) doped liquid crystal (LC) alignment properties on a rubbed polyimide (PI) layer as a function of the doping concentration of TIPS pentacene. Pretilt angles, photomicrographs, and electro-optical properties of TIPS pentacene doped LCs were comparable to those of pure LCs. However, TIPS pentacene in a LC medium supported twisted nematic-liquid crystal displays (TN-LCDs) to improve electro-optical properties. The threshold voltages observed in the TN cells decreased as the TIPS pentacene concentration increased. In addition, suitable response times were observed in TN cells.

• 한국정보전자통신기술학회논문지
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• 제14권5호
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• pp.362-368
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• 2021

본 논문에서는 알킬 사슬 길이에 따른 러빙 처리된 불소화 자기 조립 단분자막(fluorinated self-assembled monolayers; FSAM)의 수직 액정 배향 상태를 보고한다. FSAM의 증착을 위해 간단한 공정인 기체-상 방법이 사용되었다. FSAM의 가시광선 영역대 광학 평균 투과율은 77.63%~78.21%로 75.89%의 투과율을 갖는 기존의 폴리이미드막보다 우수하였다. 또한 프리틸트각 측정과 편광현미경 사진을 통해 FSAM의 우수한 수직 배향 특성을 관찰하였다. 접촉각과 FSAM의 표면에너지 측정을 통해 알킬 사슬 길이에 따른 프리틸트각이 증가하는 것을 확인하였다. FSAM의 높은 광학 투과율과 균일한 수직 배향 특성은 FSAM이 액정 배향막으로서의 가능성을 보여주었다.

• 폴리머
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• 제37권1호
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• pp.52-60
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• 2013

셀룰로오스 아세테이트(CA) 섬유를 $Na_2CO_3$ 용액으로 가수분해하여 탈아세테이트 반응시키면 레이온 섬유로 전환된다. 이때 처리조건을 조절함으로써 표면만 가수분해시켜, 표면은 레이온 성분이고 내부는 CA 성분으로 된 sheath-core형 표면가수분해 CA(SH-CA) 섬유를 얻었다. 시료들의 가수분해는 FTIR 스펙트럼 및 WAXD 패턴으로 분석하였으며, CA 성분을 아세톤으로 용출시킨 시료들의 SEM 사진으로부터 sheath-core 구조를 확인하였다. 이 sheath-core 형태의 SH-CA 섬유로 된 벨벳 직물을 사용하여, 액정디스플레이(LCD)용 폴리이미드 배향막을 러빙시키고 편광 FTIR 스펙트럼으로 분석하여 이 SH-CA 섬유 벨벳직물이 LCD용 러빙포로 사용될 수 있음을 확인하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 D
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• pp.1762-1764
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• 1999

We investigated the annealing effect on generating pretilt angle and aligning liquid crystal (LC) using the photo-depolymerization reaction in this study. In case of rubbing polyimide (PI) surface with the side chain, pretilt angle tends to increase with increasing the annealing time. It is considered because the steric interaction is increased by annealing which cause the side chain to come back to original position. For obliquely irradiating ultraviolet (UV) light on PI surface, pretilt angle shows to $0^{\circ}$ and is increased by annealing. The pretilt angle in rubbed PI surface is much higher than in photo-aligned PI surface. It is attributed to the steric interaction and the number of LC molecular arrangement on azimuthal direction. In addition. in case of obliquely irradiating UV light on PI surface. it showed LC alignment to increase by annealing. It can be regarded due to the fact that the re-alignment of LC molecule is improved to residual polymer direction by annealing.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 추계학술대회 논문집
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• pp.184-184
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• 2009

This paper introduces the characteristics of SnO2 inorganic film deposited by radio-frequency magnetron sputtering as an alternative alignment layer for liquid crystal display (LCD) applications. The pretilt angle of the SnO2 layer was shown to be a function of the ion beam(IB) incident angle, a planer alignment of nematic liquid crystal was achieved. The about $1.8^{\circ}$ of stable pretilt angle was achieved at the range from 1500 ~ 2500eV of incident energy. To characterize the film shows atomic force microscopy (AFM) on the IB irradiated SnO2 surfaceand the X-ray phtoelectron spectroscopy analysis showed that the liquid crystal(LC) alignment on the IB irradiated $SnO_2$ surface was due to the reformation of Sn-O bonds. Also, Figure 1 shows that The alignment capability of the IB irradiated SnO2 layers is maintained until annealing temperature of $200^{\circ}C$. Comparable electro-optical characteristics to rubbed polyimide were also achieved.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 추계학술대회 논문집 Vol.18
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• pp.289-290
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• 2005

We have investigated the electro-optical (EO) performances of the flexible liquid crystal display (LCD) on twisted nematic (TN) mode according to variation of cell gap in comparison with glass LCD. There were four kinds of cells which were having cell gaps of 3$\mu$m, 4$\mu$m and 5$\mu$m, especially the lowest 2$\mu$m on flexible and glass substrates separately. The EO performances of the flexible cells on the rubbed potyimide (PI) were almost the same those of glass cells. The response time of flexible cells was shorter than that of glass cells but the alignment of liquid crystal (LC) of flexible cells was weaker than that of glass cells. The residual DC of flexible cells was on the increase like that of glass cells in compliance with lowering cell gap.