• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.434-434
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• 2010

Axial type 가상음극발진기를 이용하여 전극의 기하학적 구조와 고출력 마이크로파의 출력 특성을 분석하고, 최대 파워의 조건에 대한 전자기기 효과를 알아보았다. 고출력 마이크로파 발생 장치인 Vircator는 강렬한 상대론적 전자빔 발생장치로 최대전압 600 kV, 최대전류 88 kA, 펄스폭 60 ns의 특성을 가진다. Anode와 cathode의 간격은 4 mm로 최적화 하였고, 이 조건에서 마이크로파의 출력 특성을 분석하여 보았을 때 WR-137 수신안테나에서 최대 출력143 MW와 5.4 GHz의 진동수를 측정하였다. 출력 효율을 증가시키기 위해서 도파관 중앙에 폭이 10 mm인 반사판을 사용하였고, 그 결과 반사판이 공진구조에 기여하여 정상파(standing wave)를 형성하여 마이크로파 출력 효율 향상하여 WR-137에서 최대 549 MW의 출력을 보였다. 향상된 마이크로파의 출력을 이용하여 각도와 거리를 변화해 가며 컴퓨터와 전자소자로 제작된 회로에 대해 전자기기 효과 실험을 실시하였다. 그 결과 컴퓨터의 경우 $0^{\circ}$ 1 m에서 hard kill 상태가 되었다. 전자소자 회로의 경우는 $0^{\circ}$ 30 cm에서 hard kill의 상태로 되었다. 또한 면적 대비 출력 파워로 비교 했을 경우 약 $0.484\;{\mu}J$의 마이크로파의 영향임을 확인할 수 있었다.

• Proceedings of the Korean Vacuum Society Conference
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• 2009.08a
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• pp.277-277
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• 2009

• Proceedings of the Korean Vacuum Society Conference
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• 2009.08a
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• pp.278-278
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• 2009

• Proceedings of the Korean Vacuum Society Conference
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• 2009.02a
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• pp.281.1-281.1
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• 2009

• Nuclear Engineering and Technology
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• v.27 no.4
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• pp.555-561
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• 1995

This paper examines the applicability of the modified Borresen's coarse-mesh method(MBSN) to the core power distribution monitoring program development for the Yonggwang nuclear power plant unit 3(YGN 3) which uses fixed incore detectors for monitoring core power distribution. In so doing the modified Borresen's coarse-mesh equations are solved with core internal boundary conditions provided by the fixed incore detectors and three-dimensional core power distributions are com puted for the first-cycle core of the YGN 3 PWR. The results are compared with predictions of the COLSS(Core Operating Limit Supervisory System) which is the axial power shape monitoring program of the YGN 3. It is shown that the modified Borresen's method can reproduce the core axial power shape more closely than the COLSS. Because of other advantages in computing speed and predictive capability, n conclude that the proposed MBSN has a promising practical application for core power distribution monitoring program development.

• Proceedings of the Korean Nuclear Society Conference
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• 1997.10a
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• pp.516-521
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• 1997

국내개발 액체금속로 KALIMER 노심으로 설계한 전기출력 150 MWe (열출력 392 MWth)의 U-Zr이원합금핵연료 사용 소형노심에 대하여 열수력 특성을 분석하고, 그 결과를 전기출력 333 MWe (열출력 840 MWth)의 중형노심설계 특성과 비교ㆍ분석하였다. 분석에는 국내개발 액체금속로 KALIMER 노심설계기술 개발의 일환으로서 개발한 개념설계 초기 단계에서의 노심 열수력 특성 분석 방법을 사용하였다. 열수력 특성 분석은 먼저 각 집합체의 최고 선출력에 따라 유량그룹을 설정하고, 각 집합체의 최고온도 연료봉에 대하여 냉각재 온도, 피복관 중심온도, 핵연료 중심온도 등을 계산하는 방식으로 수행하였다. 특성분석 결과 두 노심 모두 노심내 출력분포를 더욱 평탄화 하고, 노심핵연료 영역에 대한 반경방향 블랑？ 영역의 출력비율을 높이는 작업이 필요하다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.8
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• pp.735-740
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• 2007

Star sensor provides highly accurate attitude information by imaging the stars in the dark space. The sensor output is disabled when the sensor avoidance of the Sunlight or the Earth's albedo is not satisfied. This paper studies the Sun and Earth avoidance characteristics of the star sensors according to the mounting direction. Then the paper proposes a systematic way of determining the star sensors mounting direction for typical remote sensing missions

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.12
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• pp.2905-2910
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• 2015

CW Radar Sensors can be categorized into Single and Dual by its IF output type. Dual IF type is used for detecting the direction of moving objects. However, Dual IF type has more complicated circuitry than Single IF type and higher cost due to more parts required. In this paper, we propose an algorithm for Single IF type CW radar sensors to detect the direction of moving objects. It performs FFT on signals created at IF output when an object moves and determines approach, stop and recede according to amplitude variations. In order to verify the algorithm, a function generator is used to create a virtual signal and confirmed that it accurately detects the directions according to amplitude variations.

• Radiation Oncology Journal
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• v.21 no.2
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• pp.158-166
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• 2003

Purpose: To propose a conceptual design of a novel source for intensity modulated brachytherapy. Materials and Methods: The source design incorporates both radioactive and shielding materials (stainless steel or tungsten), to provide an asymmetric dose intensity in the azimuthal direction. The intensity modulated intravascular brachytherapy was performed by combining a series of dwell positions and times, distributed along the azimuthal coordinates. Two simple designs for the beta-emitting sources, with similar physical dimensions to a $^{90}Sr/Y$ Novoste Beat-Cath source, were considered in the dosimetric feasibility study. In the first design, the radioactive and materials each occupy half of the cylinder and in the second, the radioactive material occupies only a quater of the cylinder. The radial and azimuthal dose distributions around each source were calculated using the MCNP Monte Carlo code. Results: The preliminary hypothetical simulation and optimization results demonstrated the 87$\%$ difference between the maximum and minimum doses to the lumen wall, due to off-centering of the radiation source, could be reduced to less than 7$\%$ by optimizing the azimuthal dwell positions and times of the partially shielded intravascular brachytherapy sources. Conclusion: The novel brachytherapy source design, and conceptual source delivery system, proposed in this study show promising dosimetric characteristics for the realization of intensity modulated brachytherapy in intravascular treatment. Further development of this concept will center on building a delivery system that can precisely control the angular motion of a radiation source in a small-diameter catheter.

• Journal of the Korean Institute of Intelligent Systems
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• v.10 no.2
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• pp.138-145
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• 2000

A identification algorithm that finds optimal fuzzy membership functions and rule base to fuzzy model isproposed and a fuzzy controller is designed to get more accurate position and velocity control of wheeled mobile robot. This procedure that is composed of three steps has its own unique process at each step. The elements of output term set are increased at first step and then the rule base is varied according to increase of the elements. The adjusted system is in competition with system which doesn't include any increased elements. The adjusted system will be removed if the system lost. Otherwise, the control system is replaced with the adjusted system. After finished regulation of output term set and rule base, searching for input membership functions is processed with constraints and fine tuning of output membership functions is done.