• 대한교통학회지
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• 제5권1호
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• pp.47-58
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• 1987

A commodity distribution problem with intertemporal storage facilities and dynamic transportation networks is proposed. mathematical integer programming methods and multiobjective programming techniques are used in the model formulation. Dynamic characteristics of commodity distribution problems are taken into account in the model formulation. storage facility location problems and transportation link addition problems are incorporated into the intertemporal multicommodity distribution problem. The model is capable of generating the most efficient and rational commodity distribution system. Therefore it can be utilized to provided the most effective investment plan for the transportation infrastructure development as well as to evaluate the existing commodity distribution system. The model determines simultaneously the most efficient locations, sizes, and activity levels of storage facilities as well as new highway links. It is extended to multiobjective planning situations for the purpose of generating alternative investment plans in accordance to planning situations. sine the investment in transportation network improvement yields w\several external benefits for a regional economy, the induced benefit maximization objective is incorporated into the cost minimization objective. The multiobjective model generates explicitly the trade-off between cost savings and induced benefits of the investment in transportation network improvement.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 D
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• pp.2588-2590
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• 2001

Distribution ayatems at the final stage of the power supply process are directly and extensively connected to customers. There are growing demands for more efficient operation and higher reliability. This paper describes the embodiment of distribution automation using internet networks. We suggest the large region distribution server system for distribution automation functions in local area network, automated meter reading system and directed load control system with by-directional communication.

• 전기학회논문지
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• 제66권9호
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• pp.1309-1316
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• 2017

As penetration level of Distributed Generations (DGs) on weak distribution networks gets higher, voltage rise problem can often occur due to reverse power which is not expected in conventional distribution networks. It, however, cannot be effectively solved by using conventional voltage regulating devices such as On-Load Tap Changers (OLTCs), Step Voltage Regulators (SVRs) because those do not consider the presence of DGs when determining relevant setting parameter for voltage regulation. This paper presents a scheme for voltage regulation using coordinated control between OLTC and DGs which can actively participate in the regulation. The scheme decides which device should be operated first based on the characteristics of regulating devices, in order to prevent unnecessary operation of output changes of DG and excessive tap changing operation of OLTC. Computer simulations considering daily irradiation of PV and load curve are performed by using MATLAB Simulink and performance comparison between the presented scheme and conventional ones is also made. It can be concluded from simulation results that the scheme presented is very effective to regulate voltages in distribution networks with multiple DGs.

• 정보처리학회논문지:소프트웨어 및 데이터공학
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• 제11권11호
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• pp.455-464
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• 2022

제조업의 공정에서 생성되는 데이터셋은 크게 두 가지 특징을 가진다. 타겟 클래스의 심각한 불균형과 지속적인 Out-of-Distribution(OoD) 샘플의 발생이다. 클래스 불균형은 SMOTE 및 다양한 샘플링 전략을 통해서 대응할 수 있다. 그러나, OoD 탐색은 현재까지 인공신경망 영역에서만 다뤄져 왔다. OoD 탐색의 적용이 가능한 인공신경망은 제조공정 데이터셋에 대해서 만족스러운 성능을 발현하지 못한다. 원인은 제조공정의 데이터셋이 인공신경망에서 일반적으로 다루는 이미지, 텍스트 데이터셋과 비교해서 크기가 매우 작고, 노이즈가 심하다는 것이다. 또한 인공신경망의 과적합(overfitting) 문제도 제조업 데이터셋에서 인공신경망의 성능을 저하하는 원인으로 지적된다. 이에 현재까지 시도된 바 없는 SVM 알고리즘과 OoD 탐색의 접목을 시도하였다. 또한 예측모델의 정밀도 향상을 위해 배깅(Bagging) 알고리즘을 모델링에 반영하였다.

• 전기의세계
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• 제18권6호
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• pp.9-22
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• 1969

This thesis has suggested a method of applying the Maximum Principle of Pontryagin to the optimal control of distributive electrical networks. In general, electrical networks consist of branches, nodes, sources and loads. The effective values of steady state currents and voltages are independent of time but only expressed as the functions of position. Moreover, most of the node voltages and branch currents are not predetermined, that is, initially unknown, and their inherent loop characteristics satisfy only Kirchhoff's current and voltage laws. The Maximum Principle, however, needs the initial fixed values of all state variables for its standand way of application. In spite of this inconsistency this thesis has undertaken to suggest a new approach to the successful solution of the above mentioned networks by introducing scaling factors and a state variable change technique which transform the boundary-value unknown problem into the boundary-value partially fixed and partially free problem. For the examples of applying the method suggested, the control problems for minimizing copper quantity in a distribution line have been solved with voltage drop constraint imposed on. In the case of uniform load distribution it has been shown that the optimal wire diameter of the distribution line is reciprocally proportional to the root of distance. For the same load pattern as above the wire diameter giving the minimum copper loss in the distribution line has been shown to be reciprocally proportional to distance.

• Journal of Electrical Engineering and Technology
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• 제8권5호
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• pp.1012-1020
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• 2013

In this work, Self-adaptive Differential Evolutionary (SaDE) algorithm is proposed to solve Optimal Location and Size of Capacitor (OLSC) problem in radial distribution networks. To obtain the SaDE algorithm, two improvements have been applied on control parameters of mutation and crossover operators. To expand the study, three load conditions have been considered, i.e., constant, varying and effective loads. Objective function is introduced for the load conditions. The annual cost is fitness of problem, in addition to this cost, CPU time, voltage profile, active power loss and total installed capacitor banks and their related costs have been used for comparisons. To confirm the ability of each improvements of SaDE, the improvements are studied both in separate and simultaneous conditions. To verify the effectiveness of the proposed algorithm, it is tested on IEEE 10-bus and 34-bus radial distribution networks and compared with other approaches.

• Journal of Power Electronics
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• 제12권3호
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• pp.495-502
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• 2012

This paper presents an improved grid voltage control strategy for wind farms with doubly-fed induction generators (DFIGs) connected to distribution networks based on an analysis of the operation limits of DFIG systems. A modified reactive power limit calculation method in different operation states is proposed and a reactive power control strategy during grid voltage dips/rises is further discussed. A control strategy for compensating unbalanced grid voltage, based on DFIG systems, by injecting negative sequence current into the grid through the grid side converter (GSC) is proposed. In addition, the negative current limit of the GSC is discussed. The distribution principle of the negative sequence current among the different DFIG systems in a wind farm is also introduced. The validity of the proposed voltage control strategy is demonstrated by Matlab/Simulink simulations. It is shown that the stability of a wind farm and the power grid can be improved with the proposed strategy.

• KIEE International Transactions on Power Engineering
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• 제5A권3호
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• pp.260-268
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• 2005

This paper proposes an improved investment pnonty decision method of facilities considering the reliability of distribution networks. The proposed method decides an investment order of the facilities combining, by fuzzy rules, the investment priority decision by KEPCO and that by reliability evaluation indices. The reliability evaluation indices are SAIFI (System Average Interruption Frequency Index) and SAIDI (System Average Interruption Duration Index). The reliability analysis method of distribution networks applied in this paper utilizes the analytic method, where the used reliability data is the historical data of KEPCO. Particularly, we assumed that the failure rate increases as the equipment ages. To verify the performance of the proposed method, we applied it with the planned projects to reinforce the weak electrical facilities in KEPCO in 2004. The evaluation result showed that, under a limited budget, the reliability of KEPCO in the Busan region using the proposed method could be enhanced if used rather than the conventional method typically in place. Therefore, the results verify that the proposed method can be efficiently used in the actual priorities method for investing in the electrical facilities.

• Journal of information and communication convergence engineering
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• 제19권4호
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• pp.205-213
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• 2021

The properties of a scale-free network are little known; its node degree following a power-law distribution is among its few known properties. By selecting real-field scale-free networks from a network dataset and comparing them to other networks, such as random and non-scale-free networks, the topology characteristics of scale-free networks are identified. The assortative coefficient is identified as a key metric of a scale-free network. It is also identified that most scale-free networks have negative assortative coefficients. Traditional generation models of scale-free networks are evaluated based on the identified topology characteristics. Most representative models, such as BA and Holme&Kim, are not effective in generating real-field scale-free networks. A link-rewiring method is suggested that can control the assortative coefficient while preserving the node degree sequence. Our analysis reveals that it is possible to effectively reproduce the assortative coefficients of real-field scale-free networks through link-rewiring.

• 한국정보기술응용학회:학술대회논문집
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• 한국정보기술응용학회 2005년도 6th 2005 International Conference on Computers, Communications and System
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• pp.271-275
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• 2005

Queueing models are good models for fragments of communication systems and networks, so their investigation is interesting for theory and applications. Theses queues may play an important role for the validation of different decomposition algorithms designed for investigating more general queueing networks. So, in this paper we illustrate that the batch size distribution affects the loss probability, which is the main performance measure of a finite buffer queues.