• Journal of Korean Society on Water Environment
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• v.26 no.3
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• pp.439-445
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• 2010

An emergy analysis of the main energy flows driving the economy of humans and life support systems consists of environmental energies, fuels, and imports, all expressed as solar emjoules. Total emergy use (371 E20 sej/yr) of the Western Nakdong River Basin is 97 per cent from imported sources, fuels and goods and services. Emergy flows from the environment such as rain and geological uplift flux accounted for only 2.9 percent of total emergy use. Emergy yield ratio and environment loading ratio were 1.03 and 33.27, respectively. Emergy sustainability index, a ratio of emergy yield ratio to environment loading ratio, is therefore less than one, which is indicative of highly developed consumer oriented economies. It is necessary for an efficient management of Western Nakdong River Basin to reduce pollution load basically and to restructure economic activities into an environmental friendly industrial structure depending on renewable energy and resources.

• Journal of the Korean Electrochemical Society
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• v.15 no.3
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• pp.124-134
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• 2012

Environmental concerns over the use of fossil fuels and their resource constraints have spurred increasing interest of renewable energy, and the needs for energy storage from the renewable resources is getting rapidly increase. Na/$NiCl_2$ cell could be use electric vehicles as well as energy storage, because it has a high energy-efficiency, environmental-friendly, low cost. However, there remain several issues on improvement of materials, component, cell design, and process, to use in broad applications and to penetrate to market. This paper offers a comprehensive review on R&D status of the structure, chemistry, key materials, and cell design & manufacture for Na/$NiCl_2$ cells.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.6
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• pp.908-914
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• 2008

The world is facing a serious energy problem which destroying the environment. In addition, fossil fuel such as oil and coal that caused global warming and the environmental problems due to acid rain had been gradually exhausted. To solve this problem that has crisis of energy, it is necessary time and effort for research and development of renewable energy in the future. As alternative energy, small hydropower generation which has output of less or equal to 100kW is attracting considerable attention. This is because of its small, simple, renewable, and large amount of energy resources. By using a small hydropower generator of which main concept is based on using the different water pressure levels in pipe lines, energy which was initially wasted by use reducing of a valve at the end of the pipeline, is collected by turbine in the small hydropower generator. In this study, we investigated the influence of the number of runner vanes on the characteristics of tubular-type hydroturbine.

• New & Renewable Energy
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• v.3 no.3
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• pp.36-44
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• 2007

Most airfoils for wind turbines commercially available have been developed for aircrafts, which are operated at high Reynolds numbers. However, Reynolds numbers of wind turbines are very low compared to those of aircrafts. In other to improve wind turbine performances, airfoils for the use of wind turbine shall be designed such as S-series airfoils developed by NREL in America. The authors have designed new airfoils for wind turbines considering designated operation conditions of wind turbines and even local wind resources in Korea. The designed airfoils are characterized by improved roughness insensitivities compared to other airfoils such as S814 and S820. The developed KWA005-240 and KWA009-127 are for root and tip sections of a wind turbine blade, respectively. Although the results show much improved performances against NACA airfoils, performance data of post-stall regulation loses some accuracies due to the characteristics of the simulation tool of XFOIL. Therefore, wind tunnel experiments are required for more accurate evaluation of the designed airfoils. Currently, the experiments has been completed and the data analysis works are going on now. The final results obtained from the experiments will be published soon.

• New & Renewable Energy
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• v.7 no.1
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• pp.15-21
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• 2011

In recent years, many countries have been endeavoring to exploit the offshore wind energy in terms of overcoming the limitations of on-land wind energy. Considering that mountains cover 70 percent of the Korean Peninsula and arable plains for wind energy are negligibly small, Korean government aggressively drives the offshore wind development of the Korean Peninsula. As part of preliminary investigation of offshore wind resources, KEPCO-RI (Korea Electric Power Corporation-Research Institute) has been analyzing marine buoy datasets measured at 5 positions over the period of 12 years, including estimation of extreme wind speed. It can be observed that variation of yearly wind speed, monthly wind speed as well as frequency distribution of wind direction. Wind classes of buoy sites are estimated by extrapolated average wind speed using log law. In addition, wind turbine class based on IEC code is assessed for evaluation of suitable wind turbine.

• New & Renewable Energy
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• v.9 no.1
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• pp.60-68
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• 2013

In recent years, green house effect related natural disasters occur throughout the world. Carbon dioxide, mainly comes from the fossil fuel burning, is suspected to be the cause of green house effect. To reduce the emission of carbon dioxide, we need to find alternative energy resources such as photovoltaic energy. In this paper, the basic characteristics of wind force coefficient on a PV panel installed on the floating type PV energy generation system are investigated though the two-dimensional wind tunnel tests. Test variables included the angle of PV panel, direction of wind, number of rows of PV panel and attached or not attached frame. Based on the results obtained through the wind tunnel tests, it was found that the wind force coefficient can be used as a preliminary data in the design of the structure.

• Architectural research
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• v.20 no.3
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• pp.93-102
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• 2018

With the change in Earth's ecosystems due to climate change, a number of studies on zero energy buildings have been conducted globally, due to the depletion of energy and resources. However, most studies have concentrated on residential and office buildings and the performance predictions were made only in the design phase. This study verifies the zero-energy performance in the operational phase by acquiring and analyzing data after the completion of an exhibition building. This building was a retention building, in which a renewable energy system using a passive house building envelope, solar photovoltaic power generation panels, as well as fuel cells were adopted to minimize the maintenance cost for future energy-zero operations. In addition, the energy performance of the building was predicted through prior simulations, and this was compared with actual measured values to evaluate the energy performance of the actual operational records quantitatively. The energy independence rate during the measurement period of the target building was 123% and the carbon reduction due to the energy production on the site was 408.07 tons. The carbon reduction exceeded the carbon emission (331.5 tons), which verified the carbon zero and zero-energy performances.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.8
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• pp.856-862
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• 2015

Tidal current energy is an important alternative energy resource among the various ocean energy resources available. The tidal currents in the South-Western sea of Korea can be utilized for the development of tidal current power generation. Tidal power generation can be beneficial for many fishing nurseries and nearby islands in the southwest region of Korea. Moreover, tidal power generation is necessary for promoting energy self-sufficient islands. As tidal currents are always available, power generation is predictable; thus, tidal power is a reliable renewable energy resource. The selection of an appropriate hydrofoil is important for designing a tidal current turbine. This study concentrates on the selection and numerical analysis of four different hydrofoils (MNU26, NACA63421, DU91_W2_250, and DU93_W_210LM). Blade element momentum theory is used for configuring the design of a 50 W class turbine rotor blade. The optimized blade geometry is used for computational fluid dynamics (CFD) analysis with hexahedral numerical grids. Among the four blades, NACA63421 blade showed the maximum power coefficient of 0.45 at a tip speed ratio of 6. CFD analysis is used to investigate the power coefficient, pressure coefficient, and streamline distribution of a 50 W class horizontal axis tidal current turbine for different hydrofoils.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.159.1-159.1
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• 2011

Due to the global warming, the need to secure the alternative resources has become more important worldwide. Having very strong current on the west coast with up to 10 m tidal range, there are many suitable sites for the application of TCP(Tidal current power) in Korea. Not only from the current produced from the high tidal range, but also it can be widely applied to the offshore jetties and piers. The VAT(Vertical axis turbine) system could be very effective tidal device to extract the energies from the attacking flow to the structures. For the relatively slow current speed, the VAT system could be more effective application than HAT(Horizontal axis turbine) device. The performance of VAT can be evaluated by various parameters including number of blades, shape, sectional size, diameters and etc. The paper introduces the multi-layer vertical axis tidal current power system with savonius turbine. The turbine was designed with consideration of optimal blade numbers and the performance was simulated by CFD analysis.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.22 no.7
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• pp.474-481
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• 2010

Because international environmental and energy problems such as global warming and ozone depletion, exhausting of fossil energy sources are more serious than before, renewable energy system is attracting people's attention more and more. Organic waste bioenergy system among a variety of renewable energy system is expected to have an effect on building a society which is eco-friendly and recycles resources owing to carbon neutral effects. So this is considered as the role of an energy source of the building. Previous studies on the organic waste bioenergy are mainly bioenergy technology and activation plan of the bioenergy supply. But the performance evaluation studies of bioenergy systems installed in buildings are rarely. This study is to evaluate applicability of the organic waste bioenergy system as the building energy supply system by energy and environmental, economical analysis.