• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 춘계학술대회 초록집
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• pp.59.1-59.1
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• 2011

In this research, CFD calculation was implemented to analyze wind tunnel effect or rotor experiment in wind tunnel. One case included model wind turbine and all wind tunnel geometries. The other case include only rotor and nacelle system. Star-CCM+ was used for CFD analysis and rigid body motion around rotor area was applied to simulate rotating rotor. As for turbulence model, K-omega SST was used. The results were compared in 15m/s inflow condition. These results shows a good agreement with the measurement. Then, the result without wind tunnel was slightly different to the result with wind tunnel. Thus, in the case of Mexnex wind tunnel measurement, the wind tunnel don't affect the measurement result. Then, this wind tunnel and rotor size ratio can be reference for wind tunnel experiment of wind turbine rotor.

• 한국태양에너지학회 논문집
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• 제33권4호
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• pp.39-45
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• 2013

This paper presents the estimation of minimum BESS capacity for regulating the output of wind farms considering power grid operating condition in Jeju Island. To analyze the characteristics of wind farm outputs with a BESS, the real data of wind farms, Sung-San, Sam-dal and Hang-Won wind farm, located in the eastern part of Jeju island is considered. The wind farms are connected to Sung-san substation to transfer the electric power to Jeju power grid. Consequently, at PCC (Point of Common Coupling), it can see a huge wind farm connected to the substation and thus it can be expected that the smoothing effect is affected by not only the different wind speeds for each area but also the different mechanical inertia of wind turbines. In this paper, two kinds of simulation have been carried out. One is to analyze the real data of wind farm outputs during a winter season, and the other is to connect a virtual BESS to eliminate the unintended generating power changes by the uncontrolled wind farm outputs as shown in the former data. In the conclusion, two kinds of simulation results show that BESS installed in the substation is more efficient than each wind farms with BESS, respectively.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2010년 춘계학술대회논문집
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• pp.5-9
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• 2010

A numerical wind tunnel simulation is performed in order to predict wind loads acting on a building. The aim of the present study is to suggest a guideline for the numerical wind tunnel analysis, which could provide more detail wind load distributions compared to the wind code and expensive wind tunnel experiments. To validate the present numerical simulation, wind-induced loads on a 6 m cube model is predicted. Atmospheric boundary layer is used as a inlet boundary condition. Various effect of numerical methods are investigated such as size of computational domain, grid density, turbulence model and discretization scheme. The appropriate procedure for the numerical wind tunnel analysis is suggested through the present study.

• Journal of Electrical Engineering and Technology
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• 제12권2호
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• pp.689-700
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• 2017

This paper presents an effective approach for wind turbine (WT) condition assessment based on the data collected from wind farm supervisory control and data acquisition (SCADA) system. Three types of assessment indices are determined based on the monitoring parameters obtained from the SCADA system. Neural Networks (NNs) are used to establish prediction models for the assessment indices that are dependent on environmental conditions such as ambient temperature and wind speed. An abnormal level index (ALI) is defined to quantify the abnormal level of the proposed indices. Prediction errors of the prediction models follow a normal distribution. Thus, the ALIs can be calculated based on the probability density function of normal distribution. For other assessment indices, the ALIs are calculated by the nonparametric estimation based cumulative probability density function. A Back-Propagation NN (BPNN) algorithm is used for the overall WT condition assessment. The inputs to the BPNN are the ALIs of the proposed indices. The network structure and the number of nodes in the hidden layer are carefully chosen when the BPNN model is being trained. The condition assessment method has been used for real 1.5 MW WTs with doubly fed induction generators. Results show that the proposed assessment method could effectively predict the change of operating conditions prior to fault occurrences and provide early alarming of the developing faults of WTs.

• 한국항해항만학회지
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• 제46권6호
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• pp.491-500
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• 2022

큰 상부 형상을 가지는 FLNG (Liquefied Natural Gas Floating Production Storage Offloading Units, LNG FPSOs) 등의 해양구조물은 안정적인 운동성능 확보 및 계류라인 설계에 있어 정도 높은 풍하중 추정이 필수적이다. 따라서 본 연구의 목적은 FLNG의 풍하중 추정을 위한 수치해석 기법을 개발하는 데 있다. 특히, 본 연구에서 개발한 수치해석 기법은 저자의 이전연구를 FLNG에 맞추어 수정하였다. 풍하중 추정을 위한 수치해석은 15° 간격으로 0-360° 범위에서 균일 풍속 조건과 풍속 프로파일을 적용한 NPD (Norwegian Petroleum Directorate) 조건에서 수행하였다. 먼저, NPD 모델 풍속 프로파일 모델 개발을 위해 Sand-Grain Roughness 변화에 따른 풍속 프로파일을 분석하였다. 개발된 NPD 모델을 이용하여 3가지 풍향 (Head, Quartering & Beam)에 대한 메쉬 수렴성 시험을 수행하였다. 최종적으로 개발된 NPD 모델과 메쉬를 이용하여 균일한 풍속 조건과 NPD 조건에서의 풍하중을 평가하고 비교하였다. 본 연구에서는 RANS (Reynolds-averaged Navier-Stokes) 기반 Solver인 STAR-CCM+ (17.02)를 이용하였다. 결과를 요약하면, 풍속 프로파일을 적용한 NPD 모델에서의 풍하중은 균일 풍속(10m/s) 조건과 비교하여, Surge와 Yaw 하중이 최대 20.35 % 와 34.27% 증가하였다. 특히, 특정 일부 구간에서만 큰 하중의 차이를 보인 Sway (45°< α < 135°, 225°< α < 315°)와 Roll (60° < α < 135°, 225° < α < 270°)은 구간별 평균 증가율이 15.60%와 10.89% 수준으로 나타났다.

• 한국소음진동공학회논문집
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• 제27권1호
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• pp.20-27
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• 2017

This study investigated the problems in current practice of drive-train resonance analysis procedure and suggested solutions. The first problem is the resonance occurrence at the un-identified resonance point by the current practice, as for a solution the force spectrum analysis for each critical force transmitting component was suggested. The second one is the inaccurate estimation of potential resonance point in eigenfrequency analysis because of the non-consideration about the eigenfrequency dependency on rotor-speed, the fine linearization at each rotor speed point all over operational range was proposed to account for the affection. Lastly the insufficient time for resonance activation under run-up simulation condition was recognized as a problem in resonance load increasing analysis, as an alternative, steady state condition was suggested to estimate the maximum load increasing level.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• 제4B권3호
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• pp.146-152
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• 2004

Cost effective simulation schemes for Wind Power Generation Systems (WPGS) considering wind turbine types, generators and load capacities have been strongly investigated by researchers. As an alternative, a true weather condition based simulation method using a real-time digital simulator (RTDS) is experimented in this paper for the online real-time simulation of the WPGS. A stand-alone WPGS is, especially, simulated using the Simulation method for WPGS using Real Weather conditions (SWRW) in this work. The characteristic equation of a wind turbine is implemented in the RTDS and a RTDS model component that can be used to represent any type of wind turbine in the simulations is also established. The actual data related to weather conditions are interfaced directly to the RTDS for the purpose of online real-time simulation of the stand-alone WPGS. The outcomes of the simulation demonstrate the effectiveness of the proposed simulation scheme. The results also signify that the cost effective verification of efficiency and stability for the WPGS is possible by the proposed real-time simulation method.

• 한국환경보건학회지
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• 제16권2호
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• pp.21-29
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• 1990

This study investigated to find out the patterns of the wind direction and wind speeds influenced by concentration of sulfur dioxide in Taegu area for a year in 1988.The results were as follows: Prevailing wind by months where easterly wind from May to September and the other months were westerly and / or west-north-westerly wind. Condition of calm was the most at December(8.6%). Prevailing wind by seasons were westerly and easterly wind in spring and autumn, east-north-easterly and/or west-south wind in summer, the other hand, west-south-westerly and/or west-north-westerly wind in winter. Mean concentration of sulfur dioxide (SO$_{2}$) at each sites were influenced by prevailing wind and location of industrial estates. Mean wind speeds by times were the highest at the before and after 4 P.M.,but the lowest at the before and after 5 A.M. Average wind velocity were highest at Spring (3.38m / sec).

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2008년도 추계학술대회 논문집
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• pp.262-267
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• 2008

The long-term wind data are reconstructed from the short-term meteorological data to design the 4 MW offshore wind park which will be constructed at Woljeong-ri, Jeju island, Korea. Using two MCP (Measure-Correlate-Predict) models, the relative deviation of wind speed and direction from two neighboring reference weather stations can be regressed at each azimuth sector. The validation of the present method is checked about linear and matrix MCP models for the sets of measured data, and the characteristic wind turbulence is estimated from the ninety-percent percentile of standard deviation in the probability distribution. Using the Gumbel's model, the extreme wind speed of fifty-year return period is predicted by the reconstructed long-term data. The predicted results of this analysis concerning turbulence intensity and extreme wind speed are used for the calculation of fatigue life and extreme load in the design procedure of wind turbine structures at offshore wind farms.

• 한국산학기술학회논문지
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• 제17권4호
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• pp.734-742
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• 2016

최근 21세기에 접어들어 무분별한 발전의 결과로 석탄, 석유 등의 화석연료가 고갈되고 있으며, 지구 온난화가 진행중이다. 이미 유럽과 미국 등의 선진국에서는 신재생 에너지 분야에 관심을 갖고 있으며, 그 중에서도 풍력에너지가 많은 관심을 받고 있다. 풍력발전타워는 운용 중 주기적인 하중의 발생으로 만들어지는 주파수를 회피하여 설계를 해야 한다. 일반적으로 구조해석 과정 시 지반을 고정단 경계조건으로 해석한다. 하지만, 고정단 경계조건의 경우 지반 조건 상호작용을 고려하지 못하여 목표 진동수를 벗어나게 된다. 본 연구에서는 용량 별 지반경계 조건 및 기초의 근입깊이를 고려한 고유진동수 효과를 연구하였으며, 변수에 따른 차이를 확인하였다. 결과적으로 고정단 경계조건 모델은 지반조건과 근입깊이의 영향을 받지 않으며, Coupled Spring 경계조건 모델은 지반조건에는 영향을 받지만, 근입깊이에는 영향을 받지 않는다. Winkler Spring 경계조건의 경우에는 지반조건과 근입깊이에 모두 영향을 받는다. 하지만, 얕은 깊이의 지반에서는 지반조건의 영향을 받지 않으므로 Coupled Spring 경계조건 모델을 활용한 지반조건 별 해석을 수행하는 것이 효과적이다.