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박막 확산대의 상변화에 미치는 탄성응력과계면 반응장벽의 영향
許株烈,洪種波 대한금속재료학회 2002 대한금속·재료학회지 Vol.40 No.4
An explicit, finite difference scheme has been used to simulate the influence of coherency stresses and interface kinetic barriers on the phase evolution of a binary, thin-film diffusion couple. Thin-films, initially consisting of alternating layers of two terminal phases α and γ, were held at a temperature where the formation of an intermediate phase β at α/γ interface was thermodynamically probable. In the absence of both the coherency stresses and interface kinetic barriers, β phase nucleates to grow at the beginning of the phase evolution and all phase compositions at interfaces are constant during the evolution. When either the coherency stresses or interface kinetic barriers are present, however, the interfacial compositions become time-dependent and thus the following characteristics of phase evolution are possible: (1) thermodynamically stable phase β does not form at the early stages of the evolution but nucleates to grow in the middle of the evolution, and (2) thermodynamically unstable phase β can initially nucleate to grow and then shrink to disappear during the evolution. Even if the initial states of α/γ multilayers have the same overall composition, the presence of coherency constraint can result in different final equilibrium states depending on either the initial phase compositions of α and γ or the magnitude of interface kinetic barriers.
리플로우 솔더링시 솔더/Cu 계면반응속도에 미치는 Cu- 첨가 솔더의 영향
허주열,강대웅 대한금속재료학회(대한금속학회) 2000 대한금속·재료학회지 Vol.38 No.1
We have investigated the effects of Cu additions to pure Sn and eutectic Sn-Pb solders on the morphology and growth kinetics of the intermetatllics (Cu_6Sn_5) and on the consumption rate of Cu substrate during isothermal reflow soldering. The consumption rate of Cu substrate could be reduced with increasing Cu content in both Sn and Sn-Pb solders up to the respective solubilities at reflow temperatures. The effect of Cu addition was more significant for the Sn solder which had a higher Cu solubility. The Cu addition also resulted in morphological changes of the intermetallic layer. With increasing Cu content, the interface between Cu_6Sn_5 layer and solder roughened for pure Sn solder whereas it flattened fur the eutectic Sn-Pb solder. When the time(t) dependence of the intermatallic layer thickness(X ̄) was modelled as X ̄ = a×t^n, the growth constant a appeared to increase with the Cu content whereas the growth exponent n decreased. It was shown that the growth kinetics of the intermetallic layer could be well interpreted by a model of grain boundary diffusion controlled growth.
허주열(Hur, Joo-Youl),이성근(Lee, Seong-Keun) 한국지역개발학회 2009 韓國地域開發學會誌 Vol.21 No.3
The purpose of this study is the analysis on the characteristics of residents" participation for the comprehensive rural village development project by progress phase(preparation, planning, propulsion systems set up and valuation phases). For that, 169 promotion committee and ordinary residents in the 29 rural villages in Gyeongbuk province which are subject to comprehensive development were selected for questionnaire covering 16 days from April 15 to 30, 2009. The questionnaire was put into x²-test and t-test with SPSS 17.0, and the results are as below. First, in the preparation phase, initiation of comprehensive rural village development project was proposed mostly by the villages leaders or the local governments, while the ordinary residents were aware of the project later than promotion committee along with they showed a low level in joining education prepared for themselves. Second, in planning phase, the ordinary residents showed lower participation level compared with the promotion committee in vision sharing, awareness level of project contents, participation level in selecting project by sector, and in the role between the objects of planning set up. Third, in promotion system establishment phase, the ordinary residents showed lower participation level and lower awareness levels than promotion committee in promotion committee activities, village development council activities, local governments" roles, Fourth, the residents satisfaction about participating in comprehensive rural village development project appeared high in general. But the satisfaction levels of the general residents about the planning phase the about the promotion committee activities in promotion system setup phase appeared low.