• Journal of the Korean Solar Energy Society
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• v.28 no.3
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• pp.45-52
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• 2008

In order to clarify characteristics of variation in wind energy over a long-term period, an investigation was carried out at Seoguang site on Jeju island. The wind data for 10 years from Automatic Weather System (AWS) were analyzed for each year. The variation in the annual energy production (AEP) for the 2 MW wind turbine was estimated through statistical work. The result shows that the range of the yearly average wind speed at 15 m above ground level for 10 years was from -22.6% to +13.7%, which is wider range than that in Japan. The coefficient of variation for the AEP was 22.7%, which is about twice of that for the yearly average wind speed. Therefore, for estimating the wind energy potential accurately at a given site, the wind data should be analyzed over a long-term period based on the data from the meteorological station.

• 한국신재생에너지학회:학술대회논문집
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• 2007.11a
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• pp.372-375
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• 2007

750kW gearless type wind turbine, named U50, is developed by UNISON in Korea. The newly developed wind turbine should be evaluated the power curve and the estimated annual energy production by following international standard to verify the power performance characteristics. This paper shows the test and evaluation procedure according to IEC 61400-12-1 which specifies a procedure of measuring the power performance characteristics of a single wind turbine and applies to the testing of wind turbines of all types and sized connected to the electrical power network. And this paper also shows the power performance characteristics for U50 wind turbine which is determined in accordance with IEC regulation.

• Journal of the Korean Solar Energy Society
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• v.31 no.4
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• pp.19-26
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• 2011

We are carried out power performance testing for 3MW wind turbine system at Je-ju wind turbine testing Site and analyzed measured data which was stored through monitoring system. In this paper, we described the power performance testing results and analyzed an uncertainty of measured data sets. The power curve with measured power data is closely coincide with designed power curve except for the low wind speed sections(4m/s~7m/s) and the annual energy production which is given Ray leigh distribution was included with 1.5~5.9% of uncertainty in the wind speed region as 4~11m/s. Although the deviation of curve between measured power and designed power is high, the difference of annual energy production is low in the low wind speed region.

• Journal of the Korean Solar Energy Society
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• v.29 no.2
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• pp.22-30
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• 2009

In order to clarify predictive accuracy for the wind resource predicted by running WindPRO(Ver. 2.5) which is software for wind farm design developed by EMD from Denmark, an investigation was carried out at the northeast region of Jeju island. The Hangwon, Susan and Hoichun sites of Jeju island were selected for this study. The measurement period of wind at the sites was for one year. As a result, when the sites had different energy roses, though the two Wind Statistics made by STATGEN module were used for the prediction, it was difficult to exactly predict the energy rose at a given site. On the other hand, when the two Wind Statistics were used to predict the average wind speed, the wind power density and the annual energy production, the relative error was under ${\pm}20%$ which improved more than that when using only one Wind Statistics.

• Journal of the Korean Solar Energy Society
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• v.33 no.6
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• pp.1-11
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• 2013

The investigation on wind farm design using CFD technique was carried out to reduce turbulence intensity in a wind farm. A potential wind farm in Gasiri of Jeju Island was selected for the design and the commercial S/W of Meteodyn WT was used for applying CFD technique. The initial layout of wind turbines was derived using WindPRO which is mainly used for wind farm design in Korea. Then, the distribution of turbulence intensity on complex terrain was calculated and visible by Meteodyn WT. Based on the distribution, wind turbines were positioned properly. As a result, wind turbines could be deployed at positions with minimum turbulence intensity as well as maximum Annual Energy Production, AEP, using Meteodyn WT. It is necessary to take into account turbulence intensity in wind farm design to avoid wind turbine failure.

• Journal of the Korean Solar Energy Society
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• v.35 no.3
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• pp.17-25
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• 2015

The main objective of this study is to predict the wind power generation at the wind farm using various wake models. Modeling of wind farm is a prerequisite for prediction of annual energy production at the wind farm. In this study, we modeled 20 MW class Seongsan wind farm which has 10 wind turbines located at the eastern part of Jeju Island. WindSim based on the computational fluid dynamics was adopted for the estimation of power generation. The power curve and thrust coefficient with meteorology file were prepared for wind farm modelling. The meteorology file was produced based on the measured data of the Korea Wind Atlas provided by Korea Institute of Energy Research. Three types of wake models such as Jensen, Larsen, and Ishihara et al. wake models were applied to investigate the wake effects. From the result, Jensen and Ishihara wake models show nearly the same value of power generation whereas the Larsen wake model shows the largest value. New positions of wind turbines are proposed to reduce the wake loss, and to increase the annual energy production of the wind farm.

• Journal of the Korean Solar Energy Society
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• v.32 no.6
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• pp.68-75
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• 2012

Small hydropower is one of the many types of new and renewable energy, which is planning to develop, as the country is abundant in endowed resources. In order to fully utilize small hydropower resources, there is a need for greater precision in quantifying small hydropower resources and establish an environment in which energy sources can be discovered using the small hydropower resource management system. This study has given greater precision to calculate annual electricity generation and capacity of small hydropower plants of Nakdong river system by inquiring into average annual rainfall, basin area and runoff coefficient, which is anticipated to promote small hydropower resources utilization. Small hydropower resource management system was also established by additionally providing base information on quantified small hydropower resources and analysis function and small hydropower generator status, rivers, basin, rainfall gauging station, water level gauging station etc.. Small hydropower resource management system can be used gather basic information for positive applications of small hydropower energy nationwide.

• Solar Energy
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• v.9 no.3
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• pp.81-91
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• 1989

This study represents the method to predict the flow duration curve and primary design specifications of small hydropower plant at hydropower site through analyzing the monthly rainfall data. Weibull distribution was selected to characterize the rainfall data and Thiessen method was used to calculate monthly average flowrate at site. Application of these results, primary design specifications such as design flowrate, annual average load factor and utility factor, annual average hydropower density and annual electric energy production were estimated and discussed for surveyed site located in Daigi-ri, Kangwon province. And performance characteristic model of small hydro-power plant was applied to estimate these specifications.

• Journal of the Korean Wood Science and Technology
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• v.34 no.4
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• pp.54-65
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• 2006

This study was conducted to examine the biomass and energy content of 60- to 70-year-old Quercus mongolica stand facing northern and southern aspect in Mt. Baekwoon (800 m above sea level), Gwangyang, Jeollanam-do and in Mt. Halla (1,000 m above sea level), Jeju-do. The total biomass was 288.4 ton/ha in northern aspect and 241.9 ton/ha in southern aspect of Mt. Baekwoon while 368.4 ton/ha in northern aspect and 364.3 ton/ha in southern aspect of Mt. Halla. Annual net production was 20.7 ton/ha/yr in northern aspect and 17.7 ton/ha/yr in southern aspect of Mt. Baekwoon while 19.0 ton/ha/yr in northern aspect and 21.2 ton/ha/yr in southern aspect of Mt. Halla. Total biomass and annual net production of Mt. Halla were greater than those of Mt. Baekwoon. The net assimilation rate (NAR) was 5.05 in northern aspect and 4.09 in southern aspect of Mt. Baekwoon, while 4.60 in northern aspect and 3.66 in southern aspect of Mt. Halla, Total energy content was 5,666 GJ/ha in northern aspect and 4,793 GJ/ha in southern aspect of Mt. Baekwoon while 6,550 GJ/ha in northern aspect and 6,435 GJ/ha in southern aspect of Mt. Halla. Annual energy content was 365 GJ/ha/yr in northern aspect and 360 GJ/ha/yr in southern aspect of Mt. Baekwoon while 351 GJ/ha/yr in northern aspect and 347 GJ/ha/yr in southern aspect of Mt. Halla. Annual energy content of Mt. Baekwoon was greater than that of Mt. Halla.

• Korean Management Science Review
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• v.30 no.2
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• pp.1-10
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• 2013

Case studies are made to investigate the relationship between the accuracy of energy production estimation and project feasibility indicators such as rate of return on equity (ROE) and debt service coverage ratio (DSCR) for three wind farm projects. It is found out that 1% improvement in the accuracy of energy production estimation may enhance the ROE by more than 0.5% in the case of P95, thanks to improved financing terms. AHP survey shows that MCP correlation of measured in situ wind data with long term wind speed distribution and hands-on experiences of flow analysis are more important than other factors for more precise annual energy production estimation.