• 한국전기전자재료학회논문지
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• 제17권3호
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• pp.305-310
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• 2004

We have studied the optimal phase retardation value of a homogeneously aligned liquid crystal (LC) driven by fringe-field when using the LC with positive dielectric anisotropy. In general, the transmittance of a homogeneous aligned LC cell under crossed polarizer is maximum when a twist angle of LC by in-plane rotation is 45$^{\circ}$ with polarizer and the cell retardation becomes λ/2. However, the device using the LC with positive dielectric anisotropy does not follow this since the degree of rotation of the LC is dependent on electrode position and in addition the LCs tilt up along the fringe-field. At the center of common and pixel electrode, the LC is most twisted around a middle position of a cell whereas at the edge position of pixel electrode, the LC is most twisted near bottom surface of a cell. Consequently, the optimal phase retardation of the device becomes much larger than λ/2 and the transmittance can be described using the combination of the in-plane switching and twisted nematic mode.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2007년도 7th International Meeting on Information Display 제7권1호
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• pp.534-537
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• 2007

To promote liquid crystal application of nanoimprint lithography, a polymer with new concept is proposed. The material consists of a polyamic acid for good LC alignment and an epoxy resin for good imprinting. The result of sum-frequency generation (SFG) vibrational spectroscopy proves that this material is a functionally gradient material. This material shows excellent capability as a nanoimprinting material as well as an LC alignment layer.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2006년도 6th International Meeting on Information Display
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• pp.864-867
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• 2006

In order to satisfy with the clear visibility without any difficulties such as blurring and tailing, the high refreshing rate technology and fast response time of LC itself were applied to TFT-LCDs. In proportion to the decrease of holding time of 1 frame, the fast transition of LC behavior was necessary to both maintain the luminance and minimize the tailing appearance. The introduction of a new LC mixture for faster response times was realized by the good combination of newly introduced dielectrically neutral LC material so called 'Super Low Viscosity' (SLV) and highly polar $CF_2O-linkage$ LC material. This resulted in about a 20% reduction in the ${\gamma}_1$ of the new LC mixture compared to the references. In accordance with a new LC mixture with low ${\gamma}_1$, fast response time of 5ms has been made for S-IPS LCD TV application. Consequently, by applying the high frame frequency of 120Hz driving alongside the 5ms response time characteristics, the MPRT value was reduced by half.

• 한국전기전자재료학회논문지
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• 제16권11호
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• pp.1019-1022
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• 2003

We studied the nematic liquid crystal (NLC) aligning capabilities using the new alignment material of a-C:H thin film as working gas at 30W rf bias condition. A high pretilt angle of about 5$^{\circ}$ by ion beam(IB) exposure on the a-C:H thin film surface was measured. A good LC alignment by the IB alignment method on the a-C:H thin film surface was observed at annealing temperature of 250$^{\circ}C$, and the alignment defect of the 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 IB alignment method on the a-C:H thin film surface as working gas at 30W rf bias condition can be achieved.

• 한국전기전자재료학회논문지
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• 제32권4호
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• pp.302-306
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• 2019

We investigated a solution-derived $Y_2O_3$ film treated by ion beam (IB) irradiation as a liquid crystal (LC) alignment layer. With IB irradiation, homogeneous LC alignment was achieved irrespective of the annealing temperature. To verify the effect of IB irradiation, we conducted surface analyses such as X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). As $Y_2O_3$ is a high-k material, the electro-optical properties of the twisted nematic (TN) cells were superior to those of conventional TN cells based on a rubbed polymer, with an LC rising time of 4.1ms and falling time of 2.9ms. The IB-irradiated $Y_2O_3$ is a good alternative as an alignment layer for fast-switching TN LC displays.

• 논리연구
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• 제7권2호
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• pp.105-120
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• 2004

In this paper, we provide Routley-Meyer semantics for the many-valued logics ${\L}C$ and LC, and give completeness for each of them. This result shows the following two: 1) Routley-Meyer semantics is very powerful in the sense that it can be used as the semantics for several sorts of logics, i.e., many-valued logic, not merely relevance logic and substructural logic. Note that each implication of ${\L}C$ and LC does not (partially) result in "paradoxes of material implication" 2) This implies that Routley-Meyer semantics can be also used not merely for relevance systems but also for other logical systems such as ${\L}C$ and LC, each of which has its own implication by which we can overcome (partially) the problem of "paradoxes of material implication".

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1997년도 춘계학술대회 논문집
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• pp.116-119
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• 1997

We investigated new type non-robbing liquid crystal (LC) alignment techniques in the cell with slanted non-polarized ultraviolet (UV) irradiation on polyimide (Pl) film. It is shown that the uniform alignment for nematic (N) LC is obtained by using slanted non-polarized UV irradiation on Pl surface. We successfully obtained that the pretilt ang1e of NLC is generated about 3 degree in the LC cells by using slanted non-polarized UV irradiation with 70 degree on Pl surface. We consider that the pretilt angle generation for NLC is attributed to interaction between the LC molecular and the PI surface. We conclude that the uniform LC alignment is attributed to anisotropic dispersion force effect due to photo depolymerization of polymer on Pl surface.

• 한국전기전자재료학회논문지
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• 제15권10호
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• pp.902-908
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• 2002

Homogeneously aligned nematic liquid crystal displays (LCDs) driven by in-plane or fringe field were known to exhibit wide viewing angle and appeared to be black in the off state. However, the existence of spacers inside the cell causes the deformation of the liquid crystal molecules. Such a deformation of the liquid crystal causes light-leakage in the dark state, which lowers contrast ratio of the display. We found that the light-leakage due to deformation of the LC director near the spacer mainly depends on the dielectric anisotropy and the ratio of elastic constants of the LC. In this paper, the mechanism on deformation of the LC near spacer is investigated by optical polarizing microscopy.

• 한국전기전자재료학회논문지
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• 제17권5호
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• pp.536-540
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• 2004

A novel nematic liquid crystal (LC) cell with splay structure exhibiting wide viewing angle, fast response time and high transmittance at the same time has been developed. With rubbed homeotropic alignment in parallel directions, the device shows bend alignment in the absence of vertical electric field. However, with applied high voltage in a pulse form, the LC shows a optically compensated splay (OCS) orientation such that the mid-director is parallel to a substrate and at both surfaces the LCs are aligned vertically in parallel direction. In the device, the birefringence of the cell becomes tunable with applying voltage, i.e., the amount of light passed through the cell can be controlled by controlling the orientation of the LC. Since the OCS cell has a self-compensation structure such that the LC has a mirror symmetry along the mid-director, the device shows a wide viewing angle with only a single domain and a fast response time.

• 대한소아치과학회지
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• 제35권3호
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• pp.469-476
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• 2008

본 연구는 새로 개발된 레진 강화형 글래스 아이오노머인 $Ketac^{TM}$ N 100과 Fuji Fil LC의 개선된 점을 보기 위해 불소 유리량과 압축 강도를 Fuji II LC와 비교 평가해 보았다. 불소 유리량 측정을 위해 각 재료 별로 시편을 15개씩 제작하여 탈이온수에 보관하였고, 31일 동안 pH/ISE meter(750P, Istek, Korea)를 이용하여 불소 유리량을 측정하였다. 압축 강도 측정을 위해 각 재료별로 15개씩 시편을 제작하여 만능 경성 시험기(Kyung-sung Testing Machine Co., Korea)를 이용하여 시편이 파절된 시점의 최대 강도를 측정하였다. 연구 결과 얻은 결론은 다음과 같다. 1. 전반적인 불소 유리량은 Fuji Fil LC, Fuji II LC, $Ketac^{TM}$ N 100 순으로 높았다(p<0.05). 2. 압축 강도는 Fuji II LC와 $Ketac^{TM}$ N 100은 유의한 차이가 없었고(p>0.05), Fuji Fil LC는 두 재료보다 낮은 압축 강도 값을 보였다(p<0.05). 이상의 결과를 종합해보면 $Ketac^{TM}$ N 100은 대조군인 Fuji II LC와 비교 시 불소 유리량은 적었으나 압축 강도는 유사했고 Fuji Fil LC는 불소 유리량은 높았고 압축 강도는 낮았다. 이런 재료의 특성에 맞게 임상 적용을 하는 것이 중요할 것이다.