• Bulletin of the Korean Chemical Society
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• v.35 no.3
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• pp.821-827
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• 2014

An isotope dilution liquid chromatography tandem mass spectrometry (ID LC-MS/MS) method has been developed and applied to the determination of arsenobetaine (AsB, ${(CH_3)_3}^+AsCH_2COO^-$) from oyster candidate certified reference material (CRM). The exact matching isotope dilution approach was adopted for accurate determination of AsB using $^{13}C_2$-labeled AsB as an internal standard. Efficiencies of different AsB extraction methods were evaluated using a codfish reference material and a simple sonication method was selected as the method of choice for the certification of the oyster candidate CRM. The hydrophilic interaction liquid chromatography (HILIC) combined with electrospray ionization tandem mass spectrometry (ESI/MS/MS) in selected reaction monitoring (SRM) mode was optimized for adequate chromatographic retention and robust quantification of AsB from codfish and oyster samples. By analyzing 12 subsamples taken from each 12 bottles systematically selected from the whole oyster CRM batch, the certified value of AsB was determined as $6.60mg{\cdot}kg^{-1}{\pm}0.31mg{\cdot}kg^{-1}$ and it showed excellent between-bottle homogeneity of less than 0.42%, which is represented by relative standard deviation of 12 bottles from the CRM batch. The major source of uncertainty was the certified value of the AsB standard solution.

• Electrical & Electronic Materials
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• v.19 no.9
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• pp.28-32
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• 2006

A 7.0-inch transmissive type plastic TFT-LCD was developed at the resolution of 640 $\times$ 3 $\times$ 480 lines (114ppi). All of the processed of TFT, color filter and LC were carried out below $130^{\circ}C$ on PES plastic films. The process conditions of TFT, color filter and LC were optimized for large area TFT-LCD on plastic substrate. The backplane and the color filter was strongly adhered while the panel was bending by using holding spacers.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.189-189
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• 2009

This work was focused on the dielectrophoretic force of fullerenes dispersed in liquid crystal host medium, which are investigated in the homogeneously aligned liquid crystal (NLC) cells driven by external electric field. A fullerene of 10 wt% was doped into the LC medium and its electric field induced motion was controlled by both in-plane and vertical electric field. When the electric field was applied, the fullerene start to move in direction of applied electric field. The dark, grey and white states in the proposed device can be obtained by suitable combination of the polarity of applied electric field. The w and l are the width and distance between the electrodes. The reflectance at different l was measured and was found to be increased with increasing l. The dynamical motions of fullerene particles in LC medium suggest that fullerene can be designed for electronic-paper like displays.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.162-162
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• 2009

Optical bounce which occurs by over twist of the liquid crystal (LC) director has a problem of response time in fringe-field switching (FFS) modes. After removing the electric field, effective birefringence ($d{\Delta}n_{eff}$) at the edge of pixel electrode meets the $\lambda/2$ phase instantly, since tilt angle of LC directors at that position suddenly decreases compared to twist angle. In this paper, based on the careful analysis, origin of optical bounce has been explained.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.208-208
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• 2009

We used Brewster's Law to examine the mechanism of liquid crystal (LC) alignment on an organic insulation layer when subjected to ion-beam irradiation. Brewster's Law implies that the maximum rate polarized ray on a slanted insulation layers on the substrate and it illustrates the dependence of polarization and themechanical structure on the ion beam irradiation process. The pretilt angle of nematic LCs on the organic insulation surface was about $1.13^{\circ}$ for an ion beam exposure of $45^{\circ}$ for 1 minute at 1800eV. This shows the dependence of LC alignment on the polarization ratio in a slanted organic insulation layer.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.04a
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• pp.177-180
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• 2000

In this study, we investigated the pretilt angle generation and liquid crystal (LC) alignment by ultraviolet (UV) exposure during imidization of polyimide on the polymer with side chain. The generated pretilt angle of nematic (N) LC using in-situ photo-alignment method was smaller than that of the conventional UV photo-alignment method. Also, the generated pretilt angle of NLC tends to increase by annealing.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.288-288
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• 2009

We have studied polarity effects of dielectric anisotropy effects on electro-optical characteristics of a twisted nematic mode driven by fringe electric field, which has wide viewing angle characteristics. Our device is designed as normally black mode between parallel polarizers. The perfect polarization conversion of incident light, which passes through a polarizer, is achieved, when it passes through the twisted liquid crystal (LC) layer. If an electric field is applied, the LC molecules with a positive (or negative) dielectric anisotropy rotate parallel (or perpendicular) to the horizontal component of a fringe electric field as increasing transmittance. From the calculated results, enhanced transmittance of the fringe field-twisted nematic (FF-TN) mode with positive dielectric anisotropy of + 8.2 can be obtained.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.6
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• pp.487-490
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• 2001

Residual DC voltage of the in-plane switching (IPS)-liquid crystal display(LCD) by voltage-transmittance (V-T) hysteresis method was studied. Several IPS-LCD which have different concentrations of cynao LCs and different resistivities of fluorine LCs were fabricated. We found that the residual DC voltage of the IPS-LCD was decreasing with increasing concentration of cyano LCs and increasing with decreasing specific resistivity of fluorine LC materials. The residual DC voltage property can be improved by low molecular weight and high polarity of cyano LC.

• The Transactions of the Korean Institute of Power Electronics
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• v.4 no.2
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• pp.122-127
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• 1999

In this paper, the power factor correction circuit using a parallel drive method is proposed so that the high power inverter air-conditioner with 3[hp] compressor motor may obtain the cost down and the improved performance. The adequate design porcedures are presented to reduce the material costs by eliminating the power factor imprving LC filter and derating output capacitor and inverter switches. Using the determined components. the proto-type circuit with 6[kW] power consumption is built and tested to verify the operation of the proposed circuit.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.04a
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• pp.49-50
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• 2008

OCB mode has advantages such as fast response time and wide viewing angle. But it has inevitable shortcoming which initial splay state must be changed to bend state. To overcoming this problem, OCB cell filled LC with RM monomer was cured by UV when voltage applied. Through previously mentioned methods, even if electric field is none, bend state was made by stabilized LC director. In this paper, we investigated the electric characteristics of polymer stabilized OCB mode.