• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.54.1-54.1
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• 2011

The conventional energy-production system by burning fossil fuels releases many pollutants and carbon dioxide($CO_2$) to the environment. Therefore, many countries pay attention to new and renewable energy and invest in the development of these new technologies for the future energy security. One of the most promising of these technologies is a photovoltaic system. In this study, Life Cycle Assessment(LCA) is carried out to analyse the environmental issues(e.g. global warming, abiotic resource depletion) of CdTe photovoltaic system. The spatial and temporal scope of this study was set in Korea during 2004~2005. We assumed that CdTe photovoltaic system was installed in Mokpo where the amount of solar irradiation was higher than other places in Korea. Based on the present data and some assumptions, greenhouse gas emission was 39.2g $CO_2$-eq./kWh. Therefore the electricity produced by CdTe photovoltaic system is more environmentally friendly than the conventional power generation system.

• New & Renewable Energy
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• v.7 no.3
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• pp.74-82
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• 2011

Because concern on the problem of the limited energy is growing and the wind energy is considered as one of the biggest solutions, the researches on the wind energy and turbine are accomplished vigorously. The simulation tools on the non-linear characteristics of wind turbine system are various and it could describe the non-linear characteristics well but, the tool and methodology to apply non-linear control theory rarely exist. In this paper, the application procedure of sliding mode control theory to 2-DOF non-linear wind turbine system is suggested and the application results of it are also shown as compared with a torque loop control theory.

• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.87-90
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• 2008

Levelized generation cost(LGC) has been widely used in assessing feed-in tariffs(FiT) for electricity generating from new and renewable energies. Current FiTs for renewable electricity in Korea have been fixed and applied with realistic economic data by the efforts of KERI(Korea Electrotechnology Research Institute) since October 2006. Some critical issues on the estimation of LGC are, however, found in KERI's report. Major issues are the estimation of capital cost, the consideration of corporate tax, and the application of economic life cycle in the formulae for LGC. These critical issues are examined and interpreted in a correct way in this paper.

• New & Renewable Energy
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• v.3 no.4
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• pp.22-30
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• 2007

An expansion device plays an important role in optimizing the heat pumps by controlling refrigerant flow and balancing the system pressures. Conventional expansion devices are being gradually replaced with electronic expansion valves due to increasing focus on comfort, energy conservation, and application of a variable speed compressor. In addition, the amount of refrigerant charge in a heat pump is another primary parameter influencing system performance. In this study, the flow characteristics of the expansion devices are analyzed, and the effects of refrigerant charge amount on the performance of the heat pump and the variation of compressor speed are investigated at various operating conditions. Mass flow rate through capillary tube, short tube orifice, and EEV was strongly dependent on the upstream pressure and subcooling. The heat pump system is very sensitive with a variation of refrigerant charge amount. The performance of it can be optimized by adjusting the flow rate through expansion device to maintain a constant superheat at all test conditions.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.26 no.7
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• pp.30-38
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• 2012

Recently, interests in renewable energy have gradually increased. Photovoltaic system of various renewable energy is the most interest in power sources. Nowadays, the market of photovoltaic system is expected to be expanded due to the introduction of RPS(Renewable Portfolio Standard). Floating photovoltaic system is a new power system using the water surface above the dam and reservoir water. Floating photovoltaic system is different from the traditional approach to the development of solar power system causing problems such as environmental degradation. This paper investigates the analysis methods of suitable site for the development of floating photovoltaic system. The A,B,C as the optimal candidates were selected in hap cheon dam. The C is the best suitable site in A,B,C considering the expected power generation. Applied methods have effectively done to develop floated photovoltaic system.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.29 no.8
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• pp.391-400
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• 2017

Understanding of seawater fouling characteristics is critical in designing a heat exchanger adapted in an effluent utilization system for a power plant. We reviewed three types of fouling mechanisms of general, biological, and crystallizing for a plate-frame heat exchanger, to be used for heat exchanging with heated effluent from a power plant. Also, mathematical models for each type of seawater fouling were suggested. Actual thermal resistance calculated from seawater fouling models were compared and implemented in designing a plate-frame heat exchanger. The bio-fouling model revealed the largest thermal resistance and the highest number of plates for a plate-frame heat exchanger under the same heat load. Overall heat transfer coefficient and pressure drop of a plate-frame heat exchanger under fouling conditions was lower by 58 percent and higher by 2.85 times than those under clean conditions, respectively.

• New & Renewable Energy
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• v.19 no.4
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• pp.61-71
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• 2023

The necessity of energy utilization using livestock manure has been proposed with the decrease in domestic agricultural land. Livestock manure solid fuel has been investigated as a promising energy resource owing to its convenient storage and use in agricultural and livestock fields. Additional electricity production is possible through the integration of a biomass combustion boiler with the organic Rankine cycle (ORC). In this study, a mathematical system model of the cattle manure solid fuel boiler integrated with the ORC was developed to analyze the components' performance under variable operating conditions. A sensitivity analysis was conducted to confirm the electrical efficiency of the ORC turbine and the applicability of this system. The minimum required waste heat recovery rate was derived considering the system marginal price and levelized cost of electricity of the ORC. The simulation results showed that, in Korea, more than 77.98% of waste heat recovery and utilization in ORC turbines is required to achieve economic feasibility through ORC application.

• Journal of Advanced Marine Engineering and Technology
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• v.34 no.5
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• pp.625-631
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• 2010

Recently, the fossil energy and its related environmental problems (increase in PPM of $CO_2$) have been increased. Therefore, the interests on new and renewable energy have been increased as the one of the future industrial leading items. Among the renewable energy, the PV (Photo-Volatic) systems has particular merit at the electricity can be directly acquired from the sun. Usually in PV systems, the ambient temperature and air velocity have strongly related on the effect of power generation of PV panel. So the purpose of this study is to clarify relationships between power generation of PV panel and outer environmental factors like temperature and air velocity. And these types of applications using natural energy are strongly affected by the climate conditions. Therefore the data of this study were re-arranged in terms of non-dimensional correlations.

• New & Renewable Energy
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• v.5 no.2
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• pp.3-8
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• 2009

Tidal current power system is one of ocean renewable energies that can minimize the environmental impact with many advantages compared to other energy sources. Not like others, the produced energy can be precisely predicted without weather conditions and also the operation rate is very high. To convert the current into power, the first device encountered to the incoming flow is the rotor that can transform into rotational energy. The performance of rotor can be determined by various design parameters including numbers of blade, sectional shape, diameter, and etc. The stream lines near the rotating rotor is very complex and the interference effects around the system is also difficult to predict. The paper introduces the experiment of rotor performance and also the fundamental study on the characteristics of three different rotors and flow near the rotor by CFD.

• Proceeding of Spring/Autumn Annual Conference of KHA
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• 2005.11a
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• pp.327-330
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• 2005

Today, the need for alternative energy has increased due to the global environmental problems and energy depletion. In order to solve a global environmental matter and an energy issue simultaneously, the application of the renewable energies in building has been constantly demanded. therefore, we must develop new energy resources that are abundant and provide substitutes for fossil fuels and we must study the application method of the renewable energies in building. Among renewable energies, the solar energy(photovoltaic system) is clean, inexhaustible, and available everywhere in the world and is judged to have the application possibility in building. Daegu city has a plan of putting a photovoltaic system on large buildings. For instance, EXCO, exhibition and convention building, and dormitory in Kyungpook National University, Dongho elementary school, Osan building in Keimyung University, Young korea academy in Daegu, are on the process of having a photovoltaic system. Therefore a study on the performance of photovoltaic system is important for the system design and maintenance. this paper describes the first invest cost, and performance test of the 95kW utility-interactive photovoltaic power system.