• 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.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.3B
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• pp.239-253
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• 2006

For guaranteeing the international competitive power of SW industry that is the core industry for the future, the training of SW technical manpower as an architect is needed. They must confront the change of worldwide technology and also lead the design and analysis of SW industry for the future. However, SW technical manpower based on regular career tends to change his employment as a general manager in current status. For solve this situation and reconsider the quality level of SW technical manpower, we need to propose the systematic and effective growth direction for them. Therefore, we propose the systematic and effective growth direction for domestic SW technical manpower and a plan to be realized by suggesting the carrier path of high level SW analysis/design manpower in this paper.

• Proceedings of the KIEE Conference
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• 2005.05b
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• pp.4-6
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• 2005

This paper deals with the technical map of diagnosis for power cable systems. For this purpose, failure status, failure and degradation causes, and newly suggested diagnostic techniques were investigated and analyzed. From the analysis, the technical map of diagnosis for power cable systems was proposed.

• Proceedings of the SAREK Conference
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• 2005.06a
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• pp.47-47
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• 2005

• Proceedings of the SAREK Conference
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• 2003.07a
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• pp.120-120
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• 2003

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2004.11a
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• pp.451-451
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• 2004

• Steel and Composite Structures
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• v.8 no.2
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• pp.129-144
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• 2008

This paper demonstrates an application of the perturbation based stochastic finite element method (SFEM) for predicting the performance of structural systems made of composite sections with random material properties. The composite member consists of materials in contact each of which can surround a finite number of inclusions. The perturbation based stochastic finite element analysis can provide probabilistic behavior of a structure, only the first two moments of random variables need to be known, and should therefore be suitable as an alternative to Monte Carlo simulation (MCS) for realizing structural analysis. A summary of stiffness matrix formulation of composite systems and perturbation based stochastic finite element dynamic analysis formulation of structural systems made of composite sections is given. Two numerical examples are presented to illustrate the method. During stochastic analysis, displacements and sectional forces of composite systems are obtained from perturbation and Monte Carlo methods by changing elastic modulus as random variable. The results imply that perturbation based SFEM method gives close results to MCS method and it can be used instead of MCS method, especially, if computational cost is taken into consideration.

• Journal of Welding and Joining
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• v.25 no.5
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• pp.36-44
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• 2007

This paper is the first part of the study on the accuracy improvement of numerical analysis of steel welds. The aim of this paper is to raise the accuracy of thermal analysis results, such as the shape and size of the weld cross section and the hardness distribution in HAZ(Heat-Affected Zone). It is known that the factors affecting on the accuracy are thermal properties, metallurgical properties and welding heat source model. It was found that the arbitrary distributed heat source model should be used to predict practical weld cross section shape and size. Also, in order to improve the prediction accuracy of HAZ hardness distribution, it was essential to consider 2 CCT(Continuous Cooling Transformation) diagrams in calculating volume fraction of transformed phases. One is the peak temperature being around melting temperature. The other is the peak temperature being around metallurgical transformation temperature.

• Korean Journal of Organic Agriculture
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• v.29 no.1
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• pp.41-50
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• 2021

This paper analyzes the efficiency of social enterprises by analyzing bootstrapping data envelopment analysis. Unlike the definitive DEA model, we analyze the confidence intervals of efficiency estimates through the DEA model, which takes into account stochastic factors. Major analysis results are summarized as follows: First, the results of the bootstrapping DEA analysis of social enterprises estimated that the technical efficiency was 0.459 and the 95% confidence interval was 0.389 to 0.601. Second, the number of inefficient social enterprises with efficiency values of less than 0.5 was found to be 15 (55.56%) in technical efficiency, 5 (18.52%) in pure technical efficiency, and 8 (29.63%) in scale efficiency. It can be seen that a significant number of social enterprises are operating in an inefficient state. Third, looking at the returns of scale of social enterprises, 25 (67.57%) are currently in the increasing returns of scale, 10 (27.02%) are in the constant returns of scale, and 2 (5.41%) are in decreasing returns of scale. In other words, it can be seen that social enterprises are under-invested in terms of input factors.

• Proceedings of the KWS Conference
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• 2002.10a
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• pp.657-660
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• 2002

In this paper, a study on the residual stress of plate with longitudinal stiffeners is explained in terms of the welding sequences. In order to verify the results of numerical analysis, the hole drilling method (HDM) is performed, to measuring the residual stresses of the test plates in $CO_2$ Flux Cored Arc Welding (FCAW) under various welding conditions. The non-linear transient analysis technique for the numerical analysis in a large and complicate structure is considered. The residual stress of plate in consideration of the welding sequences and directions is evaluated by some numerical simulations and also by experiments. Comparison of numerical analysis results with experimental data shows the accuracy and validity of the proposed method.