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재열균열완화를 위한 스테인리스강 347H 보일러튜브의 용접공정 개선
이한상(Han-sang Lee),김희선(Hee-sun Kim),박명수(Myung-soo Park),김범신(Bum-shin Kim),이종민(Jong-min Lee) 대한용접·접합학회 2020 대한용접·접합학회지 Vol.38 No.6
Many failures at the welded joint of 347H tubes have recently occurred during the short-term operation of the boiler tubes. To mitigate reheat cracking or strain induced precipitation hardening, the finite element analysis and experiment for optimization of welding procedure were performed. Preheating, high inter-pass temperature, low and high heat input conditions were compared with existing welding procedure. According to mechanical analysis, high inter-pass temperature and high heat input condition showed the lower plastic strain and tensile residual stress at the inner area of heat-affected zone. At high temperature tensile test, the high inter-pass temperature condition had lower yield strength and higher elongation, while the high heat input condition showed higher yield strength and smaller elongation. In the specimen of high heat input condition, the dissolution of most precipitates and coarse grain were observed in the heat-affected zone. Relatively small amount of dissolution and smaller grain got shown in high inter-pass temperature condition. Therefore, high inter-pass temperature condition can be an alternative. Through X-ray diffraction analysis, it was confirmed that nitrogen was added to Super304H and carbon was substituted for the existing crystal structure of Nb(C,N). This will mitigate reheat cracking by increasing the solvus temperature of Nb(C,N) and reduce the grain coarsening.
이한상(Lee, Han-Sang) 한국외국어대학교 인도연구소 2012 남아시아연구 Vol.17 No.3
인도 및 신흥공업국에서는 아직 선진국에 비해 미성숙한 정치환경, 미발달한 금융, 노동관계 등 불완전한 경제제도를 가지고 있어서 기업내에 이를 보완하는 조직을 발달시킨 기업그룹이 널리 퍼져있다. 따라서 이들 나라에서 기업은 선진국기업에 비해 절대적으로 부족한 위험자본 및 검증된 경영진을 내부적으로 부담하고 또한 주요한 대외관계인 행정관료 및 정치인와의 접촉도 기업내부에서 다루어 새로운 경제적 기회가 창출되었을 때 그와 같은 지원을 받지 못한 기업보다 더 유리하기 때문에 보통 한 기업이 다양한 분야의 사업체들을 경영하는 그룹의 형태를 취함을 보였다. 하지만 인도는 계획경제체제이후 시장자유화체제로 전환하면서 과거보다 훨씬 정치, 경제제도가 성숙하면서 인도기업들도 치열한 경쟁 속에서 다양한 사업분야를 구조조정을 하고 한편으로는 경쟁력있는 기존사업을 강화하고 있을 뿐만 아니라 선진국에서처럼 전문분야에서 사업을 하는 전문화기업현상도 나타나고 있다. The formation of business groups in India and other newly industrialized countries is regarded to be caused by immature political surroundings and less developed product, finance and labor market in their countries. Business groups in those countries provide risky capital, tested business talents and contacts with government officials and politicians in their resources which are scare in their countries when there comes a new business opportunity. The business group survived and became the dominant business organization in those less developed countries after facing with companies which do not have those support in the new business opportunities. We found in India"s prominent business groups like, Tata, Aditya Birla and Reliance group such unrelated but various business activities. However, after the economic liberalization in 1990s, Indian business groups become more focused and did structural adjustment faced with competition. There are also tendencies of specialized business groups with the characteristics of research and service which are widely pervasive in more advanced economies with developed social infrastructure and economic systems.