• Bulletin of the Korean Space Science Society
• /
• 2008.10a
• /
• pp.25.2-25.2
• /
• 2008

Polar rain is a spatially uniform precipitation of electrons with energies around 100eV that penetrate into the polar cap region where geomagnetic field lines are connected to the Interplanetary Magnetic Fields (IMF). Since their occurrences depend on the IMF sector polarity, they are believed to originate from the field aligned component of the solar wind. However, statistically direct correlation between polar rain and solar wind has not been shown. In this presentation, we examined specifically the IMF strength influence on the polar rain flux variation by classifying of IMF sector polarities. For this study, we employed the polar rain flux data measured by STSAT-1 and compared them with the solar wind parameters obtained from the WIND and ACE satellites. We found the direct mutuality between polar rain flux and IMF strength with correlation coefficient above 0.5. This proportional tendency appears stronger when the northern hemisphere is in the away sector of the IMF, which could be associated with a favorable geometry for magnetic reconnection. Simple particle trajectory simulation clearly shows why polar rain intensity depends on the IMF sector polarity. These results are consistent with the direct entry model of Fairfield et al.(1985), while low correlation coefficient with solar wind density, the similarity between slops of both energy spectra shows that transport process occur without acceleration.

• Journal of the Korean Solar Energy Society
• /
• v.26 no.4
• /
• pp.25-30
• /
• 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
• /
• v.4 no.2
• /
• pp.3-12
• /
• 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.

• Journal of the Korean Solar Energy Society
• /
• v.24 no.3
• /
• pp.1-7
• /
• 2004

Using WAsP, which is PC-program for the vertical and horizontal extrapolation of wind data, annual energy production as well as wind energy density has been predicted for Haengwon wind farm in Jeju island. The predicted results were compared with real data derived from wind turbines in Haengwon wind farm. As the results, in order to produce more electric power, new wind turbines should be located along coastal line, which has comparatively high wind energy density. Also, the roughness length should be inputted to the Map Editor program for better agreement with real annual energy production.

• Journal of Astronomy and Space Sciences
• /
• v.28 no.1
• /
• pp.27-36
• /
• 2011

The present study examines the morning-afternoon asymmetry of the geosynchronous magnetic field strength on the dayside (magnetic local time [MLT] = 06:00~18:00) using observations by the Geostationary Operational Environmental Satellites (GOES) over a period of 9 years from February 1998 to January 2007. During geomagnetically quiet time (Kp < 3), we observed that a peak of the magnetic field strength is skewed toward the earlier local times (11:07~11:37 MLT) with respect to local noon and that the geosynchronous field strength is larger in the morning sector than in the afternoon sector. That is, there is the morning-afternoon asymmetry of the geosynchronous magnetic field strength. Using solar wind data, it is confirmed that the morning-afternoon asymmetry is not associated with the aberration effect due to the orbital motion of the Earth about the Sun. We found that the peak location of the magnetic field strength is shifted toward the earlier local times as the ratio of the magnetic field strength at MLT = 18 (B-dusk) to the magnetic field strength at MLT = 06 (B-dawn) is decreasing. It is also found that the dawn-dusk magnetic field median ratio, B-dusk/B-dawn, is decreasing as the solar wind dynamic pressure is increasing. The morning-afternoon asymmetry of the magnetic field strength appears in Tsyganenko geomagnetic field model (TS-04 model) when the partial ring current is included in TS-04 model. Unlike our observations, however, TS-04 model shows that the peak location of the magnetic field strength is shifted toward local noon as the solar wind dynamic pressure grows in magnitude. This may be due to that the symmetric magnetic field associated with the magnetopause current, strongly affected by the solar wind dynamic pressure, increases. However, the partial ring current is not affected as much as the magnetopause current by the solar wind dynamic pressure in TS-04 model. Thus, our observations suggest that the contribution of the partial ring current at geosynchronous orbit is much larger than that expected from TS-04 model as the solar wind dynamic pressure increases.

• Advances in Energy Research
• /
• v.5 no.2
• /
• pp.107-128
• /
• 2017

Energy is a major component of almost all economic, production, and service activities, and rapid population growth, urbanization and industrialization have led to ever growing demand for energy. Limited energy resources and increasingly evident environmental effects of fossil fuel consumption has led to a growing awareness about the importance of further use of renewable energy sources in the countries energy portfolio. Renewable hydrogen production is a convenient method for storage of unstable renewable energy sources such as wind and solar energy for use in other place or time. In this study, suitability of 25 cities located in Iran's western region for renewable hydrogen production are evaluated by multi-criteria decision making techniques including TOPSIS, VIKOR, ELECTRE, SAW, Fuzzy TOPSIS, and also hybrid ranking techniques. The choice of suitable location for the centralized renewable hydrogen production is associated with various technical, economic, social, geographic, and political criteria. This paper describes the criteria affecting the hydrogen production potential in the study region. Determined criteria are weighted with Shannon entropy method, and Angstrom model and wind power model are used to estimate respectively the solar and wind energy production potential in each city and each month. Assuming the use of proton exchange membrane electrolyzer for hydrogen production, the renewable hydrogen production potential of each city is then estimated based on the obtained wind and solar energy generation potentials. The rankings obtained with MCDMs show that Kermanshah is the best option for renewable hydrogen production, and evaluation of renewable hydrogen production capacities show that Gilangharb has the highest capacity among the studied cities.

• Journal of Astronomy and Space Sciences
• /
• v.26 no.4
• /
• pp.439-450
• /
• 2009

Recurrent enhancements of relativistic electron events at geosynchronous orbit (GREEs) were observed in 2006. These GREE enhancements were associated with high-speed solar wind streams coming from the same coronal hole. For the first six months of 2006, the occurrence of GREEs has 27 day periodicity and the GREEs were enhanced with various flux levels. Several factors have been studied to be related to GREEs: (1) High speed stream, (2) Pc5 ULF wave activity, (3) Southward IMF Bz, (4) substorm occurrence, (5) Whistler mode chorus wave, and (6) Dynamic pressure. In this paper, we have examined the effectiveness about those parameters in selected periods.

• 한국신재생에너지학회:학술대회논문집
• /
• 2009.06a
• /
• pp.73-76
• /
• 2009

Generally, wind or solar power system is operated as a stand-alone power system, the efficiency of which could be higher by designing wind-solar combined system considering average wind speed and solar radiation of the desert region, Mongolia. This system is designed to generate electricity for power users and pumps the ground water for irrigation using deep well pump. The ground water can be used for farming or forestation where there is no or little irrigation system. In connection with this study, a renewable energy park, Green Eco Energy Park, was developed at about 50km east of Ulaanbaatar. 3 sets of 10kW wind power generator and 70 kW of solar power module were installed there. The electricity generated from the system is used to on-site office building and deep well pump for ground water pumping. A 10kW stand-alone solar pumping system, which has no rechargeable battery system, is installed to pump the ground water with the amount of generated power. The ground water is stored in 3 artificial ponds and then it is used for raising nursery tree and farming. The purpose of this study is to provide a possible energy solution to desert regions where there is no or little power system. The system also supply power to ground water pump, and the water can be used for farming and forestation, which will also be a solution of preventing desertification or spreading of desert area.

• Journal of the Korean Solar Energy Society
• /
• v.26 no.2
• /
• pp.61-67
• /
• 2006

The use of the wind energy resource is a rapidly growing area world-wide. The number of installed units is continuously increasing, and therefore, it is important to respect and to deal with the impact of wind power generation system. From the view of an electric grid utility, there is a major problem with the impact of the wind system on the voltage of the electric grid, to which a turbine is connected. In this paper, it is investigated the voltage impact and transient state analysis on distribution line, with which wind power generation system is connected. Connections of wind power system usually occur to voltage drop due to reactive power absorption and sometime result in higher than nominal voltage.

• Journal of the Korean Solar Energy Society
• /
• v.28 no.6
• /
• pp.1-7
• /
• 2008

The wind resource potentials of South Korea are estimated as preliminary stage using the national wind map which has been being established by numerical wind simulation and GIS (Geographical Information System) exclusion analysis. The wind resource potentials are classifying into theoretical, geographical, technical and implementation potentials and the calculation results are verified by comparing to other countries' potentials. In GIS exclusion, urban, road, water body, national parks and steep slope area are excluded from onshore geographical potential while water depth and offshore distance from the shoreline are applied as offshore exclusion conditions. To estimate implementation potential, dissemination records of European countries are adopted which is about 1/8 of geographical potential. The implementation potential of South Korea would correspond 12.5GW which is 1.7 times of the national wind energy dissemination target until 2030.