• International Journal of Aeronautical and Space Sciences
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• v.17 no.4
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• pp.631-640
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• 2016

A dual-mode power management for a hybrid-electric UAV with a cruise power of 200W is proposed and empirically verified. The subject vehicle is a low-speed long-endurance UAV powered by a solar cell, a fuel cell, and a battery pack, which operate in the same voltage bounds. These power sources of different operational characteristics can be managed in two different methods: passive management and active management. This study proposes a new power management system named PMS2, which employs a bypass circuit to control the individual power sources. The PMS2 normally operates in active mode, and the bypass circuit converts the system into passive mode when necessary. The output characteristics of the hybrid system with the PMS2 are investigated under simulated failures in the power sources and the conversion of the power management methods. The investigation also provides quantitative comparisons of efficiencies of the system under the two distinct power management modes. In the case of the solar cell, the efficiency difference between the active and the passive management is shown to be 0.34% when the SOC of the battery is between 25-65%. However, if the SOC is out of this given range, i.e. when the SOC is at 90%, using active management displays an improved efficiency of 6.9%. In the case of the fuel cell, the efficiency of 55% is shown for both active and passive managements, indicating negligible differences.

• Journal of Sensor Science and Technology
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• v.23 no.4
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• pp.238-244
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• 2014

In this paper, we introduce a new passive transponder that operates without external power in a visible light identification system. The transponder consists of a solar cell, a photodiode, a microprocessor, and a visible LED. When a reader sends light to the transponder, the solar cell generates current from the reader light and supplies power to the other elements in the transponder. At the same time, the photodiode detects the pulse in the reader light and initiates a microprocessor to generate and send a responding light to the reader. In experiments, we realized a passive transponder using a solar cell that operated at a distance of 1m without external power.

• Solar Energy
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• v.11 no.3
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• pp.37-43
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• 1991

Following the oil crisis in 1979, there have been surge of movements by the government in Korea to conserve petroleum-based energy in every sector of society. One of these movements was the application of passive solar technologies into the construction of school buildings. Various passive designs are developed paying special regard to architectural and climatic factors. This paper is related to the application of the passive solar technology(direct gain system) to high school buildings.

• Journal of the Korean Solar Energy Society
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• v.35 no.2
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• pp.85-91
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• 2015

In this study, energy performance analysis of houses in zero energy demonstration town(ZeT) was carried out using the monitoring results. This ZeT was composed 29 zero energy individual houses(ZeH) which were applied passive as well as active technologies. The results are as follows. (1) Residents are generally considered to have been lacking basic mind to save energy, (2) In particular, average yearly total energy consumption per house is 12,834 kWh and specific heating energy is $53.2kWh/m^2{\cdot}yr$ which is higher than that of passive house. This is because of one of the reason just pointed out in subsection (1). (3) Most part of the residual energy load are supplied with only renewable energy, but not operating energy for geothermal heat pump which is use of cheap electricity.

• Journal of Sensor Science and Technology
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• v.25 no.5
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• pp.337-343
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• 2016

In this paper, we newly introduce a wireless identification system using a solar cell and RF transceivers. The reader sends interrogating signal to a transponder using LED visible light, and the transponder responds to the reader using RF signal. The transponder consists of a solar cell, an amplifier, a microprocessor, and an RF transmitter. The solar cell receives the visible light from the reader and generates current to supply electric power to the other devices in the transponder. At the same time, the solar cell detects interrogating signal in the reader light. The microprocessor senses the interrogating signal and generates a responding signal. The RF transmitter radiates the responding signal to the reader. The transponder is a passive circuit because it operates without external power. In experiments, the maximum read distance between a reader and a transponder was about 1.6 meter.

• Journal of the Korean Solar Energy Society
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• v.32 no.2
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• pp.42-49
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• 2012

In this article, the author carried out a theoretical study on the application techniques of a new Combined Passive Solar System (hereinafter referred to as the CPSS) of direct gain and trombe walls to get quick morning heating and to prevent afternoon overheating for office building. The numerical model proposed in this study can be used for the performance analysis of the CPSS in the winter and summer. Heating and Cooling loads are analysed for building energy consumption reduction using this numerical model. The results indicate that CPSS in the winter and summer modes could provide profitable conditions for improvement of indoor thermal comfort control and energy saving. consequently, the application of CPSS will not lead to significant reductions in the auxiliary air conditioning demand but also realize the environmentally friendly building.

• Journal of the Korean Solar Energy Society
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• v.31 no.4
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• pp.66-71
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• 2011

This study focused on the application of the Passive Solar Chamber System (PSCS) as proposed by a previous study. The seasonal performance and sizing method for the system were investigated for a feasibility of the PSCS in Korean climate. For seasonal performance, heat and ventilation performances of the PSCS were analyzed for the months of January and August. This study proposed a simple configuration method in which the designer can decide on the system size at the preliminary design stage by using system efficiency, overall heat transfer coefficient transmission, monthly solar radiation, highest and lowest temperatures. During weeks that require heating, the system showed to acquire a daily average heat amount of $860.28Wh/m^2$ day. For cooling periods, the system was computed to supply a daily average natural ventilation of $1,360.2m^3/day$ to the room. Moreover, proposed sizing method and the overall computation results showed a 6.04~7.24% error of assessment.

• Solar Energy
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• v.12 no.2
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• pp.51-61
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• 1992

A numerical study on the Trombe wall system, a kind of passive solar systems, has been peformed. The system is modelled as the 2-dimensional steady laminar flow with the natural convection. The PHOENICS code was employed to analyse the performance variation due to the change in the geometrical factor. The mass flow rate and the maximum temperature are changed by the variations in the width of the vents, the width between the window and the wall, and the location of the vents. And there exists the optimal condition to maximize the utilization factor. Further precise analysis has been performed to show the optimal geometry with regard to the above three factors.

• Solar Energy
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• v.7 no.1
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• pp.3-13
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• 1987

A batch type passive solar water systems, which perform the dual function of absorbing the solar energy and storing the heated water, have been designed and fabricated for the purpose of side-by-side testing at KIER. The test models included an A, B and C type batch systems which were classified according to the design of box and arrangement of tanks. The year-round performance tests show that B type batch system taken the step-wise tank arrangement indicates 55.7% yearly-average collection efficiency factor and 61% yearly-average maximum collection efficiency factor. Computer-aided-experimental results show that the sufficient hot water can be obtained in the early morning if the glazing is supplemented by a reflector/insulation cover. The thermal performance equation has been developed for the prediction of hourly variation of the water temperature in tank.

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.416-421
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• 2005

Most of solar system dissemination has been focused on domestic hot water system of which utilization to a building is relatively simple and safe than solar heating system. Through the survey on a cause of solar house dissemination failure in Korea, we conclude that design integration and systematic approach method for technology application are the most important element for a successful solar house. KIER(Korea Institute of Energy Research) and Hanbat National University have started new project on a development of Zero energy Solar House, called ZeSH which can be sustained just by natural energy without the support of existing fossil fuel. This is the 1st phase research of 10 years long-term ZeSH plan which develops a low-cost and $100\%$ self sufficient ZeSH. The goal of 1st phase ZeSH research is to get a $70\%$ self sufficiency only in thermal loads. Actual demonstration house, named KIER ZeSH I was designed and constructed as a result of 1st phase research work in the end of 2002. Various innovative technologies such as super insulation, high performance window, passive and active solar systems, ventilation heat recovery system are applied and evaluated to the KIER ZeSH I. A lot of computer simulations had been conducted for the optimal design and system integration in every design steps. Considering all the results from detailed hourly computer simulation, it is expected that at least $70\%$ self-sufficiency in thermal loads which is 1st phase target value can be excessively achieved in actual demonstration house. Besides, many valuable findings from the design and analysis to construction could be established such as collaboration method among the participants, practical design and construction techniques for system integration and the others. The purpose of this paper is to introduce the main findings through the development of KIER ZeSH I project. Practical guidelines in every design step for new low- or zero- energy solar house is proposed as result.