• 한국가금학회지
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• 제24권3호
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• pp.107-116
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• 1997

In order to achieve optimal reproductive performance, reliable morphological and physiological basic data on the reproductive organs are desirable. Adult male Korean ring-necked pheasant in inactive(mid of January) and active state (end of April) were used in this study. In addition, five active state pheasants were received a single dose of 60Co-ray 500 rads each to damage the testes. The objective of this study was to investigate the distribution pattern of protein gene product (PGP) 9.5 and ${\alpha}$-tubulin in the pheasant testes of the active, inactive and ${\gamma}$-ray irradiated active states. The results obtained were summarized as follows 1. The seminiferous tubules collected in inactive states( mid of Jan) showed narrow lumen, and the spermatogonia and the Sertoli cell were well preserved. The PGP 9.5 immunoreactivity of these tubules showed a positive reaction in paranucleus area of the spermatogonia, and a positive reaction in a small number of the Leydig cells in the interstitium of the seminiferous tubules. 2. The seminiferous tubules were dilated in active state(end of April) as compared with the inactive state. The PGP 9.5 reactivity in these tubules showed a positive reaction in many Leydig cells in the interstitium of the seminiferous tubules, and the testes of ${\gamma}$-ray irradiated group showed partially weak reaction in the interstitium of the seminiferous tubules. 3. The ${\alpha}$-tubulin reactivity in the seminiferous tubules of the inactive testes was strongly positive in the cytoplasmic process of the Sertoli cell from the basal stem region to the apical ex-tension. From the broad part of the stem region to the luminal space, the active testes showed a strong positive reaction. The ${\gamma}$-ray irradiated groups showed diminished reaction in the basal region.

• 한국가스학회지
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• 제18권5호
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• pp.72-77
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• 2014

우리나라는 영구 동토지역이 존재하지 않는 기후적 특성으로 인해 건설수요가 없었지만, 최근 지구 온난화 현상으로 인하여 화석연료의 사용 보다 극한지 지역의 에너지 확보가 대두되고 있다. 이에 극한지 지역에서 사용하고 있지 못한 에너지 자원의 관심이 증가함에 따라 알레스카 및 시베리아의 천연가스의 개발이 필요성이 증대하고 있다. 이에 따라 극한지 지역에서 필요한 배관 설계 기술은 현재 국내에서 사용되고 있는 천연가스와 전혀 다른 환경에서 운용될 것이 예상되며, 이에 따른 설계 기초 자료가 필요하다. 그러므로 극한지 환경에서의 토양 물성에 따라 배관에 미치는 영향 분석이 필요하다. 현재 배관의 설계는 응력 기반으로 설계되어있지만 추후 변위를 기초하는 설계법이 필요하며, 우선적으로 이를 위한 영구동토층 및 활동층에 대한 영향 분석이 필요하다. 본 연구에서는 유한요소해석을 이용한 Thermal elasto-plastic analysis를 통해 활동층의 영향에 따른 배관의 응력 및 변위 측정을 알아보고자 한다.

• 천문학회보
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• 제37권1호
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• pp.85.2-85.2
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• 2012

In this paper, we introduce the 3D modeling of the coronal magnetic field in the solar active region by extrapolating from the 2D observational data numerically. First, we introduce a nonlinear force-free field (NLFFF) extrapolation code based on the MHD-like relaxation method implementing the cleaning a numerical error for Div B proposed by Dedner et al. 2002 and the multi-grid method. We are able to reconstruct the ideal force-free field, which was introduced by Low & Lou (1990), in high accuracy and achieve the faster speed in the high-resolution calculation (512^3 grids). Next we applied our NLFFF extrapolation to the solar active region NOAA 10930. First of all, we compare the 3D NLFFF with the flare ribbons of Ca II images observed by the Solar Optical Telescope (SOT) aboard on the Hinode. As a result, it was found that the location of the two foot-points of the magnetic field lines well correspond to the flare ribbon. The result indicates that the NLFFF well capture the 3D structure of magnetic field in the flaring region. We further report the stability of the magnetic field by estimating the twist value of the field line and finally suggest the flare onset mechanism.

• 한국지반환경공학회 논문집
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• 제17권1호
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• pp.49-54
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• 2016

동토지반을 구성하는 지층 중 표층에 분포하는 활동층은 계절에 따라 동결과 융해를 반복하여 지표면의 동상을 야기한다. 동상 높이는 활동층의 두께에 큰 영향을 받으므로, 동토지반 상부 인프라시설의 안전한 설계 및 시공을 위하여 활동층의 두께 산정은 매우 중요한 부분을 차지한다. 본 연구에서는 경량화된 원위치 관입시험 방법인 동적 콘 관입기를 이용하여 동토지반에서 활동층이 분포하는 심도를 평가하고자 하였다. 동적 콘 관입시험을 적용하기 위한 대상현장으로서 알래스카에 위치한 솔로몬 지역의 동토지반이 선택되었으며, 해당 지역의 두 개소에서 지중온도계측 및 동적 콘 관입시험이 수행되었다. 적용실험 결과 동적 콘 관입시험으로부터 획득된 동적 콘 관입지수는 활동층 및 영구동토층에서 서로 상이한 값을 나타내는바 동적 관입특성에 따른 활동층과 영구동토층의 경계부 심도가 산정되었으며, 경계부 심도에서 아이스 렌즈층으로 판단되는 구간이 감지되었다. 해당 개소에서 획득된 지중온도분포도에서 영상 및 영하 온도의 경계 심도는 본 연구의 동적 콘 관입시험으로부터 획득된 활동층 분포 심도와 부합하는 결과를 보였다. 본 연구에서 적용된 동적 콘 관입기는 대형장비의 접근 및 적용에 한계가 있는 극한지 동토 지역의 활동층 심도평가를 위하여 활용될 수 있을 것이라 기대된다.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제49권8호
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• pp.551-556
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• 2000

A zero-voltage-switching(ZVS) programmable power supply employing the ZVS active clamp forward converter is suggested. Through the analysis on operation region of the supply, the constant power region and the maximum current limit region are clearly identified. Furthermore, the duty ratio range corresponding to the variation range of the output voltages and the control scheme at the minimum duty ration region are presented. Finally, in order to vefity the validity of the operation for the proposed power supply, experimental evaluation results obtained on an 1kW prototype power supply for the 198~242VAC input voltage range(220VAC$\pm$10%), the 0~25V output voltage range, and the 100kHz switching frequency are presented.

• 천문학회지
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• 제29권spc1호
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• pp.323-324
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• 1996

In the present work we introduce a new flare activity indicator, MAD and examine its characteristics by analyzing a set of successive three days' observations of a typical active region, AR2372. The computed MAD is compared with conventional activity indicator such as separator. It is found that. (1) MAD traces very well the separator, (2) it. singles out. local discontinuity of magnetic field lines and (3) it. is a good measure of describing the evolutionary status of active region.

• 천문학논총
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• 제7권1호
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• pp.71-77
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• 1992

An axisymmetric, stationary electrodynamic model of the central engine of an active galactic nucleus has been well formulated by Macdonald and Thorne. In this model the relativistic region around the central black hole must be filled by highly conducting plasma and the equations of magnetohydrodynamics are then satisfied. In this paper we analyze magnetohydrodynamic wave propagation in this region. We find that there are three distinct types of waves - the Alfven wave and two magnetosonic waves. The wave equations turn out to be not very different from those in nonrelativistic case except they are redshifted.

• 한국광학회:학술대회논문집
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• 한국광학회 2006년도 동계학술발표회 논문집
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• pp.313-314
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• 2006

We have investigated the wavelength tuning characteristics due to the vernier effect of coupled-ring reflector laser diode including active region within resonators using time-domain modeling. It is shown that the wavelength can be widely tuned with side mode suppression ratio more than 30dB by adjusting the refractive index difference between mismatched rings.

• 천문학회지
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• 제28권2호
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• pp.147-152
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• 1995

An axisymmetric, stationary electrodynamic model of the central engine of an active galactic nucleus has been well formulated by Macdonald and Thorne. In this model the relativistic region around the central black hole must be filled by highly conducting plasma. We analyze plasma wave propagation in this region and discuss the results. We find that the ionosphere cannot exist right outside of the event horizon of the black hole. Another interesting aspect is that certain resonance phenomena can occur in this case.

• 한국전산유체공학회지
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• 제21권4호
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• pp.33-39
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• 2016

Generally, thermal analysis of spent fuel storage cask has been conducted using the porous media and effective thermal conductivity model to simplify the structural complexity of spent fuel assemblies. As the fuel assembly is composed of two regions; active fuel region corresponding to UO2 pellets and unactive fuel region corresponding to the top and bottom nozzle, the heat transfer performance can be influenced depending on porous media application at these regions. In this study, numerical analysis on concrete storage cask of spent fuel was performed to investigate heat transfer effects for two cases; one was porous media application only to active fuel region(case 1) and the other one was porous media to whole length of fuel assembly(case 2). Using computational fluid dynamics code, the three dimensional, 1/4 symmetry model was constructed. For two cases, maximum temperatures for each component were evaluated below the allowable limits. For the case 1, maximum temperatures for fuel cladding, neutron absorber and baskets inside the canister were slightly higher than those for the case 2. In particular, even though the helium flows with low velocity due to buoyant forces occurred at the top and bottom of unactive fuel region, treating only active fuel region as the porous media was ineffective in respect of the heat removal performance of concrete storage cask, implying a conservative result.