• Journal of the Korea Safety Management & Science
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• v.3 no.3
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• pp.65-75
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• 2001

This research fundamentally deals with an analysis of service level for a multi-level inventory distribution system which is consisted of a central distribution center and several branches being supplied stocks from the distribution center, Under continuous review policy, the distribution center places an order for planned order quantity to an outside supplier, and the order quantity is received after a certain lead time. Also, each branch places an order for particular quantity to its distribution center, and receives the order quantity after a lead time. In most practical distribution environment, demands and lead times are generally not fixed or constant, but variable. And these variabilities make the analysis more complicated. Thus, the main objective of this research is to suggest a method to compute the service level at each depot, that is, the distribution center and each branch with variable demands and variable lead times. Further, the model will give an idea to keep the proper level of safety stocks that can attain effective or expected service level for each depot.

• Journal of Korean Society for Quality Management
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• v.49 no.3
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• pp.327-340
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• 2021

Purpose: The purpose of this study is to propose a system predicting whether an electricity distribution system is abnormal by analyzing the temperature of the deteriorated system. Traditional electricity distribution system abnormality diagnosis was mainly limited to post-inspection. This research presents a remote monitoring system for detecting thermal images of the deteriorated electricity distribution system efficiently hereby providing safe and efficient abnormal diagnosis to electricians. Methods: In this study, an object detection algorithm (YOLOv5) is performed using 16,866 thermal images of electricity distribution systems provided by KEPCO(Korea Electric Power Corporation). Abnormality/Normality of the extracted system images from the algorithm are classified via the limit temperature. Each classification model, Random Forest, Support Vector Machine, XGBOOST is performed to explore 463,053 temperature datasets. The process capability index is employed to indicate the quality of the electricity distribution system. Results: This research performs case study with transformers representing the electricity distribution systems. The case study shows the following states: accuracy 100%, precision 100%, recall 100%, F1-score 100%. Also the case study shows the process capability index of the transformers with the following states: steady state 99.47%, caution state 0.16%, and risk state 0.37%. Conclusion: The sum of caution and risk state is 0.53%, which is higher than the actual failure rate. Also most transformer abnormalities can be detected through this monitoring system.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.1
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• pp.29-36
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• 2013

This paper deals with the analysis of the customer voltage characteristic in distribution system interconnected with large scale PV system. There would be many power quality issues which are caused by reverse power flow of PV system interconnected with distribution system. In order to analyze the effect of PV system on the customer voltage, detailed modeling method of distribution system and modified modelling method of PV system are proposed using PSCAD/EMTDC in this paper. So far, less than dozens KW of PV system can be simulated with the existing modelling method. Therefore, a new modeling method which can simulate the large scale PV system is proposed by considering the relationship equation on the phase and voltage in the current control algorithm. From the simulation result of proposed modelling method, it is confirmed that an optimal operation method in distribution system is suggested by analyzing the effect of PV system on customer voltage.

• Journal of Korean Institute of Industrial Engineers
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• v.21 no.3
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• pp.313-327
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• 1995

This paper deals with ordering policies for a multi-echelon distribution system. The system we are concerned consists of one Central Distribution Center(CDC) and N nonidentical Regional Distribution Centers(RDCs) which have different demand rates, minimum filtrates, leadtimes, etc. We develop an algorithm for determining the optimal ordering policies of the CDC and the RDCs under the constraints of minimum filtrates of RDCs and maximum allowable delay of CDC.

• Journal of Korea Spatial Information System Society
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• v.11 no.2
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• pp.13-18
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• 2009

This paper presents the implementation procedure of encoding and decoding algorithms for Tornado code that can provide fault tolerance for storage and transmission system. The degree distribution satisfying heavy tail distribution is produced. Based on this distribution, a good random irregular bipartite graph is attained after plenty of trails. Such graph construction is proved to be efficient, and the experiments also demonstrate that the implementation obtains good performance in terms of decoding overhead.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.50 no.1
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• pp.28-37
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• 2001

This paper presents an efficient algorithm for the loss minimization of distribution system by automatic sectionalizing switch operation in large scale distribution systems. Simulated annealing is particularly well suited for large combinational optimization problem, but the use of this algorithm is also responsible for an excessive computation time requirement. Tabu search attempts to determine a better solution in the manner of a greatest-descent algorithm, but it can not give any guarantee for the convergence property. The hybrid algorithm of two methods with two tabu lists and the proposed perturbation mechanism is applied to improve the computation time and convergence property Numerical examples demonstrate the validity and effectiveness of the proposed methodology using a KEPCO's distribution system.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.53 no.9
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• pp.481-486
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• 2004

In operation of distribution system, $DG_s$ Distributed Generations) are installed as an alternative of extension and establishment of substations and transmission and distribution lines according to increasing power demand. In operation planning of $DG_s$, determining optimal capacity and allocation gets economical pro(it and improves power reliability. This paper proposes determining a optimal number, size and allocation of $DG_s$ needed to minimize operation cost of distribution system. Capacity of $DG_s$ (or economical operation of distribution system estimated by the load growth and line capacity during operation planning duration, DG allocations are determined to minimize total cost with power buying cost. operation cost of DG, loss cost and outage cost using GA(Genetic Algorithm).

• Proceedings of the KIEE Conference
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• 1997.11a
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• pp.250-252
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• 1997

This paper deals with voltage regulation at the power Distribution system interconnected with DSG. Modern distribution substation adopt LDC method as the voltage regulation method to deliver suitable voltages to many customers. However, the operations of DSG interconnected with distribution system, the customers' voltage violate the permissible voltage limits. Therefore, to deliver suitable voltage to many customers at the distribution substation, an advanced voltage regulation method is required. In this paper, the on line realtime MLDC (Multiple Line Drop compensation) method, considered daedband and hysterical tap changing of the ULTC, is proposed. The result from a simulation study shows that the proposed method can be practical applications for the voltage regulation at the distribution system interconnected with DSG and unbalanced load pattern among feeders.

• Proceedings of the KIEE Conference
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• 2001.05a
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• pp.155-158
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• 2001

The objective of this study is to evaluate properly reliability of underground distribution system taking into account domestic circumstance. Interruption time and number of interruption customer by distribution system based on actual condition in domestic utility are considered as important index to estimate reliability of underground distribution system. This paper presents evaluation results regarding the reliability of an underground distribution system using a model system as new urban area, evaluation results which is established whether automatic system is introduced or not are shown in detail.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.9
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• pp.20-25
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• 2010

This paper mainly proposes power flow algorithm using OOP(Object-Oriented Programming) in distribution power system. Because the most power system problems are calculated from power flow, it is an important part in power system. Recently, new power generation facilities are steadily installed in the distribution system connected with Microgrid which has been gaining popularity among the industry and utilities. This paper contributes to improve the power flow algorithm using OOP for efficient power flow according to the distribution system configuration fluctuated frequently.