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컨버전스에 대응한 BT와 NTT의 포트폴리오 변화 전략
김형석,Kim, H.S. 한국전자통신연구원 2006 전자통신동향분석 Vol.21 No.2
현재 대부분의 국내외 종합통신사업자들은 외부적인 통신산업의 경쟁 격화 및 새로운산업 트렌드 변화로 인해 매출과 영업이익이 정체되는 위기상황에 처해 있으며, 이를 타개하기 위해 미래 통신산업의 mega trend에 대응하여 사업구조를 재편하고 신규 수익모델을 창출하는 등 사업포트폴리오를 변화시키고 있다. 국내외 수많은 종합통신사업자들 중에서 일부는 미래 통신산업 mega trend 변화에 적극적으로 대응하여 다양한 전략적 옵션들을 취함으로써 성공적으로 변모해가고 있는 반면, 다른 일부는 소극적으로 대처하거나 또는 아무런 인식이 없이 본업에만 안주하여 스스로 위기를 자초하고 있는 듯 하다. 이에 본 고에서는 새로운 패러다임 변화에 적극적으로 대처하고 있는BT와 NTT 그룹의 사업포트폴리오 변화 사례 분석을 통해 국내 종합통신사업자에게 미래 서비스 사업구조 개선 방향에 대한 시사점을 제공하고자 하였다.
수퍼 2상 스테인리스강의 열처리 조건변화에 따른 첨가원소 질소의 거동
김형석,전채홍,송권,권숙인 ( Hyung Seok Kim,C . H . Jeon,Gun Song,S . I . Kwun ) 한국열처리공학회 1997 熱處理工學會誌 Vol.10 No.1
After changing the heat treating atmosphere of nitrogen gas, argon gas and vacuum, the nitrogen contents, microstructural changes, hardness and corrosion resistance of 0.25wt.%N alloyed super duplex stainless steel have been investigated in the temperature range from 1050℃ to 1350℃. The nitrogen content showed to be increased up to 0.36wt.% after heat treating the specimen in nitrogen gas at 1200℃, while the decrement of nitrogen content in vacuum atmosphere was shown down to 0.03wt.% at 1350℃. After heat treating in the mixed gas atmosphere of argon and nitrogen at 1250℃, the surface γ phase existed as α+γ phase increased with increasing nitrogen gas content. The γ single phase appeared at the surface above 80%N₂gas, while the surface α single phase was shown below 20%N₂gas. When heat treating the specimen in nitrogen gas at 1050℃, the hardness of austenite phases increased above Hv 40 at the surface layer compared to the hardness of the core parts, while decrement of denitriding effect caused to the hardness nearly unchanged between surface and the core parts after heat treating in vacuum atmosphere. The surface γ single phase specimen showed superior corrosion resistance than the surface α single phase specimen. The surface α phase existed in the α+γ microstructure showed higher corrosion resistance after heat treating in the nitrogen gas atmosphere than the a phase heat treated in the argon gas and vacuum atmosphere.
김형석,전채홍,송권,권숙인 ( Hyung Seok Kim,C . H . Jeon,Gun Song,S . I . Kwun ) 한국열처리공학회 1997 熱處理工學會誌 Vol.10 No.1
Pure copper is widely used for base material for electrical and electronic parts because of its good electrical conductivity. However, it has such a low strength that various alloying elements are added to copper to increase its strength. Nevertheless, alloying elements which exist as solid solution elements in copper matrix severely reduce the electrical conductivity. The reduction of electrical conductivity can be minimized and the strengthening can be maximized by TMT(Thermo-Mechanical Treatment) in copper alloys. In this research, the effects of TMT on mechanical and electrical properties of Cu-Ni-Al-Si-P, Cu-Ni-Al-Si-P-Zr and Cu-Ni-Si-P-Ti alloys aged at various temperatures were investigated. The Cu alloy with Ti showed the hardness of Hv 225, electrical conductivity of 59.8%IACS, tensile strength of 572MPa and elongation of 6.4%.
김형석(H. S Kim),박정국(J. G Park),임홍우(H. W Lim),조금배(G. B Cho),백형래(H. R Baek),최창주(C. J Choi) 한국조명·전기설비학회 2003 한국조명·전기설비학회 학술대회논문집 Vol.2003 No.-
Total six units of 3kW photovoltaic system and data acquisition system (DAS) are constructed for analyzing performance of PV system at field demonstration test center of Gwang-Ju in Korea. As climatic and irradiation conditions are varied. Operation characteristics of the PV system are collected and analyzed in data-acquisition system. Furthermore, not only performance test of each PV system component such as PV module and power conditioning system but also performance of total PV system e.g. system efficiency power and loss factor at the site are reviewed.