• International Journal of Contents
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• v.5 no.1
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• pp.46-50
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• 2009

Logistics is in the limelight as one of a variety of RFID applications. The RFID technology is actively being applied to improve the competitiveness power of companies through the synthetic management of products and information. The RFID system generates large volume of stream data. It has problems which occur waste of storage and long processing time when storing large data and processing queries. Recently, many studies have been done to solve the problems which are generated in RFID system. In this thesis, we propose an efficient data management scheme for path queries and containment queries which are occurred frequently. The proposed data management scheme considers a change of the containment of products during a transport and supports a path of changed products by representing a path of various containments. Also, the compression utilizing the structure of supply chain reduces the stored data volumes. In order to show the superiority of our approach, we compare it with the existing schemes. As a result, our experimental results show that our scheme outperforms the existing scheme in terms of storage efficiency and query processing time.

• Journal of the Korean Operations Research and Management Science Society
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• v.4 no.1
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• pp.41-51
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• 1979

The Classical multi-server heterogeneous queuing system can be more generalized by using the concept of the switching rules. The descriptions of these systems, the relations among the state probebilities at the various points of interest, and comparisons with the single-server system will be presented. Instead of using the imbedded markov chain we set up the simultaneous equations for the state probabilites by the supplementary variable method.

• Journal of the Korea Safety Management & Science
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• v.8 no.1
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• pp.195-206
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• 2006

본 연구는 제조자(공급자)와 중간분배자로 구성된 공급사슬에서 시간에 따라 일정률로 퇴화하는 퇴화성 제품을 다루는 중간분배자의 신뢰성있는 재고보충정책을 분석하였다. 문제 분석을 위하여 제조자는 고객의 수요를 증대시키기 위한 수단으로 중간분배자로부터의 제품대금에 대하여 일정기간 동안 신용거래를 허용한다는 가정과 함께 수송량에 따라 할인되는 수송비를 고려하여 모형을 수립하였고, 중간분배자의 경제적 재고보충정책을 결정하기 위한 해법을 개발하였다.

• Journal of the Korean Operations Research and Management Science Society
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• v.20 no.2
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• pp.1-10
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• 1995

In this study, a threshold policy is considered for the M/M/2 queueing system with server vacations. The probability generating function for the number of customers present in the system is derived using an embedded Markov chain approach. Then, assuming a linear cost structure, an efficient procedure to find an optimal threshold policy is presented. The Laplace-Stieltjes transofrm for th waiting time of an arbitrary customer under a "FIFO" discipline is also derived.o derived.

• International Journal of Railway
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• v.2 no.1
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• pp.37-42
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• 2009

Information management of products and services in every industries is gaining importance for resource planning and maintenance. In this paper, we analyzed the information classification systems for railway industry. International and domestic classification systems, such as HS, UNSPSC, eCl@ss and ISIC, are reviewed; as a result this paper presents the findings and the various issues. We proposed to-be images in adopting and utilizing the classification systems. Using the integrative information classification systems could make efficient electronic procurement, supply chain management and e-Business of railway services.

• Journal of Korea Port Economic Association
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• v.25 no.3
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• pp.139-164
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• 2009

The purpose of this paper is to investigate the value chain efficiency of Korean port investment by using the newly developed multi-year and multi-stage value chain efficiency model of DEA(Data Envelopment Analysis). Inputs[port investment amount, cargo handling capacity, and berthing capacity], and outputs[cargo handling amount, number of ship calls, revenue, and score of customer service satisfaction] are used during 14 years(1994-2007) for 20 Korean seaports by using two kinds of DEA models. Empirical main results are as follows: First, Model 1 shows that the ranking order of multi-stage value chain efficiency is Stage 2, Stage 3-1, Stage 1, and Stage 3-2. And according to the value chain average efficiency scores, ranking order is stages 2, 1, 3-1, and 3-2. In Model 2, 3(Incheon, Mogpo, and Jeju) out of 9 ports show the ranking order of Stages 2, 3-2, 3-1, and 1. And value chain average efficiency scores rank in order of Stages 2, 3-2, 3-1, and 1. Second, the difference among the value chain efficiency scores of each stage comes from the efficiency deterioration of all ports except Stages 2 and 1 in Model 1. In Model 2, value chain efficiency scores among the Stages 3-1, 3-2 compared to Stage 1 were deteriorated. The main policy implication based on the findings of this study is that the manager of port investment and management of Ministry of Land, Transport and Maritime Affairs in Korea should introduce the multi-year, multi-stage value chain efficiency method for deciding the port investment amount and evaluating the effect of port investment after considering the empirical results of this paper carefully.

• Journal of the Korean Operations Research and Management Science Society
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• v.31 no.1
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• pp.91-103
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• 2006

Given a bill of materials (BOM) tree T labeled by the breadth first search (BFS) order from node 0 to node n and a general network ${\Im}=(V,A)$, where V={1,2,...,m} is the set of production facilities and A is the set of arcs representing transportation links between any of two facilities, we assume that each node of T stands for not only a component. but also a production stage which is a possible stocking point and operates under a periodic review base-stock policy, We also assume that the random demand which can be achieved by a suitable service level only occurs at the root node 0 of T and has a normal distribution $N({\mu},{\sigma}^2)$. Then our integrated model of facility location problems and safety stock optimization problem (FLP&SSOP) is to identify both the facility locations at which partitioned subtrees of T are produced and the optimal assignment of safety stocks so that the sum of production cost, inventory holding cost, and transportation cost is minimized while meeting the pre-specified service level for the final product. In this paper, we first formulate (FLP&SSOP) as a nonlinear integer programming model and show that it can be reformulated as a 0-1 linear integer programming model with an exponential number of decision variables. We then show that the linear programming relaxation of the reformulated model has an integrality property which guarantees that it can be optimally solved by a column generation method.

• Journal of the Korean Society of Clothing and Textiles
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• v.31 no.1 s.160
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• pp.95-106
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• 2007

The purpose of this study is to investigate the relationship between the implementation and the performance of the eSCM in internet shopping malls, and to suggest collaborated strategy for internet shopping malls. We performed the surveys of suppliers for 3 fashion-specialized internet shopping malls and 3 general internet shopping mall. Additional surveys was performed by surveying the shopping mall merchandisers to research the differences of understandings on the performance of the eSCM between shopping malls and their suppliers. Total 143 questionnaries were distributed and collected from January 23 to February 28, 2006 and analyzed by SPSS 10.0. The results are as follows; 1) the efficiency of eSCM is related the factors of partnership and information, and among the subordinated factors the understanding and support of the top management, good communications, product and operating information sharing were find out to be significant. 2) The effectiveness of eSCM is influenced by the organizational and partnership factor. As the subordinated factors, the understanding and supports of the top management, the participations of members, good communications, good relationship and supports, and the technology level of eSCM were identified as significant. 3) Examining the differences of understandings on the performance of eSCM between the suppliers and the shopping mall merchandisers, the suppliers and the merchandisers show different opinions on the operating efficiency, and the customer service.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.15 no.6
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• pp.20-26
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• 2001

In this paper, we design tunnel inner section displacement measurement system which is composed of potentiometer-type displacement sensors, microcontroller-based intelligent sensing head and host computer for the management system and acquisition data. Multiple node communication bus connects the intelligent sensing heads with the host computer. For safe and re1iab1e network operation we use daisy-chain configuration, termination resistor, fail-safe biasing circuit. For tole enhancement of system utilization, we use modbus protocol. The acquisition data are transmitted to host computer and managed by database. Several data request conditions and sorting conditions are provided by management software. The utilization of designed system is confirmed by experiment.

• Korean Management Science Review
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• v.33 no.1
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• pp.17-33
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• 2016

This study investigated the relationships among proper types of e-commerce, patterns of inter-organizational information flow (IIF), benefits of e-commerce, and supply-chain performance. In IIF, it was empirically observed that environmental competition positively influences the frequency of IIF, and environmental uncertainty has a positive impact on the quality of IIF. It was also empirically confirmed that only quality of IIF has effects on the usage levels of e-procurement as well as e-partnerships. Through regression analyses and cluster analysis, it was found that under high degrees of the frequency and quality of IIF, the benefits of e-commerce are vastly realized in the firms that highly utilize e-partnerships. The results of this study also showed that when the degrees of quality of IIF are high, the levels of benefits of e-commerce are increased in the firms that employ e-procurement. The moderating effects of buyer and supplier firms' abilities on the relationships between patterns of IIF and usage levels in various types of e-commerce were empirically examined. According to the results, the moderating roles of buyer firms' capabilities and suppliers' abilities were partially demonstrated. Finally, it was found that the realization of benefits of e-commerce can lead to the improvement of supply-chain performance.