• Asia pacific journal of information systems
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• v.12 no.3
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• pp.1-20
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• 2002

For the last decade, some leading groups of corporations in Korea have integrated and managed their Information Systems(IS) functions. Each group established a separate System Management(SM) company to manage the IS and tried to get a synergy effect from the integration. These attempts, however, were not initiated by any one company. Rather they were group efforts. Moreover, the previous measuring tools evaluated IS with the scope of technical performance or quantitative user satisfaction using an absolute scale. Obscure criteria were used in an attempt to present improvements in IS function which were qualitatively weak. This study evaluates whether integration has been efficient and successful. For this purpose, we evaluate the performance efficiency of IS functions with Data Envelopment Analysis(DEA) methodology. In comparison with prior methods, DEA presents the rate of relative efficiency, the efficiency frontier for improving inefficiency, the degree of improvement(slack), and the guideline to construct any benchmark(reference set). For our DEA evaluation, this study selected a leading group of 23 companies in Korea. Our experimental results are as follows. First, efficiency was rated low on average. It also demonstrates that the motivation of performance efficiency of IS functions is deficient. Second, the result of the test to find the existence of economy of scale and scope shows that the growth of an organization and industrial characteristics do not affect IS performance efficiency from the perspective of user satisfaction. Finally, the comparison with other evaluation approaches informs us that DEA can be a complementary evaluation method which supports other measuring tools.

• Journal of Korea Water Resources Association
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• v.41 no.6
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• pp.597-603
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• 2008

This paper estimates technical efficiency of industrial water in order to afford some information for improving the efficiency of government water management policy. To estimate technical efficiency, this paper uses data envelopment analysis. The result shows that the average pure technical efficiency of industrial water is 0.407. This estimate is less than the estimates when all inputs are considered as variables in the previous researches. This result means that the managers may have not tried to improve the efficiency of industrial water usage since the cost for industrial water is trivial compared to other inputs. In addition, this result shows that the previous researches which assume that all inputs are used in efficient way may give a biased results.

• Journal of Welding and Joining
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• v.25 no.4
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• pp.49-57
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• 2007

The optimization of the cladding parameters was studied to maximize the deposition efficiency in the laser cladding using a low power pulsed Nd:YAG laser. STS304 stainless steel plate and Co alloy powder were used as a substrate and powder for cladding, respectively. The six cladding parameters were selected through preliminary experiments and their effects on the deposition efficiency were analyzed statistically. Experiments were designed and carried out using the Taguchi experimental method using a L18 orthogonal array. It was found from the results of analysis of variance(ANOVA) that the powder feed position and powder feed angle had the most significant effects on the deposition efficiency, but the powder feed rate and laser focal position had nearly no effects. The deposition efficiency could be maximized at 0mm of the powder feed position and 50o of the powder feed angle in the experimental range. From this experimental analysis, a new laser cladding head with 20o of the powder feed angle was designed and manufactured. With a new laser cladding head, the highest deposition efficiency of 12.2% could be obtained.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.10 no.6
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• pp.85-92
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• 2010

In this paper, we propose a Clustering-based Cooperative Routing using OFDM (CCRO) for supporting transmission efficiency in mobile wireless sensor networks. The main features and contributions of the proposed method are as follows. First, the clustering method which uses the location information of nodes as underlying infrastructure for supporting stable transmission services efficiently is used. Second, cluster-based cooperative data transmission method is used for improving data transmission and reliability services. Third, OFDM based data transmission method is used for improving data transmission ratio with channel efficiency. Fourth, we consider realistic approach in the view points of the mobile ad-hoc wireless sensor networks while conventional methods just consider fixed sensor network environments. The performance evaluation of the proposed method is performed via simulation using OPNET and theoretical analysis. The results of performance evaluation show improvement of transmission efficiency.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.11
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• pp.263-281
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• 2017

Global optimization that considers the processes at integrated steel mills is more important than the local optimization to improve the efficiency of a single process. Research utilizing mathematical models at integrated steel mills predominantly focus on solving problems solely for a specific process or focusing on what techniques are applied to. However, it is important to define the problems that must be solved at the steelworks, identify the objectives and constraints that can be modeled, and selection of methodologies that can be applied to the problems. The purpose of this study is to investigate the problems in improving efficiency at integrated steel mills from the viewpoint of production & operations management. We review the research have been conducted in order to solve those problems. We classified the research into 6 categories and suggested future research direction based on the global optimization. It is expected that research themes for improving the efficiency at integrated steel mills will be derived.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.11
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• pp.395-402
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• 2016

This paper presents a design methodology for improving the energy efficiency by considering the inertial properties of serial manipulators. This method employed is to put the inertia matrix, which has a critical effect on the equation of motion, into the constraints of the optimization problem. Through the optimization process, we propose a design algorithm that can double-check whether the optimized parameters satisfy the required performance or not by using an auxiliary index associated with the inertia and energy. Using this design algorithm, we were able to improve the energy efficiency by minimizing the torque. We applied this method to a 3 degrees of freedom serial manipulator and simulated it.

• Proceedings of the Korean Information Science Society Conference
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• 2010.06a
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• pp.216-217
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• 2010

• Proceedings of the KWS Conference
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• 2006.10a
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• pp.259-261
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• 2006

• Proceedings of the KOR-KST Conference
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• 2007.05a
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• pp.334-342
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• 2007

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1984.04a
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• pp.47-54
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• 1984

This paper presents the concepts of radio frequency spectrum, the efficiency of spectrum, the parameters for evaluating system performance. The various techniques for improving spectrum utilization are discussed from the standpo9int of communication theory.