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Design and validation of impedance probe for platform-independent ionospheric plasma diagnostics
Ryu Kwangsun,Lee Seunguk,Woo Chang Ho 한국물리학회 2023 Current Applied Physics Vol.51 No.-
The design of an impedance probe (IP), which is one of the instruments in the package called IAMMAP for the CAS500-3 satellite, and related plasma chamber experiments are introduced. The characteristics of the IP were estimated based on plasma and antenna theory. Trade-off studies on the possible geometry and on the circuit configuration were carried out. It was shown that the combination of a short wave monopole antenna and a capacitor bridge with a heterodyne configuration is suitable for ionospheric plasma diagnostics. The plasma chamber experiments reveal that the upper hybrid resonance frequency measured by the IP is compatible with the plasma model and with the Ne values estimated by the Langmuir probe (LP). This suggests that the compactly-designed IP and LP can serve as a good combination for in-situ measurement of the ionospheric plasma providing self-calibrated plasma parameters.
SEU Measurements of Memory Chips for the Langmuir Probe on STSAT-2
Kwangsun Ryu,Goo-Hwan Shin,Heejoon Kim,hyung-Myung Kim,민경욱 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.52 No.3
We have measured the single event effect (SEE) of candidate memory chips for a Langmuir probe, one of the secondary payloads of STSAT-2 (Science and Technology Satellite-2). The measurements were performed using the cyclotron proton accelerator at Korea Institute of Radiological and Medical Sciences. An ion chamber detector was used for the calibration of the flux of the proton beam. SEU (single event upset) cross-sections for 3 different kinds of memory chips were derived according to the incident proton energy. The SEU rate at the STSAT-2 orbit environment was estimated from the SEU cross-section and the modeled particle flux. The program memory chip for the flight model was selected from the candidates.
Simulation and Ground Test for the Total Ionizing Dose Effects of STSAT-2
Kwangsun Ryu,Dai Ho Ko,Goo hwan Shin,Heejun Kim,김형명,민경욱,sungJoon Kim 한국물리학회 2007 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.50 No.I
STSAT-2, the fifth small satellite developed by the Satellite Technology Research Center, will pass through the lower edge of the inner radiation belts. While passing through these belts, the spacecraft is expected to encounter a large number of energetic particles, which have the potential to cause failures of the satellite's microelectronics systems. The space radiation environment of STSAT-2 is estimated through computer-aided simulations. Ground radiation environment tests for the subsystems and major electrical parts of STSAT-2 were performed by using a Co-60 $\gamma$-ray irradiation facility. Of the major electrical parts, two types of MOSFETs were tested in situ. The causes of changes in the electrical performance are discussed, as are the annealing effects.
유광선(Ryu Kwangsun),신구환(Shin Goo-hwan),차원호(Cha Wonho),강성원(Kang Seongwon),김용식(Kim Youngsik),강기환(Kang Gi-Hwan) 한국태양에너지학회 2010 한국태양에너지학회 학술대회논문집 Vol.2010 No.11
Photovoltaic power generation systems are attracting considerable attention as sources of electrical power that can replace or complement the current power generation systems that utilize fossil and nuclear fuels. So far, the costs for the solar PV systems are not competitive with other power generation systems. Since the cost of concentration optics bought in volume, are much lower than solar cells, there have been various efforts to lower the manufacturing cost using various concentrator optics. The artificial increase in the solar intensity incident on solar cells using lenses or mirrors can allow solar cells to generate equivalent power with a lower cost. There are two types of concentration optics for solar energy conversion. One is to use mirrors, and the other is to use Fresnel lenses. The gains that can be achieved with a Fresnel lens or a parabolic mirror are compared. The result showed the gains are comparable and the two configurations were developed competitively. In application areas of Fresnel lenses as solar concentrators, several variations of design were devised and tested. Some PV systems still use commercially available flat Fresnel lenses as concentrators. A convex linear Fresnel lens to improve the concentration ratio and the efficiency is devised and flat linear Fresnel lens in thermal energy collection is utilized. In this study, we designed and optimized flat Fresnel lens and the ‘light pipe’ to develop 500X concentrated solar PV system. In the process, we compare the transmission efficiencies of ‘groove in case’ and ‘grooves out case’. We performed rigorous ray tracing simulation of the flat Fresnel lenses. The computer aided simulation showed the ‘grooves in case’ has the better efficiency than that of ‘grooves out case’. InGaP/InGaAs/Ge triple junction solar cell is used to convert the photon energy to electrical power. As well as the optical performance of the concentration system, the field test results of the 500X concentrated PV system will be introduced.
류준형(Joonhyoung Ryu),배창한(Changhan Bae),백광선(Kwangsun Baik),이강원(Kangwon Lee),김재원(Jaewon Kim),지해영(Haeyoung Ji) 한국철도학회 2014 한국철도학회 학술발표대회논문집 Vol.2014 No.10
철도차량에는 역행과 제동을 위하여 추진제어용 전력변환장치와 견인전동기로 구성되는 추진제어장치가 설치되어 있는데, 제어특성에 따라 특유의 스위칭 소음이 발생된다. 국내에서 운영되는 철도차량의 추진제어장치는 관련법령에 따라 소음기준에 적합하도록 제작되어야 하는데, 추진제어용 전력변환장치의 소음시험은 구성품 단계에서 견인전동기와 조합하여 운전상태를 변화시키며 발생소음이 최대인 운전상태에서 측정한다. 소음수준은 운전조건과 부하조건 등에 따라 달라지며, 측정위치에 대해서도 영향을 받는다. 본 논문에서는 운전조건에 따른 추진제어용 전력변환장치의 소음수준 변화와 주파수분석을 통하여 견인전동기 속도에 따른 주파수 분포 추이를 분석한다. In the rolling stock, there is a propulsion control unit which is consisted of traction converter and traction motor for powering and braking. It makes the typical switching noise according to the control characteristics. The propulsion control unit installed in domestic rolling stock should be suitable for related regulation. The noise test for traction converter is performed in sub-system phase which is combined to the traction motor and operated with variable powering command. The noise test results are obtained entire speed range operation from maximum equivalent noise level. The equivalent noise level is changed according to the operation mode, load condition and position of the test. This paper analyzes the variation of equivalent noise level and noise spectrum according to the operating condition.
채은경(Eunkyung Chae),류준형(Joonhyoung Ryu),백광선(Kwangsun Baik),윤용기(Yong-Ki Yoon) 한국철도학회 2011 한국철도학회 학술발표대회논문집 Vol.2011 No.10
철도 차량의 전자기 환경은 입반적인 상업 및 가정 환경에 비해 훨씬 열악하지만 대부분의 차량은 이러한 상업 및 가정 환경과 매우 근접하여 운행된다. 철도 차량에서 방사되는 전자파에 의해 상용 무선 장치 및 전자 장치가 영향을 받을 가능성이 있기 때문에 철도 관련 철도 차량의 전자기 환경은 입반적인 상업 및 가정 환경에 비해 훨씬 열악하지만 대부분의 차량은 이러한 상업 및 가정 환경과 매우 근접하여 운행된다. 철도 차량에서 방사되는 전자파에 의해 상용 무선 장치 및 전자 장치가 영향을 받을 가능성이 있기 때문에 철도 관련 전자파 적합성(EMC)규격으로 전자 파 방사의 허용치를 제한하고 있다. 하지만 규격에서 제시한 허용 기준은 실제 유럽의 여러 지점에서 측정한 방대한 전자파 자료를 기준으로 철도 시스템 내부의 안전을 위한 기준으로 철도 이외의 다른 외 부 환경에 주는 영향은 고려되지 않았다. 철도 시스템의 전자파 방사가 허용 기준을 만족한다고 하여도 외부 전자 장치에 영향을 줄 수 있기 때문에 철도 차량의 전자파 방사를 줄이는 노력이 필요하다. 철도 차량은 측정 지점을 수초이내에 지나쳐 가기 때문에 첨두치 측정 방법을 사용하여야 하지만 규격에는 측정 시간과 같은 시간 영역의 특성에 대한 상세한 규정이 없다. 본 논문에서는 철도 차량의 전자파 방사를 줄이는 노력에 앞서 전자파 방사의 가능한 정확한 측정을 위한 장비 설정 및 측정 방법에 대해서 논의하고자 한다. The railway electromagnetic environment is much more severe than most commercial and domestic environments. There are concerns about electromagnetic emissions from railways and their potential to interfere with the operation of commercial radio service and other equipment. EMC standards for railway applications are referenced as EN 50121 series and these standards describe the measurement method and specify limits for emission. However standard provide precise description of the general aspect of the measurement procedure and requirement of test equipments making a reliable measurement of the radiated emissions from a train is a problem of balance between available observation time and the measurement time required by the characteristics of the measurement system. This paper focuses on the problem of measurement.
과학기술위성 3호 대용량 메모리에 대한 오류복구 코드 및 SEU 시험 결과 분석
서인호(In-Ho Seo),유광선(Kwangsun Ryu),오대수(Dae-Soo Oh),김병준(Byung-jun Kim) 한국항공우주학회 2010 韓國航空宇宙學會誌 Vol.38 No.1
과학기술위성 3호 대용량 메모리를 SEU로부터 보호하기 위해서 4비트 심볼을 이용하는 RS(10,8) 코드를 개발 하였다. 따라서 32비트 데이터에 대해서 8비트의 페리티를 추가하였으며 1 심볼에 대해서 에러를 복구할 수 있다. 또한 우리별 3호의 결과를 이용하여 예상되는 SEU 발생률과 스크럽 주기를 계산하였다. 이 결과를 바탕으로 한국원자력 의학원에 있는 Cyclotron 양성자 가속기를 이용하여 SEU 시험을 수행 하였다. RS(10,8) Code by 4-bit symbol was developed to protect the mass memory of STSAT-3 from SEU in orbit. Therefore, one symbol can be corrected for 32-bit data with 8-bit parity configuration. Moreover, scrubbing period and SEU occurrence rate was calculated based on the KITSAT-3 result. A prediction of SEU rates was performed based on the ground experiment results with a proton accelerator in the KIRAMS(Korea Institute of Radiological Medical Sciences).