• 한국전기전자재료학회논문지
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• 제19권7호
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• pp.695-699
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• 2006

Injection time of liquid crystal (LC) by capillary action in a vertically aligned (VA) nematic LC cell takes longer than that in a homogeneously aligned (HA) LC cell because Miesowicz viscosity in the former is bigger than that in the latter. To reduce liquid crystal injection time in the VA cell, we applied vertical electric field while injecting so that the orientation of LC molecules is changed from vertical alignment to homogeneous alignment. Consequently, the injection speed is improved by 25 % when compared with the cell without an applied field.

• 한국전기전자재료학회논문지
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• 제21권12호
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• pp.1101-1104
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• 2008

We have studied electro-optic characteristics to improve viewing angle of the in-plain switching (IPS) liquid crystal display using an compensation film. The IPS mode shows relatively large light leakage and color shift in diagonal directions in a dark state. To solve this problem, we have compensated the low contrast ratio in diagonal directions using one optimized discotic film and adjusting TAC films of polarizers. The compensated IPS mode shows wide viewing angle characteristics that region of CR 50:1 is over $60^{\circ}$ of polar angle in all directions. The optimized IPS cell exhibits much better performances than other methods do in terms of CR and color uniformity.

• 한국분말재료학회지
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• 제10권1호
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• pp.40-45
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• 2003

Sintering behavior of 2xxx series Al alloy was investigated to obtain full densification and sound microstructure. The commercial 2xxx series Al alloy powder. AMB2712, was used as a starting powder. The mixing powder was characterized by using particle size analyzer, SEM and XRD. The optimum compacting pressure was 200 MPa, which was the starting point of the "homogeneous deformation" stage. The powder compacts were sintered at $550~630^{\circ}C$ after burn-off process at $400^{\circ}C$. Swelling phenomenon caused by transient liquid phase sintering was observed below $590^{\circ}C$ of sintering temperature. At $610^{\circ}C$, sintering density was increased by effect of remained liquid phase. Further densification was not observed above $610^{\circ}C$. Therefore, it was determined that the optimum sintering temperature of AMB2712 powder was $610^{\circ}C$.}C$.

• 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.

• Transactions on Electrical and Electronic Materials
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• 제11권6호
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• pp.285-287
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• 2010

This paper introduces homogeneous liquid crystal (LC) orientations on chemically modulated polystyrene (PS) surfaces using various ion beam (IB) exposure times. Transparent PS was replaced with conventional polyimide material. As a non-contact process, the IB bombardment process induced LC orientation parallel to the IB process. Through x-ray photoelectron spectroscopy, it was shown that the chemical compositional changes of the IB-irradiated PS surfaces were determined as a function of IB exposure time. Using this analysis, the optimal IB bombardment condition was determined at an IB exposure time of up to 15 seconds. Moreover, thermal stability on IB-irradiated PS surfaces were carried out which showed that a relatively high IB exposure time induced a thermally stable LC alignment property.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 추계학술대회 논문집 전기물성,응용부문
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• pp.194-196
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• 2005

A series of inorganic-organic hybrid membranes were prepared with a systematic variation of titanium dioxidenanoparticles content. Their liquid uptake, methanol permeability and proton conductivity as a function of inoranic oxide content were investigated. The results obtained show that the inorganic oxide network decreases the proton conductivity and liquid uptake. It is also found that increase in inorganic oxide content leads to decrease of methanol permeability. In terms of the morphology, membranes are homogeneous and exhibit a good adhesion between inorganic domains and the polymer matrix. The properties of the composite membranes are compared with the standard nafion membrane.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집B
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• pp.943-948
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• 2000

The Twin-fluid Swirl Nozzles are used in many parts of the industry to produce homogeneous spray. This study is to investigate the effects of outer air swiller and inner water swiller on atomization of liquid.. The experiment was carried out with increasing air-flow rate at constant liquid-flow rate and with changing outer air swiller angle and inner water swiller angle. A Particle Dynamics Analyzer(PDA) was used to measure drop size, mean and ms values of axial velocity, number density and Sauter mean diameter(SMD). The axial mean velocity and SMD of droplets were measured along the center line and radial directions. It was found that the higher air flow-rate resulted in the smaller Sauter mean diameter of liquid spray and the higher axial mean velocity of droplets. This experimental results will be conveniently used for the preliminary design stage of twin-fluid nozzle development.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 추계학술대회 논문집 Vol.14 No.1
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• pp.337-340
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• 2001

The control of high pretilt angle far nematic liquid crystal (NLC) with negative dielectric anisotropy on the rubbed blending polyimide (homeotropic and homogeneous alignment) surface were studied. High NLC pretilt angle generated on the blending polyimide (homeotropic polyimide and SE-7492 surface was measured and the NLC pretilt angle increases with blending ratio and rubbing strength. However, the NLC pretilt angle generated on the blending polyimide (homeotropic polyimide and SE-150 surface was not varied. The high pretilt angle the NLC using blending polyimide surface can be acheived.

• 한국전기전자재료학회논문지
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• 제18권2호
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• pp.174-179
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• 2005

We have designed a novel single cell gap transflective display associated with dual orientation of the liquid crystal. Owing to hybrid alignment in reflective part, the effective cell retardation value becomes half of cell retardation value in transmissive part where the LCs are homogeneously aligned. This study shows the possibility to manufacture the transflective display with a single gamma curve for reflective and transmissive region. The new device shows a high image quality with relatively easy fabrication.

• 한국전기전자재료학회논문지
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• 제14권12호
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• pp.1023-1026
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• 2001

The control of high pretilt angle for nematic liquid crystal (NLC) with negative dielectric anisotropy on the rubbed blending polyimide (PI) of homeotropic and homogeneous alignment surface was studied. High LC pretilt angle on the rubbing blending polyimide of homeotropic PI and SE-7492 surface was measured and the LC pretilt angle increased wish blending ratio and rubbing strength. However, the low LC pretilt angle on the rubbed blending polyimide of homeotropic PI and SE-150 surface was measured. The high pretilt angle of NLC can be achieved by using the blending PI surface.