• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.05a
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• pp.198-201
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• 2004

We studied the nematic liquid crystal (NLC) aligning capabilities using the new alignment material of a SiO thin film. The homogenous alignment can be obtain어 using ion beam (IB) exposure on the SIO thin film, when positive type NLC ($Delta\varepsilon$>0) was injected However, the homeotropic alignment can be obtained using ion beam (IB) exposure on the SiO thin film, when negative type NLC ($\Delta\varepsilon$>0) was injected The LC aligning ability on the SiO thin film depends on the dielectric anisotropy type of LC. It will be discussed.

• Transactions on Electrical and Electronic Materials
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• v.10 no.4
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• pp.140-142
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• 2009

We have investigated the continuous pretilt angle generation for liquid crystals using a rubbing treated mixture layer consisting of homogeneous and homeotropic polyimides. Various pretilt angles in the range from $0^{\circ}$ to $60^{\circ}$ were achieved as a function of the concentration of homeotropic PI. The transmittance characteristics used to measure the pretilt angle showed that the pretilt angles were measured with a high reliability. We observed uniform liquid crystal alignment on the rubbing treated mixture layer.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2000.11a
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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.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.11a
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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.

• Transactions on Electrical and Electronic Materials
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• v.6 no.6
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• pp.272-275
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• 2005

We studied the control of pretilt angles for homeotropic aligned nematic liquid crystal (NLC) on SiOx thin film surface by $45^{\circ}$ evaporation method with electron beam system. The uniform vertical LC alignment on. the SiOx thin film surfaces with electron beam evaporation was achieved. It is considered that the LC alignment on SiOx thin film by $45^{\circ}$ electron beam evaporation is attributed to elastic interaction between LC molecules and micro-grooves at the SiOx thin film surface created by evaporation. The pretilt angles of about $3.5^{\circ}$ in aligned NLC on SiOx thin film surfaces by electron beam evaporation of $45^{\circ}$ were measured. Consequently, the high pretilt angles of the NLC on the SiOx thin film by $45^{\circ}$ oblique electron beam evaporation method can be achieved.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.11a
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• pp.507-510
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• 2000

Alignment effects for nematic liquid crystal (NLC) using an in-situ photo-alignment method with obliquely polarized UV exposure on a polyirnide (PI) surface for homeotropic alignment were studied. The high pretilt angle in NLC can be measured by obliquely W exposure of $30^{\circ}$ on the PI surface for 10~20 min. The pretilt angle of NLC generated using the in-situ photo-alignment was higher than that of a conventional photo-alignment method.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07a
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• pp.330-333
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• 2005

We investigated the liquid crystal (LC) alignment phenomena using a-C:H and a-C:F:H thin films. Homogeneous alignment is obtained using ion beam treated hydrogenated amorphous carbon (a-C:H) thin films. Homeotropic alignment is obtained using F treated a-C:H thin films, namely, fluorinated amorphous carbon (a-C:F:H) thin films. We investigated the relationship between the surface properties of amorphous carbon based alignment layer and LC alignment phenomena.

• Macromolecular Research
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• v.17 no.7
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• pp.506-515
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• 2009

We synthesized a series of polystyrene derivatives containing various side chain terminal moieties, such as phenoxymethyl, 4-methoxyphenoxymethyl, 4-fluorophenoxymethyl, 4-methylphenoxymethyl, and 4-trifluoromethoxyphenoxymethyl groups, using polymer analogous reactions, in order to investigate the effect of the side group on their liquid crystal (LC) alignment behaviors. The polymers containing 4-fluorophenoxymethyl, 4-methylphenoxymethyl, or 4-trifluoromethoxyphenoxymethyl side groups had lower surface energy values and the LC cells fabricated using the unrubbed films of these polymers showed homeotropic LC alignment behavior. The LC cells fabricated using the rubbed films of the polymers containing phenoxymethyl or 4-fluorophenoxymethyl groups showed homogeneous planar LC alignment behavior in which the LCs were aligned perpendicular to the rubbing direction. This homogeneous planar and perpendicular alignment behavior was ascribed to the favorable anisotropic interactions between the LC molecules and the side groups preferentially oriented perpendicular to the rubbing direction.

• Transactions on Electrical and Electronic Materials
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• v.7 no.6
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• pp.301-304
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• 2006

We studied the nematic liquid crystal (NLC) aligning capabilities using the new alignment material of the SiC (Silicon Carbide) thin film. The SiC thin film exhibits good chemical and thermal stability. The good thermal and chemical stability make SiC an attractive candidate for electronic applications. A vertical alignment of nematic liquid crystal by atomic beam exposure on the SiC thin film surface was achieved. The about $87^{\circ}$ of stable pretilt angle was achieved at the range from $30^{\circ}\;to\;45^{\circ}$ of incident angle. Consequently, the vertical alignment effect of liquid crystal electro-optical characteristic by the atomic beam alignment method on the SiC thin film layer can be achieved.

• Polymer(Korea)
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• v.29 no.3
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• pp.308-313
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• 2005

The effects of molecular environments on photoisomerization of an azobenzene group were investigated using In-situ UV/Vis spectroscopy and optical anisotropy measurement technique. The reversible and repeatable photoisomeritation reactions of azobenzene were observed by irradiating the film containing 4-hydroxyazobenzene and by measuring absorption intensities of the characteristic bands of trans and cis isomers simultaneously. When the self-assembled monolayer with azobenzene groups was used as an alignment layer for a liquid crystal cell, the homeotropic alignment was induced due to their compact packing structures of azobenfene groups along the vertical direction of the substrate. By irradiating UV light on this cell, the trans-azobenzene groups change to cis-isomers through the photoisonlerieation and then resulting in the planar alignment of liquid crystal molecules.