• Journal of the Korea Safety Management & Science
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• v.3 no.3
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• pp.77-86
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• 2001

An operational strategy for inventory control on finished goods in the distribution system has been given attention to many enterprises and many studies regarding this field have been done and is also on-going currently. Many of these studies represented a large scale distribution network with a unified formulation by using defined symbols. These methods have provided the systematic approach of the distribution network but they are impossible to applying the reality system due to not considering the service rate of demand and treating the shortage of inventory. In order to overcome these unrealistic problems, the novel safety stock policy of responding to customers' inventory distribution network is suggested. this paper explores the transportation between Central Distribution Center(CDC) and Regional Distribution Center(RDC). Especially, the relation of transportation cost between CDC and RDC and cost of inventory control according to safety inventory with service level are emphasized. We could obtain the good results of this study by determining the optimal safety stock considering the various variables and constraints.

• Journal of the Korean Operations Research and Management Science Society
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• v.25 no.2
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• pp.59-66
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• 2000

In this paper we propose an approximation analysis for the system size distribution of the M/G/c system which is transform-free,. At first we borrow the system size distribution from the Markovian service models and then introduce a newly defined parameter in place of traffic intensity. In this step we find the distribution of the number of customers up to c. Next we concentrate on each waiting space of the queue separately rather than consider the entire queue as a whole. Then according to the system state of the arrival epoch we induce the probability distribution of the system size recursively. We discuss the effectiveness of this approximation method by comparing with simulation for the mean system size.

• Journal of Electrical Engineering and Technology
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• v.4 no.3
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• pp.330-336
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• 2009

This paper proposes an on-line voltage management and control solution for a distribution system which can improve the efficiency and accuracy of existing off-line work by collecting customer voltage on-line as well as the voltage compensation capability of the existing ULTC (Under Load Tap Changer) operation and control strategy by controlling the ULTC tap based on pattern clustering and recognition. The proposed solution consists of an ADVMD (Advanced Digital Voltage Management Device), a VMS (Voltage Management Solution) and an OLDUC (On-Line Digital ULTC Controller). An on-line voltage management emulator based on multi-thread programming and the shared memory method is developed to emulate on-line voltage management and digital ULTC control methodology based on the on-line collection of the customer's voltage. In addition, using this emulator, the effectiveness of the proposed pattern clustering and recognition based ULTC control strategy is proven for the worst voltage environments for three days.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2008.10a
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• pp.267-284
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• 2008

Consider a supply chain where products are produced at a manufacturing system, shipped to a distribution center, and then supplied to customers. The distribution center controls inventory based on a base-stock policy, and whenever a unit of product is demanded by a customer, an order is released to the production system. Unsatisfied demand is backordered, and the inventory and backordered units are a function of the base-stock level. The manufacturing system is modeled as an M/M/s/c queueing system, and orders exceeding the limited buffer capacity are blocked and lost. The throughput of the manufacturing system and the steady state distribution of the outstanding orders are functions of number of servers and buffers of the manufacturing system. There is a profit obtained from throughput and costs due to servers and buffers of the manufacturing system, and also costs due to inventory positions of the distribution center, and we want to maximize the total production profit minus the total cost of the supply chain by simultaneously determining the optimal number of servers and buffers of the manufacturing system and the optimal base-stock level of the distribution center. We develope two algorithms, one analytical but without guarantee of the optimal solution and one optimal but without complete analytical proofs. The problem integrates strategic problem of the manufacturing system with tactical problem of the distribution center in a supply chain.

• Journal of Distribution Science
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• v.22 no.1
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• pp.115-125
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• 2024

Purpose: This study is to analyze the purchasing process and distribution management requirements for teaching materials that have important meaning in the practical field of preschool education. Research design, data and methodology: A structured questionnaire was used to survey 103 childcare staffs regarding the purchasing process and distribution managements. The collected data underwent Likert's 5-point scale analysis and keyword grouping. Additionally, ANOVA was conducted to examine the distribution management demands based on demographic characteristics. Results: The purchasing of teaching materials involved more offline channels than online, and the purchase decisions were predominantly made by principals rather than teachers. Although the purchasing process is similar to that of general businesses, there are difficulties in purchasing due to the disorganized distribution channels and limited accessibility to product information. Additionally, the management of inventory for teaching materials is challenging due to limited personnel and storage. Childcare staffs have requirements for classification systems, evaluation criteria, environments and policies related to teaching materials distribution. The need to introduce a teaching material evaluation and certification system to ensure quality was not high. Conclusions: Most of the respondents recognized that strict management and measures should be taken for the distribution of teaching materials. There were differences in the demand of teaching material distribution depending on the respondents' status, age, education, and experience.

• Journal of the Korea Safety Management & Science
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• v.12 no.3
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• pp.169-176
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• 2010

Owing to the latest changes in the IT environment and the advancement of RFID (Radio Frequency Identification) technology, the RFID technology has been frequently applied to the field of logistics and distribution. Now it is possible to acquire information in real-time more accurately and promptly as compared to data collection in the past, through the application of the RFID technology. However, in terms of the application of the RFID technology, the range of the field of logistics and distribution is considerably widely distributed. The management system that is able to monitor the RFID system installed in logistics centers and stores distributed in environmentally many regions, in real-time in the center is insufficient. Therefore, this study proposes a management system which is capable of transmitting the report of the occurrence of errors according to the pre-defined error types at the time of the occurrence of errors in the RFID system installed at each strategic foothold, in real-time to SMS and to the integrated monitoring system, and of taking actions for those errors from a remote place by using a mobile device. The purpose of the error management system proposed in this study is to minimize a data loss in the supplying network by quickly coping with errors in the area where the RFID system is installed.

• IE interfaces
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• v.22 no.3
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• pp.234-242
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• 2009

It is most important for distribution center in retail business to delivery commodities in a timely manner. Accordingly, many companies try to make distribution center effective using the Warehouse Management System(WMS) integrated legacy system. Also, the Customer Relationship Management(CRM) is the most typical paradigm in management lately. Even though the WMS and CRM are independent system of each other, WMS, coupled with CRM makes customer satisfied more effectively. In this paper, we proposed the methodology for inventory location after analyzing and applying customer buying pattern data in the CRM through the MBA(Market Basket Analysis), which is part of data mining. We used an example modeling a real distribution center in retail through a 3D simulation tool and examined correlation between commodities using customer buying pattern. After that, we applied it to the inventory location system through the MBA in an example. Finally, we identified decrease in the time for picking, which is the majority of distribution center. Besides, we proposed a simulation methodology before applying new methodology. Consequently, it removes potential errors in advance and makes a optimized inventory location system.

• Journal of the Korean Operations Research and Management Science Society
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• v.41 no.3
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• pp.37-43
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• 2016

This note discusses the inter-loss time ofan M/G/1/1 queuing system. The inter-loss time is defined as the time duration between two consecutive losses of arriving customers. In this study, we present the explicit Laplace transform of the inter-loss time distribution of an M/G/1/1 queuing system.

• Wind and Structures
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• v.39 no.1
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• pp.1-14
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• 2024

Widespread damages from extreme winds have attracted lots of attentions of the resilience assessment of power distribution systems. With many related environmental parameters as well as numerous power infrastructure components, such as poles and wires, the increased challenge of power asset management before, during and after extreme events have to be addressed to prevent possible cascading failures in the power distribution system. Many extreme winds from weather events, such as hurricanes, generate widespread damages in multiple areas such as the economy, social security, and infrastructure management. The livelihoods of residents in the impaired areas are devastated largely due to the paucity of vital utilities, such as electricity. To address the challenge of power grid asset management, power system clustering is needed to partition a complex power system into several stable clusters to prevent the cascading failure from happening. Traditionally, system clustering uses the Binary Decision Diagram (BDD) to derive the clustering result, which is time-consuming and inefficient. Meanwhile, the previous studies considering the weather hazards did not include any detailed weather-related meteorologic parameters which is not appropriate as the heterogeneity of the parameters could largely affect the system performance. Therefore, a fragility-based network hierarchical spectral clustering method is proposed. In the present paper, the fragility curve and surfaces for a power distribution subsystem are obtained first. The fragility of the subsystem under typical failure mechanisms is calculated as a function of wind speed and pole characteristic dimension (diameter or span length). Secondly, the proposed fragility-based hierarchical spectral clustering method (F-HSC) integrates the physics-based fragility analysis into Hierarchical Spectral Clustering (HSC) technique from graph theory to achieve the clustering result for the power distribution system under extreme weather events. From the results of vulnerability analysis, it could be seen that the system performance after clustering is better than before clustering. With the F-HSC method, the impact of the extreme weather events could be considered with topology to cluster different power distribution systems to prevent the system from experiencing power blackouts.

• Journal of Distribution Science
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• v.14 no.1
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• pp.29-38
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• 2016

Purpose - The purpose of paper is to review and look into the process of port development of each country, and compare with their system of port management. Research design, data and methodology - The methods to be taken is to examine a process of port development in terms of historic and regulated point of views, and each country's port is compared with various port models. Results - China has evolved of port governance into 3 stages, which has lead to almost liberalized port management system in process of privatization slogan. Japan has three stages of port development, and key commitments have been done by local government, rather than national one. Korea has also several stages of port reforms, and national government has been deeply involved in port industry, as well as regional government and port authority in certain areas. Conclusions - whatever port management system each countries has taken, it eventually aims to port productivity in country's port. To adopt most proper port management system may be answer for country to cope with environmental changes around port industry.