TBT 중앙사무국 동정 - 중국 정보보안제품 강제인증 시행 1년 연기

송국현,Song, Guk-Hyeon 기술표준원 2009 기술표준 Vol.88 No.-

수동광부품 특성시험.측정절차 관련 규격의 제.개정 현황

송국현,Song, Guk-Hyeon 기술표준원 2005 기술표준 Vol.40 No.-

광섬유통신 산업의 기술표준동향

송국현,Song, Guk-Hyeon 한국광산업진흥회 2006 광산업정보 Vol.33 No.-

광통신은 인터넷 이용자의 증가와 디지털기술 발전에 의한 화상정보 활용의 보편화, 전자 상거래, 양방향 TV등 전송 데이터가 폭증하는 정보화 사회의 필수적인 기술이다. 이는 광섬유 한 가닥의 정보전달 능력이 수십 Gbps이며 전자파 장애에 의한 누화나 잡음이 없고 수명이 길다는 장점이 있기 때문이다.

능동광부품 인터페이스 및 시험관련 규격제정 현황

송국현,Song, Guk-Hyeon 기술표준원 2006 기술표준 Vol.49 No.-

육성용접된 Inconel 718 합금의 마찰교반을 이용한 개질처리 효과

송국현,홍도형,양병모,Song, Kuk Hyun,Hong, Do Hyeong,Yang, Byung Mo 한국재료학회 2013 한국재료학회지 Vol.23 No.9

To evaluate the development of the microstructure and mechanical properties on surface modified and post-heattreated Inconel 718 alloy, this study was carried out. A friction stir process as a surface modification method was employed, and overlap welded Inconel 718 alloy as an experimental material was selected. The friction stir process was carried out at a tool rotation speed of 200 rpm and tool down force of 19.6-39.2 kN; post-heat-treatment with two steps was carried out at $720^{\circ}C$ for 8 h and $620^{\circ}C$ for 6 h in vacuum. To prevent the surface oxidation of the specimen, the method of using argon gas as shielding was utilized during the friction stir process. As a result, applying the friction stir process was effective to develop the grain refinement accompanied by dynamic recrystallization, which resulted in enhanced mechanical properties as compared to the overlap welded material. Furthermore, the post-heat-treatment after the friction stir process accelerated the formation of precipitates, such as gamma prime (${\gamma}^{\prime}$) and MC carbides, which led to the significant improvement of mechanical properties. Consequently, the microhardness, yield, and tensile strengths of the post-heat-treated material were increased more than 110%, 124% and 85 %, respectively, relative to the overlap welded material. This study systematically examined the relationship between precipitates and mechanical properties.

겹치기 마찰교반접합된 Inconel 600/SS 400 합금의 미세조직과 기계적 특성 평가

송국현,Song, Kuk-Hyun,Nakata, Kazuhiro 한국재료학회 2012 한국재료학회지 Vol.22 No.3

The microstructures and mechanical properties of friction stir welded lap joints of Inconel 600 and SS 400 were evaluated; friction stir welding was carried out at a tool rotation speed of 200 rpm and welding speed of 100 mm/min. Electron back-scattering diffraction and transmission electron microscopy were introduced to analyze the grain boundary characteristics and the precipitates, respectively. Application of friction stir welding was notably effective at reducing the grain size of the stir zone. As a result, the reduced average grain size of Inconel 600 ranged from $20{\mu}m$ in the base material to $8.5{\mu}m$ in the stir zone. The joint interface between Inconel 600 and SS 400 showed a sound weld without voids and cracks, and MC carbides with a size of around 50 nm were partially formed at the Inconel 600 area of lap joint interface. However, the intermetallic compounds that lead to mechanical property degradation of the welds were not formed at the joint interface. Also, a hook, along the Inconel 600 alloy from SS 400, was formed at the advancing side, which directly brought about an increase in the peel strength. In this study, we systematically discussed the evolution of microstructures and mechanical properties of the friction stir lap joint between Inconel 600 and SS 400.

광섬유 통신산업

송국현,Song, Guk-Hyeon 기술표준원 2004 기술표준 Vol.33 No.-

겹치기 마찰교반접합된 Invar 42/SS 400 합금의 미세조직과 기계적 특성 발달

송국현,Song, K.H.,Nakata, Kazuhiro 대한용접접합학회 2012 대한용접·접합학회지 Vol.30 No.5

This study was conducted to investigate the microstructure and mechanical properties of friction stir lap joints. Invar 42 and SS 400 were selected as the experimental materials, and friction stir welding was carried out at a tool rotation speed of 200 rpm and welding speed of 100 mm/min. The application of friction stir welding to Invar 42 effectively reduced the grain size in the stir zone; the average grain size of Invar 42 was reduced from $11.5{\mu}m$ in the base material to $6.4{\mu}m$ in the stir zone, which resulted in an improvement in the mechanical properties of the stir zone. The joint interface between Invar 42 and SS 400 showed a relatively sound weld without voids and cracks, and the intermetallic compounds with $L1_2$ type in lap jointed interface were partially formed with size of 100 nm. Moreover, the hook in the advancing side of Invar 42 was formed from SS 400, which contributed to maintenance of the tensile strength. The evolution of microstructures and mechanical properties of friction stir lap jointed Invar 42 and SS 400 are also discussed herein.

n형 산화물반도체 가스센서의 전기저항 측정을 통한 표면흡착종의 전이특성의 평가

송국현,박재환,박순자 경북대학교 센서기술연구소 1994 센서技術學術大會論文集 Vol.5 No.1

A simple method for evaluation of transition property of surface adsorbates was presented, which is based on electrical resistance of a n-type oxide semiconductor gas sensor in air, CO or H_(2) gas flow. It was explained that temperature on the turning points in a resistance-temperature plot in air is of a function of activation energies on the transition processes of OH, O_(2)^(-), O^(-) and O_(2)^(-) adsorbates. Temperatures showing a maximum gas sensitivity was also assigned to be related to the activation energies. Based on the slope of a log(resistance) vs log(CO concentration) curve, it was described that reaction constants of the transition processes can be known. Absolute value of the slope was also ascribed to be a parameter for the gas sensitivity in a low-concentrated gas flow. It was also narrated that not only the transition properties but also role of OH^(-) or O_(2)^(-) adsorbate in the gas-sensing reaction can be determined from the recovery time characteristics.

가스센서용 $SnO_2$분말 제조시 잔류 염소이온이 Sn수화물의 열분해거동 및 분말물성에 미치는 영향

송국현,최병우,박재환,박순자,Song, Guk-Hyeon,Choe, Byeong-U,Park, Jae-Hwan,Park, Sun-Ja 한국재료학회 1994 한국재료학회지 Vol.4 No.8

Effects of residual chloride on thermal decomposition behaviour of a-stannic acid and physical properties of $SnO_{2}$ powder were observed. The powder was fabricated by hydroxide method; $\alpha$-stannic acid was precipitated by mixing acqueous solutions of $SnCl_{4}$ and $NH_{4}$OH . The precipitate was washed with $NH_{4}NO_{3}$ solution while washing was controlled to be of three grades to modify its residual chloride content. The precipitate was dried at $1100^{\circ}C$ ~ 24h and calcined in air at $500^{\circ}C$ ~ $1100^{\circ}C$ for one hour. Thermal decomposition behaviour of $\alpha$-stannic acid was examined by a DT-TGA and a FTIR. Chemical composition and physical properties of $SnO_{2}$ powder were observed by an AES, a BET and a TEM, respectively. With a reduction in chloride content, the relative crystallite size of $SnO_{2}$ powder slightly increased by a low-temperature-calcining. However, at a high calcining temperature(T), the reverse relation occured. It was suggested that chloride ion replaces part of lattice oxygen site of a-stannic acid. Also, chloride ion on the site was suggested to retard de-hydration as well as crystalization at a low T while to promote crystal growth of $SnO_{2}$ by forming oxygen vacancy at a high T.