• 제목/요약/키워드: ceramic

검색결과 14,893건 처리시간 0.037초

세라믹 Nd:YAG 레이저 매질의 균열 해석 (Analysis of Crack Behavior in a Ceramic Nd:YAG)

  • 김덕래;김병태
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 2010년도 하계학술대회 논문집
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    • pp.186-186
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    • 2010
  • The crack behavior in the ceramic Nd:YAG at a laser-diode end-pumped Nd:YAG ceramic laser was investigated. The fracture critical temperature difference of the ceramic Nd:YAG is about $355^{\circ}C$. The fracture of the 2 at% and the 4 at.% ceramic Nd:YAG occurred more than 14.9 W and 6.9 W pump powers, respectively, under lasing conditions.

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세라믹 밸브 인서트의 최근 개발동향 (Current design methodology for ceramic valve seat insert)

  • 이수완;이명호
    • 오토저널
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    • 제16권4호
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    • pp.1-5
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    • 1994
  • 1) Natural gas engine에서 intake valve와 valve seat insert가 exhuast valve와 valve seat insert보다 마모가 심하다. 2) Ceramic valve seat insert을 금속재료를 사용하는 것이 보다 더욱 효과적이다. 즉 적어도 3배 정도 마모가 적게 일어난다. 3) Ceramic valve와 ceramic valve seat insert로 결합한 경우 valve face 또는 stem 부위에서 응력이 집중되어 파손된다. 따라서 현재의 ceramic valve design methodology로는 ceramic valve은 좋은 결과를 얻을 수 없다. 4) 가장 효과적인 결합은 Tribolloy 800의 hardfacing 합금의 valve와 질화규소의 valve seat insert이다.

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GPS 용 유전체 세라믹 안테나의 설계 (The Design of Dielectric Ceramic Antenna for GPS)

  • 김현철;노용래;김인태;김윤호
    • 한국세라믹학회지
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    • 제33권9호
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    • pp.977-984
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    • 1996
  • This paper analyzes the performance of a rectangular dielectric ceramic antenna by the theoretical cavity model such as input impedance resonant frequency quality factor efficiency and bandwidth. Through a compu-ter simulation variation of the antenna characteristics is found as a function of the antenna parametes. (permit-tivity permeability antenna size etc) Based on the results we propose a new design method for the dielectric ceramic antenna to be employed in Global Positioning Systems.

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세라믹 정형 가공을 위한 성형기 개발 (Development of Thermal Imprint System for Net-Shape Manufacturing of Multi-layer Ceramic Structure)

  • 박철규;임성한;홍주표;이종길;윤성만;고장혁
    • 한국소성가공학회:학술대회논문집
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    • 한국소성가공학회 2008년도 추계학술대회 논문집
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    • pp.401-404
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    • 2008
  • In the present investigation, a high precision thermal imprint system for micro ceramic products was developed and the net-shape manufacturing of multi-layer ceramic reflector for LED (Light Emitting Diode) was conducted with a precision metal die. Workpiece used in the present investigation were the multi-layer laminated ceramic sheets with pre-punched holes. The cavity with arbitrary angle was formed on the circular and rectangular holes of the ceramic sheets. During the imprinting process, the ambient temperature of the imprint system was kept over the transition temperature of the ceramic sheet and then rapidly cooled. The results in this paper show that the present method can be successfully applied to the fabrication of very small size hole array for ceramic reflector in a one step operation.

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철도구조물에 대한 세라믹 인서트 및 앵커의 적용 방안 연구 (A Study on Ceramic Insert and Anchor Application for Railway Structures)

  • 서창범;오명열;이광일
    • 한국철도학회:학술대회논문집
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    • 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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    • pp.1177-1184
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    • 2011
  • Ceramic insert and anchor has many advantages compared with existing steel products, therefor widely applied for concrete bridge, tunnel, railroad and building etc. in Japan. Ceramic insert and anchor start-to-used in Korea is no longer, but the product has already been applied to various construction sites and have been recognized for excellence. But now in Korea, the ceramic insert and anchor are not yet widely use like in Japan. This paper was an introduction to the ceramic insert and anchor, and detailed explained the product excellent performance. Ceramic insert and anchor can be applied to many areas, but in this case the focus was the application of ceramic insert and anchor for railway structures. In this paper we detailed compared the ceramic products with existing steel products in their respective characteristic, and analyzed on their application in domestic and foreign.

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Dielectric Properties of Polymer-ceramic Composites for Embedded Capacitors

  • Yoon, Jung-Rag;Han, Jeong-Woo;Lee, Kyung-Min
    • Transactions on Electrical and Electronic Materials
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    • 제10권4호
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    • pp.116-120
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    • 2009
  • Ceramic-polymer composites have been investigated for their suitability as embedded capacitor materials because they combine the processing ability of polymers with the desired dielectric properties of ceramics. This paper discusses the dielectric properties of the ceramic ($BaTiO_3$)-polymer (Epoxy) composition as a function of ceramic particle size at a ceramic loading of 40 vol%. The dielectric constant of these ceramic-polymer composites increases as the powder size decreases. Results show that ceramic-polymer composites have a high dielectric constant associated with the $BaTiO_3$ powder with a 200 nm particle size, high insulation resistance, high breakdown voltage (> 22 KV/mm), and low dielectric loss (0.018-0.024) at 1 MHz.

열에 안정한 Ceramic Resistor의 제조에 관한 연구 (Studies on Thermostable Ceramic Resistors)

  • 안영필;김상욱;최롱
    • 한국세라믹학회지
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    • 제12권2호
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    • pp.15-20
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    • 1975
  • Ceramic resistors to be stable at high temperature were manufactured from using MgO, SiO2, SnO2, Bi2O3, and CeO2 by sintering in air at 125$0^{\circ}C$. Electrical resistivity with elevated temperatures was studied for the various system of the above oxides. The resistor, 1.0 MgO-1.0 SiO2-0.575 SnO2-0.005 Sb2O3-0.025 Bi2O3-0.013 CeO2 has the resistivity, (14.55$\pm$0.3)$\times$103 ohm in a temperature range from $25^{\circ}C$. to 80$0^{\circ}C$. It is concluded that the ceramics prepared by a dielectric compound and metal oxide semi-conductor has a good thermostability for electrical appliciations.

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