• 한국광학회:학술대회논문집
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• 한국광학회 2000년도 제11회 정기총회 및 00년 동계학술발표회 논문집
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• pp.100-101
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• 2000

편광기는 광변조기나 스위치 등과 같이 구동을 위해 하나의 편광성분을 요구하는 소자를 동작시킬 때 필수적으로 요구되는 소자이다. 편광기를 구현하는 기법에 따라 벌크형, 집적광학형 그리고 광섬유형으로 구분할 수 있다. 광섬유형은 광섬유를 절단하지 않고 제작이 가능하여 삽입손실이 작고 높은 기계적 신뢰성을 가진다. 측면 연마된 광섬유(side-polished fiber)위에 복굴절 크리스탈$^{(1)}$ , 액정크리스탈$^{(2)}$ , 금속막$^{(3)}$ , 그리고 복굴절을 가지는 평면도파로$^{(4)}$ 를 결합한 구조가 잘 알려져 있다. 특히 광섬유-평면도파로 결합 구조는 원하는 파장에서 TE혹은 TM 편광성분을 선택적으로 제거할 수 있고 평면도파로 물질선택이 용이한 구조이기 때문에 많은 주목을 받아 왔다. 하지만 지금 까지 알려진 광섬유-평면도파로 결합기를 이용한 편광기는 편광선택 작용이 발생하는 파장범위가 좁아 범용적으로 사용하는데 적합하지 않는 점이 있다. (중략)

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 C
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• pp.1453-1455
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• 1996

The odd-even effect of the alkyl chain length of rubbed polyimide Langmuir-Blodgett (LB) surfaces on the extrapolation length of 5CB has been successfully evaluated for the first time by measuring polar anchoring strength. The extrapolation length of 5CB for rubbed PI-LB surfaces with even-numbers is small compared with odd-numbers for alkyl chain lengths of greater than 7 carbons. The extrapolation length of 5CB on rubbed PI-LB surfaces with odd-numbers increases gradually as the temperature increases but tends to diverge near the clearing temperature (Tc=$35.3^{\circ}C$). The extrapolation length diverges because of rapidly decreasing surface order near $T_c$. We suggest that the polar anchoring strength on rubbed PI-LB surfaces with even-number is strong because of relatively high surface ordering caused by more crystalline surfaces. Finally, we conclude that the odd-even effects of the polar anchoring strength in NLCs are strongly related to the character of the polymer and observed clearly for long alkyl chain lengths.

• Journal of Advanced Marine Engineering and Technology
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• 제22권5호
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• pp.588-594
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• 1998

Heat transfer characteristics of distance between impinging surface and a plane jet were experi-mentally investigated. The local heat transfer coefficients were measured by a thermochromic liq-uid crystal(TLC) The jet Reynolds number studied was varied over the range from 10,000310 to 30,000310 the nozzle-to-plate distance (H/B) from 4 to 10. It was observed that the Nusselt number increases with Reynolds number the occurrence of the secondary peak in the Nusselt number is within the potential core region the potential core of the jet flow can reach the impinging surface so that the wall jet can a transition from laminar to turbulent flow resulting in a sudden increase in the heat transfer rate.

• Journal of Advanced Marine Engineering and Technology
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• 제22권2호
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• pp.200-209
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• 1998

Experiments have been conducted to determine heat transfer characteristics for a two-dimen-sional turbulent wall attaching offset jet at different oblique angles to a flat surface. The local Nusselt number distributions were measured using liquid crystal as a temperature sensor. Wall static pressure coefficient profiles were measured at the Reynolds number Re 53200(based on the nozzle width, D) the offset ratio H/D from 2.5 to 10 and the oblique angle a from $0^{\circ}$, to $40^{\circ}$ It is observed that the maximum Nusselt number point occurs slightly upstream of time-averaged reattachment point for all oblique angles. The correlations between the maximum Nusselt number and Reynolds number offset ration and oblique angle are presented.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.302-307
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• 2003

Demand of the LCD-TV is remarkably increasing with development of the LCD technology in these days. Thus, this research has analyzed thermal problems such as heat transfer characteristics inside and outside the LCD-TV using numerical simulation and experiments. The simulated results have been compared with the experimental results using an infrared (IR) camera and T-type thermocouples. The optimal design of structure has been proposed to improve the thermal efficiency of radiation from the comparison.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1996년도 춘계학술대회 논문집
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• pp.105-108
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• 1996

We have studied the anisotropic dispersion force effects for surfaces alignment of liquid crystals (LCs) on rubbed polystyrene (PS) surfaces by unidirection. In microphotographs of the textures, we obtained the nematic (N) LCs are shown to align in both direction parallel and Perpendicular to the rubbing for region up to medium rubbing, however to align in the direction perpendicular to the rubbing for strong rubbing legion. We suggest that the anisotropic dispersion force is very important rather than macro-surface groove effect to uniform alignment of LCs. We also measured the temperature dependence of extrapolation length of 5CB on rubbed PS surfaces for strong rubbing. It is shown that the polar anchoring strength of 5CB is very weak on rubbed PS surface compared to the rubbed polyimide (Pl) surface.

• 설비공학논문집
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• 제9권4호
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• pp.427-434
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• 1997

Heat transfer characteristics of a two-dimensional oblique impinging jet were experimentally investigated. The local heat transfer coefficients were measured by a thermochromic liquid crystal. The jet Reynolds number studied was varied from 10000 to 35000, the nozzle-to-plate distance(H/B) from 2 to 16, and the oblique angle($\alpha$) from $60^{\circ}$ to $90^{\circ}$. It was observed that the local Nusselt numbers in the minor flow region were larger than those in the major flow region at the same distance along the plate due to the higher levels in the turbulent intensity caused by more active mixing of the jet flow.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 하계학술대회 논문집 Vol.6
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• pp.449-450
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• 2005

Alignment characteristic of liquid crystal (LC) on in-cell retarder which is composed of reactive mesogens has been tested. The in-cell retarder which is polymerized on top of the homogeneous alignment layer (AL) has an optic axis along the rubbing direction of the homeogenous AL and does show good alignment effect of the LC without showing any defects, which possibly allows a skip of another AL on the in-cell retarder that was required conventionally to control alignment of the LC. However, the measured pretilt angle is only 0.04 degree so that disclination lines are generated for a cell that uses the in-cell retarder as an AL when the LC is tilted upward by a vertical electric field.

• 한국전기전자재료학회논문지
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• 제32권5호
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• pp.357-360
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• 2019

We demonstrate an alignment technology using an imprinting process on an inorganic NiOx film. The aligned nanopattern was fabricated on a silicon wafer by laser interference lithography. The aligned nano pattern was then imprinted onto the sol-gel driven NiOx film using an imprinting process at an annealing temperature of $150^{\circ}C$. After the imprinting process, parallel grooves had been formed on the NiOx film. Atomic force microscopy and water contact angle measurements were performed to confirm the parallel groove on the NiOx film. The grooves caused liquid crystal alignment through geometric restriction, similar to grooves formed by the rubbing process on polyimide. The liquid crystal cell exhibited a pretilt angle of $0.2^{\circ}$, which demonstrated homogeneous alignment.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2009년도 추계학술대회
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• pp.910-912
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• 2009

투명전극은 비저항이 $1{\times}10^{-3}{\Omega}/cm$이하, 면저항이 $10^3{\Omega}/sq$이하로 전기전도성이 우수하고 380에서 780nm의 가시광선 영역에서의 투과율이 80%이상이라는 두 가지 성질을 만족시키는 박막이다. 기존의 평판디스플레이의 경우, 금속 산화물 투명전극이 진공 증착 공정을 통해 도포된 유리기판상의 각 화소를 포토리소그래피 공정으로 제조된 박막트랜지스터(TFT : Thin Film Transistor)로 제어함으로써 화상을 구현한다. 본 연구에서는 스퍼터링 진공 증착 장치를 이용하여 투명 도전막(ITO: Indium Tin Oxide)을 제작하고 제작된 ITO 박막의 광 및 전기 그리고 물성적 특성을 조사하여 최상의 공정 조건을 확립하였다. a-Si:H 박막위에 형성되는 ITo 박막은 a-Si:H 박막의 특성상 온도 및 스퍼터링 전력에 대한 연구가 주요 문제이다. 본 실험에서는 $In_2O_3:SnO_2$의 조성비는 90:10 wt% 인 타겟의 특성이 우수하였고, $Ar:O_2$의 분압비는 100:1 및 42:8 의 조건이 적당하였으며, 온도는 $200^{\circ}C$ 가장 우수한 특성을 얻을 수 있었다. $200^{\circ}C$ 는 비정질 실리콘의 성능에 좋은 영향을 미치는 온도이며, 알려진 것과 같이 $23^{\circ}C$ 즉 실온의 경우에 비해 막의 균질성 및 특성이 우수 한 것을 알 수 있었다. 본 연구에서 제작한 박막은 광 투과도가 90% 이상, 비저항이 $300{\mu}{\Omega}cm$ 이하의 특성을 갖게되어 이미지센서, 태양전지, 액정 텔레비젼등 빛의 통과와 전도성등 두가지 특성에 동시에 만족 될만한 성능을 가질 수 있음을 확인하였다.