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한국에 도해하는 검은머리갈매기(Larus saundersi)의 월동 현황
이기섭,박진영,이재범,김학진,유정칠 경희대학교 한국조류연구소 1999 연구보고 Vol.7 No.1
검은머리갈매기(Larus saundersi)는 그 동안 생존집단이 약 3,000개체로 추정되어온 멸종위기의 종이나, 한국에서의 월동 개체수에 대해선 현재까지 알려진 바가 없다. 본 조사는 1994년에서 1997년까지 동계기간에 실시되었다. 조사기간 동안 1994/95년 겨울에는 548개체, 1995/96년 겨울에는 1,159개체, 1996/97년에는 2,140개체가 관찰되었다. 해마다 증가하는 것으로 되어 있으나 실제는 조사면적이 확대된 데 그 원인이 있는 것 같다. 1994/97년 동계기간 동안에는 8개 조사지역에서 최대 2,425개체가 관찰되었다. 남해안에서는 조사가 광범위하게 이루어지지 않았기 때문에 월동 개체수는 이 보다 더 많을 것으로 추정되며, 종합적인 조사가 이루어진다면 전 세계의 생존집단은 6,000개체 이상이 될 것으로 사료된다. 조사지역 8곳 중에서는 순천만과 금강하구, 만경강하구에 각각 최대 500개체 이상이 도래하여 이 지역이 검은머리갈매기의 중요한 월동지임이 밝혀졌다. 성조에 대한 유조의 비율을 보면 평균 14.8%이었으나, 조사시기에 따라 변동이 있었다. 중국 리아오닝(Liaoning) 지방에서 적색 표식한 2개체가 아산만에서 관찰되었다. 최근 한국에서 새로 3개의 번식지가 발견되었으나 한국에서의 간척사업으로 인해 본 종이 계속 감소할 위기에 처해 있어 보존대책이 시급하다. Saunders's Gulls Larus saundersi are the endangered species and the world populations of the species were estimated about 3,000 individuals. The breeding sites were known at several sites in China, and the wintering areas were known in southern China, Hong Kong, Vietnam, Taiwan, Japan and Korea. Recently, the number of Saunders's Gulls was rapidly increased in Kyushu province of Japan: about 1,000 birds wintering there. One of factors affecting on the increasing population of Saunders's Gulls in Japan may be due to the destruction of the wintering habitats of Saunders's Gulls in Korea. But the wintering population of Saunders's Gulls in Korea has not been reported by now. We surveyed during the winter season of 1994~1997, and counted 548 individuals in 1994~95, 1,159 in 1995~96, and 2,140 in 1996~97. The increasing population each year may be due to the increase of survey areas each year in Korea. The peak count obtained from 8 sites was 2,425 individuals during the winter season of 1994~97. The real wintering population of Saunders's Gulls would be more than 2,425 individuals, because we did not survey many parts of southern coast although most areas of west coast were surveyed. If we estimate the world populations of Saunders's Gulls on the basis of this study and a Japanese report made in 1996(4,387 individuals), the world populations of the species may be more than 6,000 individuals. Sunchon bay, Kum river estuary, and Mankyung river estuary are major habitats supporting over 500 individuls of the wintering Saunders's Gulls every year in Korea. The ratio of juveniles to adults was averaged on 14.8% in the wintering population of Saunders's Gulls in Korea. Two individuals tagged with red colour flags were found in Asan bay, indicating that some birds wintering in Korea bred in Liaoning province of China. Breeding sites were newly found in the three reclaimed salt marshes. The major habitats of Saunders's Gulls should be set aside for nature reserves for effective protection and management, and should be turned into Ramsar sites to protect Saunders's Gulls in Korea.
CST 승화법을 이용한 p-type 4H-SiC(0001) 에픽텍셜층 성장과 이를 이용한 MESFET 소자의 전기적 특성
이기섭,박치권,이원재,신병철,Lee, Gi-Sub,Park, Chi-Kwon,Lee, Won-Jae,Shin, Byoung-Chul,Nishino, Shigehiro 한국전기전자재료학회 2007 전기전자재료학회논문지 Vol.20 No.12
A sublimation epitaxial method, referred to as the Closed Space Technique (CST) was adopted to produce thick SiC epitaxial layers for power device applications. In this study, we aimed to systematically investigate surface morphologies and electrical properties of SiC epitaxial layers grown with varying a SiC/Al ratio in a SiC source powder during the sublimation growth using the CST method. The surface morphology was dramatically changed with varying the SiC/Al ratio. When the SiC/Al ratio of 90/1 was used, the step bunching was not observed in this magnification and the ratio of SiC/Al is an optimized range to grow of p-type SiC epitaxial layer. It was confirmed that the acceptor concentration of epitaxial layer was continuously decreased with increasing the SiC/Al ratio. 4H-SiC MESFETs haying a micron-gate length were fabricated using a lithography process and their current-voltage performances were characterized. It was confirmed that the increase of the negative voltage applied on the gate reduced the drain current, showing normal operation of FET device.