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상이한 초미세립 구조를 갖는 OFHC Cu의 연성에 영향을 미치는 요소인자
박이주(L. J. Park),감형원(H. W. Kim),이종수(C. S. Lee),황시우(S. W. Hwang),박경태(K.-T.Park) 한국소성가공학회 2010 한국소성가공학회 학술대회 논문집 Vol.2010 No.5
Tensile ductility of OFHC Cu with the different ultrafine grained (UFO) structures, which were fabricated by the different routes of equal channel angular pressing (ECAP), was associated in detail with the microstructural characteristics developed by ECAP. OFHC Cu having the lamellar and equiaxed UFO structures was prepared by ECAP of routes A and Bc respectively up to 8 and 16 passes. Their microstructures were closely examined by transmission electron microscopy and orientation image mapping. Tensile tests at room temperature were conduced on the ECAPed samples under the quasi- static condition of 10?³ s?¹ and 1 s?¹. Uniform elongation of the lamellar UFO samples decreased with increasing the ECAP passage while both uniform and total elongations of the equiaxed UFO samples increased. In the case of route A producing the lamellar UFO structure, the fractions of high angle grain boundaries and grains less than 0.5 ㎛ increased significantly but an analysis revealed that the dislocation free length decreased with increasing the ECAP passage. For route Be resulting in the equiaxed UFO structure, the fraction of high angle grain boundaries increased but the grain size distribution and the dislocation free length remained nearly unchanged with increasing the ECAP passage. From the present experiments and analyses, it was found that tensile ductility of lamellar UFO OFHC Cu is primarily controlled by the dislocation free length and that of the equiaxed one is mainly dependent on the fraction of high angle grain boundaries.
비용, 일정 및 기술적 성과를 고려한 통합 계획수립 프로세스 구현 방안
유이주,박영원,You, Yi-Ju,Park, Young-Won 한국군사과학기술학회 2007 한국군사과학기술학회지 Vol.10 No.3
The purpose of the research is to propose an integrated project planning process and its implementation method. Although there is increasing interest in the application of the Earned Value Management(EVM) method in the project management area, the progress and maturity of the technical performance have not been included in assessing the Earned Value. The main concept of the planning process is to use cost, schedule, as well as the technical performance in the assessment of the Earned Value Management for Military R&D project management practices. The resulting process can enhance the efficiency of the project work by eliminating the currently duplicated activities between traditional project planning process and the newly implemented Earned Value Management process and by shortening the early planning process duration of projects adopting EVM practices.