• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.278-281
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• 2008

This study demonstrates the advantages of a shear-free structure designed to modify vertical profiles of wind speed in the atmospheric surface layer. Computational fluid dynamics(CFD) software, FLUENT is used to interpret the velocity field modification around the structure and wind turbine. The shapes of shear-free structure, installed at upstream toward prevailing wind direction, would be fences, buildings and trees, etc. According to the simulation results, it is obvious that wind shear between heights of wind turbine's blades is decreased together with a speed-up advantage. This would lead decrease of periodic wind loading caused by wind shear and power-out increase by flow uniformity and wind speed-up.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.673-673
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• 2013

최근 시대의 흐름에 따라 많은 에너지의 사용으로 여러 가지 에너지원이 필요로 하게 되면서 지금까지는 석탄, 석유 등 매장된 에너지원을 사용하고 있지만, 최근 에너지 위기와 여러 가지의 환경문제가 대두 되면서 세계적으로 새로운 청정에너지원을 필요로 하게 되었다. 그 결과 태양광, 풍력, 지열 등 여러 가지의 신재생에너지원이 대두되게 되었으며, 여러 가지의 신재생에너지원 중 주목받고 있는 풍력에너지에 대한 연구가 현재 활발히 진행 중에 있다. 풍력발전은 바람의 에너지를 이용해 블레이드에 연결된 터빈을 구동하여 전기 에너지를 얻는 방식이며, 아직까지는 많은 곳에서 사용될 만큼 생산이 되지 않고 있지만 조만간 많은 곳에서 쓰일 것으로 예상된다. 풍력발전 시스템이 전력시장에서 차지하는 비중이 점차 증가하고 있으나 풍향, 풍속 등의 변화로 인하여 안정적인 발전 출력을 항상 보장할 수 없다. 그러므로 본 논문에서는 실제 풍력발전기로부터 수집된 풍향, 풍속, 발전출력 데이터를 처리하여 데이터베이스를 구축하고, 퍼지 뉴런에 기반한 퍼지-뉴럴 네트워크 예측 모델을 이용하여 풍력발전 출력을 예측하였다.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.33 no.2
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• pp.95-101
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• 2020

The wind turbine blades should be designed to possess a high stiffness and should be fabricated with a light and high strength material because they serve under extreme combination of lift and drag forces, converting kinetic energy of wind into shaft work. The goal of this study is to understand the basic knowledge required to curtail the process time consumed during the construction of small wind turbine blades using carbon fiber reinforced polymer (CFRP) prepeg composites. The configuration of turbine rotor was determined using the QBlade freeware program. The fluid dynamics module simulated the loads exerted by the wind of a specific speed, and the stress analysis module predicted the distributions of equivalent von Mises stress for representing the blade structures. It was suggested to modify the shape of test specimen from ASTM D638 to decrease the variance in measured tensile strengths. Then, a series of experiments were performed to confirm that the bladder compression molded CFRP prepreg can provide sufficient strength to small wind turbine blades and decrease the cure time simultaneously.

• Journal of the wind engineering institute of Korea
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• v.22 no.4
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• pp.163-169
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• 2018

In this study, wind loads exerted on the offshore wind turbine rotor in parked condition were predicted with variations of wind speeds, yaw angles, azimuth angle, pitch angles, and power of the atmospheric boundary layer profile. The calculated wind loads using blade element theorem were compared with those of estimated aerodynamic loads for the simplified blade shape. Wind loads for an NREL's 5 MW scaled offshore wind turbine rotor were also compared with those of NREL's FAST results for more verification. All of the 6-component wind loads including forces and moments along the three axis were represented on a non-rotating coordinate system fixed at the apex of rotor hub. The calculated wind loads are applicable for the dynamic analysis of the wind turbine system, or obtaining the over-turning moment at the foundation of support structure for wind turbine system.

• Composites Research
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• v.22 no.1
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• pp.22-31
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• 2009

Recently the wind energy has been alternatively used as a renewable energy resource instead of the mostly used fossil fuel due to its lack and environmental issues. This work is to propose a structural design and analysis procedure for development of the 500W class small wind turbine system which will be applicable to relatively low speed region like Korea and for the domestic use. The wind turbine blade was performed structural analysis including stress, deformation, buckling, vibration and fatigue. In addition, the blade should be safe from the impact damage due to FOD(Foreign Object Damage) including the bird strike. MSC.Dytran was used in order to analyze the bird strike penomena on the blade, and the applied method Arbitrary Lagrangian-Eulerian was evaluated by comparison with the previous study results. Finally, the structural test was carried out and its test results were compared with the estimated results for evaluation of the designed structure.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.11
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• pp.1121-1130
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• 2009

In order to investigate the offshore wind resources, the measured data from the QuikSCAT satellite was analyzed from Jan 2000 to Dec 2008. QuikSCAT satellite is a specialized device for a microwave scatterometer that measures near-surface wind speed and direction under all weather and cloud conditions. Wind speed measured at 10 m above from the sea surface was extrapolated to the hub height by using the power law model. It has been found that the high wind energy prevailing in the south sea and the east sea of the Korean peninsula. From the limitation of seawater depth for piling the tower and archipelagic environment around the south sea, the west and the south-west sea are favorable to construct the large scale offshore wind farm, but it needs efficient blade considering relatively low wind speed. Wind map and monthly variation of wind speed and wind rose using wind energy density were investigated at the specified positions.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.8
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• pp.150-157
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• 2005

This paper presents the simulation modeling and analysis of variable wind speed turbine system(VWTS) using the doubly fed induction generator(DFIG) connected the back to back converter system in the rotor side. In the simulation, using the model system which has the 660[kW] rated power, blade control and the dual converter system are modeled for verifying the control characteristics. The VWTS is controlled by the optimal pitch angle for maximum output power under the rated wind speed, and for the rated output power over the rated wind speed. And also power factor is controlled by the reactive power. To verify the effectiveness of the proposed method, simulation results are compared with the actual data from the V47 VWTS located in Hangwon wind farm in Jeju-Do. According to the comparison of these results, this method shows excellent performance.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.12
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• pp.25-34
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• 2006

In this paper, a method of designing the pitch control algorithm for the wind turbine generator system (WTGS) and results of nonlinear simulation are presented. For this, the WTGS is treated as a multibody system and the blade element and momentum theory are adopted to model the aerodynamic force and torque acting the rotor blades. For the purpose of controller design, the WTGS is approximated to 1 DOF system using the fact that the WTGS is eventually a constrained multibody system. Then a classical PID controller is designed and used to regulate the rotational speed of the generator. FORTRAN based nonlinear simulation program is written and used to evaluate the performance of the proposed controller at the various wind scenario and operational modes.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.10a
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• pp.473-476
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• 2012

Energy is one of the most important resources for human society and the history of its development and use have been part of human life. Especially as the need of eco-friendly energy development has been on the rise, the interest in alternative energy has grown consistently. This paper, so as to identify the energy output and efficiency from a micro vertical-axis wind generator. by utilizing a smart phone, presents a system to analyze the production efficiency of real-time energy, according to the wind velocity and the width and the material of the blade of the climate change system in the Meteorological Office.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.1
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• pp.59-65
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• 2011

The aerodynamic power and torque of wind turbines are extremely nonlinear. Therefore, the overall dynamic behavior of a wind turbine exhibits nonlinear characteristics that are dependent on the magnitude of the wind speed. The nonlinear aerodynamic characteristics of the wind turbine also affect the characteristics of the control system of the wind turbine. Therefore, the analysis of the nonlinear aerodynamic characteristics of wind turbine is essential in designing the wind-turbine controller. In this study, the nonlinear aerodynamic characteristics and the effects of these characteristics on the closed-loop pitch system with PI controller for an 1-mass model of the wind turbine are investigated above rated power.