• 대한전기학회논문지:전력기술부문A
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• 제49권1호
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• pp.1-5
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• 2000

This paper presents a new algorithm to restore the de-energized loads in electric power distribution systems for restoration by utilizing object-based structure and heuristic rules without branch and feeder overloading. In order to cope with a complex network configuration and frequent breaker switching operations in distribution systems, the component of power system is described as objects and the information of system configuration is constructed by connecting objects each other. Such a strategy is developed mainly based on the object search algorithm to increase computation efficiency. As a result, the proposed system has been implemented to efficiently deal with large distribution systems by reducing computational burden remarkably compared with the conventional methods.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 A
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• pp.580-582
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• 2005

This paper presents a new method which applies a genetic algorithm(GA) for determining which sectionalizing switch to operate in order to solve the distribution system loss minimization re-configuration problem. The distribution system loss minimization re-configuration problem is in essence a 0-1 planning problem which means that for typical system scales the number of combinations requiring searches becomes extremely large. In order to deal with this problem, a new a roach which applies a GA was presented. Briefly, GA are a type of random number search method, however, they incorporate a multi-point search feature. Further, every point is not is not separately and respectively renewed, therefore, if parallel processing is applied, we can expect a fast solution algorithm to result.

• Journal of Electrical Engineering and Technology
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• 제7권1호
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• pp.9-16
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• 2012

The present study presents the Phasor Discrete Particle Swarm Optimization (PDPSO) algorithm, an effective optimization technique, the multi-dimensional vectors of which consist of magnitudes and phase angles. PDPSO is employed in the configuration of micro-grids. Micro-grids are concepts of distribution system that directly unifies customers and distributed generations (DGs). Micro-grids could supply electric power to customers and conduct power transaction via a power market by operating economic dispatch of diverse cost functions through several DGs. If a large number of micro-grids exist in one distribution system, the algorithm needs to adjust the configuration of numerous micro-grids in order to supply electric power with minimum generation cost for all customers under the distribution system.

• International Journal of Air-Conditioning and Refrigeration
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• 제16권2호
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• pp.37-43
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• 2008

The air and water flow distributions are experimentally studied for a round header - ten flat tube configuration. Three different inlet orientation modes (parallel, normal, vertical) were investigated. Tests were conducted with downward flow configuration for the mass flux from 70 to $130kg/m^2s$, quality from 0.2 to 0.6, non-dimensional protrusion depth (h/D) from 0,0 to 0.5. It is shown that, for almost all the test conditions, vertical inlet yielded the best flow distribution, followed by normal and parallel inlet. Possible explanation is provided using flow visualization results.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2019년도 춘계학술대회
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• pp.579-581
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• 2019

본 연구에서는 분산 제어와 광 위상 공액이 적용된 링크에서 누적 분산이 지속적으로 증가/감소하는 광전송 링크를 제안하고자 한다. 본 연구에서 제안한 광전송 링크에서 전체 잉여 분산이 -15 ps/nm나 15 ps/nm로 설정된 경우 왜곡된 파장 분할 다중 채널의 보상이 최상으로 이루어지는 것을 확인하였다.

• 대한기계학회논문집B
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• 제24권2호
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• pp.270-279
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• 2000

Recently, according to increase in the requirement of electric power, a thermoelectric power plant equipped with pulverized coal combustion system is highly valued, because coal has abundant deposits and a low price compared with others. For efficient use of coal fuel, most of plant makers are studying to improve combustion performance and flame stability, and reduce pollutants emission. One of these studies is how to control the profile of particle injection and velocity dependant on coal nozzle configuration. Basically, nozzle which has mixed flow of gas and particle is required to have the balanced coal concentration at exit, but it is very difficult to obtain that by itself without help of other device. In this study, coal distribution and pressure drop in gas-solid flow are calculated by numerical method in nozzle with various shapes of venturi diffuser as a means to get even coal particle distribution. The tentative correlations of pressure drop and exit coal distribution are deduced as function of the height, length and reducing angle of venturi from the calculated results. When coal hurner nozzle is designed, these equations are very useful to optimize the shape of venturi which minimize uneven particle distribution and pressure drop within coal nozzle.

• 한국산학기술학회논문지
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• 제9권4호
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• pp.899-904
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• 2008

본 논문은 기존의 해석적인 수법에서 여러 신뢰도 지표가 주로 수용가의 수와 지형적인 영향만을 고려한 단점을 보완하기 위하여, 어느 특정지역의 수용가가 실제로 정전되는 경우를 상정하여 수용가의 정전비용을 계산하여, 이에 의한 영향을 신뢰도 지표 속에 나타내도록 하였다. 즉, 정전비용에 따른 수용가의 중요도를 고려하기 위하여, 수용가의 정전비용 특성을 이용한 새로운 신뢰도 평가지수를 정의하여, 양적인 면에서 뿐만 아니라 질적인 면에서도 가장 경제적으로 신뢰도를 향상시킬 수 있는 특정 계통이나 지역, 설비 등을 선택할 수 있는 새로운 신뢰도 평가수법을 제안하였다.

• 한국산학기술학회논문지
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• 제8권5호
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• pp.1034-1041
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• 2007

본 논문은 저압 감시 기능을 포함하는 개선된 배전자동화시스템 개발에 관한 연구 결과를 소개한 것으로서 연구배경, 시스템 구성, 설계, 시제품 제작, 시험 및 실계통 시범운영 등 전반적인 사항을 설명한다. 개발 시스템은 배전현장에서 별도로 수행 중인 변압기 부하감시, 전압감시 및 정전감시 및 품질감시 업무를 배전자동화시스템에 통합하여 운영함으로써 보다 경제적이고 효율적인 배전망의 운영을 위하여 개발되었다. 시스템 통합을 위한 통신망은 간선망과 지선망을 갖도록 계층적으로 구성하고, 변압기 부하 측의 저압 감시를 위한 단말장치를 새로 개발하였다. 또한, 기존 배전자동화시스템에 저압 감시 기능을 추가하기 위하여 주장치 소프트웨어를 개선하였다. 개발 시스템은 실계통 시범운영을 통하여 설계 및 성능이 검증되었다.

• 천문학회보
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• 제35권2호
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• pp.49.2-49.2
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• 2010

In order to understand the configuration of magnetic field producing a solar penumbral microjet that was recently discovered by Hinode, we performed a magnetohydrodynamic simulation reproducing a dynamic process of how that configuration is formed in a modeled solar penumbral region. A horizontal magnetic flux tube representing a penumbral filament is placed in a stratified atmosphere containing the background magnetic field that is directed in a relatively vertical direction. Between the flux tube and the background field there forms the intermediate region in which the magnetic field has a transitional configuration, and the simulation shows that in the intermediate region magnetic reconnection occurs to produce a clear jet- like structure as suggested by observations. The result that a continuous distribution of magnetic field in three-dimensional space gives birth to the intermediate region producing a jet presents a new view about the mechanism of a penumbral microjet, compared to a simplistic view that two field lines, one of which represents a penumbral filament and the other the background field, interact together to produce a jet. We also discuss the role of the intermediate region in protecting the structure of a penumbral filament subject to microjets.

• Geomechanics and Engineering
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• 제35권5호
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• pp.555-570
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• 2023

In the current study, a series of experimental and analytical evaluations were performed to introduce the horizontal pseudo static coefficient (kh) as a function of the wall configuration and the reinforcement type for analyzing reinforced soil walls. For this purpose, eight shaking table tests were performed on reduced-scale models of integrated and two-tiered walls reinforced by metal strip and geogrid to determine the distribution of dynamic lateral pressure in the walls. Then, the physical models were analyzed using Mononobe-Okabe method to estimate the value of kh required to establish the dynamic lateral pressures similar to those observed in shaking table tests. Based on the results, the horizontal pseudo static coefficient and the position of resultant lateral force (R) were introduced as a function of the horizontal peak ground acceleration (HPGA), the wall configuration, the reinforcement type as well as maximum wall displacement.