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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.
탁경모(Gyungmo Tahk),박철현(Cheolhyun Park),김수민(Sumin Kim),차원호(Wonho Cha) 한국추진공학회 2020 한국추진공학회 학술대회논문집 Vol.2020 No.7
큐브위성 발사관은 우주궤도에서 다수의 큐브위성을 발사체로부터 분리하는 목적으로 사용되며 큐브위성 발사를 위한 필수 장치이지만 아직 우리나라에서는 순수 국내 기술로 개발된 사례가 없다. 지난 수년간 국내에서 개발된 큐브위성의 발사환경시험을 통하여 해외 발사관의 기능적 불안정성으로 인해 위성의 파손과 고장이 발생할 수 있다는 사실이 밝혀졌으며 이미 일부 해외 발사관에서는 이러한 문제점을 방지할 수 있는 기술이 적용되었다. 국내에서는 2018년도부터 발사관 국산화 개발을 시작했으며 다양한 성능검증과정을 거쳐 3U 발사관 시제품 개발이 완료되었다. 이러한 결과를 바탕으로 2021년까지 세계 최고 수준의 성능을 갖는 3U, 6U, 12U 발사관 제품군을 상용화할 계획이다. Even though CubeSat dispenser is an essential device to separate CubeSats from space launch vehicles in orbit, there has never been developed in Korea. Over the past few years, the launch environmental testing for locally developed CubeSats has revealed that mechanical instability of dispenser can cause serious damage to CubeSat. Therefore, some countries already started to commercialize the advanced dispenser to prevent the CubeSat malfunction. We have been conducting localization of dispenser with various design verifications from 2018 and developed prototypes of 3U dispenser. On the basis of our R & D results, we planned to commercialize a range of 3U, 6U and 12U dispensers with world-class differentiated performance by 2021.