• Title, Summary, Keyword: Dielectric liquid

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Enhancement of Transmittance Efficiency of TFT-LCD using High Transmittance Polarizer and Dielectric Anisotropy Liquid Crystal

  • Lim, Sung-Hoon;Son, Dong-Yeon;Choi, Kyung-Seob;Choi, Jae-Ho;Lee, Jong-Hwan;Choi, Kwang-Soo
    • 한국정보디스플레이학회:학술대회논문집
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    • pp.661-663
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    • 2009
  • This paper describes a fabrication method for high transmittance panel using newly designed polarizer and liquid crystal with a high dielectric anisotropy (${\Delta}{\varepsilon}$). To enhance the transmittance of the panel without contrast ratio reduction, new polarizer with high transmittance and high ${\Delta}{\varepsilon}$ liquid crystal were used. The transmittance of the liquid crystal display (LCD) panel employed by a new polarizer was increased by 6% over that of the panel with a conventional polarizer and liquid crystal in LCD industry.

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Effects of Fluoride Additions on Sintering and Microwave Dielectric Properties of CaWO$_4$ (Fluoride 첨가에 따른 CaWO$_4$의 소결 및 고주파 유전특성)

  • 이경호;김용철;방재철
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.127-130
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    • 2002
  • In this study, development of a new LTCC material using a non-glassy system was attempted with respect to reducing the fabrication process steps and cost down. Lowering the sintering temperature can be achieved by liquid phase sintering. For LTCC application, the starting material must have quality factor as high as possible in microwave frequency range. And also, the material should have a low dielectric constant for enhancing the signal propagation speed. Regarding these factors, dielectric constants of various materials were estimated by the Clausius-Mosotti equation. Among them, CaWO$_4$ was tamed out the suitable LTCC material. CaWO$_4$ can be sintered up to 98% of full density at 1200$^{\circ}C$ for 3 hours. It's measured dielectric constant, quality factor, and temperature coefficient of resonant frequency were 10.15, 62880GHz, and -27.8ppm/$^{\circ}C$, respectively. In order to modify the dielectric properties and densification temperature, 0.5∼1.5 wt% LiF were added to CaWO$_4$. LiF addition reduced the sintering temperature/time down to 800$^{\circ}C$/10∼30min due to the reactive liquid phase sintering. Dielectric constant lowered from 10.15 to 9.38 and Q x fo increased up to 92000GHz with increasing LiF content.

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Preparation and Dielectric Properties of LCP and BaTiO3 Composites (LCP(Liquid Crystal Polymer)와 BaTiO3복합체의 제조 및 유전특성)

  • 윤기현;이승주;양병덕;김종희
    • Journal of the Korean Ceramic Society
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    • v.40 no.12
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    • pp.1183-1188
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    • 2003
  • LCP (Liquid Crystal Polymer)/BT(BaTiO$_3$) composite was prepared by mixing LCP varnish and BT slurry. And the effect of the composition of LCP/BT composites and the size of BT powder on dielectric properties of LCP/BT composite were investigated. The dispersion properties of BT slurries were also studied as a function of volume fraction of dispersant, GLYMO (3-glycidyloxypropyltrimethoxysilane) added to various sized BT powders. The quantity of optimum dispersant in BT slurry decreased with an increase of BT powder size because of the decrease of specific surface area of BT powder. LCP/BT composite sheet was prepared by tape-casting method with mixing BT slurry and LCP varnish. The dielectric constant of the composites increased from 34.3 to 44.1 and their dielectric loss increased from 0.05 to 0.063 as the size of BT powder increased from 100 nm to 500 nm.

Dielectric Characteristics of HTS Cable (고온초전도 케이블의 유전 특성)

  • Kwag, Dong-Soon;Kim, Hae-Jong;Cho, Jeon-Wook;Seong, Ki-Chul;Kim, Sang-Hyun
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.64-68
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    • 2002
  • According to the increasing power demand for the future construction of many underground cables will be required. However, construction of new ducts for power cables will be more difficult. Therefore, research work for realizing the high temperature superconducting(HTS) cable has advanced, where the development of electrical insulating system at cryogenic temperature is one of the major researches. For an electrical insulation design of HTS cable, it is important to understand not only breakdown but also partial discharge and dielectric loss($tan{\delta}$) in liquid nitrogen/paper composite insulation system. In this paper, we investigated breakdown characteristics in liquid nitrogen/paper composite insulation system for the application to HTS cable. And, we studied the breakdown characteristics of the multi-layer and butt gap of the insulation papers in liquid nitrogen. Also, we measured dielectric loss($tan{\delta}$) of the mini-model Cable made of TERLAM IPP.

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Electro-optic Characteristics of the fringe-field Driven Reflective Hybrid Aligned Nematic Liquid Crystal Cell using a Liquid Crystal with Positive Dielectric Anisotropy (유전율 이방성이 양인 액정을 이용한 fringe-Field 구동형 반사형 Hybrid Aligned Nematic 액정 디스플레이의 전기-광학 특성)

  • Song, Je-Hoon;Choi, Min-Oh;Lim, Young-Jin;Lee, Seung-Hee
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.18 no.8
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    • pp.724-728
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    • 2005
  • Electro-optic characteristics of reflective hybrid aligned liquid crystal (LC) cell driven by fringe field using a nematic LC with positive dielectric anisotropy have been studied. Optimized optical configurations are achieved by using a single polarizer, half-wave film and a cell with quarter-wave retardation. The simulation results shows an optimum cell retardation of $0.30{\mu}m$. This value may allow a practical cell gap larger than $3{\mu}m$, which makes it easy to control in the manufacturing process. Furthermore, this LC cell with optimized cell parameters shows low wavelength dispersion and the contrast ratio greater than 5 over exists about $100{\circ}$ in vertical direction and $160{\circ}$ in horizontal direction. Also, when using the LC with positive dielectric anisotropy rather than negative dielectric anisotropy, the display shows low power consumption and fast response time.

Study on single gap transflective fringe-fields switching liquid crystal display using the liquid crystal with negative dielectric anisotropy (유전율 이방성이 음인 액정을 이용한 FFS 모드의 단일 갭형 반투과형 액정 디스플레이 연구)

  • Kim, Jin-Ho;Chin, Mi-Hyung;Lim, Young-Jin;Lee, Seung-Hee
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.312-313
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    • 2008
  • A transflective liquid crystal displays associated with fringe field switching (FFS) mode of new concept is proposed. The device utilizes unique characteristic of the FFS mode in which the rotation angle of LC director is strongly dependent on electrode position in on state. We use the liquid crystal with negative dielectric anisotropy. Also we are look for optimized electrode size and the optimization of pixel electrode width and distance between them, the LC director could rotate about $22.5^{\circ}$ and $45^{\circ}$ depending on electrode positions. Consequently, we get high transmittance and high reflection on the optimized electrode condition. Respectively, a high image quality transflective display with single gap and single gamma characteristics realized.

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Shape and Dielectric Strength of Thermal Bubbles in Liquid Nitrogen (액체질소 중 열기포 형상 및 절연 특성)

  • Baek, Seung-Myeong;Kim, Hae-Jong
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.28 no.5
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    • pp.326-331
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    • 2015
  • In this paper, we study the insulating properties of the liquid nitrogen(LN2) including the thermal bubbles. The shape of the thermal bubbles in accordance with the current change was observed in the 77 K and 65 K LN2. According to the temperature of liquid nitrogen, bubbles were generated differently. The round shape of the bubble is occurred in 77 K LN2. But the layer shape of bubble is occurred in 65 K LN2. When the bubbles present, the dielectric strength of liquid nitrogen is low. However, the breakdown patterns were different according to the electrode arrangement. AC breakdown voltage(BDV) was lower than the DC BDV due to the influence of bubbles. Therefore, the design of a high-voltage superconducting equipments should consider the bubbles.

Electro-Optic Characteristics of the Dual Domain Fringe-Field Switching(FFS) Mode using the Liquid Crystal with Negative Dielectric Anisotropy (유전율 이방성이 음인 액정을 이용한 이중 도메인 FFS 모드의 전기광학 특성)

  • 김향율;고재완;노정동;서대식;이승희
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.15 no.8
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    • pp.720-725
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    • 2002
  • The fringe-field switching (FFS) mode was known to exhibit both a wide viewing angle and high transmittance, especially when using the liquid crystal (LC) with negative dielectric anisotropy. In the device, the LC director rotates almost in-plane. However, in the bright state the device shows bluish and yellowish color along parallel and perpendicular to the LC director at off-normal directions since the LC director rotates only in one direction. Such a problem was greatly improved using a wedge shape of only pixel electrodes. In this way two different field directions exist in a pixel, enabling the LC director to rotate in two opposite directions. Consequently, owing to dual domain effect when using the LC with negative dielectric anisotropy, the viewing angle characteristics are greatly improved.

Dielectric and Mechanical Properties of BNT-LCP Composites

  • Park, Myoung-Sung;Cho, Jeong-Ho;Kim, Byung-Ik;Chun, Myoung-Pyo;Nahm, Sahn
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.24 no.7
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    • pp.547-553
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    • 2011
  • We investigated the dielectric and mechanical properties of ceramic polymer composite xBNT - (1-x)LCP (x= 0, 10, 20, 30, 40 vol.%). The disk shaped BNT ($BaNd_2Ti_4O_{12}$) - LCP (liquid crystal polymer) composite samples were prepared by compression molding method. With increasing the BNT content in composites from 10 to 40 vol.%, the dielectric constant increased but the dielectric loss as well as bending strength of composites reduced. These composites were well described with modified Lichtenecker's model having k = 0.392 and 0.303 for the first and second ball milled BNT filled composites, which means that the BNT filler in composites are well dispersed. The dielectric constant of the composite comprised of the second milled BNT ($D_{50}$ = 1.39 um) was higher that of the composite of the first milled BNT ($D_{50}$= 2.45 um), which seems to be related with the different particle size and dispersion of BNT fillers in LCP matrix. The bending strength of the composite containing the second milled BNT was superior to that of the composite of the first milled BNT.