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김종도(Jongdo Kim),조희근(Heekeun Cho),윤문철(Moonchul Yoon) 한국트라이볼로지학회 2006 한국트라이볼로지학회 학술대회 Vol.2006 No.11
In this study, the analytical realization of coupled system in bearing was introduced using the times series identification and spectrum analysis, which was compared with conventional PET spectrum. Also, the numerical responses of second order system, which is coupled, were solved using the numerical calculation of Runge-Kutta-Gill method. After numerical analysis, the displacement, velocity and acceleration were acquired. Among them, the response of displacement was used for the analysis of time series spectrum. Among several time series, the ARMAX algorithm was proved to be appropriate for the spectrum analysis of the coupled system. Using the separated response of 1st and 2nd mode, the mode was calculated separately. And the responses of mixed modes were also analyzed for calculation of the mixed modes in the coupled system.
유광선(Ryu Kwang-sun),차원호(Cha Won-ho),신구환(Shin Goo-hwan),조희근(Cho HeeKeun),김용식(Kim Young-sik),강성원(Kang Seong-won),강기환(Kang Gi-Hwan) 한국태양에너지학회 2011 한국태양에너지학회 논문집 Vol.31 No.2
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 according to groove types. 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’. Based on the ray-trace results we designed and manufactured sample Fresnel lenses. The optical performance were measured and compared with ray-trace results. Finally, the optical efficiency was measured to be above 75%. All the design and manufacturing were performed based on that InGaP/InGaAs/Ge triple junction solar cell is used to convert the photon energy to electrical power. Field test will be made and analyzed in the near future.