• Title/Summary/Keyword: 부채꼴 평판

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Influence of Boundary Stress Singularities on the Vibration of Clamped and Simply Supported Sectorial Plates With Various Radial Edge Conditions (다양한 방사연단 조건을 갖는 고정 및 단순지지 부채꼴형 평판 진동에 대한 경계응력특이도의 영향)

  • Kim, Joo-Woo
    • Journal of Korean Society of Steel Construction
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    • v.10 no.4 s.37
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    • pp.601-613
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    • 1998
  • This paper reports the first-of-its-kind free vibration solutions for sectorial plates having re-entrant corners causing stress singularities when the circular edge is either clamped or simply supported. The Ritz method is employed with two sets of admissible functions assumed for the transverse vibratory displacements. Accurate frequencies and normalized contours of the transverse vibratory displacement are presented for the spectra of sector angles.

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Electrical Treeing Deterioration and Dielectric Breakdown Phenomena in Polymeric Insulator (고분자 절연재료에서 전기트리 열화 및 절연파괴 현상)

  • Cho, Yeong-Sin;Kim, Sang-Uk
    • Korean Journal of Materials Research
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    • v.9 no.4
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    • pp.398-403
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    • 1999
  • Studies on the electrical treeing deterioration and dielectric breakdown phenomena in the polymeric insulator of polyethylene and epoxy resin were carried out. Block type samples with needle-plane electrode geometry were electrically stressed and the tree pattern from the needle tip was observed. In LDPE the density of electrical tree was very high and its pattern was bush type. For the case of XLPE, branched tree was observed. As temperature and SN content increased, the dielectric breakdown voltage decreased and the treeing phenomena became more complicated. Fan type cracks were observed around the conducting tree path in the brittle DGEBA/MDA system.

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A Study on the Spray Cooling Characteristics of hot Flat Plates (고온평판의 분무냉각특성에 관한 연구)

  • 윤석훈
    • Journal of Advanced Marine Engineering and Technology
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    • v.22 no.6
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    • pp.880-887
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    • 1998
  • In order to study heat transfer characteristics of spray cooling for the purpose of uniform and soft cooling of high temperature surface a series of experiments for a hot horizontal copper flat plate was performed by downflow spray water using flat spray nozzle. Cooling curves were mea-sured under the various experimental conditions of flow rates and temperatures of cooling water Surface temperature surface heat fluxes and heat transfer coefficients of horizontal upward-facing flat surface were calculated with cooling curves measured at each radial positions near the cooling surface by TDMA method. Generally heat transfer characteristics for spray cooling is simi-lar to boiling phenomenon of pool boiling. The minimum heat flux(MHF) appear at the surface temperature of about ${\Delta}Tsat=250^{\circ}C$ and the critical heat flux(CHF) appear at about ${\Delta}Tsat=250^{\circ}C$.

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A Study on the High Temperature Region Heat Transfer Coefficients for the Spray Cooling of Hot Flat Plates (평판 분무냉각 시의 고온역 열전달계수에 관한 연구)

  • Yoon, D.H.;Oh, C.;Yoon, S.H.
    • Journal of Advanced Marine Engineering and Technology
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    • v.24 no.5
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    • pp.25-32
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    • 2000
  • In this paper, experiments investigating the high-temperature region heat transfer coefficients for the spray cooling of hot flat plates were performed by down spray water using flat spray nozzles. The heat transfer surface is made of copper and is 100mm in length and 40mm in width and 15mm in thickness. The experimental condition of spray are as follows: temperatures of the water droplets are T=20~$80^{\circ}C$ and droplets volume fluxes are D=0.001565~0.010438$m^3/m^2s$. Next, correlating equations for the heat transfer characteristics of spray cooling in the high temperature region are developed from the effects of droplets volume flux and the surface temperature of heat transfer plate.

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