• New & Renewable Energy
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• v.7 no.4
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• pp.58-65
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• 2011

In variable-speed variable-pitch wind turbines, the conventional approach for controlling power-production operation relies on a generator-torque controller and a rotor-collective blade-pitch controller. Both controllers use the generator speed measurement as the sole feedback input. In order to mitigate unwanted excitation of the control system, many filters are adopted. In this study, the characteristics of some filters for signal processing are investigated based on frequency response function. They include low-pass filters, band-pass filters, and notch filters. Especially, this study focuses on design parameters of their filters.

• New & Renewable Energy
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• v.2 no.2 s.6
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• pp.9-15
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• 2006

The application of photovoltaics into building as integrated building components has been paid more attention worldwide. Photovoltaics or solar electric modules are solid state devices, directly converting solar radiation into electricity; the process does not require fuel and any moving parts, and produce no pollutants. And the prefab building method is very effective because the pre- manufactured building components is simply assembled to making up buildings in the construction fields especially the sandwich panel. So, the purpose of this research is to integrated prefab building materials depending on the cooling type of PV modules. It is concluded that the prediction of BIPV system's performance should be based on the more accurate PV module temperature. From the basis of these results on the correlation of temperature and irradiation were obtained.

• New & Renewable Energy
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• v.2 no.2 s.6
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• pp.50-59
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• 2006

An experimental and numerical study is carried out to investigate the performance and the efficiency humidifying Membrane Electrolyte Assembly and having the double-layered catalyst in a fuel cell system which is taken into account the physical and thermal concept. Based on the principals of the problem, the equation of electronic charge conservation equation, gas-phase continuity equation, and mass balance equation are used for the numerical calculation. A unit cell for $200cm^2$ MEA is assembled and measured for finding better operational situation. After finding the optimal condition, 10 cell stacked PEMFC is fabricated. For the performance evaluation, V-I and power curves are examined in detail by changing the condition of humidity, temperature, pressure, thickness of catalyst and oxidant. It is found that the power is maximized around 500W at 80A.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.208-211
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• 2009

제4차 전력수급기본계획(2008-2022)과 제3차 신 재생에너지 기술개발 및 이용.보급계획에 의거하여 전력산업기반기금을 통해 우선 구매되는 풍력발전이 계통한계가격(SMP, System Marginal Price)에 미치는 영향을 점검하였다. 제4차 전력수급기본계획(2008-2022)에서 향후의 전원설비건설계획과 전력수요를 참고하고, 제3차 신 재생에너지 기술개발 및 이용 보급계획에 의거, 풍력발전보급계획을 반영하였다. 발전변동비의 변화는 미래의 화석연료변동에 따를 것으로 보아 명목상승률 3%, 6%, 그리고 8%의 경우를 검토하였다. 현재는 풍력발전용량이 전체발전용량에 비해 미미해서 SMP에 큰 변화를 가져다주지 못하고 있지만 2014년에는 SMP가 결정되는 구간이 LNG발전기에서 유연탄발전기로 옮겨감에 따라 SMP차이가 최대 20.02[\/KWh](발전 비용 명목 상승률8%)에 달하다가 2020년에는 다시 0[\/KWh](발전비용 명목상승률8%)으로 줄어드는 것으로 분석되었다.

• New & Renewable Energy
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• v.1 no.2 s.2
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• pp.11-18
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• 2005

A modular photovoltaic PCS with high-frequency isolation is proposed. The proposed system consists of a SEPIC converter and a full-bridge inverter Using the power slope versus voltage of the PV array, the MPPT controller is proposed that produces a smooth transition to the maximum power point. The dc current of the PV array is estimated without using a dc current sensor The disturbance of the line voltage is detected using a fast sensing technique. Experimental results obtained on a 500W prototype show high performance such as almost unity power factor, $90\%$ power efficiency, $3.6\%$ THD.

• New & Renewable Energy
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• v.5 no.2
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• pp.25-30
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• 2009

The wind tunnel test to identify the acoustic noise source position of the wind turbine blade was conducted in KARI low speed wind tunnel. Microphone array and time-domain beamforming methodology was applied to this study. To reduce the data processing time, a modified beamforming method with a criteria between calculation time step and grid size for rotating angle in the cylinderical coordinate system was proposed. The test results shows that the data processing time to identify the noise source position was reduced to 20% compared with conventional method. And the dominant noise source of the blade moves from inboard to blade tip as the frequency increases.

• New & Renewable Energy
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• v.6 no.3
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• pp.47-54
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• 2010

Foundation plays an important role in the offshore wind turbine system. Different from conventional foundations, the suction caisson is proven to be economical and reliable. In this work, three-dimensional finite element method is used to check the suitability of suction caisson foundation. NREL 5MW wind turbine is chosen as a baseline model in our simulation. The maximum overturning moment and vertical load at the mudline are calculated using FAST and Bladed. Meanwhile the soil-structure interaction response from our simulation is also compared with the experiment data from Oxford university. The design parameter such as caisson length, diameter of skirt and spacing of multipod are investigated. Accordingly based on these parameters suggestions are given to use suction caisson foundations more efficiently.

• New & Renewable Energy
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• v.7 no.1
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• pp.22-28
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• 2011

The surface solar radiations were calculated and analyzed with spatial resolutions (4 km and 1 km) using by GWNU (Gangneung-Wonju National University) solar radiation model. The GWNU solar radiation model is used various data such as aerosol optical thickness, ozone amount, total precipitable water and cloud factor are retrieved from Moderate Resolution Imaging Spectrometer (MODIS), Ozone Monitoring Instrument (OMI), MTSAT-1R satellite data and output of the Regional Data Assimilation Prediction System(RDAPS) model by Korea Meteorological Administration (KMA), respectively. The differences of spatial resolutions were analyzed with input data (especially, cloud factor from MTSAT-1R satellite). And the Maximum solar radiation by GWNU model were found in Andong, Daegu and Jinju regions and these results were corresponded with the MTSAT-1R cloud factor.

• New & Renewable Energy
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• v.3 no.2 s.10
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• pp.3-10
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• 2007

Tidal regime change with general hydrolic condition change is examined, according to Garolim Tidal Power Plant (TPP) operation. Numerical model has been developed for the Yellow and East China Seas region, in order to consider the tidal regime change by the TPP operation. The changes of tidal elevation and tidal current inside the Garolim bay are also investigated in details, along with examining the change of the tidal flat area with operation. The field measurement for the tide and current have been carried out for the validation of the numerical model and for understanding the state of current system in the present state.

• New & Renewable Energy
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• v.4 no.3
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• pp.51-57
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• 2008

The objective of this study is to develop and validate a compressed hydrogen storage system for fuel cell vehicles. The type3 composite cylinder consists of full wrapped composites on a seamless aluminum liner. The key technologies, including design, analysis, and optimized fabrication process for 350bar composite cylinder, were established and verified, and the facilities for fabrication and validation testing have been constructed. Prototype cylinders were fabricated and validated through burst test and ambient cycling test in accordance with international standard.