• Journal of Korean Institute of Industrial Engineers
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• v.28 no.3
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• pp.232-239
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• 2002

This paper analyzes how a buyer can determine the economic replenishment policy when the supplier allows delay in payments for an order of a product. For the analysis, it is assumed that the length of credit period is a function of the buyer's amount of purchase, and inventory is depleted not only by buyer's demand but also by deterioration. Investigation of the properties of the model developed allows us to develop an algorithm whose validity is illustrated using an example problem.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1997.04a
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• pp.82-87
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• 1997

In order to make unmanned machining systems with satisfactory performances, it is necessary to incorporate appropriate condition monitoring systems in the machining workstation to provide the required intelligence of the expert. This paper deals with condition monitoring for tool wear and fracture during turning operation. Developing economic sensing and identification methods for turning processes, sound pressure measurement and digital signal processing technique are proposed. The validity of the proposed system is confirmed through the large number of cutting tests.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.6 no.3
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• pp.36-43
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• 1997

In order to make unmanned machining systems with satisfactory performances, it is necessary to incorporate appropriate condition monitoring systems in the machining workstations to provide the required intelligence of the expert. This paper deals with condition monitoring for tool wear and breakage during turning operation. Developing economic sensing and identification methods for turning processes, sound pressure measurement and digital signal processing technique are proposed. The validity of the proposed system is confirmed through the large number of cutting tests.

• Korean Journal of Childcare and Education
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• v.12 no.6
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• pp.41-58
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• 2016

This study investigated the relationships between socio-economic status of family, home environment stimulation, children's behavioral problems, and interactive peer play of preschool children. Surveys of 2,150 Korean mothers with their preschool children(Mean age= 51.9 months) from the Panel Study of Korean Children by Korea Institute of Child Care and Education were analyzed using structural equation modeling. Each variable's confirmatory factor analysis showed the correlation coefficient below .85, which made a satisfactory level of discriminant validity. The model fit to the data well, with an agreeable level of index. The major findings were as follows. First, SES did not significantly affected children's interactive peer play. Second, SES significantly affected home environment stimulation and children's behavioral problems. And the relationship between SES and children's behavioral problems are significantly mediated by home environment stimulation. Third, the relationship between SES and children's interactive peer play are significantly mediated by home environment stimulation and children's behavioral problems. These results help better understand the paths among the home characteristics and children's behavioral problems on children's social development. Interpretation and implication of the results have been discussed.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.66 no.3
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• pp.123-128
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• 2017

Electric utilities has been considered the necessity to introduce AM(asset management) of electric power facilities in order to reduce maintenance cost of existing facilities and to maximize profit. In order to make decisions in terms of repairs and replacements for power transformers, not only measuring by counting parts and labor costs, but comprehensive comparison including reliability and cost is needed. Therefore, this study is modeling input cost for power transformer during its entire life and also the life cycle cost (LCC) technique is applied. In particular, this paper presents an application of heuristic harmony search(HS) optimization algorithm to the convergence and the validity of economic life assessment of power transformer from LCC technique. This recently developed HS algorithm is conceptualized using the musical process of searching for a perfect state of harmony. It uses a stochastic random search instead of a gradient search so that derivative information is unnecessary. The effectiveness of the proposed identification method has been demonstrated through an economic life assessment simulation of power transformer using HS optimization algorithm.

• Journal of Technology Innovation
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• v.21 no.1
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• pp.229-252
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• 2013

The aim for this study is to suggest a practical model to measure the financial values of the achievements from corporate research and development(R&D) projects. Performance indicators for R&D projects were identified from the extensive literature reviews and the evaluation methods to convert them into financial values were proposed to overcome the problems of excessive predictions and subjective expert assessments in existing methods. The proposed model was applied to R&D projects of an IT company in Korea for its validity test. The model is expected to be a turning point in economic evaluation of corporate R&D projects in general due to its practical and reasonable scheme.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.1B
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• pp.56-70
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• 2006

This study attempts to estimate the size of economic value that could be created by the adoption of a new internet protocol, IPv6. The existence of externality and diffusion effects in the adoption of a new platform technology makes it difficult to capture the exact costs and benefits of IPv6 adoption. Hence, this study employed multiple evaluation methods rather than relying on single method to increase the validity of results by averaging the value of different methods. Futhermore, the proposed evaluation model includes qualitative variables such as expert opinions, as well as quantitative variables, to incorporate various stakeholders' perspectives. Finally, the policy implications for IPv6 adoption and the limitations of this study are discussed.

• Environmental and Resource Economics Review
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• v.10 no.1
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• pp.95-126
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• 2001

Functional values for wastewater treatment and atmospheric regulation in coastal wetland and rice paddy ecosystems are quantified, and an illustration is given on how to integrate biophysical parameters into a valuation framework. This is one of most controversial issues in economic analysis for wetland preservation versus wetland conversion to agricultural use. This paper includes theoretical considerations for estimating functional values of environmental ecosystems, and the integration of biophysical data and replacement cost method employed. Specific physical and geographical characteristics and data on ecosystem functions and services in coastal wetlands and rice paddies are addressed for evaluating their values in economic terms. In particular this paper indicates double counting problems and overestimation in the previous studies, and demonstrates how to avoid them and to maintain the consistency of valuation process involving a least-cost method, thus enables an accurate integration of the coastal wetland ecology and wetland economics. As a result which is far away from the previous studies, the total economic present value of wastewater assimilation by coastal wetland is estimated at 7,484,640 won/ha, and the net present value of positive effect for atmospheric regulation, negative effects for air pollution and water pollution by rice paddy is estimated at -37,934 won/ha, assuming that resources are infinitely long-lived and the annual value and the rate of discount (10%) is constant every year. In conclusion, for further reliability and validity of functional values for natural resources it is very noteworthy that a general equilibrium framework that could directly incorporate the interdependence between ecosystem functions and services would be preferred to the partial equilibrium framework.

• Journal of Information Technology Applications and Management
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• v.20 no.4
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• pp.221-234
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• 2013

In this paper, we report bankruptcy risk level forecasting result for automobile parts manufacturing industry. With the premise that upstream supply risk and downstream demand risk could impact on automobile parts industry bankruptcy level in advance, we draw upon industry input-output table to use the economic indicators which could reflect the extent of supply and demand risk of the automobile parts industry. To verify the validity of each economic indicator, we applied simple linear regression for each indicators by varying the time lag from one month (t-1) to 12 months (t-12). Finally, with the valid indicators obtained through the simple regressions, the composition of valid economic indicators are derived using stepwise linear regression. Using the monthly automobile parts industry bankruptcy frequency data accumulated during the 5 years, R-square values of the stepwise linear regression results are 68.7%, 91.5%, 85.3% for the 3, 6, 9 months time lag cases each respectively. The computational testing results verifies the effectiveness of our approach in forecasting bankruptcy risk forecasting of the automobile parts industry.

• Proceedings of the KSR Conference
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• 2006.11b
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• pp.407-413
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• 2006

Railways are very important to get stability of railway structure as transportation system carrying a lot of passengers and freight. These days the construction of underground railway crossing such as expansion of new roads, construction of subway and gas pipe is increasing because of economic and social development. But these kinds of construction didn't take into account Cost-benefit analysis of railway which has the most important aspects of railway safety, so the results of construction didn't get a good evaluation. This study adapt Cost-benefit analysis to evaluate the economic validity of underground railway crossing. This study adjust about Cost-benefit analysis of railway part, and analyze the new method and technology of underground railway crossing constructed by Korean National Railroad and Railway Network Authority. Also this study divide between high frequency line and low frequency lineusing B/C, NPV, and IRR analysis. After analysis, B/C ratio method is the most suitable method among B/C, NPV, and IRR analysis method. Therefore this study can express economic benefit quantitatively and decrease the cost by adapting Cost-benefit analysis, and can clearly express the construction feasibility and investment effects of construction of underground railway crossing method.