• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.1
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• pp.98-104
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• 2004

This paper represents the fast and efficient load transfer guide for fault or outage restoration in distribution system. For restoration guide, system trace is performed to reverse direction(source side) from tie breaker in tree-structured distribution network. Search space and breaker's combinational number for restoration guide are greatly reduced. It is proposed the load transfer method including first stage restoration(single load transfer, double load transfer, triple load transfer), second stage restoration(transferring load to neighboring feeder in order to expand the capacity margin) and load cutoff guide. The proposed method can be easily applied to primary customer restoration, multi-fault recovery and distribution automation system.

• Journal of Power Electronics
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• v.18 no.5
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• pp.1479-1488
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• 2018

Power packet (PP) distribution system distributes power to different loads that share the same distribution cable in a packetized form. When compared with conventional power systems, a PP distribution system (PPDS) can reduce standby power, eliminate Point-of-Load (PoL) power conversion, and intelligently control the load demand from the source side. Due to the absence of PoL conversion, when multiple power sources at different voltage levels and conditioning requirements jointly send power to various loads at different voltage ratings, the generated voltage has an irregular shape. A large filter at each of the load sides is required to reduce such a large voltage ripple. In this paper, a single-inductor, multiple-input-single-output converter structure based multiple-energy-source mixer is proposed. It combines PP generation, maximum power point tracking (MPPT) of renewable energy sources (RESs) and filtering at the source side. To demonstrate the possible renewable energy integration, a PV panel is used as a power source together with other constant voltage sources. The PV power is approximately tracked using the constant voltage method and it is used for each of the PP generations. The proposed PP distribution system is experimentally verified and it is shown that a conventional PI controller is sufficient for stable system operation.

• Journal of Korean Society of Rural Planning
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• v.11 no.4 s.29
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• pp.93-98
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• 2005

A aggregate size distribution of soils is an important in successful crop production in reclaimed tidelands. The aggregate size distribution for this study were determined of 0.1mm, 0.25mm, 0.5mm, 1.0mm, and 2.0mm by wet sieving method. Agricultural activity, period of reclamation showed significant effects on aggregate size distribution in reclaimed tidelands. Aggregate MWD was greater in SS and KH(above 1.0m) than in YSG, GHD, SMG, and DH(below 0.5mm) reclaimed tidelands and tidelands. The percentage of aggregates less than < 2mm for SMG, GHD, and SM reclaimed tidelands and tidelands were ranged 8.9%, 36.7%, and 38.0%, respectively. The percentage of > 0.1mm aggregates for SMG, GHD, and SM reclaimed tidelands were ranged 9.0%, 26.0%, and 48.9%, respectively. Results indicated that aggregate size distribution of reclaimed tidelands and tidelands under various agricultural systems vary with reclamation period and soil type.

• Journal of computational fluids engineering
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• v.5 no.3
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• pp.8-15
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• 2000

This research is aimed to find out how the inlet angle of secondary air affects the uniformity of temperature distribution inside a small incinerator. A commercial code, PHOENICS, is used to simulate the thermal-flow field of an incinerator. The computational grid system is constructed by Multi-Block technique provided by PHOENICS. Numerical experiments are done with the five different angles of secondary air inlet. The uniformity of temperature distribution is evaluated by checking the standard deviation of temperature distribution in an incinerator. The computational results show that there is the minimum value of standard deviation at the certain angle of secondary air inlet, which means that there is an optimum angle of secondary air inlet that could improve the uniformity of temperature distribution in an incinerator. The optimum angle of secondary air inlet is between 30 degree and 45 degree in this particular case.

• Fashion & Textile Research Journal
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• v.11 no.4
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• pp.602-613
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• 2009

This study aims to improve the fit of middle and high school girls' uniforms. This study researched on the sizing system reflecting their body figures. The results are as follows. First, to classify the middle and high school girls' figures, factor analysis, and cluster analysis were conducted. 4 factors were extracted for upper body of the middle school girls, and 5 factors were extracted for the highschool girls. For the lower body, 3 factors were extracted for both the middle and high school girls. The middle school girls were then divided into 4 groups for the upper body and 4 groups for the lower body. The high school girls were divided into 4 upper and lower body groups. Third, KS size intervals were used for frequency distribution of height and bust for the bodice, height and waist for the lower body. Sizing system of the uniform company and the frequency distribution of sizes were compared. As a result, sizing system of the uniform company and the frequency distribution overlapped very little. Fourth, sizing system considering body type distribution and high frequency distribution of sizes was suggested. As a result when 6 sizes were suggested 30% of the population was covered, and when 11 sizes were suggested 55% of the population was covered.

• Journal of Electrical Engineering and Technology
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• v.11 no.2
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• pp.274-284
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• 2016

The increasing penetration of distributed energy resources on the distribution networks have brought a number of technical impacts where voltage and thermal variations have been identified as the dominant effects. Active network management in distribution networks aims to integrate distributed energy resources with flexible network management so that distributed energy resources are organized to make better use of existing capacity and infrastructure. This paper propose active solutions which aims to solve the voltage and thermal issues in a distributed manner utilizing a collaborative approach. The proposed algorithms have been fully tested on a distribution network with distributed generation units.

• Journal of Electrical Engineering and Technology
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• v.13 no.6
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• pp.2245-2253
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• 2018

With the increase of electrical consumption and the unbalance of power demand and supply, power reserve rate is getting smaller and also the reliability of the power supply is getting deteriorated. Under this circumstance, the electrical energy storage (EES) System is considered as one of essential countermeasure for demand side management. This paper proposes efficient evaluation algorithms of multiple functions for EES systems, especially the secondary battery energy storage systems, in the case where they are interconnected with the power distribution systems. It is important to perform the economic evaluation for the new energy storage systems in a quantitative manner, because they are very costly right now. In this paper, the multiple functions of EES systems such as load levelling, effective utilization of power distribution systems and uninterruptible power supply are classified, and then the quantitative evaluation methods for their functions are proposed. From the case studies, it is verified that EES systems installed at distribution systems in a dispersed manner have multiple functions involved with direct and indirect benefits and also they can be expected to introduce to distribution systems with respects to economical point of view.

• Journal of Advanced Marine Engineering and Technology
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• v.26 no.3
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• pp.313-319
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• 2002

Since the oil crisis in 1970, a great deal of effort has been made to develop automatic electric load sharing systems as a part of the efforts to save energy. A large scale electric generating system composes more than two generators whose characteristics may be different. When such a system is operated individually or in parallel, the lagrange multiplier's method has difficulty in achieving optimal load distribution because generators usually have the limitations of the operating range with inequality constraints. Therefore, a suitable operating mode of generators has to be decided according to the selection of the generators to meet electric power requirements at the minimum cost. In this study, a method which solves the optimal electric load distribution problem using the dynamic programming technique is proposed. This study also shows that the dynamic programming method has an advantage in dealing with the optimal load distribution problem under the limitations of the operating range with inequality constraints including generator operation mode. In this study, generator operating cost curve of second order equation by shop trial test results of diesel generators are used. The results indicate that the proposed method can be applied to the ship's electric generating system.

• Journal of Environmental Impact Assessment
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• v.21 no.5
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• pp.735-743
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• 2012

Since the CBD(Conservation on Biological Diversity)'s 10th Conference of the Parties adopted the protocol on access to genetic resources and benefit sharing in Nagoya 2010, the importance of endangered species studies such as habitat distribution, protection and management have been more emerged. Corylopsis coreana, an endangered species in Korea, was isolated nationally and has been damaged by anthropogenic factors. In this paper, we identified the factors affecting C. coreana habitat at the national scale and regional scale using National Survey of Natural Environment and predicted the distribution of C. coreana. Annual precipitation, precipitation of wettest quarter, temperature seasonality and Digital Elevation Model(DEM) were derived as important factors at the national scale, and precipitation of wettest quarter, DEM and solar radiation on spring were identified as important factors at regional scale. Colylopsis distribution was affected by an effect of climate significantly at the national scale, and by additionally the microclimate and topography at regional scale. These findings will be used as the basis on habitat conservation and restoration plan and climate change.

• Journal of Electrical Engineering and Technology
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• v.3 no.3
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• pp.314-319
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• 2008

Power quality simulation plays an important role in many practical cases, for example, when deciding the capacity of the related mitigation devices, assessing the influence of installing a nonlinear load in the distribution part, dissolving the quality issues between utilities and customers, and so on. For these purposes, many dedicated tools have been used in order to assess the level of quality distortions by various kinds of PQ indices. However, there are few modules that can accurately simulate the flicker phenomenon, that is, $P_{st}$ and the nonlinear and chaotic behavior of the electrical arc furnace, which is one of the representative nonlinear loads. This paper deals with the useful and simple modules for the voltage flicker simulation in the distribution and transmission level under the environment of Matlab/Simulink. With these modules, the various conditions of distribution systems and the capacities of arc furnaces with the chaotic characteristic can be easily taken into account.