http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
$MgB_2$ 초전도체의 합성에 미치는 고에너지 밀링에 의한 초기 보론 분말의 특성
이지현,신승용,김찬중,박해웅,Lee, J.H.,Shin, S.Y.,Kim, C.J.,Park, H.W. 한국초전도학회 2007 Progress in superconductivity Vol.9 No.1
We characterized the highly refined boron precursor powders which were attrition milled for different milling times. $MgB_2$ powder precursor was formed from elemental crystalline Mg and amorphous B powder. The microstructure was investigated by SEM. SEM results indicate that the size of the milled powders was reduced with increasing milling time, which were varied from 0 to 8 hours. We also studied thermal behavior of the starting precursor by DSC as a function of milling time. The thermal behavior of the powder precursors was influenced by milling time. In order to determine the thermal events at DSC peaks, we annealed the milled powder mixture at $600^{\circ}C$ and $650^{\circ}C$ under protective gas and then analyzed the formation of $MgB_2$ by the XRD. We observed that superconducting $MgB_2$ phase was formed at lower temperature by the longer high energy milling. These results show that the high energy milling of the boron precursor powder can improve the reactivity for the formation of $MgB_2$.
어트리션 볼 밀링에 의한 보론 분말의 미세화 및 $MgB_2$의 초전도특성
이지현,신승용,전병혁,김찬중,박해웅,Lee, J.H.,Shin, S.Y.,Jun, B.H.,Kim, C.J.,Park, H.W. 한국초전도학회 2008 Progress in superconductivity Vol.10 No.1
We report refinement of crystalline boron by an attrition ball milling system and the superconducting properties of the $MgB_2$ pellets prepared from the refined boron. In this work, we have conducted the ball milling with only crystalline boron powder, in order to improve homogeneity and control the grain size of the $MgB_2$ that is formed from it. We observed that the crystalline responses in the ball-milled boron became broader and weaker when the ball-milling time was further increased. On the other hand, the $B_{2}O_{3}$ peak became stronger in the powders, resulting in an increase in the amount of MgO within the $MgB_2$ volume. The main reason for this is a greater oxygen uptake. From the perspective of the superconducting properties, however, the sample prepared from boron that was ball milled for 5 hours showed an improvement of critical current density ($J_c$), even with increased MgO phase, under an external magnetic field at 5 and 20 K.
이지현,박경현,이상민,이원재,오병택,강성주,정문영,양경아,원희선,허성진,최완,Lee, J.H.,Park, K.H.,Lee, S.M.,Lee, W.J.,Oh, B.T.,Kang, S.J.,Chung, M.Y.,Yang, K.A.,Won, H.S.,Hur, S.J.,Choi, W. 한국전자통신연구원 2011 전자통신동향분석 Vol.26 No.5
본 고에서는 SaaS를 서비스로 제공하기 위한 기술인 SaaS(Software as a Service) 플랫폼 기술과 개발 동향을 소개한다. 이를 위해 국내외 SaaS 개발 시장의 동향을 살펴보고 국가 플랫폼 개발의 일환으로 2009년부터 ETRI에서 연구개발 중인 SaaS 플랫폼의 개발 및 기술 현황에 대해 살펴본다.
소형 제트엔진 배기플룸의 열유동장 및 화학성분의 IR 신호 영향성 전산해석
채준혁(J.H. Chae),이지현(J.H. Lee),이지원(J.W. Lee),하남구(N.K. Ha),김동건(D.G. Kim),장현성(H.S. Jang),명노신(R.S. Myong) 한국전산유체공학회 2019 한국전산유체공학회지 Vol.24 No.3
Because of high levels of infrared signature generated by engine exhaust plume, aircraft can be detected by infrared guided missiles equipped with a modern detector. In order to investigate the characteristics of plume IR and reduce the level of its signature, the exhaust plume around an engine nozzle was calculated with a Navier-Stokes-Fourier computational code. The narrow-band model was employed to calculate the spectral characteristics of the IR signature. Computational models were compared with the experimental results of a micro jet engine. By considering an aircraft flying at an altitude of 20,000 ft, the effects of thermal flow field and chemical components on the IR signature was investigated. As expected, the plume IR signature showed the greatest effect at 4~4.5 μm CO₂ and 5~8 μm H₂O, and the temperature affected the IR signature over the whole band. In addition, the molar fraction change in CO₂ and H₂O resulted in higher variation in plume IR signature.