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A Study on Fast Response Time for Twisted Nematic Liquid Crystal Display

  • Lee, Kyung-Jun;Jeon, Yong-Je;Hwang, Jeoung-Yeon;Seo, Dae-Shik;Jeon, Youn-Hak;Nam, Sang-Hee
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 2002년도 춘계학술대회 논문집 디스플레이 광소자 분야
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    • pp.121-123
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    • 2002
  • Fast response characteristics of twisted nematic liquid crystal display (TN-LCD) cell with different nematic liquid crystals (NLCs) and cell gap on a rubbed polyimide (PI) surface were studied. High transmittance and fast response time of the TN-LCD on the rubbed PI surface were achieved by using high birefringence ($\Delta$ n) and low cell gap. It is considered that the transmittance and response time of the TN-LCD on the rubbed PI surface decreased as $\Delta$ nd decrease.

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모형시험을 통한 무리말뚝 내 말뚝의 위치별 부주면마찰력에 관한 연구 (A Study on the Negative Skin Friction Depending upon the Locations of Piles in a Group Using Model Test)

  • 임종석;박종희;심종선
    • 한국지반공학회:학술대회논문집
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    • 한국지반공학회 2009년도 세계 도시지반공학 심포지엄
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    • pp.923-932
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    • 2009
  • Generally most of pile foundations are constructed with group pile rather than single pile. The study on efficiency and bearing capacity which are major elements for rational design of this group pile has been actively progressed, whereas there are truly only a few studies of negative skin friction working on group pile due to the consolidation of ground. The purpose of this study is to determine, among the elements of negative skin friction applied to pile, the occurrence modality of negative skin friction at center, side, and corner of $3{\times}3$ group pile using model test and, based on those observations, to propose the effective design direction of group pile.

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Development of Digital Gas Metal Arc Welding System and Welding Current Control Using Self-tuning Fuzzy PID

  • Doan, Phuc Thinh;Pratama, Pandu Sandi;Kim, Suk-Yoel;Kim, Hak-Kyeong;Yeun, Hwang-Yeong;Byun, Gi-Sig;Kim, Sang-Bong
    • 한국해양공학회지
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    • 제25권6호
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    • pp.1-8
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    • 2011
  • This paper describes a new method for a digital gas metal arc welding (GMAW) system. The GMAW system is an arc welding process that incorporates the GMAW power source (PS-GMAW) with a wire feed unit (WFU). The PS-GMAW requires an electric power of constant voltage. A constant magnitude is maintained for the arc current by controlling the wire-feed speed of the WFU. A mathematical model is derived, and a self-tuning fuzzy proportional-integral-derivative (PID) controller is designed and applied to control the welding current. The electrode wire feeding mechanism with this controller is driven by a DC motor, which can compensate for both the molten part of the electrode and undesirable fluctuations in the arc length during the welding process. By accurately maintaining the output welding current and welding voltage at constant values during the welding process, excellent welding results can be obtained. Simulation and experimental results are shown to prove the effectiveness of the proposed controller.