• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 추계학술대회 초록집
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• pp.189.2-189.2
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• 2010

The purpose of this study is fatigue damage assessment for large sized casting parts (hub and mainframe) of the 3MW offshore wind turbine by computer simulation. Hub and mainframe durability assessment is necessary because wind turbine have to guarantee for 20 years. Fatigue life evaluation must be considered all of fatigue load conditions as the components are wind load transmission path. Palmgren-Miner linear damage accumulation hypothesis is applied for fatigue life estimation with stress-life approach. S-N curve for the spheroid graphite cast iron EN-GJS-400-18-LT is derived according to durability guidelines. Reduction factors were applied for survival probability, surface roughness, material quality and partial safety factor according to Germanischer Lloyd rules. To calculate fatigue damage, stress tensors, extracted from the unity load calculation from ANSYS is multiplied with time track of fatigue loads extracted from GH bladed. Damage accumulation is performed with all of fatigue load conditions at each finite element nodes. In this study maximum nodal damage value is under 1.0. casted parts are safe. This research was financially supported by the Ministry of Knowledge Economy(MKE), Korea Institute for Advancement of Technology(KIAT) and Honam Leading Industry Office through the Leading Industry Development for Economic Region.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 추계학술대회 초록집
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• pp.151.1-151.1
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• 2010

Natural gas hydrates (NGH) provide 170 gas volumes per unit volume of the medium and are easier to make with moderate pressure and temperature (40 bar at 3 C). Once they form, their preservation temperature is 20 C at 1 bar, which is much milder than the LNG preservation. In case of using the NGH, The small and medium sized gas well has advantages for development because of NGH's these characteristics. According to the cost evaluation report of Gudmundsson in Norway and the research of MES in Japan, the gas well that uses the NGH has a cost saving effect about 10~20% compared LNG. The effect depends on distance and production. However, cost saving and efficiency of liquefaction process is increased by the development of LNG liquefaction technology. Therefore, these factors have to be reflected in economic analysis. The purpose of this research is to compare the cost of Gas Supply Chain according to the transport type, distance and gas reserves. Especially, we consider not only the cost of facility but also the total cost (production cost, transport cost, etc).

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 추계학술대회 초록집
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• pp.84.1-84.1
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• 2010

Since the discovery of the carbon nanotube(CNTs), they have attracted much attention because of unique properties that may impact many fields of science and technology. The considerable properties of CNTs include high surface area, outstanding thermal, electrical conductivity and mechanical stability. However, uniform deposition of Pt nanoparticles on carbon surface remains inaccessible territory because of the inert carbon surface. In this study, we prepared directly oriented CNTs on carbon paper as a catalyst support in cathode electrode. carbon surface was functionalized using aryl diazonium salt for increasing adhesion of Ni particles which is precursor for growing CNTs. For fabricate electrode, CNTs on carbon paper were grown by chemical vapor deposition using Ni catalyst and Pt nanoparticles were deposited on CNTs oriented carbon paper by polyol method. The performance was measured using Proton electrolyte Membrane Fuel Cell(PEMFC). The structure and morphology of the Pt nanoparticles on CNTs were characterized by Scanning electron Microscopy(SEM) and Transmission electron Microscopy (TEM). The average diameter of Pt nanoparticles was 3nm.

• 한국유체기계학회 논문집
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• 제18권4호
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• pp.36-42
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• 2015

This is a study about one of the most widely used hydro machinery all over the world - pump-turbine. The system has an impeller which pumps water to an upper reservoir during the night and the same impeller acts as a runner for turbine mode during the day for providing stable electrical power to the grid. The internal flow analysis is investigated in this study to help understand how the water passes through the passage of the vanes and blades, providing the designer with useful information on the behavior of recirculation flows which could reduce the efficiency of the pump-turbine. The 100 kW pump-turbine model has H = 32 m, $Q=0.336m^3/s$ and $N=1200min^{-1}$. For this study there are 7 blades, 19 stay vanes and 20 guide vanes. From this study, it was observed that this pump-turbine design showed very good internal flow characteristics with no flow separation and no recirculation flows in normal operation mode.

• 한국유체기계학회 논문집
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• 제18권4호
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• pp.49-55
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• 2015

The pumped storage plant operates with quick change of the discharge as well as quick changes between pump mode and turbine mode. This study focuses on the cavitation analysis of a pump-turbine model because in turbo-machinery, cavitation can reduce the performance and shorten service life. The pump-turbine model system consists of 7 blades, 20 stay vanes (including tongue) and 20 guide vanes. This study adopts the Rayleigh-Plesset model as a cavitation model, which illustrates cavitation by using the air volume fraction method. The pump mode and turbine mode at the operating condition of partial loading, normal and excessive loading are analyzed to investigate the cavitation performance of the pump-turbine. It was observed that this pump-turbine design showed very good cavitation characteristics with no cavitation bubbles in all operating conditions. Overall value of air volume fraction of both mode at different operating condition are lower than 1, which confirms low possibility of cavitation occurrence at current situation.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2008년도 춘계학술대회 논문집
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• pp.154-156
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• 2008

A prototype of the desiccant cooling system with a regenerative evaporative cooler was built and tested for the performance evaluation. The regenerative evaporative cooler is to cool a stream of air using evaporative cooling effect without an inc6rease in the humidity ratio. It is comprised of multiple pairs of dry and wet channels and the evaporation water is supplied only to the wet channels. By redirecting a portion of the air flown out of the dry channel into the wet channel, the air can be cooled down to a temperature lower than its inlet wet-bulb temperature at the outlet end of the dry channels. Incorporating a regenerative evaporative cooler eliminates the need for deep dehumidification in the desiccant rotor that is necessary to achieve low air temperature in the system with a direct evaporative cooler. Subsequently, the regenerative evaporative cooler enables the use of low temperature heat source to regenerate the dehumidifier permitting the desiccant cooling system more beneficial compared with other thermal driven air conditioners. At the ARI condition with the regeneration temperature of $60^{\circ}C$, the prototype showed the cooling capacity of 4.4 kW and COP of 0.75.

• 한국재료학회지
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• 제18권11호
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• pp.571-576
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• 2008

The simulation program for solar cells, PC1D, was briefly reviewed and the device modeling of a multicrystalline Si solar cell using the program was carried out to understand the internal operating principles. The effects of design parameters on the light absorption and the quantum efficiency were investigated and strategies to reduce carrier recombination, such as back surface field and surface passivation, were also characterized with the numerical simulation. In every step of the process, efficiency improvements for the key performance characteristics of the model device were determined and compared with the properties of the solar cell, whose efficiency (20.3%) has been confirmed as the highest in multicrystalline Si devices. In this simulation work, it was found that the conversion efficiency of the prototype model (13.6%) can be increased up to 20.7% after the optimization of design parameters.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2005년도 제17회 워크샵 및 추계학술대회
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• pp.405-413
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• 2005

본 연구에서는 3톤/일의 플라스틱 투입량을 기준으로 혼합폐플라스틱으로부터 대체연료유를 생산할 수 있는 소용량 중심의 폐플라스틱 유화설비를 설계 제작하였으며 장기간에 걸친 시운전을 통하여 유화설비의 운전성 평가에 대한 실증연구를 수행하였다. 대상 폐플라스틱으로는 플라스틱 재활용 업체에서 분리 선별된 폴리에틸렌과 폴리프로필렌 그리고 이들을 혼합한 폐플라스틱을 각각 적용하였으며 $400\sim420^{\circ}C$의 분해 운전온도에서 폐플라스틱의 종류에 따른 시운전 평가를 하였다. 본 실증연구로부터 폴리에틸렌의 경우에 있어서는 79%의 재생유 회수율을 그리고 폴리프로필렌의 경우에 있어서는 80%의 재생유 회수율을 각각 얻을 수 있었으며 플라스틱 종류별 안정적인 운전조건을 확보할 수 있었다. 또한 폐플라스틱 투입량에 대한 설계용량과 운전용량과의 비교로부터 약 40$\sim$50%의 설계오차가 발생한 것으로 평가되었으며 이는 유화설비의 설계를 위하여 사용된 혼합폐플라스틱의 부정확한 물성 값에 기인한 것으로 판단된다. 따라서 본 연구로부터 얻은 시운전결과를 바탕으로 설계인자들을 확립하는 과정이 반드시 필요할 것으로 판단된다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2005년도 제17회 워크샵 및 추계학술대회
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• pp.267-275
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• 2005

차세대 재생산성 에너지로 각광을 받고 있는 바이오디젤은 현재 주로 알칼리촉매를 이용하는 화학공정으로 생산하고 있으나 고에너지 요구성이며 대규모 생산시 폐수발생 등 환경오염 유발요인이 있기 때문에 친환경 생물공정의 필요성이 대두되고 있다. 생물촉매 리파제(lipase)를 이용하는 친환경 생물공정은 화학공정에 비해 다양한 장점을 제공하고 있으나 고가의 효소생산 비용문제로 실용화에 어려움이 있다. 따라서 본 연구에서는 저비용의 생물학적 바이오디젤 생산 시스템 구축을 위해 고활성의 효소 개발, 경제적 재조합 대량생산, 반복 재사용을 위한 효소고정화 등을 통해 고효율의 생산반응계를 개발하였다. 우선 바이오디젤 생산공정에 적합한 리파제로서 CalB(Lipase B of Candida antarctica)를 선택하고 분자 진화기술을 이용하여 효소활성을 17배 향상시킨 CalB14를 개발하였다. CalB14를 효모 발현시스템을 이용하여 경제적 대량생산하기 위해 단백질분비를 획기적으로 개선할 수 있는 맞춤형 분비융합합인자기술(TFP technology)을 이용하여 재조합 CalB를 2 grams/liter 수준으로 분비생산하였다. 생산된 효소를 반복 재사용이 가능하도록 다양한 레진에 고정화하였고 최적의 바이오디젤 전환반응용 고정화효소를 개발하였다. 고정화효소를 효율적으로 재사용하기 위해 바이오디젤 생산용 고정상반응기(packed-bed reactor)를 제작하였으며 기질을 12시간내에 95% 이상 바이오디젤로 수십회 이상 반복전환할 수 있는 경제적인 생물학적 바이오디젤 전환 시스템을 구축하였다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2005년도 제17회 워크샵 및 추계학술대회
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• pp.151-164
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• 2005

태양전지는 요구전력의 필요에 따라 직 병렬로 연결하여 태양전지 모듈(solar cell module)로 제품화한다. 태양전지가 실제로 전자제품에 연결해서 사용하기 위해서는 주변장치(BOS, Balance of System)가 사용된다. 또한 일사량의 강도에 따라 불균일한 직류전기가 발생되므로, 태양광발전시스템은 모듈을 직 병렬로 연결한 태양전지 어레이(solar cell array)와 안정된 전기공급을 위한 전력조정기(power conditioning system, 이하 PCS)가 필요하다. 또한 직류가 아닌 교류를 필요로 하는 응용제품에는 직 교류변환장치 인버터(inverter)를 필요로 한다. 본 과제는 전시를 위한 연구개발 목적보다는 태양광 시스템 보급 양산기술에 중심을 두어 태양광 산업경제를 활성화 하고자한다. 따라서 본 과제는 기존에 연구개발과 특수목적 시장 중심인 초고효율 태양전지 개발보다 경제적인 기여도와 파급효과가 크다.