• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2004.05a
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• pp.424-428
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• 2004

A wind turbine system converts wind energy into electric energy, the system operated under normal environmental conditions. In case of particular turbulent wind flow such as typhoon, hurricane etc, the control of a blade used to a yaw control and a pitch control method. A small wind turbine has not a speed control system to only a manual tail safety brake. This paper shows a automatic tail safety brake controller based on feedback control using wind velocity. The controller composed of wired motor, relay system, steel wired motor him down a perpendicular to wind flow and then the blade speed reduced high to zero. The operation of automatic tail safety controller verified by manual test.

• Proceedings of the KIPE Conference
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• 2019.07a
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• pp.309-310
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• 2019

현재 화석연료 고갈과 미세 먼지 등의 환경 문제는 전 세계적인 이슈가 되어가고 있으며, 이에 따라 태양광, 풍력 등 신재생 에너지 사용 및 설치가 늘어나고 있다. 반면에, 다양한 분산 전원의 증가로 인해, 계통 불안정 문제 역시 전면에 대두되고 있으며, ESS등 계통 보조 시스템에 대한 관심과 실제 설치는 점점 선택이 아닌 필수적 조건으로 자리잡고 있다. 시장의 확대에 따라, 해당 시스템의 신뢰성과 효율에 대한 관심 역시 증가되고 있으며, 최대한의 성능을 위해 태양광 및 ESS등의 전압은 LV(Low Voltage)의 한계점인 1500V를 달성하였고, 이에 따라 ESS와 PCS역시 해당 전압에서의 동작 및 효율적인 동작 및 설치를 위해 발전하고 있다. 본 논문에서는 이러한 상황에 맞춰 효율적인 PCS 개발을 위한 방안을 제안하도록 한다.

• Prospectives of Industrial Chemistry
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• v.14 no.2
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• pp.10-25
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• 2011

지속적으로 증가하고 있는 에너지 수요에 대처하기 위해 신재생에너지 기술 확보를 위한 노력이 계속되고 있다. 연료전지는 풍력, 태양전지와는 달리 환경적 제약 없이 연속적인 에너지 공급이 가능하여 건물용 분산발전용으로 적합한 요건을 갖추고 있다. 최근 시작된 시범보급 사업으로 건물용 연료전지의 초기 시장 진출이 시작되었고 공공 기관 대체에너지의무화와 그린홈 보급사업 시행으로 시장 확대가 기대된다. 본 논문에서는 건물용 연료전지 시스템의 기본원리와 국내외 개발 동향에 대해 살펴보았으며 핵심부품에 대한 기술개발 현황에 대해 기술하였다.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.8
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• pp.789-798
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• 2013

The procedures and relevant programs developed for analyzing mechanical load data of wind turbine generator systems, which are obtained through type certification tests, are verified. The following issues according to IEC 61400-13 are covered in the developed programs: data validation, time series analysis, summary load statistics, generation of fatigue load spectra, and estimation of equivalent loads. A capture matrix for normal power production is generated to determine whether the collected data sets are sufficient to carry out fatigue analysis. Fatigue load spectra are obtained through the rainflow counting method using 50 load ranges; finally, equivalent loads are calculated using different S-N curve slopes, m, according to the relevant materials. Case studies are performed using aero-elastic simulation data of the NREL 5 MW baseline wind turbine with a monopile foundation.

• Journal of the Korea Convergence Society
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• v.6 no.6
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• pp.177-183
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• 2015

The image information acquired by a model submarine is transmitted through the repeater. The control signal of a position for submarine and its speed is also controlled by the repeater. Shooting images of underwater circumstances are transmitted to the repeater where the received signal controls a position and speed of underwater submarine. This repeater is combined by a buoy that is floating on the surface to relay the signal of image as well as control between a control unit and a submarine whereas the repeater communicates wirelessly with a control unit. Due to wire communication between the repeater and the submarine, the underwater exploration can be smoothly carried out without a risk of loss of a model submarine. Also, connecting to the repeater and control unit wirelessly makes it possible to conduct easily the underwater exploration. The convergence technology that combines a wireless communication and a control as well as a model submarine is designed.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.1
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• pp.1-9
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• 2014

Structural loading on a wind turbine is due to cyclic loads acting on the blades under turbulence and periodic wind field. The structural loading generates fatigue damage and fatigue failure of the wind turbine. The individual pitch control(IPC) is an efficient control method for reducing structural loading. In this paper, we present an IPC design method using Decentralized LQR(DLQR) and Disturbance accommodating control(DAC). DLQR is used for regulating rotor speed and DAC is used for canceling out disturbances. The performance of the proposed IPC is compared with CPC, which was designed with a gain-scheduled PI controller. We confirm the effect of fatigue load reduction with the use of damage equivalent load(DEL).

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.6
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• pp.2971-2978
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• 2013

Recently, with the world-wide issues about global warming and CO2 reduction, a number of distributed generations(DGs) such as photovoltaic(PV) and wind power(WP), are interconnected with the distribution systems. However, DGs can change the direction of the power flow from one-direction to bi-direction, and also change the direction and amount of fault current of existing distribution systems. Therefore, it may cause the critical problems on the power quality and protection coordination. This paper proposes an operation algorithm for bi-directional protection coordination using and apply it for the evaluation system for protection coordination. From the simulation results It is found that the proposed method is more effective and convenient than existing method.

• Journal of the Korean Geosynthetics Society
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• v.14 no.4
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• pp.129-137
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• 2015

Recently, offshore wind farms are increasingly expected, because there are huge resource and large site in offshore. Jeju island has optimum condition for constructing a wind energy farm. Unlike the mainland, Jeju island has stratified structure distribution between rock layers sediments due to volcanic activation. In these case, it can be occur engineering problems in whole structures as well as the safety of foundation as the thickness and distribution of sediment under top rock layer can not support sufficiently the structure. One of the most obvious applications of the pressuremeter test is the solution of the problem of laterally loaded piles. A hyperbolic non-linear p-y criterion for rock is developed in this study that can be used in LPILE program, to predict the deflection, moment, and shear reponses of a shaft under the applied lateral loads. Finally, a comparison between the predicted and measured response at two different sites is shown to give an idea of the accuracy of the IFP method.

• Journal of the Korean Geosynthetics Society
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• v.15 no.1
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• pp.1-10
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• 2016

Recently, offshore wind farms are increasingly expected, because there are huge resource and large site in offshore. Jeju island has optimum condition for constructing a wind energy farm. Unlike the mainland, Jeju island has stratified structure distribution between rock layers sediments due to volcanic activation. In these case, it can be occur engineering problems in whole structures as well as the safety of foundation as the thickness and distribution of sediment under top rock layer can not support sufficiently the structure. In this study, field lateral load test of the pile for analyzing lateral behavior of the offshore wind turbine which is embedded in basalt. After calculating the subgrade resistance and the horizontal deflection from the measured strain to derive p-y curve from the lateral load test results, the subgrade resistance amplifies the error in the process of differentiation and the error of piecewise polynomial curve fitting is the smallest. In order to calculate the horizontal deflection from the measured strain, the six-order polynomial was used.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.10
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• pp.1281-1289
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• 2011

This paper deals with several statistical distribution functions for the analysis of fatigue life data of composite laminates for small wind-turbine blades. A series of tensile tests was performed on triaxial glass/epoxy laminates for loading directions of $0^{\circ}$, $45^{\circ}$, and $90^{\circ}$. Then, fatigue tests were carried out to determine the fatigue life at the aforementioned loading directions and the fatigue stresses at four levels. Two-parameter Weibull, three-parameter Weibull, normal, and log-normal distributions were used to fit the fatigue life data of the triaxial composite laminates. The three-parameter Weibull distribution most accurately described the fatigue life data measured experimentally for all the cases considered. Furthermore, the variation of fatigue life was simultaneously affected by the loading direction and fatigue stress level.