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원자력터빈의 전략개발을 위한 LTAM 미래고장률 결정 및 적용
신혜영(Hye-young Shin),윤은섭(Eunsub Yun) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.11
Long Term Asset Management(LTAM) means a plan developed by using LCM(Life Cycle Management) process for optimum life cycle management of significant plant assets at each plant across the fleet. As a part of development of LTAM Strategies on nuclear turbines, a method so as to determine the future failure rates for low pressure turbine facilities at a nuclear plant was studied and developed by using both plant specific and industry-wide performance data. INPO's EPIX data were analyzed and some failure rate evaluation values considering preventive maintenance practices were calculated by using EPRI's PM Basis software. As the result, failure rate functions applicable to a priori and a posteriori replacement of low pressure turbines at a nuclear plant were developed and utilized in an assessment of economics of LCM alternatives on the nuclear turbine facilities in the respects of 40-year and 60-year operation bases.
고에너지 전자빔투사방법에 의한 Cr₃C₂/SUS316L 표면복합재료의 제조와 미세조직분석
윤은섭,이성학 대한금속재료학회 2004 대한금속·재료학회지 Vol.42 No.8
The present study is concerned with fabrication and microstructural analysis of Cr₃C₂/SUS316L surface composites using high-energy electron-beam irradiation. Three kinds of powder mixtures, i.e., 50Cr₃C₂-50CaF₂(flux), 100Cr₃C₂, and 87.5Cr-12.5C (wt.%), were placed on an SUS₃16L stainless steel substrate, which was then irradiated with electron beam. In the specimens fabricated without flux powders, the surface composite layer of 3.5-4.8 mm in thickness was successfully formed without defects by the self-fluxing effect, and contained a large amount (up to 18 vol.%) of Cr_(7)C₃ carbides in the austenite matrix. The composite layer fabricated with Cr and C powders having lower melting points than Cr₃C₂ powders was thicker than that fabricated with Cr₃C₂ powders because of more effective melting of powders during electron-beam irradiation. The hardness and wear resistance of the surface composite layer were directly influenced by hard primary Cr_(7)C₃ carbides, and thus were about two times greater than those of the untreated stainless steel substrate.
고에너지 전자빔 투사방법으로 제조된 2층 비정질 합금 표면복합재료의 미세조직 연구
이규홍,윤은섭,이성학,김낙준 대한금속재료학회 2004 대한금속·재료학회지 Vol.42 No.9
This study is concerned with the fabrication of two-layered amorphous/Cu surface composites by high-energy electron-beam irradiation. The mixture of Zr-base amorphous powders and LiF+MgF₂ flux was deposited on a pure Cu substrate, and then electron beam was irradiated on these powder mixture to fabricate a one-layered surface composite. A two-layered surface composite was also fabricated by irradiating electron beam again onto the powder mixture deposited on the one-layered surface composite. The composite layers of 1.6~1.7 mm in thickness were homogeneously formed without defects, and the two-layered composite contained a few fine crystalline phase particles in the amorphous matrix. This fabrication could be achieved by (1) the use of flux which protected the oxidation environments, (2) the second electron-beam irradiation which melted already-formed crystalline particles, and (3) the fast cooling rate of the irradiation method which provided the high amorphous forming ability. Such a development of the fabrication technique of amorphous alloy surface composites presented new applicability of amorphous alloys to structures and components requiring excellent mechanical properties.