• Wind and Structures
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• 제9권6호
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• pp.493-503
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• 2006

The demand for energy in the world increases everyday. Blade energy which is wind turbine is a significant resource which must be appreciated in this field. Especially, in places where wind potential is high, the usage of wind energy is a beneficial factor for every country's economy. In this study, first, 6 different miniature rotor were produced by using 6 different NACA profiles. Rotors were produced with three blades. The electrical performance and the speed of start of action values that are provided from each rotor form were established by measuring them in the wind tunnel. The calculation of area and volumetric values of each profile and wind surfaces were made with AutoCad technical drawing program. As a result, it was searched whether there is any relation between electrical performance values and speed of start of motion that rotors produced and volumetric values of rotors. The aim of this study is to find out whether rotor blade volume is one of factors that influences rotor performance. The general tendency observed here is that the increase in the volume of rotor blade leads to an increase in the speed of start of motion and to a decrease in the rotor performance.

• 한국환경과학회지
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• 제30권1호
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• pp.19-28
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• 2021

To reduce pollution, decrease the production of carbon dioxide, and to maintain a secure supply of energy, interest continues to grow in the area of renewable energy especially since there is a finite supply of cheap oil. Wind energy is one of the most viable options to consider and supply part of the energy needed to reduce dependence on foreign oil. However, it is difficult to predict the wind speed in an environment with many obstacles such as buildings and trees and getting accurate dimensions of those obstacles is difficult particularly on sloped mountainous terrain. In this study a drone was used to create a 3-D map of the campus of the Catholic University of Pusan. The dimensions and elevations for the 3-D map were used to make a model of the school campus in the CFD program Envi-met. Simulations were run for five different wind directions and 4 different elevations to find the location that would give the highest electrical output for a wind turbine. When considering all of these variables it was found that the optimal location was above the Student Union which had a 40% higher wind speed and could produce 274% more electrical power than the original wind speed.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 춘계학술대회 초록집
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• pp.184.3-184.3
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• 2010

This study suggests a modeling of grid-connected wind turbine generation systems and performs simulation according to increase/decrease of real wind speed. MATLAB & SIMULINK implemented modeling of grid-connected wind turbine generation system. Terminal voltage, grid voltage, and active/reactive power shall be observed following the performance of simulation.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2008년도 추계학술대회 논문집
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• pp.321-323
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• 2008

This study suggests a modeling of grid-connected wind turbine generation systems and performs simulation according to increase/decrease of real wind speed. MATLAB/Simulink implemented modeling of grid-connected wind turbine generation system. Terminal voltage, grid voltage, and active/reactive power shall be observed following the performance of simulation.

• Journal of Mechanical Science and Technology
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• 제14권11호
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• pp.1267-1275
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• 2000

A series do wind tunnel tests were conducted for Korean high-speed train model with various shape components to assess the contributions to aerodynamic drag. In order to elucidate the ground effects, two different wind tunnels, one with a moving ground system and the other with a fixed ground, were used for the same model and the results of both were compared and analyzed in detail. The result show that a suitable ground simulation is necessary for the test of a train model with many cars and detailed underbody. But the relative difference of the drag coefficients for the modifications of shape components can be measured by a fixed ground test with high accuracy and low cost. The effects of the nose shape, the inter-cargap and the bogie-fairing on total drag were discussed and some ideas were prosed to decrease the aerodynamic resistance of high speed train.

• 플랜트 저널
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• 제12권3호
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• pp.32-38
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• 2016

본 연구에서는 해안 복잡지형에 2열 배치된 풍력단지 운영사례를 분석하여 후류에 의한 풍력발전기의 영향을 분석하여 풍속의 변화 그리고 난류강도의 변화를 분석하였다. 주풍향 대비 인접 풍력발전기와 이격거리가 날개직경(rotor diameter,RD) 90m 기준 4RD인 경우 후류에 의해 풍속감소 및 난류강도의 증가로 인한 발전량의 감소를 확인 할 수 있었다. 특히 후류에의한 급격한 순간풍향의 변화시, 풍력발전기의 불시정지로 발전량이 현저히 감소되었고 이를 보완하기 위하여 요브레이크를 설비를 보강 함으로써 불시정지 빈도를 감소하고 발전량을 제고하는데 효과가 있음을 확인할 수 있었다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 춘계학술대회 논문집
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• pp.1166-1171
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• 2008

Through Korean high speed train development project "G7 Leading Technology Development Project" from 1996 to 2002, HSR-350X has been developed. It can run the maximum operating speed of 350 km/h. Based on this technology, KTX-2 which will be served commercially has been developed till 2007. This paper introduces the aerodynamic analysis of the High-Speed EMU and shows the results of optimized aerodynamic nose shape design techniques and clean pantograph panhead original techniques study. These are the important parts of developments for high speed train which maximum speed is 400 km/h. Especially for decrease of tunnel micro pressure waves, the optimized nose area distributions were derived and the characteristics of micro pressure wave were analyzed. The robust optimized pantograph panhead shapes investigated to improve the performance and decrease the vortex flow which is thought to be its noise source. These shapes are clean and robust to external disturbances like unsteady accelerated flow or side wind was derived. Finally aerodynamic performances was verified with PIV and smog visualization by wind tunnel test.

• 설비공학논문집
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• 제22권11호
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• pp.773-780
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• 2010

The dispersion of plume which is emitted from a chimney is governed by a lot of factors： wind, local terrain, turbulence intensity of atmosphere, and temperature, etc. In this study, we numerically investigate the plume dispersions for various altitudinal temperature gradients and wind speeds. The normal atmosphere has the temperature decrease of $0.6^{\circ}C/100m$, however, actually the real atmosphere has the various altitudinal temperature profiles according to the meteorological factors. A previous study focused on this atmospheric temperature gradient which induces a large scale vertical flow motion in the atmosphere thus makes a peculiar plume dispersion characteristics. In this paper, the effects of the atmospheric temperature gradient as well as the wind speed are investigated concurrently. The results for the developing processes in the atmosphere and the affluent's concentrations at the ambient and ground level are compared under the various altitudinal temperature gradients and wind speeds.

• 농업과학연구
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• 제50권3호
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• pp.427-435
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• 2023

This study was conducted to evaluate the spraying performance according to the flight conditions of agricultural drones for the development of a variable control system. The analyzed flight conditions comprised six factors: spraying direction, flight speed, altitude, wind speed, wind direction, and rotor rotational speed. The ratio of the area sprayed on the water-sensitive paper was used as the coverage, and the distribution and amount of the coverage were evaluated. The coverage distribution based on the distance from the drone was used to evaluate a spray pattern, and the distribution was expressed as a Gaussian function approximation. In addition, the probability distribution based on coverage was expressed as the cumulative probability via Gamma function approximation to analyze the spraying efficiency in the target area. The results showed that the averaged coverage decreased significantly as the flight speed and wind speed increased, and the wind direction changed the spray pattern without a coverage decrease. This study contributes to the development of a control technique for the precision control system of agricultural drones.

• 신재생에너지
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• 제7권2호
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• pp.43-50
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• 2011

The only practical way to measure wind resource at high-altitude over 100 m above ground for a feasibility study on a high-rise building integrated wind turbine might be ground-based remote sensing. The remote-sensing campaign was performed at a 145 m-building roof in Jamsil where is a center of metropolitan city Seoul. The campaign aimed uncertainty assessment of Leosphere WindCube LIDAR and Scintec MPAS SODAR through a mutual comparison. Compared with LIDAR, the data availability of SODAR was about 2/3 at 550 m altitude while both showed over 90% under 400 m, and it is shown that the data availability decrease may bring a distortion of statistical analysis. The wind speed measurement of SODAR was fitted to a slope of 0.92 and $R^2$ of 0.90 to the LIDAR measurement. The relative standard deviation of wind speed difference and standard deviation of wind direction difference were evaluated to be 30% and 20 degrees, respectively over the whole measurement heights.