• Optical Science and Technology
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• v.20 no.2
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• pp.8-11
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• 2016

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.422-426
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• 2005

This experimental study represents the results of an analysis on the characteristics of flux density distribution in the focal region of solar concentrator. The characteristics of flux density distributions are investigated to optimally design and position a cavity receiver. This was deemed very useful to find and correct various errors associated with a dish concentrator. We estimated the flux density distribution on the target placed along with focal lengths from the dish vertex to experimentally determine the focal length. It is observed that the actual focal point exists when the focal length is 2.17m. The total integrated power and percent power was 2467W and $85.8\%$, respectively, in the case of small dish, and also 2095W and $79\%$, respectively, in the case of KIERDISH II. As a result of the percent power within radius, approximately $90\%$ of the incident radiation is intercepted by about 0.06 m radius. The minimum radius of receiver in KIERDISH II is found to be 0.15m and approximately $90\%$ of the incident radiation is intercepted by receiver aperture.

• Journal of Energy Engineering
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• v.21 no.2
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• pp.124-132
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• 2012

This study presents the simulation results of Photopia when a lecture room with north-facing windows were illuminated by two different types of daylighting systems to improve the imbalance in its lighting conditions. Especially, the candela power distribution curves (CDCs) on a clear sunny day at the summer solstice, reaching $80^{\circ}$ in solar altitude, were analyzed with respect to the illuminance available at task areas (work planes). The difference between its illuminance on the north and south areas exceeded 1,000 lux without any daylighting system. This, however, decreased drastically with the application of a daylighting system. When a light tube system was introduced, it reduced from 906lx to 603lx and, even further to 308lx with the application of a dish concentrator system. Generally, the performance of a light tube system was greatly influenced by solar altitude while its effect on the dish concentrator system was rather negligible.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.11
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• pp.907-914
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• 2014

The objective of this study was to increase the generating efficiency of concentrated photovoltaics (CPV) by using hybrid solar tracking. Further, the proposed system was demonstrated to have the ability to extract thermal energy from a concentrated photovoltaic system by using thermal absorbers containing heat pipe, which could then be used for a heating system or hot-water supply. The average electrical efficiency was 16 during the day, and the average thermal efficiency was 62. Therefore, this system demonstrated a total efficiency (electrical thermal) of 78. All the processes, i.e., tracking of the sun, calculation of the sun's position, reinstatement of the heating device toward the east for tracking on the next day, and system shutdown, were programmed using Simulink. A parametric analysis of the heat pipe, concentration ratio, and inlet velocity was also performed in terms of the operating temperature of the CPV and the outlet temperature. The simulation and experimental results for the thermal absorber were found to be in good agreement.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.7 s.196
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• pp.19-25
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• 2007

• Journal of the Korean Solar Energy Society
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• v.27 no.4
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• pp.129-136
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• 2007

자연광의 이용은 큰 어려움 없이 지속 가능한 에너지 기술을 구현할 수 있는 방안으로 고려되고 있다. 여러 개의 작은 반사경을 적용한 태양 추적식 자연채광 시스템은 비교적 단순한 메카니즘을 적용하여 그 성능과 효용성의 극대화를 꾀할 수 있으며, 또한 그 제작, 설치 작동 그리고 활용성에서 상당한 이점이 있다. 본 연구에서는 작은 mini-dish형 반사경(직경<30cm 이하)을 이용한 화이버 광학 집광기의 설계, 제작 및 작동 특성에 대하여 소개하고, 아울러 광추적 프로그램인 Photopia를 이용하여 그 성능에 대한 시뮬레이션을 수행하였다. 주요 구성 요소에서의 광추적에 의한 시뮬레이션 결과치는 실제 시스템의 설계 및 성능 예측에 중요한 기술적 데이터를 제공하며, 특히 실측이 곤란한 측정 면에서의 빛의 경로 해석에 유용하게 적용될 수 있다.

• Journal of the Korean Solar Energy Society
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• v.28 no.3
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• pp.27-34
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• 2008

A series of outdoor tests were conducted on a fiber optic solar concentrator system for its performance on daylighting. The system is comprised of four main components - a parabolic dish reflector, a convex mirror, a homogenizer tube and an optical fiber cable. Results show that the system could be successfully applied for indoor lighting if some improvements are made for light transmiting (optical) cables. A maximum concentration ratio of 90 was observed delivering the illuminance of 4,800 lux at a distance of 1.2m from the diffuser for the outdoor illuminance of 102,100 lux.

• Journal of the Korean Solar Energy Society
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• v.37 no.1
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• pp.39-45
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• 2017

This paper presents the effect of solar collectors on the performance of solar tracking daylighting systems. A series of measurements were made for two different types of solar collectors mounted on double axis solar trackers: Parabolic dish concentrator and Fresnel Lens. Indoor light levels were measured at different locations of an office space (longitude: 126.33 E, latitude 33.45 N) as photo sensors were placed on a task plane 80 cm above the floor. To accurately monitor the applicability of the systems, measurements were performed under clear and overcast sky conditions with the roll-screen (on the south window) in the down position. Comparing the illuminance data, the system with Fresnel lens outperformed that of parabolic dish concentrator. On clear days, the former delivered the light levels of 400~600 lux on the task plane whereas the latter recorded 100~200 lux. Depending on the amount of cloud cover, on overcast days, illuminance readings fluctuated to some extent.

• Bulletin of the Korea Photovoltaic Society
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• v.2 no.2
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• pp.21-28
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• 2016

3족과 5족 물질로 구성된 III-V 고효율 화합물 태양전지는 태양광 스펙트럼에 대한 많은 파장영역대의 빛을 흡수할 수 있는 장점을 갖고 있어 지구상에서 만든 태양전지 중 가장 효율이 높다. 그러나, III-V 화합물 물질은 실리콘 보다 고가의 비용이 들므로 이를 극복하기 위해서 집광렌즈 및 빛을 추적하기 위한 추적기 등 집광시스템으로 구성되어야 한다. 본고에서는 고효율의 III-V 화합물 태양전지의 현재 기술개발동향 및 고효율 저가화를 위한 방안으로 기판재활용 기술, 태양광 태양열 복합활용 시스템 및 소형집광모듈 등을 소개하고자 한다.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.1
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• pp.49-56
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• 2014

In this study, the generation efficiency of the limited area of a concentrator solar cell was increased by using a solar concentrator and a tracking device. Heat generated by the solar cell was collected using a thermal absorber for supplying hot water or heating. Thus, the concentrator solar cell system provided electricity and heat simultaneously. Tracking of the sun by detecting the sun's position, repositioning of heating device towards the east after sunset, and shutting down of system after sunset were successfully implemented using an illuminance sensor (CdS) and Simulink, a commercial software package. We performed parametric analysis of the velocity, fin installation, and entrance location with respect to the operating temperature of the concentrator solar cell. A heat transfer simulation model was developed for comparing the actual temperature profiles of the concentrator solar cell and thermal absorber, and good agreement was found between the results of the simulations and the experiments.