광섬유 기술의 현황 및 향후 전망

송국현 한국전기전자재료학회 2003 전기전자재료 Vol.16 No.2

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.

광섬유 통신산업

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

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

수산화물법에 의해 제작된 $\alpha$-stannic acid의 열분해 거동과 $SnO_{2}$분말의 성질에 미치는 잔류염소이온의 영향을 관찰하였다. $SnCl_{4}$와 $NH_{4}$OH 수용액을 중화시켜 $\alpha$-stannic acid침전물을 제작하고 $NH_{4}NO_{3}$수용액으로 세척하였다. 분말내의 잔류 염소이온의 양을 주절하기 위하여 세척정도를 3단계로 조정하였다. 세척후 $100^{\circ}C$에서 건조하고, $500^{\circ}C$ ~ $1100^{\circ}C$에서 하소함으로써 $SnO_{2}$분말을 제조하였다. $\alpha$-stannic acid의열분해 거동ㅇ르 DT-TGA 와 FTIR을 통하여 관찰하고, $SnO_{2}$분말의 조성과 입자크기 및 비표면적을 각각 AES, TEM 및 BET을 통하여 측정하였다. 잔류 염소이온 양이 감소되면, 저온 하소시 일차입자의 상대적 크기가 커지는 반면 고온하소시에는 상대적으로 감소되었ㄷ. 잔류 염소이온의 일부는 $\alpha$-stannic acid내의 격자산소 자리에 위치함으로써, 저온가열시 결정수탈리와 결정화를 지연시키고 또한 고온가열시에는 이의 증발에 의해 산소공공이 생성되어 소결을 촉진시킨다고 제의하였다. 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.

광섬유통신 산업의 기술표준동향

송국현,Song, Guk-Hyeon 한국광산업진흥회 2004 광산업정보 Vol.25 No.-

업체탐방기-전기.전자부품용 재료 생산업체 대주정밀화학(주)

송국현,Song, Guk-Hyeon 기술표준원 2002 기술표준 Vol.7 No.-

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.

수동광부품 특성시험.측정절차 관련 규격의 제.개정 현황

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

산화물 반도체의 결정입도가 가스감도와 표면특성에 미치는 영향

송국현,박순자,Song, Guk-Hyeon,Park, Sun-Ja 한국재료학회 1993 한국재료학회지 Vol.3 No.4

The effects of $SnO_2$ crystallite size on the powder characteristics, the resistance in air and the sensitivity to 0.5 vol % $H_2$, CO-air mixture were observed. The size of SnO, powder was controlled by calcining temperature variation ($500^{\circ}C$ ~$1100^{\circ}C$) of $\alpha$-stannic acid fabricated from $SnCl_4 \cdot xH_2O$. Its crystallite size. evaluated from TEM image, was in the range of 8-54nm. With the reduction of crystallite size, the adsoption peak of $H_2O$ on FTIR curve became more clear while the lattice parameters were invariable. As the crystallite size decreased, with elements of thick film, the temperatures showing a minimum resistance in air and a maximum sensitivity to H, gas reduced. The temperature variations were assigned to the changes of activation energy of the active adsorbates, and it was suggested that the decrease of activation energy can be one of the reasons for the' sensitivity increase with the' fine powder. Hydroxide법으로 ${\alpha}$-주산산(stannic acid)을 만든후, 하고온도를 $500^{\circ}C$~$1100^{\circ}C$로 조정하여 일차입자(Crystallite)크기가 8-54nm인 $SnO_2$ 분말을 제작하였다. 분말의 입자(drystalite)클기에 따른 분말특성와 $H_2$, CO가스(0.5v/o)에 대한 감응성 미치공기중에서의 저상변화특성에 미치는 영향을 조사하였다. 입자크기가 감소함에 따라, 분말의 FTIR 흡습특성은 증가하였으나, 격자상수는 일정하였다. 후막소자에서, $H_2$가스에 대해 최대감도를 나타내는 온도와 공기중에서 최소저항을 나타내는 온도는 입자크기가 미세해짐에 따라 점차 낮아졌다. 최소저항점과 최대감도점의 온도저하를 산소흡착종의 활성화에너지의 감소라고 유추하였고, 이러한 에너지의 감소가 미세입자에 의한 감도향상요인 중의 한가지라고 제의하였다.