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동력 분산형 고속전철의 전자파 Source 및 Victim에 관한 연구
김윤명(Gimm Yoon-Myoung),주영준(Ju Young-Jun),구은희(Koo Eun-Hee),구본철(Koo Bon-Chul),유재성(Yoo Jae-Seong) 한국철도학회 2008 한국철도학회 학술발표대회논문집 Vol.- No.-
The high-speed EMU is assembled with distributed EMI sources. Therefore, it contains more electromagnetic sources nearby the distributed victims than the existing concentrated traction system. The electromagnetic sources and victims are identified in this research, and the methodology how to handle EMI/EMS/EMC of the high-speed EMU will be developed for safer operation. It includes measurement method, safety standards of control units and others, and performance evaluations of the firstly developed trial products for the EMU. Also influences by modern telecommunication equipments and effect of PLD(power line disturbance) are to be surveyed in this research.
플라즈마 용사한 NiCrAlY/8wt% Y2O3-ZrO2 2층 단열코팅층의 레이저 표면개질에 관한 연구
김종영,이선호,강춘식,유재성 대한금속재료학회(대한금속학회) 1997 대한금속·재료학회지 Vol.35 No.12
NiCrAlY/8wt%Y₂O₃-ZrO₂, two layer TBC was fabricated by plasma spray method and its surface modification was performed by CO₂ laser and then the change of characteristics and failure mechanism during thermal shock test were investigated. The more specific energy of laser beam, the more crack width and thickness of melted layer originated by laser treatment. In the same specific energy, they decreased by reducing laser power. After laser treatment, residual stress was altered tensile stress, adhesion strength reduced due to the horizontal crack at the bottom of interface between melted and unmelted layer, surface corrosion of ceramic layer was suppressed due to densification and the life cycle by thermal shock test were increased. The failure procedure during the thermal shock test was as follows; buckling occurred first, then spalling followed after a few cycles and fracture region was expanded. The failure resulted from buckling is believed to occur because of compressive stress developed by cooling. It is thought that thermal shock lifetime after laser treatment is improved owing to the stress relaxation caused by vertical crack to surface and residual tensile stress.