• 대한전기학회:학술대회논문집
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• 대한전기학회 1990년도 하계학술대회 논문집
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• pp.154-157
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• 1990

This paper describes a new method of calculating expected energy generation and loss of load probability (L.O.L.P) for electric power system operation and expansion planning. The method represents an equivalent load duration curve (E.L.D.C) as a mixture of cumulants approximation (M.O.C.A), which is the general case of mixture of normals approximation (M.O.N.A). By regarding a load distribution as many normal distributions-rather than one normal distribution-and representing each of them in terms of Gram-Charller expansion, we could improve the accuracy of results. We developed an algorithm which automatically determines the number of distribution and demarcation points. In modelling of a supply system, we made subsets of generators according to the number of generator outage: since the calculation of each subset's moment needs to be processed rapidly, we futher developed specific recursive formulae. The method is applied to the test systems and the results are compared with those of cumulant, M.O.N.A and Booth-Baleriaux method. It is verified that the M.O.C.A method is faster and more accurate than any other methods.

• 전기학회논문지P
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• 제55권2호
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• pp.67-72
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• 2006

Most of the load distributions in low voltage power feeder distribution systems are designed with approximately balanced and connected at the three phase four wire systems. However, in the user power distribution systems, most of the loads are single & three phase and unbalanced, generating load unbalance. Load unbalance factor is mainly affected by the impedance of load system. Unbalanced current will draw a highly unbalanced voltage. This paper presents a new calculation method for unbalance factor under the load variation at the three phase four wire system. Load unbalance factor is measured by the power quality measurement apparatus and compared with the current unbalance factor. Two methods are indicated similar results.

• Steel and Composite Structures
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• 제27권5호
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• pp.623-632
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• 2018

Performance-Based Plastic Design (PBPD) method has been recently developed to evaluate the behavior of structures in different performance levels. The PBPD method utilizes a base shear force and a lateral load pattern that are estimated based on energy and yielding mechanism concepts. Using of current lateral force pattern results in weak structural members in upper stories of a structure so that the values of the story drift in these stories are larger than the target drift, particularly in high-rise buildings. Therefore, such distribution requires modifications to overcome this drawback. This paper proposes a modified lateral load pattern for steel Eccentrically Braced Frames (EBFs) based on parametric study. In order to achieve the modified load pattern, a group of 26 EBFs has been analyzed under a set of 20 earthquake ground motions. Additionally, results of nonlinear dynamic analyses of EBFs have been post-processed by nonlinear regression analysis in order to derive the new load pattern. To prove the efficiency of present study, three EBFs as examples were designed by modified pattern and current PBPD distribution. Inelastic dynamic analyses results showed that the story drifts using modified lateral load pattern were well within the target values in comparison with current pattern in PBPD, particularly where the effect of the height is significant. The modified load pattern reduces the possibility of underdesigning in upper levels and overdesigning in lower levels of the frames.

• 한국지진공학회논문집
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• 제8권1호
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• pp.39-58
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• 2004

성능에 기초한 내진설계 분야에서 구조물의 내진성능평가를 위해서는 비탄성 지진거동을 보다 정확하게 예즉할 필요가 있다. 성능기초 설계기준에 반영되어 있는 내진성능 평가 방법 가운데 하나인 pushover해석을 이용한 방법은 몇몇 연구자들에 의하여 다양한 해석 방법론이 개발되었다. 이 방법을 사용하여 비탄성 전체 또는 국부적 지진응답을 보다 정확하게 평가하기 위해서는 사용되는 횡하중 분배가 구조시스템과 지반운동의 동적특성에 부합되도록 반영되어야 한다. 그리고 구조물의 변형능력을 합리적으로 평가하여 성능점을 보다 정확하게 산정해야 한다. 본 연구에서는 개선된 적응적 횡하중 분배방법과 건물의 등가응답을 이용하여 비탄성 지진응답을 정확하고 효율적으로 평가할 수 있는 방법을 제안하였다. 제안된 방법은 건물의 전체 비탄성 거동에 대한 내진성능을 평가하고 국부적인 비탄성 지진응답을 정확하게 산정하는데 사용될 수 있다. 또한 제안된 방법의 정확성과 타당성을 검증하기 위해서 비탄성 시간이력해석과 기존의 다른 해석방법들에 의한 비탄성 지진응답과 비교하였다.

• 조명전기설비학회논문지
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• 제29권7호
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• pp.14-21
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• 2015

Distribution systems are operated in radial structure, but temporal loop structure could be founded the live load transfer. Main purposes of reconfiguration of distribution network are load balancing, loss minimization and voltage drop maintaining. In the loop structure, huge loop current can be flowed between two substations in case of large voltage angle difference. Protection devices of distribution line can be triped by this huge loop current. So, precise calculation of loop current is very important for secure switching. This paper proposes a novel calculation method of loop current using the voltage angle differences measured at the tie switches. Feasibility of the propose method has been verified by various case studies based on Matlab simulation.

• 대한전기학회논문지
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• 제31권7호
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• pp.11-17
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• 1982

In this paper, a reliable and convenient evaluation method for the adequacy of any radial distribution line's voltage drop is proposed for improvement of the voltage regulation of the distribution line under operation. Using the voltage measurement of the first load branch point and the last point on the given distribution line its average line voltage drop and the line voltage drop variance by pure load variation are computed. And by these values and allowable or required line drop from proper voltage regulation view point, present adequency index and operation improvement index of the line drop are newly introduced for the evaluation of the given distribution line's voltage regulation. As a result of application to the 4 cases of study, the proposed method is proved to be reliable and convenient.

• 대한토목학회논문집
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• 제26권5D호
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• pp.821-829
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• 2006

교통하중은 포장 설계 및 해석에서 가장 중요한 입력 변수로서 포장 파손의 주요 원인이 된다. 따라서 정확한 포장 설계 및 해석을 위해서는 적절한 교통하중 정량화가 선행되어야 한다. 전통적으로 교통하중은 혼합된 교통흐름을 설계목적의 하나의 값으로 변환시켜주는 ESALs 관점에서 추정되어왔으나 이는 AASHO 도로 테스트를 통해 도출된 지극히 경험적인 값으로 전 노선망에 대해 평균적인 계수로 적용하기에는 한계가 있다. 이러한 등가단축하중계수의 문제점을 해결하기 위해 선진국에서는 역학적 개념을 도입한 많은 연구를 진행한 결과 역학적-경험적 설계법(Mechanistic-Empirical Design)에 적용할 수 있는 축하중 분포(Axle Load Spectra)를 이용한 교통하중 정량화 방안을 수립하였다. 본 논문에서는 일반국도에 설치 운영되고 있는 WIM 시스템을 통해 수집된 화물차 하중 데이터를 이용하여 축하중 분포 특성(Axle Load Spectra)을 이해하고 혼합정규분포함수에 기초한 축 형태별 하중 분포 모형식을 제시하였으며, 이를 기존 하중 분포 모형과 비교 평가하였다. 본 논문에서 제시한 화물차 축하중 분포 특성 및 축하중 분포 모형식은 향후 일반국도 및 고속도로의 포장 설계법 개발을 위한 교통하중 정량화 방안 수립 시, 과적 차량 단속 정책 수립 시, 도로 유지관리를 위한 계획 수립 시 기초자료로써 활용가능하다.

• Journal of Electrical Engineering and Technology
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• 제8권4호
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• pp.712-718
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• 2013

With the development of industry and the improvement of living standards, better quality in power electric service is required more than ever before. This paper deals with the optimal algorithms for voltage regulation in the case where Distributed Storage and Generation (DSG) systems are operated in distribution systems. It is very difficult to handle the interconnection issues for proper voltage managements, because the randomness of the load variations and the irregular operation of DSG should be considered. This paper proposes the optimal on-line real time voltage regulation methods in power distribution systems interconnected with the DSG systems. In order to deliver suitable voltage to as many customers as possible, the optimal sending voltage should be decided by the effective voltage regulation method by using artificial neural networks to consider the rapid load variation and random operation characteristics of DSG systems. The simulation results from a case study show that the proposed method can be a practical tool for the voltage regulation in distribution systems including many DSG systems.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2006년도 정기 학술대회 논문집
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• pp.725-732
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• 2006

This study has been started for the development of a refined live load distribution formula that has safety and precision toward I type prestressed concrete girder bridge. This type of bridge is mainly applied to short span bridges that are $25{\sim}40m$ in length. Based on various structure analysis models that are currently being applied as preceding studies for the development of live load distribution method. an analysis of flexural stiffness ratio for barrier and diaphragm has been performed. As the result of parametric analysis for the changes in flexural stiffness ratio, the effect of barrier on load distribution showed as insignificant in all structural analysis models while analyzing the deflection distribution. Also. the deflection distribution of the models with stiffness of 25% in which the diaphragm eccentricity is accounted for as same as the models with stiffness of 100% in which the diaphragm eccentricity is unaccounted for. This results are verified through the comparison with a experimental data.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 A
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• pp.285-288
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• 2000

This paper presents a technique for contingency ranting using line capacity calculation method and outage distribution factors(LODF) which are established by generation shift distribution factors from DC load flow solutions. By using the LODF, the line flow can be calculated a ccording to the modification of base load flow if the contingency occur. To obtain contingency ranting, maximum power tansferred to the load is obtained when load impedance $Z_r$ equal to line impedance $Z_s$. ( $Z_r$/ $Z_s$=1) The proposed algorithm has been validated in tests on a 6-bus test system.