• Title/Summary/Keyword: vertical alignment

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Electro-optical performance using a PDT-VA cell (PDT-VA 셀을 이용한 전기광학 특성)

  • 김형규;황정연;서대식;한은주;김재형
    • Proceedings of the Korean Institute of Navigation and Port Research Conference
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    • 2000.11a
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    • pp.133-136
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    • 2000
  • We investigated the improvement of viewing angle using a patterned double twisted (PDT) vertical-alignment (VA) cell mode on a homeotropic alignment layer. Good voltage-transmittance curves for negative dielectric anisotropic nematic liquid crystal (NLC) using the PDT-VA cell without a negative compensation film were obtained. The viewing angle of the PDT-VA cell without a negative compensation film was wider than that of a conventional VA cell.

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Electro-optical performance using a PDT-VA cell (PDT-VA 셀을 이용한 전기광학 특성)

  • 김형규;황정연;서대식;한은주;김재형
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2000.11a
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    • pp.133-136
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    • 2000
  • We investigated the improvement of viewing angle using a patterned double twisted (PDT) vertical-alignment (VA) cell mode on a homeotropic alignment layer. Good voltage-transmittance curves for negative dielectric anisotropic nematic liquid crystal (NLC) using the PDT-VA cell without a negative compensation film were obtained. The viewing angle of the PDT-VA cell without a negative compensation film was wider than that of a conventional VA cell.

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A Study on Satellite Alignment Measurements Accuracy Improvement (인공위성 정렬 측정 정확도 향상을 위한 연구)

  • Choi, Jung Su;Kim, In-Gul
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.48 no.12
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    • pp.987-995
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    • 2020
  • Accurate alignment between high-performance payloads and attitude control sensors is essential factor to guarantee accurate attitude orientation and high pointing stability of the satellite. Space craft developers often use theodolite measurement system for satellite alignment during ground AIT(Assembly Integration and Test) phase. When measuring theodolite, errors may occur due to line of sight error, tilting axis error, vertical index error, and vertical axis error. In addition, errors that can occur during alignment measurements with multiple theodolites are analyzed through the alignment cube measurements test. Based on the alignment cube measurements test, a technical method that can improve the alignment measurement accuracy was suggested and it's measurements results satisfied the satellite design requirements.

Development of Proximity Exposure System with Vertical Structure for Plasama Display Panel (PDP용 수직형 구조의 근접 노광장치 개발)

  • Park, Jeong-Gyu;Jeong, Su-Hwa;Lee, Hang-Bu
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.24 no.9 s.180
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    • pp.2371-2380
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    • 2000
  • In this paper, we developed the proximity exposure system with the vertical structure of glass and mask stage to minimize the mask's warp caused by the pull of gravity. This system, which canirradiate the ultra violet through 1440 H 850 $\textrm{mm}^2$ and 1330X 1015 $\textrm{mm}^2$ exposure area, has the followingcharacteristics. The glass stage can be inclined by 80 degrees at vertical structure to load substrate withsafety on it. When the glass stage is the vertical state, the gap control, alignment control and exposureof ultra violet are executed. So, it enhances the pattern uniformity by minimizing the mask's warp. Theglass stage can also control the gap between the mask and the substrate by the coarse and fine motioncontrol. The mask stage can adjust the posture of photomask to the position of substrate by imageprecessing method. The galss stage for the gap control and the mask stage for the alignment aredesigned independently for each function.

Effect of Electric field on an Injection Velocity in a Vertically Aligned Nematic Liquid Crystal (수직배향 네마틱 액정셀에서의 주입속도에 미치는 전기장 효과)

  • Jeon, Yeon-Mun;Kim, Sang-Gyun;Kim, Youn-Sik;An, Myeong-Hwan;Lee, Seung-Hee
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.19 no.7
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    • pp.695-699
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    • 2006
  • Injection time of liquid crystal (LC) by capillary action in a vertically aligned (VA) nematic LC cell takes longer than that in a homogeneously aligned (HA) LC cell because Miesowicz viscosity in the former is bigger than that in the latter. To reduce liquid crystal injection time in the VA cell, we applied vertical electric field while injecting so that the orientation of LC molecules is changed from vertical alignment to homogeneous alignment. Consequently, the injection speed is improved by 25 % when compared with the cell without an applied field.

EO Characteristics in the Vertical-Alignment (VA)-In Plane Swiching (IPS) Cell on a Homeotropic Photopolymer Surface (수직 광폴리머 표면을 이용한 VA-IPS 셀의 전기 광학 특성)

  • Pieh, Sung-Hoon;Hwang, Jeoung-Yeon;Kim, Jae-Hyung;Seo, Dae-Shik
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2002.07b
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    • pp.945-948
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    • 2002
  • We studied electro-optical (EO) performances of a vertical-alignment (VA)-in plane switching (IPS) cell on a photopolymer surfaces. The VA-IPS cell, dark in voltage-off state, reveals bright uniformity in all directions due to the dual domainlike dierector configuration in the voltage-on state. For voltage-transmittance (V-T) measurement, the transmittance characteristics of the VA-IPS cell on the photopolymer surface was better than that of the VA-IPS cell on a polyimide(PI) surface.

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Viewing Angle Switching of Vertical Alignment Liquid Crystal Display (수직배향 액정 디스플레이의 시야각 스위칭)

  • Lim, Young-Jin;Jeong, Eun;Choi, Min-Oh;Lee, Seung-Hee
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2006.11a
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    • pp.49-50
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    • 2006
  • We have developed vertical alignment liquid crystal display (VA-LCD), of which the viewing angle can be controlled. The VA-LCD has the function of switching between the wide viewing mode and narrow viewing angle mode using one homogeneous aligned (HA) LC layer and one compensation film with a negative C-plate. The retardation of the HA layer at off axis can be controlled by applying an electric field while keeping the retardation value to be zero at normal direction. Consequently, the device exhibits a viewing mode over $170^{\circ}$ in terms of CR = 10 in wide viewing mode and about $60^{\circ}$ in terms of CR = 2 in narrow viewing angle mode m horizontal direction.

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Reducing of cross-talk by patterning of common electrode in the patterned vertical alignment (PVA) mode (PVA모드에서 공통 전극 패턴을 통한 전기장 간섭의 감소 효과)

  • Jeon, Yeon-Mun;Kim, Youn-Sik;Hwang, Seong-Jin;Lee, Seung-Hee;Lyu, Jae-Jin;Kim, Kyeong-Hyeon
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2006.11a
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    • pp.43-44
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    • 2006
  • We have studied electro-optical characteristics and stability of liquid crystal director depending on electrode patterning of common electrode on top substrate in patterned vertical alignment (PVA) mode. In the present studies, new type of common electrode pattern was suggested to enhance a dark state by reducing interference area due to data signal. According to the simulation result, PVA device with new common electrode pattern contributed to Improvement of an aperture ratio.

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An Optical Configuration for Vertical Alignment Liquid Crystal cell with Wide Viewing Angle

  • Ji, Seung-Hoon;Lee, Gi-Dong
    • Journal of Information Display
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    • v.9 no.2
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    • pp.22-27
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    • 2008
  • We propose an optical configuration of a vertical alignment (VA) liquid crystal (LC) cell to eliminate the light leakage in the diagonal direction. VA LC cell has an excellent contrast ratio in the normal direction due to the no phase-retardation. However, change of the phase-retardation occurs in all directions, which causes the light leakage and deteriorates the characteristics of the dark state. We designed the LC cell structure composed of multiple combinations with two A-plates and two C-plates in order to achieve wide viewing property on the Poincare sphere. From calculations, we show that the proposed structure can improve the viewing angle characteristics by compensating for the light leakage in all directions.

Characteristics of the Running behavior and Safety for Tilting train due to Vertical Alignment (틸팅열차의 주행안전성과 고저틀림의 상관성 분석)

  • Choi, Il-Yoon;Um, Ju-Hwan;Lim, Yun-Sik
    • Proceedings of the KSR Conference
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    • 2010.06a
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    • pp.1937-1942
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    • 2010
  • Vehicle dynamic behavior should be investigated to establish the track irregularity criteria because they have an impact on vehicle dynamic behavior. The tilting train which have been developed in Korea will be operated on the conventional line. Therefore, it should be checked that the track irregularity criteria of conventional line is still available for the new vehicle. In this paper, the influence of vertical alignment on running behavior and safety for tilting train was instigated by numerical analysis. The wavelength and amplitude of vertical alignment were considered in scenario of this numerical analysis. This research is based on just numerical analysis and the final result which include measurement will be published in the future.

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