• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.3
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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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• 2007.08a
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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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• 2006.08a
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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.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.11
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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.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.32 no.4
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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.

• Korean Journal of Logic
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• v.7 no.2
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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".

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.04a
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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.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.10
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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.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.5
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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.

• Journal of the korean academy of Pediatric Dentistry
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• v.35 no.3
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• pp.469-476
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• 2008

This study was performed to compare the fluoride release pattern and compressive strength of recently developed resin-modified glass ionomers($Ketac^{TM}$ N 100 and Fuji Fil LC) with those of conventional glass ionomer restorative material(Fuji II LC). Fifteen sample discs(6 mm diameter and 1 mm height) were prepared for each tested material. The fluoride release was measured by pH/ISE meter(750P, Istek, Korea) for 31 days. For compressive strength experiment, fifteen cylindrical specimens were prepared for each tested material. Each specimen was submitted to compressive strength testing in an universal testing machine(Kyung-sung Testing Machine Co., Korea) at crosshead speed of 5.0mm/min until failure. The results can be summarized as follows; 1. Fuji Fil LC released the highest amount of fluoride, followed by Fuji II LC and $Ketac^{TM}$ N 100(p<0.05). 2. The compressive strength of Fuji Fil LC was the lowest(p<0.05). However, no significant difference was found from Fuji II LC and $Ketac^{TM}$ N 100(p>0.05). By considering the above results, careful case selection and accurate clinical application is recommended when using $Ketac^{TM}$ N 100 and Fuji Fil LC.