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방전가공된 니켈기 초내열합금 표면의 특성변화에 대한 연구
강신호(S.H. Kang),김대은(D.E. Kim) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.6
Nickel based heat resistant alloys are inevitably used in gas turbine industry due to the excellent thermal properties such as the creep and corrosion resistance. The alloys are also well known as hard-to-cut materials ranging from 10 to 40 in machinability index. With this machinability, it seems to be impossible to efficiently form cooling passages with high aspect ratio in the materials. To settle this problem in gas turbine manufacturing industries, Electrical Discharge Machining (EDM) has been a versatile solution. Regardless of hole shape, as far as the material is electrically conductive, EDM can drill up to 1:150 aspect ratio. However depending on the machining condition, EDMed surface is subject to material alteration and this could increase fatigue crack susceptibility. Moreover carbon or oxygen migrated from working fluids can change the surface to be brittle. In this study, various experiments were conducted to evaluate EDM’s negative effects when applied for Ni-based alloys.
강신호(S.H. Kang),최희숙(H.S. Choi),양성호(S.H. Yang),이정혁(J.H. Yi) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.6
Recently, a number of the heavy duty gas turbines have been installed in several power plants in Korea. The gas turbines are newer models, which are categorized as a 1300 class engine, adopting the upgraded materials and the protective technologies such as coating and cooling. Therefore corresponding technology development for repair and rejuvenation of hot gas path components are inevitable. The higher operational temperature accelerates material degradation as well as thermally induced stress in the components. To prevent catastrophic failure, the periodic repair using adequate knowledge and processes are essential. In order to cure thermal stress cracking occurred in fixed vanes, Activated Diffusion Healing is now a versatile solution following the hydrogen or fluoride ion cleaning. For early stage of the creep damaged materials for rotating blades, Hot Isostatic Pressing (HIP) or rejuvenation heat treatment is applicable to encourage metallurgical recovery. These are the state of the art technologies that are immediately available in Korea.
낙농분야 농업정보화의 실태와 효율적 지도체계에 관한 연구
김세헌,한경식,강신호,임지영 한국유가공기술과학회 2001 Journal of Dairy Science and Biotechnology (JMSB) Vol.19 No.1
This survey suggests current dairy information system in Kyong-ki province and personal computer education for dairy farmers in Korea. With the development of internet and dairy database system, more effective, quick delivery of dairy management and technology would be possible. Dairy expert's E-mail advice and using multimedia will be a great method to provide dairy technologies in Korea.