• Title/Summary/Keyword: $\pi$ -mode

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Study of wide viewing angle and response time by using new VA-$\pi$ cell mode cell mode (새로운 VA-$\pi$ cell mode cell mode를 이용한 광시야각 및 응답속도에 관한 연구)

  • 이정호;김진호
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 1999.11a
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    • pp.549-552
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    • 1999
  • We have developed an novel vertical-alignment (VA) - $\pi$ cell mode that provides a wide viewing angle and fast response times for negative dielectric anisotropy nematic liquid crystal (NLC) on a homeotropic polyimide (PI) surfaces. We had the good voltage-transmittance curves and low driving voltages were achieved with the novel VA - $\pi$ cell mode without negative compensation film. Iso-viewing angle characteristics using the novel VA - $\pi$ cell mode without negative compensation film of NLC was also successfully observed. As well a fast response time of 31.7ms for the novel VA - $\pi$ cell mode was measured. Consequently, It is seen that by using the novel VA - $\pi$ cell mode the iso-viewing angle, fast response time, and low driving voltage characteristics can be achieved.

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A Study on wide viewing angle and fast response time using new VA-$\pi$ cell mode (새로운 VA-$\pi$ 셀 모드를 이용한 광시야각과 고속 응답에 관한 연구)

  • 서대식;이정호
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.13 no.4
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    • pp.332-336
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    • 2000
  • We have developed a novel vertical-alignment(VA) -$\pi$ cell mode that provides a wide viewing angle and fast response times for nematic liquid crystal(NLC) with negative dielectric anisotropy on a homeotropic polymide(PI) surfaces. Good voltage-transmittance curves and low driving voltages were achieved with the new VA-$\pi$ cell mode without a negative compensation film. Iso-viewing angle characteristics using the new VA-$\pi$ cell mode without a negative compensation film was also successfully observed. As well a fast response time of 31.7 ms for a new VA-$\pi$ mode was measured. Consequently the iso-viewing angel fast response time and low driving voltage characteristics using a VA-$\pi$ cell can be achieved.

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Study on Design PI Controller Adopted Sliding Mode Control for DC Servo Motor Position Control (슬라이딩 모드 제어 이론을 적용한 PI 제어기에 의한 직류 서보 모타의 위치 제어에 관한 연구)

  • Park, Kyeong-Bae;Won, Jong-Soo
    • Proceedings of the KIEE Conference
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    • 1989.11a
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    • pp.29-32
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    • 1989
  • This paper proposes new position control method for DC servo motor by PI controller adopting sliding mode control. By adding sliding mode controller to conventional PI controller good robustness is obtained with good transient response and no steady state error which are merits in PI controller. In order to use microprocessor for digital control the principles of sliding mode control conventionally explained in continous-time system are extended to discrete-time system.

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The P/PI Mode Switching Method of Gopinath Flux Observer for Sensorless Vector Control of Induction Motors (유도전동기 센서리스 벡터제어를 위한 고피나스 자속관측기의 P/PI 모드 전환)

  • Kang, Myeong-Kyu;Choi, Jong-Woo
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.66 no.12
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    • pp.1732-1739
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    • 2017
  • This paper presents a sensorless vector control algorithm of closed loop Gopinath flux observer to enhance the robustness at low speed by switching P/PI mode. Closed loop Gopinath flux observer has the problem in sensorless vector control of induction motor at low speed. This paper solves the problem using the characteristic function of closed loop Gopinath flux observer. P mode shows better performance than PI mode under the cut-off frequency of observer. But P mode always has a flux error due to DC offset, so this paper combines P mode and PI mode. This algorithm shows good performance over wide speed range. The performance has been confirmed through computer simulations using MATLAB SIMULINK and experiments.

PI-based Feedforward Control for Driving Mode Transformation of Rescue Robot capable of Obstacle Overcoming (장애물 극복이 가능한 구조로봇의 주행모드 변형을 위한 PI-based Feedforward 제어)

  • Jeong, Hae-Kwan;Kang, Hyun-Suk;Kwak, Yoon-Keun
    • Journal of Institute of Control, Robotics and Systems
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    • v.14 no.5
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    • pp.489-495
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    • 2008
  • This paper offers a practical control scheme for driving mode transformation of a rescue robot already developed. The rescue robot, VSTR(Variable Single-Tracked Robot), has two driving modes, so can traverse untidy terrain and overcome obstacles such as stairs easily by use of timely driving mode transformation. Classical PI control scheme was used firstly for driving mode transformation, but stationary phenomenon, which might have a bad effect on the performance in real situation, came into existence. Therefore, we suggest a new controller, PI-based feedforward controller, which should be a good alternative for the problem, and compare it with other nonlinear control scheme.

Wide viewing angle and fast response time using novel vertical-alignment - 1/4 ${\pi}$ cell mode

  • Lee, Jeong-Ho;Seo, Dae-Shik;Kim, Hyang-Yul
    • 한국정보디스플레이학회:학술대회논문집
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    • 2000.01a
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    • pp.9-10
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    • 2000
  • The wide viewing angle and fast response time characteristics of negative dielectric anisotropy nematic liquid crystal (NLC) using a novel vertical-alignment (VA) - 1/4 ${\pi}$ cell mode on a homeotropic alignment layer were investigated. Good voltage-transmittance curves and low driving voltage using the novel VA - 1/4 ${\pi}$ cell mode without a negative compensation film were obtained. The iso-viewing angle characteristics of NLC using the novel VA - 1/4 ${\pi}$ cell mode without a negative compensation film can be achieved. The fast response time of 24.4 ms in NLC was successfully measured. The iso-viewing angle, fast response time, and low driving voltage characteristics using the novel VA - 1/4 ${\pi}$ cell mode can be achieved.

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High Temperature Characterization of Accumulation-mode Pi-gate pMOSFETs (고온에서 accumulation-mode Pi-gate p-MOSFET 특성)

  • Kim, Jin-Young;Yu, Chong-Gun;Park, Jong-Tae
    • Journal of the Institute of Electronics Engineers of Korea SD
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    • v.47 no.7
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    • pp.1-7
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    • 2010
  • The device performances of accumulation-mode Pi-gate pMOSFETs with different fin widths have been characterized at high operating temperatures. The device fin height is 10nm and fin widths are 30nm, 40nm, and 50nm. The variation of the drain current, threshold voltage, subthreshold swing, effective mobility, and leakage current have been investigated as a function of operating temperatures. The drain current at high temperature is slightly larger than at room temperature. The variation of the threshold voltage as a function of the operating temperature is smaller than that of the inversion-mode MOSFETs. The effective mobility is decreased with the increase of operating temperature. It is observed that the effective mobility is enhanced as the fin width decreases.

Magnetic Properties of SmCo Thin Films Grown by Using a Nd-YAG Pulsed Laser Ablation Method (Nd-YAG Pulsed Laser Ablation법으로 제작한 SmCo계 박막의 자기특성)

  • 김상원;양충진
    • Journal of the Korean Magnetics Society
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    • v.10 no.1
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    • pp.30-36
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    • 2000
  • SmCo films were deposited on Si(100) substrate by a Nd-YAG pulsed laser ablation of the targets of Sm$\_$100-x/Co$\_$x/ (73$\leq$x$\leq$93) at the substrate temperature of 600∼700$\^{C}$ and the laser beam energy density of Q switching mode or fixed Q mode. The magnetic properties of the films obtained from the Q switching mode exhibited a 4 $\pi$ Ms of 5200∼7700 Gauss, iHc of 190-250 Oe, and 4$\pi$M$\_$r//4$\pi$M$\_$s/ of 0.4∼0.74, respectively, while the fixed Q mode gave the magnetic properties of corresponding films of a 4$\pi$M$\_$r//4$\pi$M$\_$s/ = 0.32∼0.91 and iHc of 430-6290 Oe, respectively. The fixed Q mode gave the better magnetic properties of the SmCo films which seems to be due to a formation of magnetically hard minor phases in droplet of Sm-rich intermetallics. However, the resultant rough surface of the SmCo films is a problem to be solved by a continued study.

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Wide Viewing Angle Characteristics Using Novel Vertical-Alignment 1/6$\pi$ Cell Mode (새로운 VA-1/6$\pi$셀 모드를 이용한 광시야각 특성)

  • 황정연;서대식;한은주;김재형
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.13 no.10
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    • pp.883-886
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    • 2000
  • We have developed a novel vertical-alignment(VA) - 1/6$\pi$ mode that provides a wide viewing angle for nematic liquid crystal (NLC) with negative dielectric anisotropy on a homeotropic polyimide (PI) surfaces. Good voltage-transmittance curves were achieved with the new VA - 1/6$\pi$ cell model without a negative compensation film. The viewing angle of a new VA -1/6$\pi$ cell without a negative compensation film was wider than that of a conventional VA cell. Finally, the wide viewing angle using the new VA-1/6$\pi$ cell mode can be achieved.

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Inheritance of Resistance to Bacterial Spot and to Phytophthora Blight in Pepper (고추의 더뎅이병(病) 저항성(抵抗性)과 역병(疫病) 저항성(抵抗性)의 유전(遺傳))

  • Kim, Byung Soo;Kwon, Young Seok;Shon, Eun Young
    • Current Research on Agriculture and Life Sciences
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    • v.9
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    • pp.127-133
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    • 1991
  • PI201232, a pepper line resistant to Phytophthora capsici Leonian, was crossed with PI2713222 and P1163192, resistant to Xanthomonas campestTis pv. vesicatoria (Doidge) Dye and inheritance of the resistance to each disease and genetic relationship between the two disease resistances was studied. Non-hypersensitive resistance to race 3 of X. c. pv. vesicatoria of PI271322 was inherited in a quantitative mode. Resitance to P. capsici of PI201232 was inherited in a mode close to two dominant alleles. Hypersensitive resistance to race 1 of X. c. pv. vesicatoria of PI271322 was inherited in a mode of single dominant allele. PI 163192 was consistently resistant to both race 1 and race 3 of X c. pv. vesicatoria and the resistance was inherited in a quantitative mode with high dominance effect. Resistance to X. c. pv. vesicatoria was inherited independently from resistance to P. capsici.

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