• 대한전자공학회논문지SD
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• 제37권6호
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• pp.17-23
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• 2000

본 연구에서는 Sq색소를 이용하여 적색발광의 디바이스를 제작하고, 발광효율을 증가시키기 위해 OXD7과 $Alq_3$층을 발광층과 음극사이에 삽입하여 그 효과를 관측하고, 기구특성을 검토하였다. 정공운송층으로서 TPD, 발광층 호스트재료로서 $Alq_3$, 게스트 재료로서 Sq를 사용하였다. 그 결과 $Alq_3$층의 삽입은 효율을 증가시킬 수 있었지만, 삽입된 $Alq_3$층에서의 발광 때문에 색순도 높은 적색발광을 얻지 못했다. OXD7층의 삽입은 정공을 블로킹하고 정공을 누적시킨다. 이는 전자와 정공의 재결합확률을 증가시키기 때문에 색순도 높은 적색발광을 유지하면서 휘도 특성과 발광효율이 향상되었다.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제50권12호
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• pp.624-630
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• 2001

The trend of the regulations on environmental issues are getting tight. Responding to this trend new technologies such as moving electrodes, wide pitch and pulsed power supply are also introduced in the electrostatic precipitator(EP) systems. The introduction of wide pitch and moving electrodes enhances the system performance of the EPs by improving air-flow and by improving the ash reentrainment on rapping. The power supplies for the EPs developed up to date include thyristor-based dc or intermittent type, SMPS(switching mode power supply) type and the pulsed-power supply type. The use of the pulsed ones is known to improve dust-collecting efficiency of high resistivity ash and reduces back corona occurrence in the collecting plate. There are two kinds of pulsed-power supplies; one with pulsed transformers and the other with direct dc switching devices. The latter uses rotary spark gap switches or semiconductor switches. Both have the merits and demerits: the spark gap switches are simple and robust but has short life time, hence, high maintenance cost, whereas the semiconductor switches have long life time but are costly. In this study, A high voltage power supply with superimposing voltage pulse on dc source was developed for EPs. This study describes circuit topology, operating principle of the scheme, and analysis of experimental results on Dong-Hae Power Plant. The pulsed power supply consists of a variable dc power supply with ratings of 60kV, 800mA and pulse generator which is made of high voltage thyristor-diode switch strings, an LC resonant tank and a blocking inductor. The pulse generator generates variable pulse-voltage up to 70kV using a high frequency resonant inverter with a variable dc source. Two prototypes were built and tested on 250MW DongHae power plant to verify the possibility of the commercial use and the normal operation in the transient states.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2002년도 추계종합학술대회
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• pp.481-485
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• 2002

본 연구에서는 수직형 LPE 장치를 이용하여 meltback 방법으로 제작된 PBH-LD에 대한 누설전류를 해석하였다. PBH-LD에서 활성층 이외의 p-n 다이오드와 p-n-p-n 전류차단층과 같은 누설경로에 따른 이들의 영향을 조사하였다. 이러한 누설전류의 영향을 알아보기 위해 누설 폭이 "0" 일 때와 누설 폭이 $W_{ι}$ 일 때를 비교하였다. 그 결과 누설 폭에 따른 임계전류는 누설 폭을 줄이거나, 고유저항 ($\rho$$_{ι}$$\rho$$_{a}$ )비를 증가시켜줌으로써 임계전류가 낮아짐을 확인하였다. 본 연구에서 제작된 LD의 경우 활성층의 폭 $W_{a}$ 가 약 1.4$\mu\textrm{m}$이고 누설 폭이 약 0.6$\mu\textrm{m}$로, 제작된 LD의 cavity length와 임계전류를 비교해 본 결과 고유저항비가 약 0.5일 때 누설 폭에 따른 계산된 임계전류값과 실제 제작된 PBH-LD의 임계전류값이 일치함을 확인하였다. 따라서, 제작된 PBH-LD의 p-InP 차단층의 도핑농도를 $10^{18}$ c $m_{-3}$ 에서 $10^{17}$ $cm^{-3}$으로 줄여 누설영역의 저항을 크게 함으로써 누설전류를 더 줄일 수 있으리라 생각된다.다.

• 전기전자학회논문지
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• 제25권3호
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• pp.517-527
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• 2021

본 논문에서는 단일칩 마이컴을 이용한 위상변위 방식 직류-직류 전력변환기를 제안한다. 제안한 전력변환기의 1차측은 위상변위 방식에 의하여 단극성 펄스폭변조(unipolar PWM)로 동작하는 풀브리지 전력구조이며, 2차측은 4개의 다이오드로 구성된 풀브리지 전파정류기이다. 제안한 전력변환기의 제어는 단일칩 마이컴에 의해 수행되고, 그 MOSFET 스위치들은 부트스트랩 회로에 의해 구동된다. 그래서 전력변환기의 전체 시스템은 간단하다. 제안한 전력변환기는 공진회로와 저지커패시터를 이용하여 고효율을 달성한다. 본 논문에서는 먼저, 제안한 전력변환기의 전력회로의 동작을 각 동작모드를 따라 설명한다. 그리고 제안한 전력변환기의 전력회로 설계방식을 보이고 제안한 전력변환기를 동작시키는 마이컴 상의 소프트웨어 제어 알고리즘과 피드백 및 스위치 구동 회로에 관하여 간략히 설명한다. 그 후, 본 논문에서 제시한 설계와 구현방식에 의하여 설계하고 제작된 시제품 전력변환기의 실험결과를 통하여 제안한 전력변환기의 동작 특성을 입증한다. 실험결과에서 약 92% 정도의 최고 효율을 얻었다.

• 대한방사선치료학회지
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• 제12권1호
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• pp.91-104
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• 2000

Recently linear accelerator in radiation therapy in asymmetric field has been easily used since the improvement and capability of asymmetrical field adjustment attached to the machine. It has been thought there have been some significant errors in dose calculation when asymmetrical radiation fields have been utilized in practice of radiation treatments if the fundamental data for dose calculation have been measured in symmetrical standard fields. This study investigated how much the measured data of dose distributions and their isodose curves are different between in asymmetrical and symmetrical standard fields, and how much there difference affect the error in dose calculation in conventional method measured in symmetrical standard field. The distributions of radiation dose were measured by photon diode detector in the water phantom (RFA-300P, Scanditronix, Sweden) as tissue equivalent material on utilization of 6 MV linear accelerator with source surface distance (SSD) 1000 mm. The photon diode detector has the velocity of 1 mm per second from water surface to 250 mm depth in the field size of $40mm{\times}40mm\;to\;250mm{\times}250mm\;symmetric\;field\;and\;40mm{\times}20mm\;to\;250mm{\times}125mm$ asymmetrical fields. The measurements of percent depth dose (PDD) and subsequent plotting of their isodose curves were performed from water surface to 250mm dmm from Y-center axis in $100mm{\times}50mm$ field in order to absence the variability of depth dose according to increasing field sizes and their affects to plotted isodose curves. The difference of PDD between symmetric and asymmetric field was maximum $4.1\%\;decrease\;in\;40mm{\times}20mm\;field,\;maximum\;6.6\%\;decrease\;in\;100mm{\times}50mm\;and\;maximum\;10.2\%\;decrease\;200mm{\times}100mm$, the larger decrease difference of PDD as the greater field size and as greater the depth, The difference of PDD between asymmetrical field and equivalent square field showed maximum $2.4\%\;decrease\;in\;60mm{\times}30mm\;field,\;maximum\;4.8\%\;decrease\;in\;150mm{\times}75mm\;and\;maximum\;6.1\%\;decrease\;in\;250mm{\times}125mm$, and the larger decreased differenced PDD as the greater field size and as greater the depth, these differences of PDD were out of $5\%$ of dose calculation as defined by international Commission on radiation unit and Measurements(ICRU). In the dose distribution of asymmetrical field (half beam) the plotted isodose curves were observed to have deviations by decreased PDD as greater as the blocking of the beam moved closer to the central axis, and as the asymmetrical field increased by moving the block 10 mm keeping away from the central axis, the PDD increased and plotted isodose curves were gradually more flattened, due to reduced amount of the primary beam and the fraction of low energy soft radiations by passing thougepth in asymmetrical field by moving independent jaw each 10 h beam flattening filter. As asymmetrical radiation field as half beam radiation technique is used, the radiation dosimetry calculated in utilizing the fundamental data which measured in standard symmetrical field should be converted on bases of nearly measured data in asymmetrical field, measured beam data flies of various asymmetrical field in various energy and be necessary in each institution.