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조성구,김찬형,Cho Sung Koo,Kim Chan-Hyeong 한국의학물리학회 2004 의학물리 Vol.15 No.4
MOSFET 선량계는 기존의 선량계들에 비해 여러 가지 장점이 있기 때문에 최근에 방사선 치료뿐만 아니라 방사선 진단 등 기타 여러 분야에서 선량검증을 위해 시도되고 있다. 하지만 이렇게 사용되기 위해서는 중ㆍ저에너지 범위의 광자선에 대한 MOSFET 선량계의 방사선학적 특성파악이 선행되어야 한다. 본 연구에서는 고감도 MOSFET 선량계의 여러가지 방사선학적 특성을 자세하게 연구할 수 있는 3차원 몬테칼로 전산모사 모델을 개발하였다. 고감도 MOSFET 선량계의 검출부위는 매우 얇아서 MCNP에서 기본적으로 제공하는 Tally를 사용하면 검출부위에 흡수된 에너지를 정확하게 결정할 수 없으므로 검출부위에 주어진 에너지를 전자들의 트랙들로부터 직접 계산하는 방법을 채택하였다. 개발된 모델은 에너지 의존도, 전자 기여도, 깊이 의존도 등의 MOSFET 선량계의 방사선학적 특성을 연구하기 위해 사용되었다. 에너지 의존도는 15 keV에서 6 MeV 에너지 범위에서 정량화하였는데 약 40 keV에서 최대 6.6으로 나타났다. 본 연구에서는 PTRAC 파일과 Sabrina 코드를 이용하여 MOSFET 선량계 각 부분에서의 전자 기여도를 조사하였다. 깊이 의존도는 신체 내 평균 깊이를 15 cm로 가정할 때 0.662 MeV의 경우는 교정인자 1.16 그리고 1.25 MeV의 경우는 교정인자 1.11을 사용하여 깊이 의존도에 의한 오차를 줄일 수 있다. Due to their excellence for the high-energy therapy range of photon beams, researchers show increasing interest in applying MOSFET dosimeters to low- and medium-energy applications. In this energy range, however, MOSFET dosimeter is complicated by the fact that the interaction probability of photons shows significant dependence on the atomic number, Z, due to photoelectric effect. The objective of this study is to develop a very detailed 3-dimensional Monte Carlo simulation model of a MOSFET dosimeter for radiological characterizations and calibrations. The sensitive volume of the High-Sensitivity MOSFET dosimeter is very thin (1 ${\mu}{\textrm}{m}$) and the standard MCNP tallies do not accurately determine absorbed dose to the sensitive volume. Therefore, we need to score the energy deposition directly from electrons. The developed model was then used to study various radiological characteristics of the MOSFET dosimeter. the energy dependence was quantified for the energy range 15 keV to 6 MeV; finding maximum dependence of 6.6 at about 40 keV. A commercial computer code, Sabrina, was used to read the particle track information from an MCNP simulation and count the tracks of simulated electrons. The MOSFET dosimeter estimated the calibration factor by 1.16 when the dosimeter was at 15 cm depth in tissue phantom for 662 keV incident photons. Our results showed that the MOSFET dosimeter estimated by 1.11 for 1.25 MeV photons for the same condition.
이중 여자 비동기 발전기를 포함한 풍력단지 시모의 해석
조성구(Cho, Sung-Koo),송화창(Song, Hwa-Chang),이장호(Lee, Jang-Ho) 한국신재생에너지학회 2009 한국신재생에너지학회 학술대회논문집 Vol.2009 No.11
As a result of increasing environmental concern, the penetration of renewable power on power systems is now increasing. Wind energy can be considered as the most economical energy sources to generate electricity without depletion of fossil fuel. The penetration of wind energy from wind farm is getting larger and larger, so we need adequate control strategies for wind farm. To devise adequate control strategies for wind farm, time domain simulation analysis needs to be performed. This presents a Simultaneous Implicit-based time domain simulation algorithm for wind farm with DFAG (Doubly Fed Asynchronous generator) connected to the external power systems. This paper shows an illustrative example with a 5-bus test system.
태양광 직류 전로 사고 실증실험을 통한 태양광 단락사고 특성
조성구(Cho Sung-Koo),정도연(Jung Do-Yun),김재현(Kim Jae-Hyun),김지연(Kim Ji-Yeon),김준태(Kim Jun-Tae) 한국태양에너지학회 2022 한국태양에너지학회 논문집 Vol.42 No.5
The rapid development of the solar industry over the past several years has expanded the significance of photovoltaic (PV) systems. Fault analysis in photovoltaic arrays is a fundamental task to increase reliability, efficiency, and safety in PV systems. If no fault is detected, it may reduce power generation, accelerate system aging, and increase the risks of fire hazards. In this study, we considered the line–line fault through verification experiments in PV arrays for fire hazard analysis and analyzed accident characteristics to improve electrical safety in PV systems. This paper presents a comparison and analysis of accident characteristics regarding the location of the accident, use of blocking diodes, and PV inverter operation. String line–line fault protection in systems without blocking diodes should be designed considering the current acceptable ratings of all facilities in the path, from the combiner box to the PV module. In addition, the array line-line fault characteristics include short-circuit current from the solar array and back feed current from the inverter based on the accident point. These accident currents contribute to fire accidents with strong arcs from the short-circuit point.
비절연인버터 방식 BIPV시스템에서의 감전 사고 위험성 분석
조성구(Sung-Koo Cho),정진수(Jin-Soo Jung),임현성(Hyun-Sung Lim),채동주(Dong-Ju Chae),홍성준(Seong-Jun Hong) 한국조명·전기설비학회 2017 조명·전기설비학회논문지 Vol.31 No.9
Recently, As a result of government policy to promote renewable energy sources, BIPV(Building Integrated Photo Voltaic) System replacing building finishing material with photo voltaic module has been increasing. Building integrated photo voltaic system is installed in a building by inserting a solar cell in the building finishing material. Thus BIPV systems have possibility of an electric shock accident due to decreased insulation performance because it is easy to contact human body from conductor. Especially, in case of a system using transformerless inverter system, it is structurally vulnerable to safety, so that the risk of accidents may increase. Therefore, the risk of human shock due to accidents should be studied through actual accident experiments. In this paper, as a study for the development of standards for securing human body electrical safety in BIPV system, we considered the hazard of electrical safety in the BIPV systems applied transformerless inverter and conducted analysis risk of electric shock through verification experiment.
조성구(Sung-Koo Cho),송화창(Hwachang Song),이장호(Jangho Lee) 대한전기학회 2010 전기학회논문지 Vol.59 No.11
As a result of increasing environmental concern, the penetration of renewable power on power systems is now increasing. Wind energy can be considered as the most economical energy sources to generate electricity without depletion of fossil fuel. To devise adequate control strategies for wind farm , time domain simulation analysis needs to be performed. This presents a continuation time integration (CTI)-based time domain simulation algorithm for wind farm with doubly fed asynchronous generator (DFAG) connected to the external power systems. This paper depicts how to time trajectories are traced using CTI-based time domain simulation. Also this paper describes the possibilities of hierachical control for wind farm output limitation, and the coordinated control has been designed by hierarchical control structured from central control level to wind farm control board and to an individual wind turbine level. Finally it shows an illustrative example of time domain simulation result with two test systems through case study.