• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.113-116
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• 2007

The fuel cell which converts directly chemical energy of fuel into electric energy has higher efficiency than the conventional power generation which involves several additional processes. Especially, polymer electrolyte membrane fuel cell (PEMFC) of which the electrolyte is a thin proton conductive polymer membrane is affordable for portable power applications and small-scale distributed power generation including household and small building. It is very important to not only increase the efficiency of FC itself but determine the optimal operation mode. The optimal operational planning of lkW household PEMFC system based on the daily electricity and heat demand patterns was performed. The estimated economic gain was up to 20% by adoption of PEMFC system.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.5
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• pp.596-603
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• 2013

The increase of distributed power generation is closely related to interest in microgird including renuable energy sources such as photovoltaic (PV) systems and fuel cell. By the growing interest of microgrid all over the world, many studies on microgrid operation are being carried out. Especially operation technique which is core technology of microgrid is to supply heat and electricity energy simultaneously. Optimal microgrid scheduling can be established by considering CHP (Combined Heat and Power) generation because it produce both heat and electricity energy and its total efficiency is high. For this reason, CHP generation in microgrid is being spotlighted. In the near future, wide application of microgrid is also anticipated. This paper proposes a mathematical model for optimal operation of microgrid considering both heat and power. To validate the proposed model, the case study is performed and its results are analyzed.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1750-1752
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• 2005

This paper presents a variable speed wind generation system where fuzzy logic controllers is used as efficiency optimizer. The fuzzy logic controller increments the machine flux by on-line search to improve the generator efficiency in case of light load. The speed of the induction generator is controlled according to the variation of the wind speed in order to produce the maximum output power The generator reference speed is adjusted according to the optimum tip-speed ratio. The complete control system has been developed by simulation study.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.10
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• pp.1540-1546
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• 2017

In piezoelectric device applications, it is important to improve a system efficiency because of the low generated power. In this paper, an optimal driving method is proposed to improve a system efficiency for a piezoelectric energy harvesting system. The proposed method considers disappear energy in input capacitors and the converter efficiency according to the input voltage magnitude to minimize energy losses. Experimental results based on various energy generation cases verify that the proposed method significantly improves the system efficiency; the efficiency is approximately 9.97% higher than that of the conventional method.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.10a
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• pp.924-925
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• 2014

This paper present a method of GRM constant generation in case of prime number P=3 over finite fields. Also we discuss the method which is the optimal GRM generation compare with polarity. The proposed method is the efficiency and optimization compare with earlier method.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.7
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• pp.20-25
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• 2010

With the diversification of distribution facilities, existing distributed generation can be subdivided into Microgrids, which are smaller units for application. These Microgrids, subdivided as such and connected to distribution systems, should operate under driving plans that will ensure their economic efficiency and, accordingly, the configuration of those distribution systems that include Microgrids should also be changed. The perception of the necessity to secure the economic efficiency of distribution systems is gradually increasing and studies intended to assess the economic efficiency of Microgrids and Smartgrids are ongoing. In this paper, the power generation capacity of an economically operative Microgrid was calculated using the MonteCarlo simulation, which is a method based on the probability theory considering the power generation cost of Microgrids linked with power supply systems and reverse sales costs, etc., and an optimum distribution systems was configured based on the results of these calculation.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.1
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• pp.162-168
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• 2009

This thesis is based on the research and experiment of the optimal efficiency generation of electric power. The research and experiment were conducted to search the optimal generation of electric power from a specific amount of solar energy from Photovoltaic Power System with a solar position tracker were used. The changes in the array angles and spacing of the PV Module were also taken into account as well. Here are the findings and the conclusions. First of all, based on experiment using the various anglers, the efficiency generation of electric power increased to a maximum of approximately $12{\sim}17$[%] more at the PV module inclination angle of 30[$^{\circ}$] than at the inclination angles of 20[$^{\circ}$] and 40[$^{\circ}$]. As a result, we have found that installing the PV module inclination at the angle of 30[$^{\circ}$] brought about the most efficient conversion effect of the Photovoltaic Power System. But, when the solar cell is installed on a roof or rooftop where snow builds up, it is the most appropriate to install the solar energy at an 35[$^{\circ}$] angle so that snow slides down and not build up on the module.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.5
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• pp.683-689
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• 2012

Photovoltaic(PV) system is one of power generation systems. Solar light in PV system is like the fuel of the car. The quantity of electricity generation, therefore, is fully dependent on the available quantity of solar light on the system of each site. If a utility can predict the solar power generation on a planned site, it may be possible to set up an appropriate PV system there. It may be also possible to objectively evaluate the performances of existing solar systems. Based on the theories of astronomy and meteorology, in this paper, Perez model is simulated to estimate the available quantity of solar lights on the prevailed photovoltaic systems. Consequently the conditions for optimal power generation of each PV system can be analyzed. And the maximum quantity of power generation of each system can be also estimated by applying assumed efficiency of PV system. Perez model is simulated in this paper, and the result is compared with the data of the same model of Meteonorm. Simulated site is Daejeon, Korea with typical meteorological year(TMY) data of 1991~2010.

• Journal of Electrical Engineering and Technology
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• v.11 no.6
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• pp.1590-1599
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• 2016

The installation of distributed generation (DG) in the electrical networks has numerous advantages. However, connecting and disconnecting of DGs (CADD) leads to some problems in coordination of protection devices due to the changes in the short circuit levels in the different points of network. In this paper, an adaptive method is proposed based on available setting groups (SG) of relays. Since the number of available SG is less than possible CADD states, a classifying index (CI) is defined to categorize the several states in restricted setting groups. Genetic algorithm (GA) with a suitable objective function (OF) is used as an optimization method for the classification. After grouping, a modified coordination method is applied to achieve optimal coordination for each group. The efficiency of the proposed technique is demonstrated by simulation results.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.7
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• pp.3100-3116
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• 2016

With the rapid development of urban traffic system and fast increasing of vehicle numbers, the traditional centralized ways to generate the source-destination shortest path in terms of travel time(the optimal path) encounter several problems, such as high server pressure, low query efficiency, roads state without in-time updating. With the widespread use of smart cameras in the urban traffic and surveillance system, this paper maps the optimal path finding problem in the dynamic road network to the shortest routing problem in the smart camera networks. The proposed distributed optimal path generation algorithm employs the delay routing and caching mechanism. Real-time route update is also presented to adapt to the dynamic road network. The test result shows that this algorithm has advantages in both query time and query packet numbers.