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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
Journal of the Korean society for New and Renewable Energy
Journal Basic Information
Journal DOI :
The Korean Society for New and Renewable Energy
Editor in Chief :
Volume & Issues
Volume 8, Issue 4 - Dec 2012
Volume 8, Issue 3 - Sep 2012
Volume 8, Issue 2 - Jun 2012
Volume 8, Issue 1 - Mar 2012
Selecting the target year
Design and Performance Evaluation of the Savonius Tidal Current Turbine
Jo, Chul-Hee ; Ko, Kwang-Oh ; Lee, Jun-Ho ; Lee, Kang-Hee ;
Journal of the Korean society for New and Renewable Energy, volume 8, issue 2, 2012, Pages 6~13
DOI : 10.7849/ksnre.2012.8.2.006
Due to global warming, the need to secure an alternative resource has become more important nationally. Having very strong current on the west coast with up to 10 m tidal range, there are many suitable site for the application of TCP (Tidal Current Power) in Korea. On the south west regions between many islands that create strong current in the narrow channels. The rotor is one of the essential components which can convert tidal current energy into rotational energy to generate electricity. The design optimization of rotor is very important to maximize the power production. The performance of rotor can be determined by various parameters including number of blades, shape, sectional size, diameters and etc. This paper introduces the multi-layer vertical axis tidal current power system which can be applied to offshore jetties and piers effectively. Various cases of VAT turbine were designed. Specifically, the number of blades and turbine shape are changed in several cases. Also, performance analysis was carried out by CFD.
The Generation of Typical Meteorological Year for Research of the Solar Energy on the Korean Peninsula
Jee, Joon-Bum ; Lee, Seung-Woo ; Choi, Young-Jean ; Lee, Kyu-Tae ;
Journal of the Korean society for New and Renewable Energy, volume 8, issue 2, 2012, Pages 14~23
DOI : 10.7849/ksnre.2012.8.2.014
The TMY (Typical Meteorological Year) for the solar energy study is generated using observation data with 22 solar sites from KMA (Korea Meteorological Administration) during 11 years (2000-2010). The meteorological data for calculation the TMY are used solar radiation, temperature, dew point temperature, wind speed and humidity data. And the TMY is calculated to apply the FS (Finkelstein and Schafer) statistics and RMSE (Root Mean Squared Error) methods. FS statistics performed with each point and each variable and then selected top five candidate TMM months with statistical analysis and normalization. Finally TMY is generated to select the highest TMM score with evaluation the average errors for the 22 whole points. The TMY data is represented average state and long time variations with 22 sites and meteorological data. When TMY validated with the 11-year daily solar radiation data, the correlation coefficient was about 0.40 and the highest value is 0.57 in April and the lowest value is 0.23 in May. Mean monthly solar radiation of TMY is 411.72 MJ which is 4 MJ higher than original data. Average correlation coefficient is 0.71, the lowest correlation is 0.43 in May and the highest correlation is 0.90 in January. Accumulated annual solar radiation by TMY have higher value in south coast and southwestern region and have relatively low in middle regions. And also, differences between TMY and 11-year mean of is distributed lower 100 MJ in Kyeongbuk, higher 200 MJ in Jeju and higher 125 MJ in Jeonbuk and Jeonnam, respectively.
A Comparative Study on the Formation of Methane Hydrate Using Natural Zeolite and Synthetic Zeolite 5A
Park, Sung-Seek ; Park, Yun-Beom ; Kim, Nam-Jin ;
Journal of the Korean society for New and Renewable Energy, volume 8, issue 2, 2012, Pages 24~32
DOI : 10.7849/ksnre.2012.8.2.024
Natural gas hydrates have a high potential as the 21st century new energy resource, because it have a large amount of deposits in many deep-water and permafrost regions of the world widely. Natural gas hydrate is formed by physical binding between water molecule and gas mainly composed of methane, which is captured in the cavities of water molecules under the specific temperature and pressure.
methane hydrate can be decomposed to the methane gas of
and water of
at standard condition. Therefore, there are a lot of practical applications such as separation processes, natural gas storage transportation and carbon dioxide sequestration. For the industrial utilization of methane hydrate, it is very important to rapidly manufacture hydrate. However, when methane hydrate is artificially formed, its reaction time may be too long and the gas consumption in water becomes relatively low, because the reaction rate between water and gas is low. So in this study, hydrate formation was experimented by adding natural zeolite and Synthetic zeolite 5A in distilled water, respectively. The results show that when the Synthetic zeolite 5A of 0.01 wt% was, the amount of gas consumed during the formation of methane hydrate was higher than that in the natural zeolite. Also, the natural zeolite and Synthetic zeolite 5A decreased the hydrate formation time to a greater extent than the distilled water at the same subcooling temperature.
Vertical Integration of Solar business and its Value Analysis: Efficiency or Flexibility
Kim, Kyung-Nam ; Jeon, Woo-Chan ; SonU, Suk-Ho ;
Journal of the Korean society for New and Renewable Energy, volume 8, issue 2, 2012, Pages 33~43
DOI : 10.7849/ksnre.2012.8.2.033
Why solar companies preferred vertical integration of whole value chain? Major solar companies have built internally strong vertical integration of entire PV value chain. We raise a question whether such integration increases the corporate value and whether market situation affects the result. To test these questions, we conducted multi-variant analysis where characteristic factors mainly affect the corporate value measured in terms of Tobin'Q, based on the financial and non-financial data of PV companies listed in US stock market between 2005 and 2010. We hypothesize that since integration increases the overall efficiency but decreases the flexibility to adjust to various market situation, the combined effect of the efficiency gain and the flexibility loss ultimately determines the sign of integration effect on the corporate vale. We infer that the combined effect will be influenced heavily by business cycle, as in boom market (Seller's market) the efficiency gain may be larger than the flexibility loss and vice versa in bust market. We test whether the sign of combined effect changes after the year of 2009 and which factors influence most the sign. Year of 2009 is known as the year when market shifted from Seller's to Buyer's market. We show that 1) integration increases corporate value in general but after 2009 integration significantly decreases the value, 2) the ratios such as Production/Total Cost, Cash turnover period chosen for reversal of the flexibility measure are negatively affect Tobin's Q and especially stronger after 2009. This shows the flexibility improves corporate value and stronger in the recess period (Buyer's market). These results imply that solar company should set up integration strategy considering the tradeoff between efficiency and flexibility and the impact of the business cycle on both factors. Strategy only based on the price competitiveness determined in boom time can bring undesirable outcomes to the company. In addition, Strategic alliances in some value chains as a flexible bondage should be taken in account as complementary choice to the rigid integration.
Performance Characteristics of an Axial Propeller Small-hydro Turbine with Various Cambers of Runner Blade
Byeon, Sun-Seok ; Kim, Tae-Youn ; Han, Sang-Meok ; Kim, Jeong-Hwan ; Kim, Youn-Jea ;
Journal of the Korean society for New and Renewable Energy, volume 8, issue 2, 2012, Pages 44~51
DOI : 10.7849/ksnre.2012.8.2.044
The aim of this paper is to examine the hydraulically optimized camber of a blade. Prior studies have tried to determine the sound method of design on small-hydro turbines. These have appeared to realize a reasonably efficient small-hydro turbine. Nonetheless, specific and accurate design data have not as yet been established for the shape of the runner blade. Hence, this study examines the performance characteristic of an axial propeller turbine with 0~8% camber variations. The results of output power, efficiency, and pressure distribution of the turbine are graphically depicted. The definition of camber refers to the NACA airfoil. The commercial finite element analysis (FEA) packages, ANSYS, and CFX are used in this study. The results revealed the performance characteristics on small-hydro turbine and suggested a highly efficient section shape of the runner.