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Monte Carlo Calculation on the Dose Modulation Using Dynamic Magnetic Fields for 10 MV X-rays
김기환,오영기,신교철,김진기,정동혁,김정기,조문준,김선영,Kim, Ki Hwan,Oh, Young Kee,Shin, Kyo Chul,Kim, Jhin Kee,Jeong, Dong Hyeok,Kim, Jeung Kee,Cho, Moon June,Kim, Sun Young Korean Society of Medical Physics 2007 의학물리 Vol.18 No.4
움직이는 자기장을 이용한 팬텀 속 선량 변조에 관한 몬테칼로 계산을 수행하였다. 본 연구의 목적은 빔 축을 따라 이동하는 횡 자기장을 이용하여 특정감이 영역에 균일한 선량을 얻는 것이다. 이를 위해 두 가지 구성 즉, 깊이 방향으로 일정한 속도 그리고 점차 감소하는 속도를 가지는 자기장에 대해 깊이 선량율을 구하였다. 연속적 움직임에 대한 근사로서 단계별 이동과 시간인자를 도입하였다. 위치별 정지한 자기장 대한 김이 선량율 자료에 최소제곱법을 적용하여 자기장 위치에 따른 최적의 시간인자를 구하였다. 몬테칼로 계산결과를 통하여 자기장의 속도를 변화시킴으로써 평탄한 선량 분포를 얻을 수 있음을 확인하였다. 이 때 3 T 자기장 세기에 대한 계산결과 평탄 영역의 선량은 자기장이 없을 때에 비해 약 10.1% 증가하는 것으로 나타났다. Monte Carlo calculations were performed to demonstrate the dose modulation with dynamic magnetic fields in phantom. The goal of this study is to obtain the uniform dose distributions at a depth region as a target on the central axis of photon beam under moving transverse magnetic field. We have calculated the depth dose curves for two cases of moving magnetic field along a depth line, constant speed and optimal speed. We introduced step-by-step shift and time factor of the position of the electromagnet as an approximations of continuous moving. The optimal time factors as a function of magnetic field position were calculated by least square methods using depth dose data for static magnetic field. We have verified that the flat depth dose is produced by varying the speed of magnetic field as a function of position as a results of Monte Carlo calculations. For 3 T magnetic field, the dose enhancement was 10.1% in comparison to without magnetic field at the center of the target.
Bethanidine의 Norepinephrine 및 Tyramine의 승압 효과에 미치는 영향
김기환(Kee Hwan Kim) 대한약학회 1978 약학회지 Vol.22 No.3
An influence of bethanidine (B) on pressor effects of norepinephrine (NE) and tyramine (TR) was investigated in the whole rabbits. B, in a dose 1.0, 3.0,and 5.0mg/kg, i.v., potentiated significantly the pressor effects of NE and TR. Reserpine and desipramine did not increase the NE effect that had been potentiated by B. B also made little modification of NE effect that had been potentiated by reserpine and desipramine. B increased the NE effect that had been potentiated by tranylcypromine and guanethidine. The NE pressor effect potentiated by B was decreased by tranylcypromine, but not influenced by guanethidine. The TR pressor effect potentiated by B was not altered by reserpine and guanetbidine, but decreased by desipramine and tranylcypromine. B increased the TR pressor effect that had been potentiated by guanethidine. B, when given after administration of reserpine, tranylcypromine or desipramine, exerted little influence on the TR effect. The mechanism of potentiation of NE and TR pressor effects by B seems to be similar to guanethidine, and the potency of B on the influence of NE and TR effects seems to be greater than guanethidine.
Tiny PLC 기반의 엘리베이터 모델을 이용한 자동화 교육
김기환(Kee-Hwan Kim) 전력전자학회 2005 전력전자학술대회 논문집 Vol.- No.-
The development of control related applications requires knowledge of different subject matters like mechanical components, control equipment and physics. To understand the behavior of these heterogeneous applications is not easy especially the students who begin to study the electronic engineering.
김기환(Kim Kee Hwan),김용주(Kim Yong Ju),신대철(Shin Dae Chul) 전력전자학회 2001 전력전자학술대회 논문집 Vol.2001 No.7
One of the frequently used relay in industry is SR relay. The SR relay has roughly two kinds. Wenn the power is off, one can memorize the previous state and the other can be set automatically to the initial setting position. Those relays are constructed mechanically, so that they have some disadvantages, such as electro magnetical and acoustic noise.<br/> Such problem can be easily solvedby using a microprocessor. In this contribution will show the opportunity, how easily the relay function with a microprocessor can be reconstructed. As an example the function of Impulse Set Reset Relay will be discussed.
김기환(Kee-Hwan Kim),이태구(Tae-Gu Lee) 대한전기학회 2007 대한전기학회 학술대회 논문집 Vol.2007 No.4
In this paper we have designed a monitoring and controlling system, which rainwater harvests. Atmega 128 microprocessor family is used for the monitoring and controlling of the system. Through the Internet, the rainwater bank system can be monitored and controlled by using JAVA program. Monitoring and controlling of the system are also possible without Internet connection.