• Title/Summary/Keyword: Liquid Layer

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Effects of UV Irradation on the Alignment of Liquid Crystal (러빙배향된 액정셀에 대한 자외선 조사효과)

  • Kim, Young-Sik;Kim, Jae-Hyung
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2001.11b
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    • pp.324-327
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    • 2001
  • Liquid crystal alignments on a rubbed polyimide layer were investigated by using optical transmission method. Using this technique, we also studied the pretilt angle of the polymer molecules near the surface of a side-chain polymer layer as a function of the rubbing strength. In particular, we obtained the optical characteristics of liquid crystal orientations and pretilt angles for LC cell photo-aligned by UV as well after rubbing alignment. High pretilt angle of 3.84 degree was obtained on the weekly rubbed polymide layer duribg UV irradation time of 60min.

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Capillary Force Lithographic Patterning of a Thermoplastic Polymer Layer for Control of Azimuthal Anchoring in Liquid Crystal Alignment

  • Kim, Hak-Rin;Shin, Min-Soo;Bae, Kwang-Soo;Kim, Jae-Hoon
    • Journal of Information Display
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    • v.9 no.1
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    • pp.14-19
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    • 2008
  • We demonstrated the capillary force lithography (CFL) method for controlling the azimuthal anchoring energy of a liquid crystal (LC) alignment layer. When a thermoplastic polymer film is heated to over the glass transition temperature, the melted polymer is filled into the mold structure by the capillary action and the aspect ratio of the pattern is determined by the dewetting time of the CFL process. Here, the proposed method showed that the azimuthal anchoring energy of the LC alignment layer could be simply controlled by the surface relief patterns which were determined by the dewetting times during the CFL patterning.

Effects of UV Irradation on the Alignment of Liquid Crystal (러빙배향된 액정셀에 대한 자외선 조사효과)

  • 김영식;김재형
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2001.11a
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    • pp.324-327
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    • 2001
  • Liquid crystal alignments on a rubbed polyimide layer were investigated by using optical transmission method. Using this technique, we also studied the pretilt angle of the polymer molecules near the surface of a side-chain polymer layer as a function of the rubbing strength. In particular, we obtained the optical characteristics of liquid crystal orientations and pretilt angles for LC cell photo-aligned by UV as well after rubbing alignment. High pretilt angle of 3.84 degree was obtained on the weekly rubbed polymide layer during UV irradation time of 60min.

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The Effect of Liquid Water in Fuel Cell Cathode Gas Diffusion Layer on Fuel Cell Performance (가스 확산층(GDL)내부의 물이 연료전지 성능에 미치는 영향)

  • Park, Sang-Kyun
    • Journal of Advanced Marine Engineering and Technology
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    • v.39 no.4
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    • pp.374-380
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    • 2015
  • In this paper, a dynamic model describing the 2 phase effect on the gas diffusion layer depending on load change of a fuel cell stack was developed to examine the effects of liquid water in fuel cell cathode gas diffusion layer on the fuel cell performance. For the developed model, 2 phase effect on the performance of a fuel cell stack depending on the load changes, concentration distribution of water vapor and oxygen inside a gas diffusion layer, the effect of the thickness and porosity of the gas diffusion layer on the fuel cell stack voltage were examined. As a result, a fuel cell stack voltage for the 2 phase model within the scope of the research become lower than that for the 1 phase model regardless of the load. Although oxygen molar concentration for the gas diffusion layer adjacent to the catalyst layer was the lowest, water vapor concentration is the highest. In addition, as thickness and porosity of the gas diffusion layer increased and decreased, respectively, the fuel cell stack voltage decreased.

Optimization of $p^+$ seeding layer for thin film silicon solar cell by liquid phase epitaxy

  • Lee, Eun-Joo;Lee, Soo-Hong
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.15 no.6
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    • pp.260-262
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    • 2005
  • Thickness optimization of heavily doped p-type seeding layer was studied to improve performance of thin film silicon solar cell. We used liquid phase epitaxy (LPE) to grow active layer of $25{\mu}m$ thickness on $p^+$ seeding layer. The cells with $p^+$ seeding layer of $10{\mu}m\;to\;50{\mu}m$ thickness were fabricated. The highest efficiency of a cell is 12.95%, with $V_{oc}=633mV,\;J_{sc}=26.5mA/cm^2$, FF = 77.15%. The $p^+$ seeding layer of the cell is $20{\mu}m$ thick. As thicker seeding layer than $20{\mu}m$, the performance of the cell was degraded. The results demonstrate that the part of the recombination current is due to the heavily doped seeding layer. Thickness of heavily doped p-type seeding layer was optimized to $20{\mu}m$. The performance of solar cell is expected to improve with the incorporation of light trapping as texturing and AR coating.

Shearing and Electro-optical Properties of Stressed Cholesteric Liquid Crystal Cells

  • Lee, Jung-Min;Kang, Dae-Seung
    • Journal of Information Display
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    • v.11 no.2
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    • pp.91-93
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    • 2010
  • The shearing effects on the electro-optical properties of a stressed cholesteric liquid crystal were investigated. A photopolymer was dispersed in the cholesteric liquid crystal cell. By carefully choosing the mixing ratio between the liquid crystal and the photoreactive monomer, and by applying suitable mechanical shearing on the substrates, a cholesteric liquid crystal display with a low threshold voltage and no alignment layer was demonstrated.

Pore-network Study of Liquid Water Transport through Multiple Gas Diffusion Medium in PEMFCs (고분자 연료전지의 다공성층 내에서의 액상수분 이동에 관한 공극-네트워크 해석 연구)

  • Kang, Jung-Ho;Lee, Sang-Gun;Nam, Jin-Hyun;Kim, Charn-Jung
    • 한국전산유체공학회:학술대회논문집
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    • 2011.05a
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    • pp.46-53
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    • 2011
  • Water is continuously produced in polymer electrolyte membrane fuel cell (PEMFC), and is transported and exhausted through polymer electrolyte membrane (PEM), catalyst layer (CL), microporous layer (MPL), and gas diffusion layer (GDL). The low operation temperatures of PEMFC lead to the condensation of water, and the condensed water hinders the transport of reactants in porous layers (MPL and GDL). Thus, water flooding is currently one of hot issues that should be solved to achieve higher performance of PEMFC. This research aims to study liquid water transport in porous layers of PEMFC by using pore-network model, while the microscale pore structure and hydrophilic/hydrophobic surface properties of GDL and MPL were fully considered.

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Study on Electro-Optic Characteristics Dependent on Passivation Layer Thickness in the FFS mode using a Liquid Crystal with Positive Dielectric Anisotropy (유전율 이방성이 양인 액정을 이용한 FFS모드의 절연층 두께에 따른 전기 광학 특성 연구)

  • Lee, Ji-Youn;Park, Sang-Hyun;Oh, Sang-Min;Lee, Seung-Hee
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2005.07a
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    • pp.485-486
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    • 2005
  • Fringe-field switching mode which has a horizontal and vertical electric field exhibits high transmittance and wide viewing angle characteristics. In the FFS mode, a passivation layer between common and pixel electrodes exists, which functions as preventing current leakage of fringe-field. In this paper, we have studied LC behavior, transmittance and operating voltage characteristics with applied voltage as a function of the passivation layer thickness and defined optimal value of the layer to be about $0.5{\mu}m$.

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An Experimental Study on the Frost Prevention using Micro Liquid Film of an Antifreezing Solution (마이크로 부동액막을 이용한 착상방지에 관한 실험적 연구)

  • Chang Young- Soo;Yun Won -Nam
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.17 no.5
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    • pp.459-467
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    • 2005
  • The effect of anti freezing solution liquid film on the frost prevention is experimentally investigated. It is desirable that the antifreezing solution spreads widely on the heat exchanger surface forming thin liquid film to prevent frost nucleation and reduce the thermal resistance across the film. A porous layer coating technique is adopted to improve the wettedness of the anti freezing solution on a parallel plate heat exchanger. The antifreezing solution spreads widely on the heat exchanger surface with 100 $\mu$m thickness by the capillary force resulting from the porous structure. It is observed that the antifreezing solution liquid film prevents a parallel plate heat exchanger from frosting. The reductions of heat and mass transfer rate caused by thin liquid film are only $1\~2\%$ compared with those for non-liquid film surface.

Tape-Type Liquid Leakage Film Sensor (액체누설 감지용 테이프형 필름센서)

  • Yu, D.K.;Kim, K.S.;Yub, H.K.;Han, G.H.;Jin, D.J.;Kim, J.H.;Han, S.H.;Cho, G.S.
    • Journal of the Korean Vacuum Society
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    • v.20 no.2
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    • pp.146-154
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    • 2011
  • The adhesive-tape of a liquid leak film sensor including the alarm system is developed. The sensing film is composed of three layers such as base film layer, conductive line layer, and protection film layer. The thickness of film is 300~500 um, the width is 3.55 cm, and the unit length is 200 m. On the conductive line layer, three conducting lines and one resistive line are formulated by the electronic printing method with a conducting ink of silver-nano size. When a liquid leaks for the electricity to be conducted between the conductive line and the resistive line, the position of leakage is monitored by measuring the voltage varied according to the change of resistance between two lines. The error range of sensing position of 200 m film sensor is ${\pm}1m$.