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고품질 4H-SiC 단결정 성장을 위한 다공성 흑연 판의 역할
이희준,이희태,신희원,박미선,장연숙,이원재,여임규,은태희,김장열,전명철,이시현,김정곤,Lee, Hee-Jun,Lee, Hee-Tae,Shin, Hee-Won,Park, Mi-Seon,Jang, Yeon-Suk,Lee, Won-Jae,Yeo, Im-Gyu,Eun, Tai-Hee,Kim, Jang-Yul,Chun, Myoung-Chul,Lee, Si-Hyun 한국결정성장학회 2015 한국결정성장학회지 Vol.25 No.2
본 연구에서는 PVT법으로 4H-SiC 단결정 성장 시 다공성 흑연판을 사용하여 Si/C 비율이나 온도구배, 물질전달의 향상시킴으로써 고품질의 SiC 단결정 기판 제작을 목적으로 연구를 진행하였다. 연구에 사용된 SiC 소스 물질은 흑연 도가니에 넣어 흑연 단열재로 쌓인 구조로 실험을 하였다. 성장온도는 $2100{\sim}2300^{\circ}C$, 그리고 성장압력은 10~30 Torr의 압력으로 아르곤과 질소 분위기에서 성장시켰다. 종자정은 2인치의 $4^{\circ}$ off-axis 4H-SiC의 C면 (000-1)을 사용하였고 다공성 흑연판은 SiC 소스 물질 위에 삽입하였다. 4H-SiC 결정다형 안정화를 위한 C-rich 조건이나 균일한 온도구배를 만들어주기 위해 다공성 흑연판을 삽입하여 실험을 진행하였다. 일반적인 도가니의 경우, 성장된 wafer에서 6H-, 15R-SiC와 같은 다양한 결정다형이 관찰된 반면에 다공성 흑연판을 삽입한 도가니에서는 4H-SiC만 관찰되었다. 또한 다공성 흑연판을 삽입한 도가니에서 성장된 결정에서 MP나 EP의 낮은 결함밀도를 보였으며 결정성 또한 향상된 것을 학인하였다. The present research is focused on the effect of porous graphite what is influenced on the 4H-SiC crystal growth by PVT method. We expect that it produces more C-rich and a change of temperature gradient for polytype stability of 4H-SiC crystal as adding the porous graphite in the growth cell. The SiC seeds and high purity SiC source materials were placed on opposite side in a sealed graphite crucible which was surrounded by graphite insulator. The growth temperature was around $2100{\sim}2300^{\circ}C$ and the growth pressure was 10~30 Torr of an argon pressure with 5~15 % nitrogen. 2 inch $4^{\circ}$ off-axis 4H-SiC with C-face (000-1) was used as a seed material. The porous graphite plate was inserted on SiC powder source to produce a more C-rich for polytype stability of 4H-SiC crystal and uniform radial temperature gradient. While in case of the conventional crucible, various polytypes such as 6H-, 15R-SiC were observed on SiC wafers, only 4H-SiC polytype was observed on SiC wafers prepared in porous graphite inserted crucible. The defect level such as MP and EP density of SiC crystal grown in the conventional crucible was observed to be higher than that of porous graphite inserted crucible. The better crystal quality of SiC grown using porous graphite plate was also confirmed by rocking curve measurement and Raman spectra analysis.
이희준,Lee, Hui-Jun 한국과학기술단체총연합회 1995 과학과 기술 Vol.28 No.5
해방되던 해인 1945년 9월 조선지리학회로 출범하여 올해 창립50돌을 맞는 대한지리학회 회원8백50명의 대규모 학회로 자리잡았다. 또한 21세기가 열리는 2000년엔 제29차 국제지리학연합 총회와 학술대회를 서울로 유치해 4~5천명의 국내외 지리학자가 참석하는 대규모 행사를 준비중에 있다.
DC 인버터 저항 스폿 용접에서 후전류 효과에 관한 연구
이희준,이세헌,Lee, Hui-Jun,Rhee, Se-Hun 한국생산제조학회 2009 한국생산제조학회지 Vol.25 No.2
Resistance spot welding has been investigated to apply for manufacturing car bodies because of its high productivity. So quality of resistance spot weld is one of the major concerns for both automobile and aerospace industry. Current design trends in automotive manufacture have shifted emphasis to alternative lightweight materials in order to aid in producing vehicles with higher fuel efficiency and lower down the vehicle emission level for environmental control. There is increasing emphasis to provide lighter cars. Therefore there is an effort to use high strength steels such as HSLA, dual phase, in car body. However there is used in restricted because of difficulty in producing consistently high quality resistance spot welds. In this study, resistance spot welding schedules were developed to achieve acceptable welds with improved static mechanical properties. Improved resistance spot welding schedules were developed using post heating current to reduce the cooling rate, or in-process tempering to reduce the hardness of the weld produced. The effects of resistance spot welding process parameter on hardening fracture mode and static mechanical properties of the joints were determined.
이희준,구현모,이기동,Lee, Hui-Jun,Gu, Hyeon-Mo,Lee, Gi-Dong 선박안전기술공단 2006 선박안전 Vol.21 No.-
선박검사기술협회는 레저선박 검사수임을 위하여 2003년부터 3년간의 자체연구개발 계획을 수립하고, 1차년도 수상레저안전관리에 관한 연구(2003), 2차년도 레저선박 특수안전기준에 관한 연구(2004)에 이어 최종적으로 레저선박검사 가이드북 개발(2005)을 수행했다. 이는 레저선박의 기술∙선진외국의 레저선박 검사기준 검토에 이어 국내 실정에 맞는 레저선박 검사실무에 맞춤형 연구개발을 수행을 목적으로 하였으며, 본문은 2005년 12월에 종료한 레저선박 검사 가이드북 개발 연구에 대한 요약본이다.
이희준,Lee, Hui-Jun 선박안전기술공단 2005 선박안전 Vol.20 No.-
본 논문은 선박검사기술협회가 한국해사재단으로부터 위탁받은 "도선업무에 적합한 도선선 모델개발"의 결과로 지난 4월 1일부터 10월 30일까지 총 7개월간 도선선의 적정 규모와 선형, 경제성 분석 및 도선사의 안전을 위한 각종 장비에 대해 연구한 결과이다. 이번 연구는 국내 해양물류의 중요한 역할을 담당하고 있는 도선사들의 안전과 효율적 도선선 운영에 대한 국내 최초의 연구로서의 의미와 향후 국내 특수 선박들에 대한 연구 필요성을 확인할 수 있었다.
이희준,Lee Hee-Joon 대한경영정보학회 2000 경영과 정보연구 Vol.4 No.-
Over the past decades the concept of Third-Party Logistics(TPL) has generated considerable interest in American and European industries. It involves outsourcing logistics activities that have traditionally been performed within an organization. The functions performed by the third-party logistics can encompass the entire logistics process or, more commonly, selected activities with that process. Increasing corporate emphasis on such concepts as reengineering and supply chain management has led many companies to consider the use of such third-party logistics. This study examines the possibility of applying existing American research of the third-party logistics to Korean companies and investigates the criteria for the use of third-party logistics in Korea. To design the model and generate the hypotheses, this study conducted a comprehensive literature survey on the third-party logistics. To test the hypotheses, this study collected data from 229 companies from the public companies in Korea through a questionnaire survey and conducted descriptive analysis, correlation analysis, factor analysis, and multiple regression analysis using the SPSS for Windows Ver. 7.5 package. This study is hoped that it may contribute to the understanding and introducing of the third-party logistics in the fields of the firms. But there were some restrictions that the respondents were not covered all kinds of firms. These and other major findings from this study imply that existing American studies may be applicable the Korean companies and that this study may complement the deficiencies of the existing studies. Thus, the summary of the literature review, the research model and hypotheses, and empirical findings in this study will provide useful ideas for future research and deep insights for successful logistics management.
수계 중금속의 미생물학적 처리 - 균주 개량에 관한 연구 -
이희준,최영길 ( Heu Joon Lee,Young Keel Choi ) 한국환경생물학회 1993 환경생물 : 환경생물학회지 Vol.11 No.2
Two strains of yeasts, HYM 40 and HYM 20 which have resistance against heavy metals such as cadmium and lead and have ability to accumulate the heavy metals were isolated in the Han river and industrial sewage. These yeasts were identified as Torulopsis inconspicua. These strains can accumulate lead up to 180㎎/g dried cell and cadmium up to 147.5㎎/g dried cell. In the electron microscopic analysis, it was found that these heavy metals were in the cell wall. In order to compare the wild types with the amino acid auxotroph mutants in accumulation ratio, in case of cadmium, mutant M-3 accumulated 43.65% after 2 hours incubation and wild type did 31.64% after 4 hours incubation. On the other hand, mutant M-3 accumulated lead up to 79.18% and wild type did up to 37.22% after 2 hours, 4 hours incubation, respectively. On the basis of these results, when M-2 and M-3 were treated with 40% of PEG and 30mM of CaCl_2 for protoplast fusion, F-l accumulated cadmium up to 46.81% within 4 hours and lead up to 85. 63% within 2 hours. These results represent improvement of heavy metal accumulating abilities. When compared with original strain, this fusant shows 46% of increase rate in case of cadmium and 118% in case of lead.