• Title/Summary/Keyword: Ericksen-Leslie Theory

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Strong Orientation Anchoring and Shear Flow of a Nematic Liquid Crystal

  • Won Hee HAN
    • International journal of advanced smart convergence
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    • v.13 no.2
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    • pp.103-109
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    • 2024
  • A nonlinear numerical analysis of orientation and velocity fields of the full Ericksen-Leslie theory for a nematic liquid crystal under shear flow is given. We obtained for the first time the three-dimensional orientation and two component velocity profiles evolutions for both in- and out-of-shear plane orientation anchorings. Complex evolution routes to steady state were found even for shear aligning nematic. As the Ericksen number increases monotonic evolution of velocity and orientation shifts towards multi-region nucleating director rotation growth with complex secondary flow generations. We found that contrary to the in-shear-plane anchorings like homeotropic or parallel anchorings, binormal anchoring gives rise to substantial non-planar three-dimensional orientation with nonzero secondary flow.

Analysis of response time of twisted-nematic liquid-crystal cells with low twist angle

  • Nam, Chul;Park, Woo-Sang
    • 한국정보디스플레이학회:학술대회논문집
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    • 2000.01a
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    • pp.195-196
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    • 2000
  • Fast response time is realized by using LTN-LCDs. To calculate the dynamic electro-optical characteristics, Ericksen-Leslie theory is used for the dynamic profile of molecules and order tensor representation is adopted for the free energy calculation.

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Simulation of Liquid Crystals Considering Flow Effect (흐름효과를 고려한 액정의 시뮬레이션)

  • Kim Hoon;Park Woo-Sang
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.19 no.3
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    • pp.260-266
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    • 2006
  • In this paper, We coupled fluid balance and director balance equation from Ericksen-Leslie's continuum theory and observed the motion of Liquid Crystal molecular. We simulated flow velocity and director distribution in which flow effect is considered in switching on and switching off state. We interpreted the dynamic response characteristic caused by the flow. As the result of the simulation, We could see the flow effect. In the case of Twisted Nematic(TN) cell, this flow caused abnormal twist temporarily in switching off state. We could prove that this abnormal twist is a direct cause of optical bounce phenomenon known well until now with the result of simulation. In addition, We analyzed the mechanism of the fast response due to flow in the case of Optically Compensated Bend(OCB) cell.

Simulation of Electro-optical Properties of IPS-LCDs and VA-LCOs Considering Flow Effect (흐름효과를 고려한 IPS-LCDs, VA-LCDs의 전기광학적 특성 시뮬레이션)

  • Kim, Hoon-Bae;Park, Woo-Sang
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.20 no.2
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    • pp.167-172
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    • 2007
  • In this paper, we analyzed the molecular behavior of IPS-LCDs and VA-LCDs by using numerical simulation. The numerical simulation was performed on the basis of Ericksen-Leslie continuum theory. To improve the accuracy of the calculation, we considered fluid balance equation and director balance equation at the same time. thus, we calculated the flow effect for both switching on and off states. As the results of simulation, we confirmed abnormal twist in IPS-LCDs and fast molecular behavior in VA-LCDs which could influence response time.

Analysis on the Flow Effect of the Twisted Nematic liquid Crystals (Twisted Nematic(TN) 액정에서의 흐름효과 해석)

  • Kim, Hoon;Park, Woo-Sang
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2005.07a
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    • pp.76-78
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    • 2005
  • We coupled fluid balance equation and director balance equation from Ericksen-Leslie's continuum theory and observed the motion of Twisted Nematic (TN) Liquid Crystals. We simulated flow velocity distribution and director distribution. We interpreted the dynamic response characteristic caused by the flow. As the result of the simulation, We could see the flow effect. And this flow caused abnormal twist to 4msec in switching off state. We could prove that this abnormal twist is a direct cause of optical bounce phenomenon known well until now with the result of simulation.

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Theoretical Analysis of Biaxial Films for the Optical Compensation of TN-LCDs (TN-LCD 광학보상을 위한 Biaxial Film의 이론적 해석)

  • Kim, Bong-Sik;Kang, Choon-Ky;Park, Woo-Sang
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.25 no.3
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    • pp.209-212
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    • 2012
  • In this paper, we have studied on the optimal design of the optical compensation film for the TN-LCDs. To have wide viewing angle panels, several methods such as multi-domain method, optical path method, and phase compensation method have been proposed. Among these methods, this paper focused on the phase compensation method. In the phase compensation method, the phase retardation generated from the optical birefringence for the off-axis incident is compensated by using optical films with refractive anisotropy. To compensate the phase retardation of the TN-LCDs, we have proposed design concept for the biaxial optical films and analyzed the optical performance for the proposed structures. The calculation of the dynamic motion of the liquid crystals was based on the Ericksen-Leslie theory and the optical performance of the TN-LCD was calculated from the Extended Jones Matrix Method. From the results, we have confirmed that the optical characteristics of the TN-LCDs with the biaxial films have been improved considerably compared with the TN-LCDs compensated by the combination of the uniaxial films.