• 한국의학물리학회지:의학물리
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• 제22권2호
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• pp.85-91
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• 2011

GEANT4 Medical Linac 2 예제 코드를 이용하여 선형가속기 전자선의 에너지 분포를 계산하였다. 입사 전자의 평균 에너지는 6, 9, 12, 16, 20 MeV이었으며, 전자선 특성에 영향을 주는 전자선 산란박 물질, 두께, 위치에 따른 에너지 분포를 계산하였다. 산란박 물질은 납, 구리, 알루미늄, 금을 사용하였다. 산란박 위치를 변경하여 선형 가속기 헤드 속 산란박 위치가 전자 및 광자 에너지 분포에 미치는 영향을 분석하였다. 의료용 선형가속기 시뮬레이션의 기초자료인 에너지 분포에 대해 여러 가지 산란박 조건을 적용하여 경향을 나타내었다. 이 결과는 선형가속기 헤드 설계에 이용될 수 있을 것으로 본다.

• 천문학회보
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• 제37권1호
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• pp.100.2-100.2
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• 2012

We have investigated excitation processes of the 3-micron bands of $CH_4$, $C_2H_2$, and $C_2H_6$ over the auroral regions of Jupiter including particle bombardments, Joule heating, scattering of solar radiation, and possible chemiluminescence. We also considered possible LTE or Non-LTE conditions of these processes. We constructed particle precipitation models including $H_2$, He, H, and the hydrocarbon molecules for the atmosphere of the auroral regions. We present preliminary results from these models, and comparisons of the model results with spectroscopic observations in the 3 micron wavelength range of Jupiter.

• 천문학회지
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• 제29권spc1호
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• pp.17-18
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• 1996

COBE's results on the anisotropy of the cosmic microwave background radiation (CMBR) is discussed. Some ambiguities in the linear GI cosmic perturbation theory are clarified. The problem of the last scattering surface and the deficiencies of the linear cosmic perturbation theory are mentioned. The possible ways to overcome the theoretical difficulties are discussed also.

• 천문학회보
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• 제42권2호
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• pp.55.2-55.2
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• 2017

We present a numerical code for the random scattering histories of Lyman alpha photons in the intergalactic medium. The numerical code calculates the radiative transfer under generic three dimensional density, ionization fraction, and peculiar velocity fields based on N-body + radiation transfer simulations of the epoch of reionization. The code is tested with models having analytical solutions, which have idealized geometry and simplified velocity fields. The emergent line profiles can give constraints to the ionization structure around Lyman alpha sources in the early universe.

• 한국전자파학회논문지
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• 제8권6호
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• pp.629-635
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• 1997

주기적인 축방향 슬롯이 있는 동축선로 도파관 구조에 TE 편파가 입사될 때 특성모드 이론(characteristic mode theory)을 사용하여 가중 고유방정식(weighted eigenvalue equation)을 유도하고, 일반적인 수치방볍 으로 특성값(characteristic values)과 특성전류(characteristic currents)를 구하여 미지의 등가 자기전류, 산 란패턴과 RCS(radar cross section)를 구하였다. 그리고 이 수치 결과들을 모멘트법을 이용하여 구한 결과들과 각각 비교하여 특성모드에 의한 해석방볍의 타당성을 보였다.

• 대한기계학회논문집B
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• 제30권3호
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• pp.270-277
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• 2006

Inverse radiation problems were solved for estimating boundary temperature distribution in a way of function estimation approach in an axisymmetric absorbing, emitting and scattering medium, given the measured radiative data. In order to reduce the computational time fur the calculation of sensitivity matrix, automatic differentiation and Broyden combined method were adopted, and their computational precision and efficiency were compared with the result obtained by finite difference approximation.. In inverse analysis, the effects of the precision of sensitivity matrix, the number of measurement points and measurement error on the estimation accuracy had been inspected using quasi-Newton method as an inverse method. Inverse solutions were validated with the result acquired by additional inverse methods of conjugate-gradient method or Levenberg-Marquardt method.

• 한국광학회:학술대회논문집
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• 한국광학회 1990년도 제5회 파동 및 레이저 학술발표회 5th Conference on Waves and lasers 논문집 - 한국광학회
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• pp.29-33
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• 1990

Efficient numerical method is developed for treating electromagnetic problems of scattering and radiation from surfaces. Special consideration is given to the treatment of edges so that rather arbitrary geometrical configurations may be handled. For the conducting body problems considered, an electric field integral formulation is used, and the method of moments is applied using pulse expantions to present currents. Numerial results indicate that the approach is free os anomalies in the behavior of current for body of revoution.

• Nuclear Engineering and Technology
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• 제52권9호
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• pp.2138-2150
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• 2020

We report the status of the cold neutron triple-axis spectrometer (Cold TAS) and thermal neutron triple-axis spectrometer (Thermal TAS) installed at HANARO. Cold TAS, whose specifications are standard across the world, is in the final phase of commissioning. Proper instrument operation was confirmed through a feasibility study of phonon measurements and data analyses with resolution convolution. In contrast, Thermal TAS is in the initial phase of commissioning, and improvement of the monochromator drum is now in progress from the viewpoint of radiation shielding. In addition, we report recent activities in the development of neutron basic elements, that is, film-coated Si-wafer collimators, which are promising for use in triple-axis spectroscopy, particularly in Cold TAS.

• 대한전자공학회논문지
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• 제8권6호
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• pp.17-24
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• 1971

본 논문에서는 임의의 형상을 가진 유전체 안테나에 대한 새로운 해석 방법을 기술한다. 이 방법에서는 분극 전류 및 뇌하 밀도의 개념을 종래의 Stratton-Chu 형식에 도입하고 산란 원칙에 따라 유전체 내의 전계강도에 대해 적분 방정식을 세웠다. 이 적분 방정식을 수치 계산법으로 풀기 위해 유전체의 체적을 세분하고 작은 구로서 등가적으로 표시한다. 따라서 이 방법에 의해서는 임의의 형상의 유전체 안테나의 해석이 가능하다. 이와같이 해서 유전체 내의 전계강도를 구하고 그 강도에 입각해서 안테나의 복사특성, 입력 임피이단스 및 유전체 손실들을 산출했다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.1639-1644
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• 2003

A hybrid genetic algorithm is developed for estimating the wall emissivities for an absorbing, emitting, and scattering media in a two-dimensional irregular geometry with diffusely emitting and reflecting opaque boundaries by minimizing an objective function, which is expressed by the sum of square errors between estimated and measured temperatures at only four data positions. The finite-volume method was employed to solve the radiative transfer equation for a two-dimensional irregular geometry. The results show that a developed hybrid genetic algorithms reduce the effect of genetic parameters on the performance of genetic algorithm and that the wall emissivities are estimated accurately without measurement errors.