• 한국전기전자재료학회논문지
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• 제16권6호
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• pp.501-509
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• 2003

We have designed transflective liquid crystal display(LCD) associated with in-plane switching of a LC director driven by fringe-field, unlike other LCD mode. Reflective area consists of a λ/2 compensation film and a LC cell with retardation value(dΔn) of λ/4 with their optic axes making an angle of 15$^{\circ}$ and 75$^{\circ}$ against polarizer, respectively. In the transmissive area, top and bottom polarizers are parallel each other, an LC has a dΔn of λ/2, and another λ/2 compensation film is inserted between the LC cell and bottom polarizer. With the configuration, both devices show dark state initially. When an incident light is 550nm, the device shows wide-viewing-angle characteristics such that in the reflective area the contrast ratio target than 5 exists up to 55$^{\circ}$ of polar angle in all directions and in transmissive area it exists about 100$^{\circ}$ in vortical direction and 110$^{\circ}$ in horizontal direction.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2015년도 제49회 하계 정기학술대회 초록집
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• pp.163-163
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• 2015

The effect of nematic liquid crystal(5CB-4-Cyano-4'-pentylbiphenyl) on the amorphous indium gallium zinc oxide thin film transistors(a-IGZO TFTs) was investigated. Through dropping the 5CB on the a-IGZO TFT's channel layer which is deposited by RF-magnetron sputtering, properties of a-IGZO TFTs was dramatically improved. When drain bias was induced, 5CB molecules were oriented by Freedericksz transition generating positive charges to one side of dipoles. From increment of the capacitance by orientation of liquid crystals, the drain current was increased, and we analyzed these phenomena mathematically by using MOSFET model. Transfer characteristic showed improvement such as decreasing of subthreshold slope(SS) value 0.4 to 0.2 and 0.45 to 0.25 at linear region and saturation region, respectively. Furthermore, in positive bias system(PBS), prevention effect for electron trapping by 5CB liquid crystal dipoles was observed, which showing decrease of threshold voltage shift [(${\delta}V$]_TH) when induced +20V for 1~1000sec at the gate electrode.

• 한국결정성장학회지
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• 제15권6호
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• pp.260-262
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• 2005

Thickness optimization of heavily doped p-type seeding layer was studied to improve performance of thin film silicon solar cell. We used liquid phase epitaxy (LPE) to grow active layer of $25{\mu}m$ thickness on $p^+$ seeding layer. The cells with $p^+$ seeding layer of $10{\mu}m\;to\;50{\mu}m$ thickness were fabricated. The highest efficiency of a cell is 12.95%, with $V_{oc}=633mV,\;J_{sc}=26.5mA/cm^2$, FF = 77.15%. The $p^+$ seeding layer of the cell is $20{\mu}m$ thick. As thicker seeding layer than $20{\mu}m$, the performance of the cell was degraded. The results demonstrate that the part of the recombination current is due to the heavily doped seeding layer. Thickness of heavily doped p-type seeding layer was optimized to $20{\mu}m$. The performance of solar cell is expected to improve with the incorporation of light trapping as texturing and AR coating.

• 공업화학
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• 제29권5호
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• pp.620-625
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• 2018

SLES를 주성분으로 사용한 액체세정제는 공기 중에 노출하여 방치하는 경우 표면에 피막이 형성되는 경우가 있다. 이는 제형 중의 수분이 증발하면서 세정제 주성분인 계면활성제의 농도변화로 인한 미셀의 상변화로 판단된다. SLES는 30~60% 영역에서 강한 육방정계 액정상이 나타나고, 60% 이상에서는 라멜라 액정상을 보인다. 본 연구에서는 SLES 주성분으로 사용된 액체세정제의 표면 겔링 현상은 내용물에서 수분 증발로 인하여 발생하는 현상이다. 액체세정제에서 수분이 증발되면서 계면활성제의 농도가 높아지는 결과였다. 표면 겔링 상태는 편광현미경으로 관찰한 결과 혼합 계면활성제 시스템의 액정상으로 확인되었다. 결론적으로 SLES를 주성분으로 사용하는 처방에서 겔링 필름 형성을 방지하기 위하여 수용성이 좋은 AOS를 증량하고 액정형성을 방지할 수 있는 이차 계면활성제인 SAS를 도입하고, 하이드로트로프로 SXS와 PEG1500을 적용하였다. 이와 같이 개선된 액체세정제 처방4와 5는 공기 중에 노출되어도 표면에 피막이 형성되는 겔링현상을 방지할 수 있었다.

• 한국염색가공학회지
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• 제15권1호
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• pp.39-47
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• 2003

Phosphorescent PET/liquid color films and phosphorescent PET/disperse dyes films were prepared by melt casting method using Hot press. Then, weight ratios and exhaustion percent of films were 0.7, 1.2, 1.5, 2.0, and 2.3 wt.%. The effects of L/C and D/D contents(wt.%) of films on the thermal properties, crystal structure, H(%), brightness$(mcd/mm^2)$, morphology, and tensile properties were investigated by means of DSC and WAXD, etc. It was found that the melting temperature and crystalline diffraction peaks were not changes with increasing the liquid color contents and disperse dyes exhaustion. Also, in case of using liquid color to phosphorescent PET film, the H(%) and brightness$(mcd/mm^2)$ value were superior to phos.PET/disperse dyes film. The tensile strength and the tensile modulus were decreased with increasing the contents of liquid color and exhaustion of disperse dyes in the phosphorescent PET film. Also, the elongation at break was increased with increasing the contents of liquid color and exhaustion of disperse dyes in the phosphorescent PET film.

• 한국정보전자통신기술학회논문지
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• 제12권1호
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• pp.72-77
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• 2019

정보전달 매체 중 시각을 통하여 우리에게 정보를 제공해 주는 디스플레이는 직관적으로 정보를 전달해 줌으로써 매우 중요한 정보전달 수단이라고 할 수 있으며 액정표시장치는 디스플레이 중에서 가장 많이 보급되어 있는 정보전달기기라고 할 수 있다. 본 논문에서는 액정디스플레이 제작을 위하여 필수적인 러빙 기반 액정 배향 공정을 대체할 수 있는 공정으로서 solvent assisted micromolding을 연구하였으며 가장 일반적인 액정 배향막인 polyimide에 나노구조를 형성함으로써 균일하게 액정 배향을 달성하고자 하였다. Polyimide 나노구조 형성 시 공정 온도에 따라 용매에 의한 고분자 용해효과와 몰드의 나노구조 안으로 polyimide 분자의 모세관 효과 사이의 상보적 상관관계가 존재하였으며 최적온도 도출을 통해 높은 단차를 갖는 나노구조를 형성할 수 있었다. 이러한 나노구조는 액정 분자를 균일하게 배향할 수 있었으며 일정한 선경사각을 형성할 수 있음을 증명하였다.

• 한국위성정보통신학회논문지
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• 제7권3호
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• pp.54-57
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• 2012

최근 비접촉식 액정배향방법에 대한 요구가 산업계 전반으로 확산되면서, 기존의 UV 광배향을 비롯하여, 여러 가지 비접촉식 액정 배향방법이 활발히 연구되고 있다. 본 연구에서는 이러한 비접촉식 액정배향방법 중에서 SiOF 무기막에 이온빔을 정량적으로 조사하는 방법을 사용하여 액정을 배향하고, 이 기술을 사용하여, 상용화 수준의 IPS(In-Plane Switching) 방식의 액정 셀을 제작함으로써 전기광학 특성을 평가하였다. 특히 이러한 무기막 배향의 경우 배향안정성에 많은 문제를 가지고 있는 것이 보통이나, 본 연구에서 제안한 방법으로 제조된 평가셀은 $200^{\circ}C$의 높은 온도로 열처리를 하여도 배향성을 잃지 않고 균일한 배향을 지속하는 것을 관찰할 수 있었다.

• 한국응용과학기술학회지
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• 제13권2호
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• pp.29-37
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• 1996

The phase separated structure and the electo-optical properties of the polymer /liquid crystal(LC) composite films including a dye were investigated. The phase separated structure of the polymer /LC / dye composite film(GH composite film) including below 2wt% dye against LC was almost same with the composite film which does not include dye. But the electro-optical properties of the GH composite film strongly depended on weight fraction of the dye against the LC. The response time of the GH composite film increased with the increase of the dissolved dye in LC because the dye acts as a registivity for the orientation of LC molecules by the electric filed.

• 한국응용과학기술학회지
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• 제12권2호
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• pp.29-39
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• 1995

The phase separated structure and the electro-optical properties of the (polymer/liquid) crystal : LC) composite film strongly depended on the weight fraction of LC in it. The continuous LC phase was formed in a three-dimensional polymer network when the LC weight fraction was above 40wt%. The aggregation structure of the composite film could be controlled by controlling the solvent evaporation velocity during the film preparation process. The smaller LC domains or channels were formed in the case of the faster solvent evaporation velocity. The composite film exhibited reversible light scattering-light transmission switching upon electric field -OFF and -ON states, respectiverly. The light scattering properties of the composite film strongly depended on the spatial distortion of the nematic directors as well as the mismatch in refractive indices between matrix polymer and LC.

• Transactions on Electrical and Electronic Materials
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• 제5권1호
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• pp.15-18
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• 2004

We studied the nematic liquid crystal (NLC) aligning capabilities using the new alignment material of a-C:H thin film by plasma enhanced chemical vapor deposition (PECVD) system for 30 sec under 30W rf power at a gas pressure of 1.4＊10$\^$-1/ torr. A high pretilt angle of about 5 by ion beam exposure on the a-C:H thin film surface was measured. A good LC alignment by the ion beam alignment method on the a-C:H thin film surface was observed at annealing temperature of 250$^{\circ}C$, and the alignment defect of NLC was observed above annealing temperature of 300$^{\circ}C$. Consequently, the high LC pretilt angle and the good thermal stability of LC alignment by the ion beam alignment method on the a-C:H thin film by PECVD method as working gas at 30W rf bias condition can be achieved.