• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.2192-2197
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• 2003

The purpose of this 3-D numerical simulation is evaluate the application of a commercial CFD code to predict 3-D flow and power characteristics of wind turbines. The experimental approach, which has been main method of investigation, appears to be its limits, the cost increasing with the size of the wind turbines, hence mostly limited to observing the phenomena on rotor blades. Therefore, the use of Computational Fluid Dynamics (CFD) techniques and Navier-Stokes solvers are considered a very serious contender. The flow solver CFX-TASCflow is employed in all computations in this paper. The 3-D flow separation and the wake distribution of 2 and 3 bladed Horizontal Axis Wind Turbines (HAWTs) are compared to Heuristic model and smoke-visualized experimental result by NREL(National Renewable Energy Laboratory). Simulated 3-D flow separation structure on the rotor blade is very similar to Heuristic model and the wake structure of the wind turbine is good consistent with smoke-visualized result. The calculated power of the 3 bladed rotor by CFD is compared with BEM results by TV-Delft. The CFD results of which is somewhat consist with BEM results, under an error less than 10%.

• Journal of Advanced Marine Engineering and Technology
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• 제27권7호
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• pp.906-913
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• 2003

The purpose of this 3-D numerical simulation is to evaluate the application of a commercial CFD code to predict 3-D flow and power characteristics of wind turbines. The experimental approach, which has been main method of investigation, appears to be its limits, the cost increasing with the size of the wind turbines, hence mostly limited to observing the phenomena on rotor blades. Therefore. the use of Computational Fluid Dynamics (CFD) techniques and Navier-Stokes solvers are considered a very serious contender. The flow solver CFX-TASCflow is employed in all computations in this paper. The 3-D flow separation and the wake distribution of 2 and 3 bladed Horizontal Axis Wind Turbines (HAWTs) are compared to Heuristic model and smoke-visualized experimental result by NREL(National Renewable Energy Laboratory). Simulated 3-D flow separation structure on the rotor blade is very similar to Heuristic model and the wake structure of the wind turbine is good consistent with smoke-visualized result. The calculated power of the 3 bladed rotor by CFD is compared with BEM results by TU-Delft. The CFD results of which is somewhat consist with BEM results. under an error less than 10%.

• Journal of Advanced Marine Engineering and Technology
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• 제38권5호
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• pp.541-549
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• 2014

Horizontal axis tidal turbines are machinery inherited from the principle of wind turbines to enable the application of utilizing ocean's current energy. Its function does not differ from that of wind case, which is to convert fluid's kinetics energy to mechanical torque, therefore generates electricity. Since the ocean has been an enormous source of untapped power, tidal turbines have been being investigated recently to meet human's demand of energy with respect to environment friendly approach. This paper introduces a couple of turbine designs which are anticipated to have high performance. A comparison among recent works on the same topic is also made for validation.

• 대한기계학회논문집A
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• 제34권12호
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• pp.1885-1891
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• 2010

풍력터빈의 토크제어는 정격풍속 이하에서 매우 중요하다. 토크제어의 주된 목적은 바람이 가진 공기역학적 파워로부터 최대의 파워를 얻도록 하는 것이다. 풍력터빈의 토크제어 방법은 토크모드 제어와 속도모드 제어로 크게 두 경우로 구분된다. 토크모드 제어는 풍력터빈에서 잘 알려지고 전통적으로 사용되는 방법으로 발전기 회전속도의 제곱에 비례하도록 발전기의 토크크기를 발생시킨다. 속도모드 제어에서는 발전기의 토크크기를 발생하기 위하여 PI 제어기를 사용한다. 본 논문에서는 실제 풍속이 난류인 점을 고려하여 2.75 MW 풍력터빈을 대상으로 두 토크제어 방법을 적용한 수치실험 결과를 제시하고 응답특성을 비교한다.

• 대한기계학회논문집B
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• 제34권10호
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• pp.901-906
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• 2010

복잡한 지형에 위치한 풍력발전소의 유동장을 분석하기 위해 3차원 유동해석이 수행되었다. 본 논문의 목적은 복잡한 지형과 풍력발전기의 배치가 풍력발전소의 성능에 미치는 영향을 연구하는 것이다. 자세한 블레이드 형상을 고려한 총 49대의 풍력발전기가 계산 도메인에 포함되었다. 풍력발전기의 회전운동을 고려하기 위해 고정회전자 기법이 사용되었고, 블레이드에 작용하는 토크를 계산함으로써 풍력발전기의 성능을 평가하였다. 수치해석 결과를 통하여 풍력발전소 전체의 자세한 유동장과 지형적 영향으로 풍속이 감소되는 국부적인 영역을 예측하였고, 상류의 발전기에서 발생하는 후류가 하류에 위치한 발전기의 성능에 미치는 영향도 분석되었다. 본 연구의 해석기법은 추후 건설되는 풍력발전소의 부지와 풍력발전기의 최적 위치를 선정하는 데 사용될 수 있을 것으로 사료된다.

• Smart Structures and Systems
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• 제24권1호
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• pp.53-65
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• 2019

Misaligned wind-wave and seismic loading render offshore wind turbines suffering from excessive bi-directional vibration. However, most of existing research in this field focused on unidirectional vibration mitigation, which is insufficient for research and real application. Based on the authors' previous work (Sun and Jahangiri 2018), the present study uses a three dimensional pendulum tuned mass damper (3d-PTMD) to mitigate the nacelle structural response in the fore-aft and side-side directions under wind, wave and near-fault ground motions. An analytical model of the offshore wind turbine coupled with the 3d-PTMD is established wherein the interaction between the blades and the tower is modelled. Aerodynamic loading is computed using the Blade Element Momentum (BEM) method where the Prandtl's tip loss factor and the Glauert correction are considered. Wave loading is computed using Morison equation in collaboration with the strip theory. Performance of the 3d-PTMD is examined on a National Renewable Energy Lab (NREL) monopile 5 MW baseline wind turbine under misaligned wind-wave and near-fault ground motions. The robustness of the mitigation performance of the 3d-PTMD under system variations is studied. Dual linear TMDs are used for comparison. Research results show that the 3d-PTMD responds more rapidly and provides better mitigation of the bi-directional response caused by misaligned wind, wave and near-fault ground motions. Under system variations, the 3d-PTMD is found to be more robust than the dual linear TMDs to overcome the detuning effect. Moreover, the 3d-PTMD with a mass ratio of 2% can mitigate the short-term fatigue damage of the offshore wind turbine tower by up to 90%.

• ETRI Journal
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• 제37권2호
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• pp.283-294
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• 2015

A model that precisely forecasts how much wind power is generated is critical for making decisions on power generation and infrastructure updates. Existing studies have estimated wind power from wind speed using forecasting models such as ANFIS, SMO, k-NN, and ANN. This study applies a projected clustering technique to identify wind power patterns of wind turbines; profiles the resulting characteristics; and defines hourly and daily power patterns using wind power data collected over a year-long period. A wind power pattern prediction stage uses a time interval feature that is essential for producing representative patterns through a projected clustering technique along with the existing temperature and wind direction from the classifier input. During this stage, this feature is applied to the wind speed, which is the most significant input of a forecasting model. As the test results show, nine hourly power patterns and seven daily power patterns are produced with respect to the Korean wind turbines used in this study. As a result of forecasting the hourly and daily power patterns using the temperature, wind direction, and time interval features for the wind speed, the ANFIS and SMO models show an excellent performance.

• 한국태양에너지학회 논문집
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• 제25권3호
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• pp.53-60
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• 2005

Energy resource is very important to the survival in the polar region. Wind energy, which is one of renewable energy, can guarantee the clean, inexhaustible, natural resource in the polar region. It is essential to assess the wind energy resource of the site where wind turbines will be installed. In the present study, the wind characteristics of the antarctic King Sejong station are analysed from its meteorological observation data. The wind resource of the Sejong station is also simulated and predicted using WAsP program. From the results, the Sejong station has very excellent wind resource and the site where small wind turbines will be installed is determined.

• 한국공간구조학회논문집
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• 제18권1호
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• pp.117-125
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• 2018

Recently, various building integrated wind power (BIWP) approaches have been used to produce energy by installing wind power generators in high-rise buildings constructed in urban areas. BIWP has advantages in that it does not require support to position the turbine up to the installation height, and the energy produced by the wind turbine can be applied directly to the building. The accurate evaluation of wind speed is important in urban wind power generation. In this study, a wind tunnel test and computational fluid dynamics (CFD) analysis were conducted to evaluate the wind speed for installing wind turbines between buildings. The analysis results showed that the longer the length of the buildings, which had the same height, the larger the wind speed between the two buildings. Furthermore, the narrower the building's width, the higher the wind velocity; these outcomes are due to the increase in the Venturi effect. In addition, the correlation coefficient between the results of the wind tunnel test and the CFD analysis was higher than 0.8, which is a very high value.

• Wind and Structures
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• 제18권2호
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• pp.117-134
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• 2014

It is believed that offshore wind farms may satisfy an increasing portion of the energy demand in the next years. This paper presents a comparative study of the fatigue performances of tripod and jacket steel support structures for offshore wind turbines in waters of intermediate depth (20-50 m). A reference site at a water depth of 45 m in the North Atlantic Ocean is considered. The tripod and jacket support structures are conceived according to typical current design. The fatigue behavior is assessed in the time domain under combined stochastic wind and wave loading and the results are compared in terms of a lifetime damage equivalent load.