• Journal of the Korean Solar Energy Society
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• v.32 no.5
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• pp.59-67
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• 2012

In this study,the compact type solar thermal and ground coupled heat pump hybrid system for space heating/cooling and hot water supply has been developed. This hybrid system was installed in Zero Energy Solar House(ZeSH) in KIER for the demonstration. The thermal performance and operational characteristics of this hybrid system were analysed especially. The results are as follows. (1) This hybrid system was designed in order to address the existing disadvantages of solar thermal/ground coupled heat pump system. For this design, all parts except solar collector and ground coupled heat pump were integrated into a single product in a factory. The compact type unit includes two buffer tanks, an expansion tank, pumps, valves, a controller, etc. This system has an advantage of easy installation with simple plumbing work even in narrow space. (2) The thermal charging and discharging time of the buffer tanks and its characteristics by ground coupled heat pump, and heat pump COP according to geo-source temperature and buffer storage temperature have been studied. This system was found to meet well to the heat load without any other auxiliary heating equipment. (3) The operating hours of the ground coupled heat pump as a backup device of solar thermal can be reduced significantly by using solar heat. It was also found that the minimum heating water supply setting temperature and maximum cooling water supply setting temperature make an influence on the heat pump COP. The lower heating water and the higher cooling water temperature, the higher COP. In this respect, the hybrid system's performance can be improved in ZeSH than conventional house.

• Current Optics and Photonics
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• v.4 no.1
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• pp.50-56
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• 2020

The design of a concentration system for a solar side-pumped slab laser was investigated. The side size of the slab laser medium is 2 mm × 20 mm. Based on the principle of the edge ray, a secondary concentrating system consisting of a rectangular parabolic mirror (RPM) and a rectangular dielectric-filled compound parabolic concentrator (RDCPC) was demonstrated. The focal length of RPM is 1200 mm and the size is 734 mm × 2000 mm. The outlet size of the RDCPC is 2 mm × 20 mm. The concentration effect was analyzed by using Tracepro optical software. The results showed that the concentration efficiency reached 81.3% and the uniformity of the spot was 91.4% after optimization. This design of concentration system is of great reference value for a solar side-pumped slab laser.

• Proceedings of the KSME Conference
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• 2001.11b
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• pp.794-799
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• 2001

The simulation analyses of a solar power system with monolithic concentrator by using a stirling engine are carried out to predict the system performance in four test sites. The site has different intensities and distributions of direct solar radiation respectively. Seoul, Pusan and Cheju in Korea, and Naha in Japan are selected as test sites. To accomplish the same demand of a 25 kW output that the power level of a system has, it needs to take the matching of collector/receiver with engine/generator systems. In such a case, also, the size of the collector is sometimes adjusted. In this study, the diameter of the collector is decided by using the solar radiation of design point, which is defined as the sum of average and standard deviation $\sigma$ of maximum direct solar radiation distribution for a day during a year in the respective test site. It is found that the average power output during the system operating time in the case of slope error ${\sigma}_s=2.5$ is within the range of 9 to 13 kW.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.22 no.12
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• pp.859-866
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• 2010

This study examined the economics of a solar water heating system for an office building using life cycle cost (LCC) optimization simulations. The numerical simulations were conducted with TRNSYS and GenOpt employing the Hooke-Jeeves algorithm. The solar collector area, slope, mass flow rate per collector area and storage tank volume were selected as the main design parameters of the solar water heating system. The LCC optimization simulations of the system were carried out for cases where water temperature was $60^{\circ}C$ and $50^{\circ}C$. The results showed that for water temperature at $60^{\circ}C$ and $50^{\circ}C$ the collector area could be decreased by 17% and 28%, storage tank volume could be decreased by 49% and 54%, and mass flow rate per collector area increased by 5% and 9% respectively compared to a non-optimized system. The LCC of the system was reduced by 4% for $60^{\circ}C$ and 7% for $50^{\circ}C$. The initial installation cost of the system was reduced by 24% for $60^{\circ}C$ and 34% for $50^{\circ}C$. However, the operating cost of the system increased by 16% for $60^{\circ}C$ and 36% for $50^{\circ}C$ compared to a traditional solar water heating system.

• Proceedings of the KIPE Conference
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• 2009.11a
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• pp.206-208
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• 2009

In this paper, a systematical controller design method for a twostage grid-connected photovoltaic power conditioning system is proposed. For a pre-stage boost converter to achieve the stable operation in the entire region of solar array, the digital resistive current mode controller is used. This algorithm is very simple to implement with a digital controller and there is no power stage parameter dependency in the controller design. For a post-stage single-phase full-bridge inverter, a PI controller with a feedforward compensation for the inner current control is employed. Furthermore, in case that the operating point of the solar array under varying environmental conditions is higher than the required voltage for the inverter current control, the bypass mode for the boost converter is possible for the more efficient operation. The proposed control scheme is validated through the experiment of the prototype two-stage power conditioning system hardware with a 200W solar array.

• Journal of the Korean Solar Energy Society
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• v.22 no.1
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• pp.81-86
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• 2002

Solar daylighting system provides free and comfort lighting, but its design and control has been key issue due to heavy light collecting system. One of the solutions for the heavy weight issues would be using a light framed film such as fresnel and prism lens. This prototype system consists of light collector, light transformer and light guide luminaire. The light collector which is installed at window or the rooftop concentrates solar light, the collected beam is converted to suitable light by the light transformer. and the prism light guide luminaire has been used to distribute light emitted from light transformer for illumination. In this paper, the design concept and performance of light collector in this prototype system are presented.

• Journal of Korea Society of Digital Industry and Information Management
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• v.12 no.2
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• pp.1-6
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• 2016

Several efforts to replace the use of existing fossil energy resources have already been made around the world. As a result, a new industry of renewable energy has been created, and efficient energy distribution and storage has been promoted intensively. Among the newly explored renewable energy sources, the most widely used one is solar energy generation, which has a high market potential. An energy storage system (ESS) is a system as required. In this paper, the design and implementation of an ESS for the efficient use of power in stand-alone street lights is presented. In current ESS applied to stand-alone street lights, either 12V~24V DC (from solar power) or 110V~220V AC (from commercial power) is used to recharge power in systems with lithium batteries. In this study, an ESS that can support both solar power and commercial power was designed and implemented; it can also perform emergency recharge of portable devices from solar powered street lights. This system can maximize the scalability of ESSes using lithium batteries with efficient energy conversion, with the advantage of being an eco-friendly technology. In a ripple effect, it can also be applied to smart grids, electric vehicles, and new, renewable storage markets where energy storage technology is required.

• Journal of the Korean Society of Clothing and Textiles
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• v.44 no.6
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• pp.1224-1239
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• 2020

This study develops a wearable solar energy harvesting device that absorbs solar energy to generate and store power which can be used during outdoor activities by users even after dark. For this study, a prototype hat for outdoor activities at night was developed after the design of a solar energy harvesting generation, storage, and delivery system was designed that could store energy to light up LEDs. First, the main control board of the system was designed to integrate the charging function, the darkness detection circuit, the battery voltage sensing circuit, and the LED driving circuit in order to reduce bulkiness and minimize the connection structure. It was designed to increase convenience. Second, the system was designed as a wearable fashion product that connected each part with fiber bands and manufacturing it so as to be detachable from the hat. Third, charging and LED operation tests show that the battery is fully charged after 5 hours even in winter when the illuminance value is low. In addition, the LED operation experiment verified the effectiveness of a buffered system that could operate the LEDs for about 3 hours at night.

• 한국신재생에너지학회:학술대회논문집
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• 2005.11a
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• pp.684-687
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• 2005

KIER has been running a demonstration project for 10kWe solar thermal power generation. the project is to build and operate the first solar thermal power generation system in Korea. For concentrating solar thermal energy $40m^2$ dish type concentrator was adapted and a stirling engine is going to be integrated to the system for power production. At the moment building the dish concentrator including mirror and sun tracking system was completed and it's performance are being closely evaluated. This paper will introduce some detailed designs and construction procedures which we have experienced so far.

• Solar Energy
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• v.2 no.2
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• pp.1-9
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• 1982

This paper presents a method. for estimating the useful output of solar heating sys-terns. Heating load calculations, climatic data and various conditions are used in this procedure to estimate the fraction of the monthly heating load supplied by solar energy for a particular system the design procedure presented in this paper referred to the f-chart method. The results of this study are as follows; 1) The collected energy is not rised lineary to collector area. 2) If the heating area has equivalent solar collector area, the solar energy utilization for space heating is over 90%. 3) Transmittance- absorptance product for radiation at normal incidence, (${\tau}{\alpha}$)/(${\tau}{\alpha}$)n, during most of the heating season is 0.92 for a two-cover collector. 4) Orientation of the collector has little effect on the annual performance of solar heating system within the $15^{\circ}$.