• ETRI Journal
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• v.45 no.3
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• pp.519-533
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• 2023

This paper implements a simultaneous solar and thermal energy harvesting system, as a hybrid energy harvesting (HEH) system, to convert ambient light into electrical energy through photovoltaic (PV) cells and heat absorbed in the body of PV cells. Indeed, a solar panel equipped with serially connected thermoelectric generators not only converts the incoming light into electricity but also takes advantage of heat emanating from the light. In a conventional HEH system, the diode block is used to provide the path for the input source with the highest value. In this scheme, at each time, only one source can be handled to generate its output, while other sources are blocked. To handle this challenge of combining resources in HEH systems, this paper proposes a method for collecting all incoming energies and conveying its summation to the load via the current mirror cells in an approach similar to the maximum power point tracking. This technique is implemented using off-the-shelf components. The measurement results show that the proposed method is a realistic approach for supplying electrical energy to wireless sensor nodes and low-power electronics.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1993.05a
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• pp.64-69
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• 1993

The solar energy collection of a passive solar system depends on the finish of collecting surfaces. In this study, the test models of T.W system with different wall surface finishes were constructed, and the temperature distribution through the models was monitored. At the same time, a computer program based on F.D.M was developed in order to simulate various surface finishes. The difference of indoor temperature between the model with white color finish ($\alpha$=0.25) and the one with black color finish ($\alpha$=0.95) was about 1$0^{\circ}C$. For the wall with selective coating, the indoor temperature was 4-5$^{\circ}C$ higher than that of red brick wall, and 3-4$^{\circ}C$ higher than that of wall with black paint.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.129.2-129.2
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• 2011

Knowledge of the detailed solar radiation components are essential for modeling many solar systems. This is particularly the case for applications that concentrate the incident energy to attain high photo-dynamic efficiency achievable only at the higher intensities. In order to estimate the performance of concentrating solar systems, it is necessary to know the intensity of the beam radiation, as only this component can be concentrated. The Korea Institute of Energy Research(KIER) has began collecting detailed solar radiation component data since August, 1988. KIER's component data will be extensively used by solar system users or designers as well as by research institutes.

• Solar Energy
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• v.6 no.1
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• pp.70-76
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• 1986

Since the solar radiation is the main input for sizing any solar system, it will be necessary to understand and evaluate the insolation data. The Korea Institute of Energy and Resources (KIER) has began collecting horizontal insolation data since May, 1982 at 15 different locations. Because of a poor reliability of existing data, KIER's new data will be extensively used by the solar system users as well as by research institutes. Among some significant results, we obtained the good results more than we had expected, it is very encouraging that the mean value of Korea's solar radiation is increased by more than 30%.

• Journal of the Korean Solar Energy Society
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• v.23 no.4
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• pp.11-20
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• 2003

This study aims to develop the program for active solar heating system design & analysis. The program, named ASOLis, is consisted of three user's interface like as system input/output, library, and utilities and used TRNSYS as a calculation engine for the system analysis. ASOLis simplifies user's input data through the database and can design 37 different types of solar systems. Solar system is configurated by two separated parts "solar thermal collecting part" and "load supplying part". Due to the user-friendly layout, all design parameters can be changed quickly and easily for the influence on system efficiency. For the reliability, ASOLis compared with experimental result. As a result, ASOLis is expected to be used as a vital tool for the design and analysis of active solar heating system.

• Environmental and Resource Economics Review
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• v.11 no.4
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• pp.633-657
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• 2002

This study presents a demand modelling for landfill gas, which is used as alternative energy source for district cooling business. By analyzing the cost minimizing behavior of producer facing with three alternative energy sources such as electricity, cooling heat water, and gas, a demand function for landfill gas is derived from the optimal operating time of gas fired production facility, and estimated using unpublished data, which are associated with Seoul city's development plan for Sang-am area. The estimation results repeals that Seoul City could supply the land-fill gas of 13.76 million cubic meters each year at the price of about 16 won per cubic meters. However, if the investment costs associated with installation of gas collecting facilities are treated as sunk costs, annual amount of gas supplied is expected to increase to 14.22 million cubic meters at a lower unit price of 14.76 won.

• Journal of the Korean Solar Energy Society
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• v.25 no.1
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• pp.11-18
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• 2005

Since the direct normal insolation is a main factor for designing any solar thermal power system, it is necessary to evaluate its characteristics all over the country. We have begun collecting direct normal insolation data since December 1990 at 16 different locations and considerable effort has been made for constructing a standard value from measured data at each station. KIER(Korea Institute of Energy Research's new data will be extensively used by solar thermal concentrating system users or designers as well as by research institutes. From the results, we can conclude that 1) Yearly mean $5.4kWh/m^2/day$ of the direct normal insolation was evaluated for clear day all over 16 areas in Korea. 2) Clear day's direct normal insolation of spring and summer were $5.53kWh/m^2/day$ and $5.84kWh/m^2/day$, and for fall and winter their values were $5.3kWh/m^2/day$ and $4.94kWh/m^2/day$ respectively. So, spring and summer were higher, and fall and winter were lower than the yearly mean value.

• Journal of Hydrogen and New Energy
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• v.26 no.6
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• pp.554-559
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• 2015

Single cell of PEMFC (polymer electrolyte membrane fuel cell) is composed of bipolar plates, gasket, GDL and the MEA. Bipolar plate's function is the collecting electricity, helping oxygen/hydrogen gas diffuse evenly and draining the water and heat. In this work, we have conducted experiments to low contact resistance and improve the performance of a $25cm^2$ single cell by using metal forms. We have following experimental cases: 1) Conventional graphite serpentine channel bipolar plate; 2) Channel-less bipolar plate with nickel(Ni) based metal foam which coated by various materials. We focused the difference in contact resistance and performance of the single cell with metal foam depending on various coating materials. The experimental results show the similar performance of single cells between with serpentine channel bipolar plates and with channel-less bipolar plate using metal foams. In addition, single cell with metal foam shows potential to higher performance than conventional channel.

• Journal of the Korean Society for Marine Environment & Energy
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• v.11 no.1
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• pp.35-41
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• 2008

Overtopping wave energy convertor is an offshore wave energy convertor for collecting the overtopping waves converting the water pressure head into electric power through the hydro turbines. This paper presents a numerical wave tank based on the commercial CFD code Fluent. The Reynolds Averaged Naiver-Stokes and VOF model is utilized to generate the 2D numerical linear propagating waves, which has been validated by the analytical solutions. Several incident wave conditions and shape parameters are calculated in the optimal designing investigation of the overtopping characteristics and discharge for the overtopping wave energy convertor.

• Journal of the Semiconductor & Display Technology
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• v.14 no.2
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• pp.17-22
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• 2015

In recent years, wireless sensor networks have become an important part of data communications. Sensors provide information about the required measurements or control states over wireless networks. The energy efficient routing protocol of wireless sensor networks is the key issue for network lifetimes. The routing protocol must ensure that connectivity in a network is remained for a long period of time and the energy status of the sensor in the entire network must be in the same level in order not to leave the network with a wide difference in the energy consumptions of the sensors. In this paper we propose a new routing protocol based on AODV protocol that considers the energy efficiency when the protocol determines the routing paths, which is called AODV-EE. The proposed method prevents an imbalance of power consumption in sensors of wireless networks. From the simulation results it is shown that the proposed algorithm can be effectively used in collecting and monitoring data without concerning about the disconnection of the networks.