• 제목/요약/키워드: active turbulence

검색결과 45건 처리시간 0.023초

국내 중소하천에 설치된 아이스하버 어도 내부 흐름 특성 규명 (Investigation for flow characteristics of ice-harbor type fishway installed at mid-sized streams in Korea)

  • 백경오;민병조
    • 한국수자원학회논문집
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    • 제55권1호
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    • pp.33-42
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    • 2022
  • 본 연구에서는 3차원 상용 수치모형 Flow-3D를 활용하여 상류 수위(유입유량) 변동, 격벽의 간격(pool의 길이) 변화, 잠공 유무 등에 따른 아이스 하버 어도 내 흐름 양상을 분석하였다. 수치모의 결과의 적합성을 입증하기 위해 경안천 대곡교 하류에 설치된 실제 어도에서 3차원 초음파 유속계를 사용하여 어도 출구부 단면 유속과 유량을 관측하였다. Flow-3D 모형에는 난류 모듈로 4가지를 선택할 수 있는데, 관측 자료로 검증 결과 RNG 모형이 아이스하버 어도 내 흐름 특성을 가장 잘 재현하였다. 하천의 유량 전량이 어도로만 유입되어 흐른다는 조건에서 수위 변화에 따른 어도 내 유속구조를 모의해 보았다. 그 결과 최저수위에서는 잠입류와 표면류가 혼재하여 발생하였는데, 최저수위에서 약 10 cm 이상만 수위가 상승하여도 모든 pool에서 잠입류가 사라지고 오직 표면류만 발생하였다. 예상과 달리 수위가 조금 상승해도 흐름이 꽤 단순하게 표면류 위주로 발생하였다. 격벽간 간격을 늘려주면 수위가 상승하더라도 잠입류와 표면류가 혼재되어 나타나는 현상이 지속되었다. 그리고 격벽 하단에 잠공이 있는 경우가 없는 경우에 비해 잠입류가 여러 pool에서 생성되는 경향을 보였다. 보다 적극적인 어도 사후 관리로 잠공 폐색을 막아 어도 내 다양한 흐름이 생성될 수 있도록 유도하는 것이 필요해 보인다.

Development of the Infrared Space Telescope, MIRIS

  • 한원용;이대희;박영식;정웅섭;이창희;남욱원;문봉곤;박성준;차상목;표정현;박장현;가능현;선광일;이덕행;이성우;박종오;이형목
    • 천문학회보
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    • 제36권1호
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    • pp.64.1-64.1
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    • 2011
  • MIRIS (Multipurpose Infra-Red Imaging System), is a small infrared space telescope which is being developed by KASI, as the main payload of Science and Technology Satellite 3 (STSAT-3). Two wideband filters (I and H) of the MIRIS enables us to study the cosmic infrared background by detecting the absolute background brightness. The narrow band filter for Paschen ${\alpha}$ emission line observation will be employed to survey the Galactic plane for the study of warm ionized medium and interstellar turbulence. The opto-mechanical design of the MIRIS is optimized to operate around 200K for the telescope, and the cryogenic temperature around 90K for the sensor in the orbit, by using passive and active cooling technique, respectively. The engineering and qualification model of the MIRIS has been fabricated and successfully passed various environmental tests, including thermal, vacuum, vibration and shock tests. The flight model was also assembled and is in the process of system optimization to be launched in 2012 by a Russian rocket. The mission operation scenario and the data reduction software is now being developed. After the successful mission of FIMS (the main payload of STSAT-1), MIRIS is the second Korean space telescope, and will be an important step towards the future of Korean space astronomy.

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근대의 서화가 송은(松隱) 이병직(李秉直)의 생애와 수장활동 (The Life and Art Collection Activities of Modern Korean Painter and Calligrapher Yi Byeong-jik)

  • 김상엽
    • 동양고전연구
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    • 제41호
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    • pp.477-516
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    • 2010
  • 최근 한국미술사학계에서는 우리나라의 미술시장과 미술품 수장가에 대한 연구가 활발히 시도되고 있다. 이 분야의 연구는 명품대가(名品大家) 및 그 유파, 영향 등을 추적하고 분석하던 종래의 연구경향과 한계를 극복하고 미술과 사회, 미술품 유통과 소비 등 기존의 연구방식과 관점으로는 접근하기 힘들었던 주제에 접근하고자 하는 시도라는 점에서 의미가 크다. 이 글에서는 일제시기의 손꼽히는 서화가이자 수장가 가운데 한 사람인 송은 이병직(1896-1973)의 생애와 예술 및 수장활동을 살펴보고자 하였다. 이 작업은 필자가 최근 시도하고 있는 한국 근대 수장가 연구의 일환으로서 주요 수장가 개인의 구체적 삶의 양상을 복원하고 수장활동 및 수장품의 대강을 파악하는 데에 일차적 목적이 있다. 일제강점기 당시 굴지의 수장가 가운데 한사람이었던 이병직은 자신의 방대한 수장품을 1937년과 1941년 두 번의 경매회에서 처분하였고, 1950년 6.25 두 주 전에는 또 한 번의 경매회를 개최하여 전적류를 처분하였다. 이병직이 이처럼 자신의 수장품을 처분한 것은 교육에의 투자를 위함으로 여겨진다. 이와 함께 격동의 시대를 거치면서도 '국보' "삼국유사"를 안전하게 잘 간수한 사실은 수장가로서의 모범을 보여준 미담이다. 이병직이야말로 수장과 사회로의 환원 및 보존이라는 측면에서 모범적 수장가의 모습을 보여준 인물이 아닐까 싶은 것이다. 그러나 이병직의 일생을 제한하고 규정한 것은 그가 내시였다는 점이다. 이병직이 뛰어난 서화가, 중요한 수장가, 예리한 감식안이었지만 미술계에서 주류가 되지 못한 것은 그가 내시였다는 점이 가장 큰 요인이었으리라 추정되는 것이다.

고려.조선시대의 수학과 사회 (Mathematics and Society in Koryo and Chosun)

  • 정지호
    • 한국수학교육학회지시리즈A:수학교육
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    • 제24권2호
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    • pp.48-73
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    • 1986
  • Though the tradition of Korean mathematics since the ancient time up to the 'Enlightenment Period' in the late 19th century had been under the influence of the Chinese mathematics, it strove to develop its own independent of Chinese. However, the fact that it couldn't succeed to form the independent Korean mathematics in spite of many chances under the reign of Kings Sejong, Youngjo, and Joungjo was mainly due to the use of Chinese characters by Koreans. Han-gul (Korean characters) invented by King Sejong had not been used widely as it was called and despised Un-mun and Koreans still used Chinese characters as the only 'true letters' (Jin-suh). The correlation between characters and culture was such that, if Koreans used Han-gul as their official letters, we may have different picture of Korean mathematics. It is quite interesting to note that the mathematics in the 'Enlightenment Period' changed rather smoothly into the Western mathematics at the time when Han-gul was used officially with Chinese characters. In Koryo, the mathematics existed only as a part of the Confucian refinement, not as the object of sincere study. The mathematics in Koryo inherited that of the Unified Shilla without any remarkable development of its own, and the mathematicians were the Inner Officials isolated from the outside world who maintained their positions as specialists amid the turbulence of political changes. They formed a kind of Guild, their posts becoming patrimony. The mathematics in Koryo significant in that they paved the way for that of Chosun through a few books of mathematics such as 'Sanhak-Kyemong', 'Yanghwi-Sanpup' and 'Sangmyung-Sanpup'. King Sejong was quite phenomenal in his policy of promotion of mathematics. King himself was deeply interested in the study, createing an atmosphere in which all the high ranking officials and scholars highly valued mathematics. The sudden development of mathematic culture was mainly due to the personality and capacity of king who took anyone with the mathematic talent into government service regardless of his birth and against the strong opposition of the conservative officials. However, King's view of mathematics never resulted in the true development of mathematics perse and he used it only as an official technique in the tradition way. Korean mathematics in King Sejong's reign was based upon both the natural philosophy in China and the unique geo-political reality of Korean peninsula. The reason why the mathematic culture failed to develop continually against those social background was that the mathematicians were not allowed to play the vital role in that culture, they being only the instrument for the personality or politics of the king. While the learned scholar class sometimes played the important role for the development of the mathematic culture, they often as not became an adamant barrier to it. As the society in Chosun needed the function of mathematics acutely, the mathematicians formed the settled class called Jung-in (Middle-Man). Jung-in was a unique class in Chosun and we can't find its equivalent in China or Japan. These Jung-in mathematician officials lacked tendency to publish their study, since their society was strictly exclusive and their knowledge was very limited. Though they were relatively low class, these mathematicians played very important role in Chosun society. In 'Sil-Hak (the Practical Learning) period' which began in the late 16th century, especially in the reigns of Kings Youngjo and Jungjo, which was called the Renaissance of Chosun, the ambitious policy for the development of science and technology called for. the rapid increase of he number of such technocrats as mathematics, astronomy and medicine. Amid these social changes, the Jung-in mathematicians inevitably became quite ambitious and proud. They tried to explore deeply into mathematics perse beyond the narrow limit of knowledge required for their office. Thus, in this period the mathematics developed rapidly, undergoing very important changes. The characteristic features of the mathematics in this period were: Jung-in mathematicians' active study an publication, the mathematic studies by the renowned scholars of Sil-Hak, joint works by these two classes, their approach to the Western mathematics and their effort to develop Korean mathematics. Toward the 'Enlightenment Period' in the late 19th century, the Western mathematics experienced great difficulty to take its roots in the Peninsula which had been under the strong influence of Confucian ideology and traditional Korean mathematic system. However, with King Kojong's ordinance in 1895, the traditional Korean mathematics influenced by Chinese disappeared from the history of Korean mathematics, as the school system was hanged into the Western style and the Western mathematics was adopted as the only mathematics to be taught at the Schools of various levels. Thus the 'Enlightenment Period' is the period in which Korean mathematics shifted from Chinese into European.

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고려.조선시대의 수학과 사회 (MATHEMATICS AND SOCIETY IN KORYO AND CHOSUN)

  • 정지호
    • 한국수학사학회지
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    • 제2권1호
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    • pp.91-105
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    • 1985
  • Though the tradition of Korean mathematics since the ancient time up to the "Enlightenment Period" in the late 19th century had been under the influence of the Chinese mathematics, it strove to develop its own independent of Chinese. However, the fact that it couldn't succeed to form the independent Korean mathematics in spite of many chances under the reign of Kings Sejong, Youngjo, and Joungjo was mainly due to the use of Chinese characters by Koreans. Han-gul (Korean characters) invented by King Sejong had not been used widely as it was called and despised Un-mun and Koreans still used Chinese characters as the only "true letters" (Jin-suh). The correlation between characters and culture was such that , if Koreans used Han-gul as their official letters, we may have different picture of Korean mathematics. It is quite interesting to note that the mathematics in the "Enlightenment Period" changed rather smoothly into the Western mathematics at the time when Han-gul was used officially with Chinese characters. In Koryo, the mathematics existed only as a part of the Confucian refinement, not as the object of sincere study. The mathematics in Koryo inherited that of the Unified Shilla without any remarkable development of its own, and the mathematicians were the Inner Officials isolated from the outside world who maintained their positions as specialists amid the turbulence of political changes. They formed a kind of Guild, their posts becoming patrimony. The mathematics in Koryo is significant in that they paved the way for that of Chosun through a few books of mathematics such as "Sanhak-Kyemong, "Yanghwi - Sanpup" and "Sangmyung-Sanpup." King Sejong was quite phenomenal in his policy of promotion of mathematics. King himself was deeply interested in the study, createing an atmosphere in which all the high ranking officials and scholars highly valued mathematics. The sudden development of mathematic culture was mainly due to the personality and capacity of King who took any one with the mathematic talent onto government service regardless of his birth and against the strong opposition of the conservative officials. However, King's view of mathematics never resulted in the true development of mathematics per se and he used it only as an official technique in the tradition way. Korean mathematics in King Sejong's reign was based upon both the natural philosophy in China and the unique geo-political reality of Korean peninsula. The reason why the mathematic culture failed to develop continually against those social background was that the mathematicians were not allowed to play the vital role in that culture, they being only the instrument for the personality or politics of the King. While the learned scholar class sometimes played the important role for the development of the mathematic culture, they often as not became an adamant barrier to it. As the society in Chosun needed the function of mathematics acutely, the mathematicians formed the settled class called Jung-in (Middle-Man). Jung-in was a unique class in Chosun and we can't find its equivalent in China of Japan. These Jung-in mathematician officials lacked tendency to publish their study, since their society was strictly exclusive and their knowledge was very limited. Though they were relatively low class, these mathematicians played very important role in Chosun society. In "Sil-Hak (the Practical Learning) period" which began in the late 16th century, especially in the reigns of King Youngjo and Jungjo, which was called the Renaissance of Chosun, the ambitious policy for the development of science and technology called for the rapid increase of the number of such technocrats as mathematicians inevitably became quite ambitious and proud. They tried to explore deeply into mathematics per se beyond the narrow limit of knowledge required for their office. Thus, in this period the mathematics developed rapidly, undergoing very important changes. The characteristic features of the mathematics in this period were: Jung-in mathematicians' active study an publication, the mathematic studies by the renowned scholars of Sil-Hak, joint works by these two classes, their approach to the Western mathematics and their effort to develop Korean mathematics. Toward the "Enlightenment Period" in the late 19th century, the Western mathematics experienced great difficulty to take its roots in the Peninsula which had been under the strong influence of Confucian ideology and traditional Korean mathematic system. However, with King Kojong's ordinance in 1895, the traditonal Korean mathematics influenced by Chinese disappeared from the history of Korean mathematics, as the school system was changed into the Western style and the Western matehmatics was adopted as the only mathematics to be taught at the schools of various levels. Thus the "Enlightenment Period" is the period in which Korean mathematics sifted from Chinese into European.od" is the period in which Korean mathematics sifted from Chinese into European.pean.

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