• Proceedings of the KIEE Conference
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• 1998.07d
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• pp.1261-1263
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• 1998

In this paper, we obtained that the monodomain alignment of nematic liquid crystal (NLC) increases with increasing irradiation time with linearly polarized ultraviolet (LPUV) light irradiation on polyimide (PI) surfaces. It was found that the monodomain alignment of NLC is obtained in a cell with normally LPUV light irradiated on PI surface at 30 min. and then oblique LPUV is secondly irradiated on PI surfaces rotated by $90^{\circ}$. The pretilt angle of NLC is generated about $2.5^{\circ}$ with oblique angle of $60^{\circ}$ and then decreased with increasing the oblique angle of IN light irradiation. It is considered that the pretilt angle of NLC is attributed to the photo-depolymerization of polymer with the oblique angle of UV light. The voltage-transmittance and response time characteristics of photo-aligned twisted nematic (TN)-LCD with UV light irradiation time of 60 min. were almost same in comparison with rubbing treated TN-LCD.

• Proceedings of the KIEE Conference
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• 1997.07d
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• pp.1585-1587
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• 1997

We investigated the generation of high pretilt angle for nematic liquid crystal (NLC) in the cell with slanted non-polarized ultraviolet (UV) light irradiation on two kinds of the polyimide (PI) film. It was shown that the monodomain alignment in NLC is obtained in the cell with slanted non-polarized UV light irradiation on PI surface. The pretilt angle of NLC is generated about 3 degrees in the cell with slanted non-polarized UV light irradiation with 70 degrees on PI surface without side chain. But, the pretilt angle of NLC is generated about 1 degree in the cell with slanted non-polarized UV light irradiation with 80 degrees on PI surface with side chain. We consider that the pretilt angle generation in NLC is attributted to anisotropic dispersion force between the LC molecular and the PI surface.

• The Korean Journal of Pesticide Science
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• v.19 no.1
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• pp.1-4
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• 2015

The current official perfluorochemicals (PFCs) analysis method is established with hydrophilic-lipophilic balance (HLB) solid phase extraction (SPE) clean-up method with LC-tandem mass spectrometry ($MS^n$). Herein the HLB clean-up method from the official method by Korean government was modified with Envi-Carb$^{TM}$ to improve the clean-up efficiency for agricultural water and the unexpected UV disturbance in the water was effectively removed by the adsorbent treatment without a significant disturbance of quantitation. And quadrupole time of flight mass spectrometry (qTOFMS) was suggested to the available $MS^n$ instruments for the residue analysis of PFCs based on the ng/L of quantitation limits in water as well.

• Analytical Science and Technology
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• v.22 no.1
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• pp.65-74
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• 2009

Active components of lacquer tree referred to as urushiol congeners, which are catechol derivatives with various alkyl or alkenyl substituents. The olefin side chains typically have one, two or three double bonds. In this study, the each congener's ratio analysis of extracts from korean lacquer tree are compared to the one from other asian lacquer tree. Extraction was performed using liquid-liquid extraction (LLE) method with soxhlet system from tree's bark and sap. Extracts were analyzed by reverse phase liquid chromatography and on-line electro spray ionization mass spectrometry (LC-MS/MS).

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.773-775
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• 2004

For high end, large area displays, all current LC modes require some degree of optical compensation to improve the front of screen viewing experience. Currently most optical films are laminated to the outside of the LCD cell, between the glass and polariser. In this paper we wish to show how it is possible to integrate the compensating optical film within a VA mode LCD cell. The paper will describe the process of making the biaxial film through the process of in-situ photopolymerisation of an aligned film of reactive mesogens in the cholesteric phase using polarised UV light. The film can be made on the colour filter array side of the LCD panel. In addition the process of fabricating a VA mode LCD containing this film will be described and the performance of this module will be presented

• Korean Journal of Veterinary Research
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• v.48 no.1
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• pp.33-38
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• 2008

In veterinary medicine amitraz has been used as an insecticide to eliminates mites, lice, and ticks in dogs, cats, goats, swine and cattle. The objective of present study was to developed an analytical method using one-step extraction and determination of the amitraz in veterinary drugs by liquid chromatography (LC). The amitraz was analyzed by LC equipped with Waters XTerra RP18 ($4.8{\times}250mm;\;5{\mu}m;\;Waters,\;USA$) analytical column, using 75% acetonitrile (acetonitrile/D.W; 75/25) at 1.0 ml/ min. The UV-VIS detection of amitraz was made at 290 nm. Calibration graphs were linear with very good correlation coefficients ($r^2>0.9999$) from $80{\sim}120{\mu}g/ml$. The limit of detection was $0.09{\mu}g/ml $ and limit of quantification was $0.27{\mu}g/ml $. The method showed good intra-day precision (CV 0.05~0.09%) and inter-day precision (CV 0.06~0.18%).

• Food Science and Biotechnology
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• v.18 no.4
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• pp.842-848
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• 2009

The purpose of this study was to determine the extent of domoic acid (DA) a potent neurotoxin, responsible for the syndrome amnesic shellfish poisoning (ASP) contamination of various species of bivalve shellfish purchased from fish market in Korea and the implications for food safety. Liquid chromatography (LC) methods were applied to quantify DA in shellfish after sample clean-up using solid-phase extraction (SPE) with strong anion exchange (SAX) cartridges. Toxin detection was achieved using photodiode array ultraviolet (LC-UV) and electrospray ionization-mass (LC-ESI-MS). DA was identified in 4 bivalve shellfishes of 872 shellfishes collected from March, 2006 to October, 2007 in Korea. DA amount of 3 surf clams (Mactra veneriformis) collected at Seoul, Daejeon, and Daegu were 4.13, 1.99, and 1.94 mg/kg, respectively. DA amount of 1 pink butterfly shell (Peronidia venulosa) collected at Seoul was 3.02 mg DA/kg. The amounts of DA that were present in 4 bivalve shellfishes were within EU guideline limits for sale of shellfish (20 mg DA/kg).

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.330-330
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• 2008

It is widely investigated to liquid crystal (LC) alignment using non-contact alignment method such as ion-beam (IB) irradiation, UV alignment, and oblique deposition. Because conventional rubbing method has some drawbacks. These include defects from dust and electrostatic charges and rubbing scratch during rubbing process. In addition, rubbing method needs additional process to remove these defects. Therefore rubbing-free methods like ion-beam irradiation are strongly required. We studied LC alignment effect on poly imide surface by IB irradiation and electro-optical (EO) characteristics of twisted nematic liquid crystal display (TN-LCD). In this experiment, a good uniform alignment of the nematic liquid crystal (NLC) with the ion-beam exposure on the polyimide (PI) (SE-150 from Nissan Chemical) surface was observed. We also achieved low pretilt angle as a function of ion-beam irradiation intensity. In addition, it can be obtained the good EO properties of the IB-aligned TN-LCD on PI surface. Some other experiments results and discussion will be included in the poster.

• Journal of Information Display
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• v.5 no.2
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• pp.23-26
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• 2004

For high end, large area displays, all current LC modes require some degree of optical compensation to improve the front of screen viewing experience. Currently most optical films are laminated to the outside of the LCD cell, between the glass and polariser. In this paper we wish to show how it is possible to integrate the compensating optical film within a VA mode LCD cell. The paper will describe the process of making the biaxial film through the process of in-situ photopolymerisation of an aligned film of reactive mesogens in the cholesteric phase using polarised UV light. The film can be made on the colour filter array side of the LCD panel. In addition the process of fabricating a VA mode LCD containing this film will be described and the performance of this module will be presented.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.604-606
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• 2009

We propose a method to control the pretilt angle of liquid crystal (LC) by doping a proper amount of UV curable reactive mesogen (RM) monomers in hometropic polyimide (PI). The intermediate pretilt angles are produced by anchoring competition between homeotropic PI and the polymerized RM which direction is along the LC molecules under electric field.