• 한국생산제조학회지
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• 제21권1호
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• pp.102-108
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• 2012

A study of terahertz waves (T-ray) was made for the nondestructive evaluation of FRP (Fiber reinforced plastics) composite materials. The to-be-used systems were time domain spectroscopy (TDS) and continuous wave (CW). The composite materials investigated include both turbine blades of wind energy (non-conducting polymeric composites) and conducting carbon fiber composites. Terahertz signals in the TDS mode resembles that of ultrasound; however, unlike ultrasound, a terahertz pulse was not able to detect a material with conductivity. This was demonstrated in CFRP (Carbon fiber reinforced plastics) laminates. Refractive index (n) was defined as one of mechanical properties; so a method was solved in order solve the "n" in the material with the cut parts of the turbine blades of wind energy. The defects and anomalies investigated by terahertz radiation were foreign material inclusions and simulated disband. Especially, it is found that the T-ray went through the turbine blade with greater thickness (about 90mm).

• Wind and Structures
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• 제21권6호
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• pp.597-607
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• 2015

With an increasing demand of a renewable energy, new offshore wind turbine farms are being planned in some parts of the world. Foundation installation asks a significant cost of the total budget of offshore wind turbine (OWT) projects. Hence, a cost reduction from foundation parts is a key element when a cost-efficient designing of OWT budget. Mono-piles have been largely used, accounting about 78% of existing OWT foundations, because they are considered as a most economical alternative with a relatively shallow-water, less than 30 m of seawater depth. OWT design standards such as IEC, GL, DNV, API, and Eurocode are being developed in a form of reliability based limit state design method. In this paper, reliability analysis using the response surface method (RSM) and numerical simulation technique for an OWT mono-pile foundation were performed to investigate the sensitivities of mono-pile design parameters, and to find practical implications of RSM reliability analysis.

• 한국산학기술학회논문지
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• 제13권9호
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• pp.4186-4192
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• 2012

풍력발전기가 경제적, 환경적 요인에 따라 대형화, 해상화 되고 있어 접근이 어렵고, 부품 및 유지보수 비용이 증가하고 있다. 풍력발전기 상태 모니터링을 통하여 고장 요소를 최소화 하고, 고장 시 2차 사고를 예방하여 운영유지 및 보수비용을 낮추고 신뢰성을 증가시켜야 한다. 본 논문에서는 IEC 61400-25-2에서 표준으로 추진하는 풍력발전기 모니터링에 적합한 센서 중 실제 풍력발전기 상태 모니터링에 필요한 온도, 습도, 전압, 전류, 풍향, 풍속 센서를 ZigBee 무선 통신 소자와 결합하여 무선 센서노드를 구성하고 이를 이용한 간단한 네트워크를 통하여 센서 신호를 전송한다. 각 무선 센서노드에서 전송되는 신호는 라우터를 통하여 중앙 모니터링 터미널에 전송한다. 또한 LabVIEW로 신호를 수집 및 처리하고, TCP/IP 통신 변환을 통해 인터넷 환경이면 언제 어디서든지 사용자 및 관리자가 모니터링 할 수 있도록 한다.

• 대한기계학회논문집
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• 제16권1호
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• pp.162-174
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• 1992

본 연구에서는 경제성이 있는 GFRP를 사용하여 국내지형과 기상조건에 적합한 소형 풍차날개를 제작하기 위한 효율적인 설계기법을 제시한다. Fig.1에 나타낸 바 와 같이 먼저 재료역학에 바탕을 두고 풍차날개의 기본구조를 결정하고 최종형상은 유 한요소해석을 통해 결정한다.

• 신재생에너지
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• 제6권4호
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• pp.41-49
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• 2010

Over the last decade, wind turbine industry has rapidly increased around world. These days many parts of the wind generators are induction generator. But it has some problems such as gearbox failure, rotor excitation and maintenance. Thus many manufacturers are considered permanent magnet synchronous generator named PMSG and direct drive. PMSG uses NdFeB magnet has many the advantage compare with induction generator. In this study, 3MW class outer rotor type PMSG for wind turbine is proposed. The generator features 2.6m stator outer radius, 1200mm stator length, 81 pole pairs, 14 rated rpm, 42kN/$m^2$ shear force density and 94.2% efficiency. Design and analysis generator using FEM program. Then calculate and derivate no load voltage, losses, conductor temperature. To reduce total harmonic distortion and cogging torque, the stator is applied the stator skewing. And to evaluate the designed generator, compare with other generators by active mass per rating torque and torque density.

• 한국태양에너지학회 논문집
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• 제37권5호
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• pp.1-11
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• 2017

A study on Nacelle Lidar (Light detection and ranging) measurement error and the data reliability verification was carried out at Haengwon wind farm on Jeju Island. For measurement data error processing, the characteristics of Nacelle Lidar measurements were analyzed by dividing into three parts, which are weather conditions (temperature, humidity, atmosphere, amount of precipitation), mechanical movement (rotation of wind turbine blades, tilt variation of Nacelle Lidar) and Nacelle Lidar data availability. After processing the measurement error, the reliability of Nacelle Lidar data was assessed by comparing with wind data by an anemometer on a met mast, which is located at a distance of 200m from the wind turbine with Nacelle Lidar. As a result, various weather conditions and mechanical movement did not disturb reliable data measurement. Nacelle Lidar data with availability of 95% or more could be used for checking Nacelle Lidar wind data reliability. The reliability of Nacelle Lidar data was very high with regression coefficient of 98% and coefficient of determination of 97%.

• 한국전산유체공학회지
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• 제18권3호
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• pp.51-59
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• 2013

A significant change in aerodynamic characteristics of wind turbine blade can occur by ice formed on the surface of the blade operated in cold climate. The ice accretion can result in performance loss, overloading due to delayed stall, and excessive vibration associated with mass imbalance. In this study, the impact of ice accretion on the aerodynamic characteristics of NREL 5MW wind turbine blade sections is examined by a CFD-based method. It is shown that the thickness of ice accretion increases from the root to the tip and the effects of icing conditions such as relative wind velocity play a significant role in the shape of ice accretion. In addition, the computational results are used to assess the degradation in the lift and drag coefficients of the blade sections.

• 전력전자학회논문지
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• 제21권6호
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• pp.497-505
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• 2016

Operating wind turbine generators at maximum power point requires maximum power point tracking (MPPT) control methods. However, conventional methods cannot track the appropriate maximum power point in situations involving wind turbine systems based on a series operation strategy. These systems comprise one or more local maximum power points, and conventional methods can detect only one local maximum power point closed by a current operation point. This study proposes an advanced MPPT method for the series operation strategy of a small, grid-connected wind turbine system. In determining the appropriate maximum point, operations at certain local maximum power points are analyzed. The results show one appropriate point, which is tracked by the proposed MPPT method. The effectiveness of the proposed method is verified by the experimental results.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 춘계학술대회 초록집
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• pp.180.2-180.2
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• 2010

Simulation technology for dynamic analysis of wind turbine is developed. The Aerodyn and the DAFUL are chosen for aerodynamic analysis and multi-body and flexible body dynamics respectively. Subroutines and variables of Aerodyn developed by NREL are analyzed with hub-height wind data, full field turbulent wind data and Airfoil data. The interface to perform coupled analysis between AeroDyn and DAFUL, GUI for modeling several parts of wind turbines are developed. The program will be extended to analyze the coupled analysis of aerodynamic and hydrodynamic behavior for floating offshore wind turbines.

• Journal of international Conference on Electrical Machines and Systems
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• 제2권4호
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• pp.478-485
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• 2013

This paper focuses on the design and control of a new concept for wind turbines with a planetary gearbox to realize a power split. This concept, where the generated wind power is split into two parts, is to increase the utilization of the wind power and may be particularly suitable for large scale off-shore wind turbines. In order to reduce the cost of the power electronic devices, a synchronous generator, which is driven by the planetary gear, is directly connected to the power grid without electronic converter. A servo drive, which functions as the control actuator, is connected to the power grid by a power electronic converter. With small scale power electronic device, the current harmonics can also be reduced. The speed of the main shaft is controlled to track the optimal tip speed ratio. Meanwhile the speed of the synchronous generator is controlled to stay at the synchronous speed. The minimum rated power of the servo motor and the converter, is studied and discussed in this paper. Different variants of the wind turbine with a planetary gear are also compared. The controller for optimal tip speed ratio and synchronous speed tracking is given.