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이선기,박정하,Lee, Seon-Gi,Park, Jeong-Ha 한국시스템엔지니어링협회 2003 시스템엔지니어링워크숍 Vol.1 No.-
Construction industry recognizes the necessity to manage is business from viewpoint of processes, and consider developing, evaluating and improving standard processes as important managerial target. SW-CMM provides basic framework for this process management. However, appropriate tailoring and adjustment are essential for SW-CMM concept to be applied to construction business. SW-CMM makes construction manager understand the capability of business process, based on which the priority of process improvement is judged. The capability is prescribed by common features. This paper introduces the basic frame for diagnosing construction business processes with SW-CMM, and presents the case study of analysing processes focusing on communication management.
사류 임펠러의 입구각 변화가 내부유동 및 펌프특성에 미치는 영향
이선기,Lee, Seon-Gi 대한기계학회 1997 大韓機械學會論文集B Vol.21 No.8
For the improvement of the pump characteristics in the partial capacity range, it must be verified that the influence of the impeller design factor on the internal flows and the influence of the impeller internal flows on the pump characteristics. In this paper, in order to understand the influence of inlet angles on flow conditions and characteristics of a mixed flow pump, experiments were carried out for three kinds of impeller, which have the same outlet angle distributions and meridional section shapes. Results show that separation and stall in the partial capacity range can be controlled by the inlet angles. The relationship between the separation - stall at the impeller leading edge and the discharge flow conditions is clarified.
750℃에서 Alloy 800H 용접재의 저주기 피로 및 수명 예측
이선기(Seon Gi Lee),김선진(Seon Jin Kim),김우곤(Woo Gon Kim),김응선(Eung Seon Kim) 대한기계학회 2020 大韓機械學會論文集A Vol.44 No.5
본 연구의 목적은 750℃에서 alloy 800H 용접재의 저주기 피로 및 수명 예측을 평가하기 위한 것이다. 저주기 피로 시험은 완전 양진 변형률 제어로 하였으며 ±0.3, ±0.45, ±0.6 및 ±0.75%의 서로 다른 전변형률 진폭에서 10-3/s의 일정한 변형률 속도로 수행하였다. 모든 전변형률 진폭에서 용접재의 피로 수명은 전변형률 진폭의 증가와 함께 감소하였다. 반복 응력 반응 거동의 경우 모재는 초기 반복 경화현상을 보였으나, 용접재의 경우 반복 연화 현상이 나타났다. 모재와 더불어 용접재의 수명 평가는 Coffin-Manson 법에 의해 평가되었다. 예측된 모재와 용접재의 저주기 피로 수명은 실험 데이터와 잘 일치하는 것으로 나타났으며, 천이수명은 용접재의 경우가 모재보다 작게 나타났다. 또한, 모든 조건에서 균열 발생 및 전파는 입내 파괴의 파손 모드를 보였다. This work aims to investigate the low-cycle fatigue and life prediction of alloy 800H weldment at 750 ℃. Low cycle fatigue tests were conducted using a series of fully reversed strain-control tests at four different strain amplitude, namely ±0.3, ±0.45, ±0.6 and ±0.75 %, under a constant strain rate of 10<SUP>-3</SUP>/s. In all test conditions, the fatigue life of alloy 800H weldments decreased with increasing the strain amplitude. The cyclic stress response behavior of the base metal showed the initial cyclic hardening phenomenon, whereas the weldments showed the cyclic softening phenomenon. The life evaluation of the base metal and weldment was evaluated by the Coffin-Manson method. For both the base metal and weldment, the low cycle fatigue lives predicted using the Coffin-Manson method were found to coincide well with the experimental data. The transition life of the weldment was lower than that of the base metal. Finally, under all testing conditions, crack initiation and propagation data showed the failure mode to be typically transgranular.