• 연구논문집
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• s.27
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• pp.167-174
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• 1997

Point of Production/Manufacturing Execution Systems are an essential component of operations in today's competitive business environments, which require greater production efficiency and effectiveness. POP/MES focuses on the valuing-adding processes, helping to reduce manufacturing cycle time, improve product quality, reduce WIP, reduce or eliminate paperwork between shifts, reduce lead time and empowering plant operations staff. In this paper, we implement POP/MES to manage real-time plant floor data which is gathered by I/O server into database management system. I/O server is a software allows data exchange between factory real-time database and several hardware devices such as PLC, DCS, robot and sensor through ethernet TCP/IP protocol.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2003.05a
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• pp.980-983
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• 2003

The purpose of this paper is to construct a CIDEAR (Cross Impact Data Envelopment Analysis Assurance Region) model which evaluates proposed R&D projects considering cross impacts among them and selects them to utilize R&D resources effectively as well as to maximize effectiveness of investments. For this purpose, the following six steps are designed as the main procedure. $\lceilDecision\;Theory\;&\;Evaluation\;Model\rfloor$, $\lceilAR\;Decision\;&\;Evaluation\;Model\rfloor$, $\lceilResource\;&\;Performance\;Analysis Model\rfloor$, $\lceilCross\;Impact\;Assumption\;Model\rfloor$, $\lceilpriority\;Oder\;Decision\;Model\rfloor$, $\lceilEfficiency\;Cause\;Analysis\;Model\rfloor$. $\lceilCIDEAR\rfloor$ model can deal with the affairs of R&D projects having the characteristics of mutual independence as well as mutual dependence. Hence it is possible to evaluate and select R&D projects more accurately than any other models.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2003.05a
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• pp.668-673
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• 2003

Line Capacity is a criteria for transport capacity and is used to evaluate railroad investment alternatives or to decide train frequency when establish transportation plan. There are two methodologies to increase transport capacity of railway. One is to invest railroad equipment or vehicles, and the other is to improve operation efficiency through optimization. Such all efforts are intended to increase transport capacity by improving line capacity. So far, this criteria is calculated statical and experimental numerical formula. But, line capacity has special attribute that changes dynamically according to operational conditions, so there is a need of new line capacity estimation system. In this paper, we present a new estimation method of line capacity based on the probability simulation, and apply to normal railline section and special structured railine section.

• Journal of the Korean Operations Research and Management Science Society
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• v.25 no.2
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• pp.47-57
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• 2000

In this paper we consider an n-job non-preemptive and identical parallel machine scheduling problem of minimizing the sum of earliness and tardiness with different release times and due dates. In the real world this problem is more realistic than the problems that release times equal to zero or due dates are common. The problem is proved to be NP-complete. Thus a heuristic is developed to solve this problem To illustrate its suitability a proposed heuristic is compared with a genetic algorithm for a large number of randomly generated test problems. Computational results show the effectiveness and efficiency of proposed heuristic. In summary the proposed heuristic provides good solutions than genetic algorithm when the problem size is large.

• Journal of the Korean Operations Research and Management Science Society
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• v.25 no.1
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• pp.1-13
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• 2000

Electronic Data Interchange (EDI) has a significant impact on business practices by eliminating paper related adult trails and enabling transactions to be processed at high speed without human intervention. Major advantages advangtages and benefits derived from EDI, however, depend upon the usage of EDI controls. Management must determine whether their investment on EDI controls is appropriate, as the establishment of EDI controls demandds much resources and high skills. This study proposes data envelopment analysis model to identify efficient and inefficient EDI control systems in various context of input (formal and automated EDI controls) and output (EDI implementation and performance). DEA can also determine the factors that are significantly different between efficient and inefficient groups. The model is tested using data collected form EDI adopters.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.3
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• pp.454-468
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• 1997

This paper presents a bitwidth optimization algorithm for efficient hardware sharing in digital signal processing system. The proposed algorithm determines the fixed-point representation for each signal through bitwidth optimization to generate the hardware requiring less area. To reduce the operator area, the algorithm partitions the abstract operations in the design description into several groups, such that the operations in the same group can share an operator. The partitioning result are fed to a high-level synthesis system to generate the pipelined fixed-point datapaths. The proposed algorithm has been implemented in SODAS-DSP an automatic synthesis system for fixed-point DSP hardware. Accepting the models of DSP algorithms in schematics, the system automatically generates the fixed-point datapath and controller satisfying the design constraints in area, speed, and SNR(Signal-to-Noise Ratio). Experimental results show that the efficiency of the proposed algorithm by generates the area-efficient DSP hardwares satisfying performance constraints.

• Korean Management Science Review
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• v.31 no.2
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• pp.49-63
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• 2014

With the huge concerns on the inefficiency of public enterprises, particularly a significant amount of debt, an increasing number of studies have been carried out to analyze the levels of inefficiency and investigate the causes of that inefficiency. However, very limited range of analytical methodologies have been used in the efficiency analysis and moreover, the effects of external factors have been little addressed. This study explores the efficiency of urban railway corporations in Korea by utilizing a method of stochastic frontier analysis (SFA). In particular, the potential effects of external factors including residential and floating populations of a station were statistically analyzed. A total of seven Korean urban railway corporations were selected to compare each other in terms of operational efficiency. The results present three important findings. First, the Cobb-Douglas model was found to be more valid for SFA compared to the Translog model. Second, the efficiencies of urban railway corporations in Seoul and Busan are relatively high whereas those of Daejeon and Gwangju are very low in efficiency in the area of sales revenue. In an aspect of number of transport of passengers, Gwangju Metro also showed the lowest efficiency. Third, the external factors are significantly associated with the efficiency, indicating that the efficiencies of Daejeon Metro and Gwangju Metro would increase while the efficiency of Seoul Metro would decreases when the external variables are excluded in the efficiency analysis. The results provide several meaningful implications for managers of the urban railway corporations as well as policy makers who are attempting to resolve the inefficiency problems of public enterprises.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2004.05a
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• pp.31-34
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• 2004

This research proposes the lateral transshipment policy that can deal efficiently with stockout in the two-echelon distribution network in supply chain. The lateral transshipment policy can be expected for retailers to response the change of customers' demands efficiently. Because of various factors, such as demand fluctuation, replenishment quantity, lead time, and so on, it is very difficult to decide optimal lateral transshipment time and quantity. We suggest the new lateral transshipment policy based on the service level in this research. The efficiency of this policy is proved by simulation experiments.

• Journal of the Korean Operations Research and Management Science Society
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• v.13 no.2
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• pp.9-17
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• 1988

This vehicle scheduling problem with multiple depots and multiple vehicle types (VMM) is to determine the optimal vehicle routes to minimize the total travel costs. The object of this paper is to develope an exact algorithm for the VMM. In this paper the VMM is transformed into a mathematical model of the vehicle problem with multiple depots. Then an efficient branch and bound algorithm is developed to obtain an exact solution for this model. In order to enhance the efficiency, this algorithm emphasizes the follows; First, a heuristic algorithm is developed to get a good initial upper bound. Second, an primal-dual approach is used to solve subproblems which are called the quasi-assignment problem, formed by branching strategy is presented to reduce the number of the candidate subproblems.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1997.10a
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• pp.11-14
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• 1997

Flexibility and efficiency in producing a large number of productions in small-to-medium lot sizes are necessary to be competitive. Many firms are concerned about cellular manufacturing system(CMS) to surmount the abrupt change in management environment and to innovate their manufacturing systems. The purpose of this study 1) align BPR with CMS, 2) present the methodology for constructing a CMS and 3) apply to a firm ad verify it. The results of this paper are to present 1) the systematic methodology for constructing CMS at first in our country, 2) the methodology integrating managerial aspects, technological aspects and behavioral aspects, 3) the customer-oriented methodology based on customer value.