• Publications of The Korean Astronomical Society
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• v.30 no.2
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• pp.47-51
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• 2015

Ground Level Enhancements (GLEs) in cosmic ray intensity observed during the period of 1997-2012 have been studied with energetic solar features and disturbances in solar wind plasma parameters and it is seen that all the GLEs have been found to be associated with coronal mass ejections, hard X-ray solar flares and solar radio bursts. All the GLEs have also been found to be associated with sudden jumps in solar proton flux of energy of ${\geq}60Mev$. A positive correlation with correlation coefficient of 0.48 has been found between the maximum percentage intensity (Imax%) of Ground Level Enhancements and the peak value of solar proton flux of energy (${\geq}60Mev$). All the Ground Level Enhancements have been found to be associated with jumps in solar wind plasma velocity (JSWV) events. A positive correlation with correlation coefficient of 0.43 has been found between the maximum percentage intensity (Imax %) of Ground Level Enhancements and the peak value of solar wind plasma velocity of associated (JSWV) events. All the Ground Level Enhancements have been found to be associated with jumps in solar wind plasma pressure (JSWP) events. A positive correlation with correlation coefficient of 0.67 has been found between the maximum percentage intensity (Imax %) of Ground Level Enhancements and the peak value of solar wind plasma pressure of associated (JSWP) events and of 0.68 between the maximum percentage intensity (Imax %) of Ground Level Enhancements and the magnitude of the jump in solar wind plasma pressure of associated (JSWP) events.

• Journal of the Korean Solar Energy Society
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• v.25 no.4
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• pp.29-35
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• 2005

Wind turbines can produce an unpolluted electricity getting energy only from the natural resource. It is one of the most economic power generating system among renewables up to now. Currently, ther are many wind turbines in operation world-wide under various external conditions. A wind turbine is composed of many machine components. So it is likely that the many accidents have been occurred in many wind turbines. In this paper, we reviewed "Wind turbine Accident data" of Caithness Windfarms Information Forum 2005. We classified this data and analyzed. The most of wind turbines in our country are foreign product. It is like that application it is possible with information which is important for wind farm operations and maintenance and for the wind turbine design and manufacturing.

• Journal of the Korean Solar Energy Society
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• v.33 no.6
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• pp.32-38
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• 2013

In an efforts to encourage renewable energy deployment, the government has initiated so called 1 million green homes program but the accumulated installation capacity of small wind turbine has been about 70kW. It can be explained in several ways such that current subsidy program does not meet public expectations, economic feasibility of wind energy is in doubt or acoustic emission is significant etc. The author investigated annual energy production of Skystream 3.7 wind turbine using measured power curve and wind resource data. The measured power curve of the small wind turbine was obtained through power performance tests at Wol-Ryoung test site. AEP(Annual Energy Production) and CF(Capacity Factor) were evaluated at selected locations with the measured power curve.

• Journal of the Korean Solar Energy Society
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• v.30 no.5
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• pp.44-55
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• 2010

The proposed offshore wind farm projects, i.e., Mooudo offshore, Yeonggwang-Gochang offshore, Saemangeum offshore, Imjado offshore and Gadeokdo-Dadeapo offshore, were compared and analyzed using the Korea National Wind Mapand Wind Farm Suitability Assessment System developed by the Korea Institute of Energy Research. The suitability of the proposed areas was comprehensively assessed using geographic, economic constraints, wave condition and wind resource factors, but the focus of this paper was on the geographic constraints and wave conditions. Imjado had several geographical constraints, despite having a good wind power density, while Saemangeum had a relatively low wave height, shallow water depth, close substation and slow tidal current. It is anticipating that the present comparison and analysis could be used as reference guidelines when selecting and preparing the design of large-scale offshore wind farm in the near future.

• Journal of the Korean Solar Energy Society
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• v.36 no.2
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• pp.9-17
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• 2016

In order to examine how accurately the wind farm design software, WindPRO and Meteodyn WT, predict annual energy production (AEP), an investigation was carried out for Seongsan wind farm of Jeju Island. The one-year wind data was measured from wind sensors on met masts of Susan and Sumang which are 2.3 km, and 18 km away from Seongsan wind farm, respectively. MERRA (Modern-Era Retrospective Analysis for Research and Applications) reanalysis data was also analyzed for the same period of time. The real AEP data came from SCADA system of Seongsan wind farm, which was compare with AEP data predicted by WindPRO and Meteodyn WT. As a result, AEP predicted by Meteodyn WT was lower than that by WindPRO. The analysis of using wind data from met masts led to the conclusion that AEP prediction by CFD software, Meteodyn WT, is not always more accurate than that by linear program software, WindPRO. However, when MERRA reanalysis data was used, Meteodyn WT predicted AEP more accurately than WindPRO.

• Solar Energy
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• v.10 no.2
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• pp.3-9
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• 1990

The recent technology of Wind Energy Conversion System(WECS) in the world is well-developed and the feasibility of WECS is better than the past time. So, it is necessary to re-analyze the characteristics of wind energy in this country. This paper deals with the analysis of wind energy distribution in Korean Peninsula, Cheju and Ullung island. The assessment was performed based on the raw data collected 64 meteorological stations for the last 10 years. The wind energy characteristics were analyzed hourly, monthly, seasonally and annually. The Weibull distribution was assumed and two parameters in all areas were calculated and the wind energy potential distribution in Korea was obtained.

• Journal of the Korean Solar Energy Society
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• v.30 no.2
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• pp.22-32
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• 2010

The world is facing environmental problem described as climate change and exhaustion of fossil fuel. In order to solve theses problems, importance of renewable energy is extremely growing. For stable energy supply, it is need to apply hybrid renewable energy systems in urban-scale, because some renewable energy system' outputs are greatly influenced by climatic condition. Especially, solar irradiation and wind velocity are influenced by urban geometric environment as well as climatic condition. Therefore it is necessary to evaluate the renewable energy potential according as urban form. This study aims to evaluate the potential of solar energy and wind energy in urban-scale and classify urban type according as characteristics of urban forms. The results of this study will be used to develop renewable energy system application guidelines for urban and energy planning.

• Journal of Electrical Engineering and Technology
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• v.12 no.2
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• pp.576-585
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• 2017

Dynamic thermal rating (DTR) of overhead transmission lines can provide a significant increase in transmission capacity compared to the static thermal rating. However, the DTR are usually estimated by the traditional thermal model of overhead conductor that is highly dependent on the solar, wind speed and wind direction data. Consequently, the estimated DTR would be unreliable and the safety of transmission lines would be reduced when the solar and wind sensors are out of function. To address this issue, this study proposed a novel thermal model of overhead conductor based on the thermal-electric analogy theory and Markov chain. Using this thermal model, the random variation of conductor temperature can be simulated with any specific current level and ambient temperature, even if the solar and wind sensors are out of function or uninstalled. On this basis, an estimation method was proposed to determine the DTR in the form of probability. The laboratory experiments prove that the proposed method can estimate the DTR reliably without measured solar and wind data.

• Journal of the Korean Solar Energy Society
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• v.26 no.4
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• pp.25-30
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• 2006

10kW wind turbine has been successfully commissioned at the King Sejong station in April, 2006. The wind turbine installed is a part of the R&D program for developing a solid wind/diesel hybrid power control system for a remote area such as Antarctica. At the same time, the current research aims to develop an anti-icing and de-icing technologies for a small wind turbine rated under 50kW. Since its commissioning, the turbine has generated about 500kWh for 47days without any system faults. Although sufficient data have not been obtained yet, any trouble has not occurred in the wind/diesel hybrid system based on the current analysis. Concerning on the environmental impact by the wind turbine operation, the turbine is installed within the station boundary in order to meet the Madrid protocol. Therefore, wind turbine operation meets the international requirements for preservation of antarctic ecosystem.

• Solar Energy
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• v.4 no.2
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• pp.3-12
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• 1984

In this paper, how to design the wind power generation system is presented. It is shown that the wind system optimization can be achieved by consideration of the four factors; wind statistics, efficiency of conversion of wind energy to electrical energy, average annual energy extracted and load factor. The wind is characterized by a weibull probability function. The Weibull parameter is calculated for the characterizing wind and the primary design specification of ten different sites. Some graphs are presented, which can be used to design a wind system for maximum output of a specified load factor at given site. Two different systems, $V_c=0.4V_R$ and $V_c=0.5V_R$ are discussed, as samples, for investigation of the effects on the system through the variation of cut-in speed.