• Journal of Electrical Engineering and Technology
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• 제13권4호
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• pp.1483-1493
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• 2018

Recently, more power facilities are needed to cope with the increasing electric demand. However, the additional construction of generators, transmission and distribution installations is not easy because of environmental problems and citizen's complaints. Under this circumstance, a microgrid system with distributed renewable resources emerges as an alternative of the traditional power systems. Moreover, the configuration of power system changes with more DC loads and more DC installations. This paper is written to introduce an idea of a genetic algorithm-based solution to determine the optimal capacity of the distributed generators depending on the types of system configuration: AC-link, DC-link and Hybrid-link types. In this paper, photovoltaic, wind turbine, energy storage system and diesel generator are considered as distributed generators and the feasibility of the proposed algorithm is verified by comparing the calculated capacity of each distributed resource with HOMER simulation results for 3 types of system configuration.

• 한국에너지공학회:학술대회논문집
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• 한국에너지공학회 1999년도 추계 학술발표회 논문집
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• pp.231-236
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• 1999

This paper is to propose a concept and performance of the gravity engine which could extract energy from sea or river as a clean and renewable and sustainable power, the tidal or hydro-power. The vertical motion of the buoyancy cylinder of the present gravity engine is converted to the mechanical work directly without any hydraulic loss. The increased gravity potential during high tide is harnessed proportional to the length of the buoyancy cylinder times tidal height which is greater than the conventional tidal power using water mill. This energy amplification results from the net energy gain between the resource energy and the imposed energy to extract water out of the buoyancy cylinder. Its efficiency is higher than the conventional water mill due to its direct mechanical conversion.

• 펄프종이기술
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• 제42권5호
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• pp.15-23
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• 2010

Bio-ethanol is the most potential next generation automotive fuel for reducing both consumption of crude oil and environmental pollution from renewable resources such as wood, forest residuals, agricultural leftovers and urban wastes. Lignocellulosic based materials can be broken down into individual sugars. Therefore, saccharification is one of the important steps for producing sugars, such as 6-C glucose, galactose, mannose and 5-C xylose, mannose and rhamnose. These sugars can be further broken down and fermented into ethanol. The main objective of this research is to study the feasibility and optimize saccharification and fermentation process for the conversion of lignocellulosic biomass to low cost bioethanol.

• 펄프종이기술
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• 제42권5호
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• pp.1-14
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• 2010

Bio-ethanol is a promising alternative energy source for reducing both consumption of crude oil and environmental pollution from renewable resources like lignocellulosic biomass such as wood, forest residuals, agricultural leftovers and urban wastes. Based on current technologies, the cost of ethanol production from lignocellulosic materials is relatively high, and the main challenges are the low yield and high cost of the hydrolysis process. Development of more efficient pretreatment technology (physical, chemical, physico-chemical, and biological pretreatment), integration of several microbiological conversions into fewer reactors, and increasing ethanol production capacity may decrease specific investment for ethanol producing plants. The purpose of pretreatment of lignocellulosic material is to improve the accessible surface area of cellulose for hydrolytic enzymes and enhance the conversion of cellulose to glucose and finally high yield ethanol production which is economic and environmental friendly.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2006년도 춘계학술대회
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• pp.292-295
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• 2006

2005년 말 현재, 국내의 상업운전 중인 풍력발전기는 93.5MW(KPX 2005)에 불과하여 민간의 풍력에너지 개발 참여를 위한 사업타당성 조사에서 상업운전에 이르는 풍력발전단지 개발절차에 대한 사례 연구가 미비하다. 최근 신재생에너지 보급을 위한 정부의 강력한 의지와 맞물려 민간의 대규모 풍력발전단지 개발 계획이 속속 진행되고 있는 여건에서, 국내 최초의 대단위 상업용 풍력발전단지인 영덕풍력발전의 개발 및 운영사례를 통해 국내 풍력발전단지 개발 시 고려사항과 발생 가능한 문제점 및 해결방안을 제시한다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2010년도 추계학술대회
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• pp.74-75
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• 2010

As global warming due to burning fossil fuels and natural resource depletion issues have emerged, the development of renewable energy sources such as photovoltaics (PV) has been brought to recent interest. Amongst the vast efforts to harvest and convert solar energy into electricity, the module integrated converters (MIC) has become a worthy topic of research for grid-connected photovoltaic systems. Due to the required high-boosting qualities, only a restricted amount of DC/DC converter topologies can be applied to MICs. This paper investigates the possibility of a tapped-inductor boost converter as a candidate for PV MICs. A dual-inductor interleaving scheme operating slightly above the boundary of the two conduction modes (BCM) is suggested for reduction of input current ripple and minimization of component stress. A digital controller is used for implementation, assuring maximum power tracking and transfer while providing sufficient computational space for other grid connectivity applications, etc. For verification, a 200W converter is designed and simulated via computer software including component losses. High efficiency over a wide power range proves the feasibility of the proposed PV MIC system.

• 한국태양에너지학회 논문집
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• 제33권4호
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• pp.46-50
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• 2013

This paper investigated wind turbine degradation quantitatively by analyzing the short-term operation records of the Shinan Wind Power Plant. Instead of a capacity factor which is needed to be normalized its variability due to monthly wind speed change, this study suggests an analysis method by taking the difference between the theoretical power output calculated from the nacelle wind speed and actual power output as the quantitative index of performance degradation. For three-year SCADA data analysis of the Shinan Wind Power Plant, it was confirmed that power output degradation rate of 0.54% per year. This value is within the average reduction rate 0.4%/year~0.9%/year of normalized capacity factor of the onshore wind power plants in U.K. and Denmark; however, lower than the rate 2%/year of Canadian wind power plants.

• 한국태양에너지학회 논문집
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• 제33권3호
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• pp.1-8
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• 2013

In order to identify positive or negative effect of seawall on wind turbine, a wind tunnel experiment has been conducted with a 1/100 scaled-down model of Goonsan wind farm which is located in West coast along seawall. Wind speedup due to the slope of seawall contributed to about 3% increment of area-averaged wind speed on rotor-plane of a wind turbine which is anticipated to augment wind power generation. From the turbulence measurement and flow visualization, it was confirmed that there would be no negative effect due to flow separation because its influence is confined below wind turbine blades' sweeping height.

• 한국산업융합학회 논문집
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• 제25권1호
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• pp.71-78
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• 2022

With the advent of cutting-edge technology, renewable energy is significantly considered as alternative resources to supply electric power. However, many barriers such as energy intermittency, high initial installation cost, and low-efficiency generation challenged building new infrastructure with clean energy. Efforts reducing greenhouse gas emissions and reliance on fossil fuels resulted in the decentralization of power generation like distributed energy resource (DER). This paper is to introduce and evaluate the feasibility of building-integrated photovoltaics (BIPV) in a high-rise building in Ulsan. To optimize BIPV, a variety of methods to minimize efficiency decrease and maximize electric power generation after installing BIPV on the building's facade are suggested. The variables causing power losses are analyzed. By utilizing System Advisor Model (SAM), actual power generated from solar panels is measured by Thin-film PV, Mono-crystalline PV, and Poly-crystalline PV.

• 통상정보연구
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• 제13권3호
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• pp.119-142
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• 2011

제한된 석유자원으로 인해 세계적으로 석유를 확보하기 위한 경쟁이 치열하게 전개되고 있다. 급속한 경제성장과 정체된 국내석유 생산으로 인해 중국은 1993년 이후 석유 순수입국으로 전환되었다. 따라서 중국은 급속히 증가하는 수요에 대응하기 위해 해외석유자원의 안정적이고 장기적인 확보에 우선순위를 두고 있다. 이를 위해 다양한 전략 예를 들어 해외석유자원개발, 석유수입국의 다변화 등을 취해 왔다. 예를 들어 세계 최고의 외환보유고 2010년 기준으로 3조달러를 보유하고 있는 중국은 이를 활용하여 해외 석유자원 개발을 적극적으로 추진하고 있다. 이 논문은 중국의 해외석유자원개발전략을 분석하고 정책적 시사점을 제시하는 데 있다. 중국은 안정적인 석유확보를 위해 석유 생산국에 차관 공여, 해외 석유개발에 대한 해외직접투자, 석유탐사 및 생산업체의 인수합병 그리고 석유수입국의 지리적 다변화 등의 다양한 정책을 추진해 오고 있다. 또한 중국은 석유자원 확보를 위해 다른 국가와 협력보다는 공격적인 전략을 추진해 왔는데 이는 주변 국가와의 갈등과 자원개발에 대한 비용 급증을 가져왔다. 이제 중국은 장기적으로 협력적 관계를 모색해야 할 뿐만 아니라 재생에너지에 대한 투자를 확대함으로써 미래 지향적인 에너지 자원의 확보를 추진해 나갈 필요가 있다.