• Transactions on Electrical and Electronic Materials
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• v.17 no.2
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• pp.109-112
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• 2016

We demonstrated an alternative electrically controlled birefringence liquid crystal (ECB-LC) system with ion beam (IB)-irradiated yttrium gallium oxide (YGaO) alignment films using a sol-gel process. The surface roughness of the films was dependent on the annealing temperature; aggregated particles on surface were observed at lower annealing temperatures, whereas a smooth surface could be obtained with higher annealing temperatures. Higher transmittance in the visible region was observed at higher annealing temperatures. The film had an amorphous crystallographic state irrespective of the annealing temperature. Furthermore, ECB-LC cell with our IB-irradiated YGaO film yielded faster response time when compared to ECB-LC cell with rubbed polyimide. Considering the fast response time and high transmittance, the IB-irradiated YGaO-base LC system is a powerful alternative application for the liquid crystal display industry.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1999.10a
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• pp.332-338
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• 1999

Surface hardening of plain carbon steel (SM$%C) by Laser are usually much finer and stronger than those of the base metals. The present study was undertaken to investigate the wear resistance and a processing parameters such as, power density, pulse width, defocusing distance, and molten depth for surface modification of plain carbon steel. The wear test was carried out under experimental condition using the wear test device, and in which the annular surfaces of wear test specimens as well as mating specimen of alumina ceramics(Al2O3) was rubbed in dry sliding condition. It is shown that molten depth and width depend on defocusing distance. The wear loss on variation of sliding speed was much in lower speed range below 0.2m/sec and in higher speed range above 0.7m/sec, but wear loss was little in intermediate speed range. It depends on oxidation speed and wear speed.

• Tribology and Lubricants
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• v.11 no.4
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• pp.13-20
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• 1995

The present study was undertaken to investigate the purity variation of the alumina ceramics on the water lubrication mechanism. The annular surface of wear testing specimens of the alumina ceramics with different alumina purity against STB2 was rubbed in the distilled water under various sliding speed, contact pressure and sliding distance. The friction coefficient decreased lowered with formation of corrosion products due to the tribochemical reation as the sliding speed and contact load was increased. With increased sliding speed, the lower purity of 85 percent contribute largely to even degree of the friction surface, even it have about $\mu$ of 0.3 degree by the influence of a pore and impurities SiO$_{2}$. The friction surface of ceramics protacted by oxide was transfer from STB2.

• Journal of Periodontal and Implant Science
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• v.37 no.4
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• pp.767-777
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• 2007

The present study was performed to evaluate the effect of Tetracycline-HCI on the change of implant surface microstructure according to application time. Anodic oxidation surface were utilized. Implant surface was rubbed with 50mg/ml Tetracycline-HCI solution for ${\frac{1}{2}}min.$, 1min., $1{\frac{1}{2}}min.$, 2min., $2{\frac{1}{2}}min.$, and 3min. respectively in the test group. Then, specimens were processed for Ra Value test and scanning electron microscopic observation. The results of this study were as follows. 1. The anodic oxidation surface roughness tests don't show significant difference on conditioning with saline and Tetracycline-HCI. 2. The anodic oxidized surfaces showed the craterous structures. The surface conditioning with Tetracycline-HCI didn't influence on its micro-morphology. In conclusion, Anodic oxidation implant surface is stable to detoxificate with 50mg/ml Tetracycline-HCI of implant surface.

• Polymer(Korea)
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• v.24 no.2
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• pp.211-219
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• 2000

Fluorene-based light emitting polymer blends with liquid crystalline characteristics were studied on effective energy transfer and dichroic characteristics. Incorporating 0.5 wt% of the non-liquid crystalline into the liquid crystalline polymer suppressed the PL emission at 420 nm on photoexcitation at 360 nm, but generated a new PL emission of the non-liquid crystalline polymer at 480 nm. The highest PL intensity at 480 nm, which was 13 times stronger than those of the two polymers before blending, was observed for a blend with 2.0 wt% of the non-liquid crystalline polymer. When the molecules of the blends were aligned on a rubbed polyimide surface by a heating-cooling process, the dichroic ratio and the order parameter were 2.0 and 0.25, respectively. Time-correlated single photon counting (TCSPC) study revealed that the time required for energy transfer between the two chromophores was shortened by 93 ps when the blends were aligned on the rubbed polyimide surface by the heating-cooling process. The thermal treatment also enhanced the energy transfer efficiency by 9%.

• Journal of Periodontal and Implant Science
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• v.37 no.4
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• pp.779-789
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• 2007

The present study was performed to evaluate the effect of Tetracycline-HCI on the change of implant surface microstructure according to application time. Implant with hydroxyapatite surface was were utilized. Implant surface was rubbed with 50mg/ml Tetracycline-HCI solution and sterilized saline for ${\frac{1}{2}}min.$, 1min., $1{\frac{1}{2}}min.$, 2min., $2{\frac{1}{2}}min.$, and 3min. respectively in the test group. Then, specimens were processed for scanning electron microscopic observation and measured surface roughness by optical interferometer. The results of this study were as follows. 1. Hydroxyapatite surface showed that round particles were deposited irregularly. 2. The roughness of surfaces conditioned with Tetracycline-HCI and saline was lessened and the cracks were increased relative to the application time. In conclusion, the detoxification with 50mg/ml Tetracycline-HCI must be applied respectively with appropriate time according to hydroxyapatite implant surfaces.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.537-540
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• 1999

Effect of alignment layers on pretilt angle generation and electrical characteristics in nematic liquid crystal(NLC) by using photo-alignment techniques on polyimide (PI) surface with side chain were studied. The generated pretilt angle of the NLC on rubbed PI surface with 1-layer is almost the same as that of the 2-layers. However, the generated pretilt angle of the NLC on photo-induced PI surface with 2-layers is larger than that of the 1-layer. Therefore, the pretilt angle of the NLC on photo-induced PI surface is attributed to surface roughness due to photo-depolymerization of the polymer with UV light irradiation on PI surface. Next we observed the same characteristics of voltage-transmittance (V-T) and response time for 1- and 2-layers on PI surface. We also observed the same voltage holding ratio (VHR) characteristics for 1- and 2-layers on photo-aligned PI surface. Consequently, we suggest that the VHR of photo-aligned TN-LCD is higher than that of the rubbing-aligned TN-LCD.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.2
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• pp.151-156
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• 2000

Effects of alignment layers on pretilt nagle generation and electrical characteristics in nematic liquid crystal(NLC) by using photo-alignment techniques on polyimide PI) surface with side chain were studied. The generated pretilt angle of the NLC on rubbed PI surface with 1-layer is almost the same as that with the 2-layers. However, the generated pretilt angle of the NLC on photo-induced PI surface with 2-layers is larger than that with the 1-layer. The different mechanism of pretilt generation in NLC was observed on the rubbing and photo-alignment method. Therefore, the pretilt angle of the NLC on photo-induced PI surface is attributed to surface roughness due to photo-dissociation on the polymer with UV light irradiation on PI surface. We observed the same characteristics of voltage-transmittance (V-T) and response time for 1- and 2-layers on PI surface. Consequently, we sugest that the VHR of photo-aligned TN-LCD is higher than that of the rubbing-aligned TN-LCD.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.12
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• pp.3404-3412
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• 1994

The present study was undertaken to investigate the dry wear process and wear mechanism of the alumina ceramics in the purity variation which are used for the mechanical seal, roll, liner and dies. The wear test was carried out under different experimental condition using the wear testing device and in which the annular surface rubbed on dry sliding condition various sliding speed, contact pressure and sliding distance. In case of alumina purity 95%, there was speed range which wear loss increased rapidly owing to enlargement of heat impact force and temperature rise of wear surface. According as the alumina purity increased, wear loss decreased but alumina purity 85% with much void and defect had the most wear loss than any other alumina purity. The friction coefficient of sliding initial stage of wear curves has a large value but according to increase of sliding distance, it decreased owing to drop of the shear strength of wear surfaces.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.04a
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• pp.120-122
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• 1997

In this paper, the viewing angle characteristics of amorphous (a) - twisted nematic (TN) - liquid crystal display (LCD) on poly(viny)cirmamate (PVC) alignment surfaces were investigated. It was found that the threshold voltage is increased with increasing the polymerization on PVC surfaces. We suggest that the threshold voltage is affected to the surface anchoring strength with increasing the polymerization of the alignment film. Also, we obtained that the viewing angle of a-TN-LCD is increased with increasing the polymerization on PVC surfaces. Finally, we considered that the viewing angle of a-TN-LCD on PVC surfaces is large compared to TN-LCD on rubbed polyimide (Pl) surface.