• Korean Journal of Agricultural Science
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• v.38 no.2
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• pp.349-360
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• 2011

The international oil price have being fluctuated due to the exhaustion of fossil energy problem became big social issue. Rural villages are relatively sensitive to the energy problem, reflecting the characteristics of rural sustainable and stable introduction of renewable energy sources that are available is essential. In addition, through the influx of young workers in rural areas to regain vitality, efforts to improve rural living environment has been under the rural newtown project. In this study, a survey aimed at rural dwellers through the AHP, interview to report of realization about renewable energy and review the current policies. The results of realization survey though AHP are as follows, (1) the advantage of the natural environment (2) the superiority of government supporting policy and being economic, (3) easy to use, (4) ecologically stable, and (5) policy stable, respectively. In addition, renewable energy sources among the inhabitants of rural areas by solar energy was the highest score. The impact of regional characteristics compared with other energy sources receive little, easy to apply and has already been considerable technological development is considered.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.9
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• pp.1808-1818
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• 2015

Recently, the wind power has experienced great attentions and growths among many renewable energy sources. To increase the power generation performance and economic feasibility, the size of wind turbine (WT) is getting bigger and most of wind power plants are being constructed on offshore. Therefore, the maintenance cost is relatively high because boats or helicopters are needed operators to reach the WT. In order to combat this kind of problem, remote monitoring and control system for the WT is needed. In this paper, the small-scale WT monitoring and control system is implemented using wireless sensor network technologies. To do this, sensor devices are installed to measure and send the WT status and control device is installed to receive control message for specific operation. The WT is managed by control center through graphic user interface (GUI) based monitoring and control software. Also, smart device based web-program is implemented to make the remote monitoring of the WT possible even though operators are not in control room.

• The Transactions of the Korean Institute of Power Electronics
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• v.11 no.3
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• pp.258-265
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• 2006

In this paper, an active clamping sepic-flyback converter has been proposed, which is suitable for a fuel cell based power generation system. The proposed converter is superposition of sepic converter mode and flyback mode. It has outstanding high boosting output voltage, component utilization and high efficiency characteristics under the inherently severe low output voltage of the fuel cell generator. In this paper, the validity of the proposed converter has been verified by the informative simulation and experimental results that make used of the PEMFC.

• Journal of Advanced Marine Engineering and Technology
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• v.36 no.8
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• pp.1136-1142
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• 2012

With concern for new renewable energy sources rising, the offshore wind turbine energy market is growing. In order to install offshore wind turbines safely in a harsh environment, jack-up rigs need to be used. Recently, a WTIV(Wind Turbine Installation Vessel), which has a self-propelling system, was developed to replace traditional jack-up rigs. Since the jack-up rig works at 60 meters of depth in offshore and the seafloor is composed mostly of soft clay and sand, it is necessary to conduct a stability examination for ground subsidence before using it. This study conducts an improved numerical analysis of the effect of jack-up rig loading on the soft ground by using FLAC3D considering consolidation theory. This includes analyzing the amount of subsidence when applying different cases of surchargings. It can be concluded that the mid-loading method has an advantage as regards clay layers and the pre-loading method has an advantage as regards sand layers.

• Journal of Korean Society on Water Environment
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• v.26 no.5
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• pp.754-760
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• 2010

This study was carried out not only to evaluate optimal operating condition to increase biogas production, but also to estimate feasibility of renewable energy from anaerobic digester of sewage sludge. Semi- continuous Fed and Mixed Reactors (SCFMRs) were operated in various condition to quantify the reactor variables. The result of SCFMR operation showed that the biogas productivity and total volatile solids (TVS) removal of total solids (TS) 4% reactor at hydraulic retention time (HRT) 20 days with Organic Loading Rate (OLR) of $1.45kg/m^3-d$ were $0.39m^3/m^3-d$ and 26.7%, respectively which was two times higher than that of TS 2.5% reactor. Consequently the daily biogas production of $20,000m^3$ would be possible from the total volume of $52,000m^3$ of anaerobic digesters of the municipal wastewater treatment plant in D city. In feasibility study for the Biogas utilization, combined heat and power system (CHP) and CNG gasification were examined. In case of CHP, the withdrawal period of capital cost for gas-engine (GE) and micro gas-turbine (MGT) were 7.7 years and 9.1 years respectively. biogas utilization as Clean Natural Gas (CNG) shows lower capital cost and higher profit than that of CHP system. CNG gasificaion after biogas purification is likely the best alternative for Biogas utilization which have more economic potential than CHP system. The withdrawal period of capital cost appeared to be 2.3 years.

• Journal of Ocean Engineering and Technology
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• v.26 no.4
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• pp.37-41
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• 2012

Due to global warming, the need to secure alternative resources has become more important nationally. Because of the very strong current on the west coast, with a tidal range of up to 10 m, there are many suitable sites for the application of TCP (tidal current power) in Korea. In the southwest region, a strong current is created in the narrow channels between the numerous islands. A rotor is an essential component that can convert tidal current energy into rotational energy to generate electricity. The design optimization of a rotor is very important to maximize the power production. The performance of a rotor can be determined using various parameters, including the number of blades, shape, sectional size, diameter, etc. There are many offshore jetties and piers with high current velocities. Thus, a VAT (vertical axis turbine) system, which can generate power regardless of flow direction changes, could be effectively applied to cylindrical structures. A VAT system could give an advantage to a caisson-type breakwater because it allows water to circulate well. This paper introduces a multi-layer vertical axis tidal current power system. A Savonius turbine was designed, and a performance analysis was carried out using CFD. A physical model was also demonstrated in CWC, and the results are compared with CFD.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.380-381
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• 2011

전력거래소는 2014년 나주본사이전 이후 1억kW 대용량 전력계통을 운영하기 위한 차기 계통운영시스템(이하 차기EMS) 구축을 계획하고 있다. EMS(Energy Management System)는 전국의 발, 변전소에서 계통정보를 실시간으로 취득하여 전력계통을 감시하며, 연료비 기반의 최적 경제점을 찾아 발전기를 제어하고, 전력계통을 수식화한 상태추정 결과를 기반으로 상정사고분석, 고장전류계산 등 전력계통운영을 위한 종합시스템이다. 국내 EMS의 역사는 1979년 미국의 L&N 시스템 도입을 시작으로 1988년 일본의 Toshiba EMS, 2001년 Alstom사의 NEMS를 구축하여 현재 운영중에 있다. 하지만, 외산 제품 도입에 따른 기술이전, 유지보수의 어려움을 타개하기 위해 2004년 한국형 EMS(이하 K-EMS) 연구개발계획을 수립하고 전력거래소를 주축으로 한 산학연을 구성하여 2010년 K-EMS 개발을 성공적으로 완료하였다. 차기 EMS는 국내 기술력으로 개발된 정부연구과제 성과물인 K-EMS를 기반으로 구축이 이루어지며, 총 3년간의 개발 및 시험과정을 거쳐 실계통운영을 담당할 예정이다. 차기EMS가 설치되어 운영예정인 급전소는 전력수급 균형유지와 발전소 운영 총괄 지휘 및 765kV, 345kV 송전망 운영역할을 담당할 나주급전소와 154kV 비수도권 송전망 운영을 담당할 천안급전소, 154kV 수도권 송전망 운영을 책임질 서울급전소 이상 3곳이다. 차기EMS는 발전 및 송, 변전 설비의 대형화, 다양한 FACTS 설비, 신재생에너지원으로 대표되는 분산전원의 등장과 같은 급변하는 전력계통 변화에 능동적인 역할을 성공적으로 수행할 것으로 기대하고 있다.

• Journal of the Korean Applied Science and Technology
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• v.29 no.3
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• pp.516-530
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• 2012

Gasohol which is the mixture of gasoline and ethanol, is used to gasoline vehicles worldwide currently. This study is performed by the methods of the review of references, and includes the background introduced, manufacturing processes, amounts produced, original properties, specifications, ways of applied currently, regulations and policies as a fuel for gasoline vehicles on individual countries through the scope of worldwide, especially focused on bioethanol and gasoline. By the reason above, it is prepared by focused on multiple angles for the person who want to getting information and searching desired ways in the future regarding to bioethanol and gasohol. It is concluded that gasohol is one of the useful renewable energies, and must to take a step forward by the approaching of multiple points, and finally showed some directions by the way of comparing of the situations and references nowaday.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.7
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• pp.258-264
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• 2018

This paper presents application of a differential search (DS) meta-heuristic optimization algorithm for optimal operation of a micro grid system. The DS algorithm simulates the Brownian-like random-walk movement used by an organism to migrate. The micro grid system consists of a wind turbine, a diesel generator, a fuel cell, and a photovoltaic system. The wind turbine generator is modeled by considering the characteristics of variable output. Optimization is aimed at minimizing the cost function of the system, including fuel costs and maximizing fuel efficiency to generate electric power. The simulation was applied to a micro grid system only. This study applies the DS algorithm with excellence and efficiency in terms of coding simplicity, fast convergence speed, and accuracy in the optimal operation of micro grids based on renewable energy resources, and we compared its optimum value to other algorithms to prove its superiority.

• The Journal of the Korea Contents Association
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• v.16 no.11
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• pp.488-498
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• 2016

Much of the information is stored as data, research has been activated for analyzing the data and predicting the special circumstances. In the case of power data, the studies, such as research of renewable energy utilization, power prediction depending on site characteristics, smart grid, and micro-grid, is actively in progress. In this paper, we propose a power prediction model using the substation environment data. In this case, we try to verify the power prediction result to reflect the multiple arguments on the power and weather data, rather than a simple power data. The validation process is the effect of multiple factors compared to other two methods, one of power prediction result considering power data and the other result using power pattern data that have been made in the similar weather data. Our system shows that it can achieve max prediction error of less than 15%.