• 대한산업공학회지
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• 제21권3호
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• pp.299-311
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• 1995

Conventional discounted cash flow techniques fail to capture the risk associated with investments. This paper proposes an annual cash flow model that considers risk, cost structure and inventory liquidation in the evaluation of investment alternatives. The risk differential of investments is included using the capital asset pricing model while the stochastic version of the cost-volume-profit approach is used to consider inventory liquidation and cost structure. Tradeoffs between fixed and variable costs have been investigated, and portrayed using iso-cash flow curves. The proposed cash flow model has been developed, in particular, to enable an accurate evaluation of advanced manufacturing systems.

• 전기학회논문지
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• 제58권4호
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• pp.700-707
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• 2009

The application of renewable energy in electric power systems is growing rapidly in order to make provision for the inequality of the climate, the dwindling supplies of coal, oil and natural gas and a further rise in oil prices. Solar cell generators(SCG) is one of the fastest growing renewable energy. This paper presents a methodology on probabilistic production cost simulation of a power system including SCGs. The generated power by SCGs is variable due to the random variation of solar radiation. In order to solve this problem, the SCGs is modeled as multi-state operational model in this paper. Probabilistic production cost of a power system can be calculated by proposed method considering SCGs with multi-state. The results show that the impacts of SCGs added to a power system can be analyzed in view point of production cost using the proposed method.

• 조명전기설비학회논문지
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• 제26권12호
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• pp.50-55
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• 2012

This paper presents an application of optimization method for efficient operation in micro grid. For operational efficiency, the objective function in a diesel generator consists of the fuel cost function similar to the cost functions used for the conventional fossil-fuel generating plants. The wind turbine generator is modeled by the characteristics of variable output. The cost function of fuel cell plant considers the efficiency of fuel cell. Particle swarm optimization(PSO) and sequential quadratic programming(SQP) are used for solving the problem of microgrid system operation. Also, from the results this paper presents the way to attend power markets which can buy and sell power from upper lever grids by connecting a various generation resources to micro grid.

• International Journal of Reliability and Applications
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• 제17권1호
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• pp.85-105
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• 2016

In this paper accelerated life testing is incorporated in quality control technique of acceptance sampling plan to induce early failures in high reliability products.Stress under accelerated condition can be applied in constant-stress, step-stress and progressive-stress or combination of such loadings. A ramp-stress results when stress is increased linearly (from zero) with time. In this paper optimum failure-censored ramp-stress accelerated life test sampling plan for log-logistic distribution has been formulated with cost considerations. The log-logistic distribution has been found appropriate for insulating materials. The optimal plans consist in finding optimum sample size, sample proportion allocated to each stress, and stress rate factor such that producer's and consumer's interests are safeguarded. Variance optimality criterion is used when expected cost per lot is not taken into consideration, and bilevel programming approach is used in cost optimization problems. The methods developed have been illustrated using some numerical examples, and sensitivity analyses carried out in the context of ramp-stress ALTSP based on variable SSP for proportion nonconforming.

• 제어로봇시스템학회논문지
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• 제20권7호
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• pp.750-755
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• 2014

Product shortage which causes backordering and/or lost sales cost is very popular in chemical industries, especially in commodity polymer business. This study deals with backordering cost in the supply chain optimization model under the framework of process-inventory network. Classical economic order quantity model with backordering cost suggested optimal time delay and lot size of the final product delivery. Backordering can be compensated by advancing production/transportation of it or purchasing substitute product from third party as well as product delivery delay in supply chain network. Optimal solutions considering all means to recover shortage are more complicated than the classical one. We found three different solutions depending on parametric range and variable bounds. Optimal capacity of production/transportation processes associated with the product in backordering can be different from that when the product is not in backordering. The product shipping cycle time computed in this study was smaller than that optimized by the classical EOQ model.

• 무역상무연구
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• 제14권
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• pp.219-233
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• 2000

Korea has been faced a difficult situation with regard to the cost of physical distribution(PD). The problem have arisen from the fact that Korean firms have far different cost structures of the PD according to its industry or business. High PD costs sometimes reduce firms' operating income and perceived competitive disadvantages not only in domestic but in world-wide business. In this research, we examine the factors affecting firm's PD cost by investigating financial and non-financial variables such as variable cost to sales ratio and number of employee of a firm. Analyses are performed to construct research models with t-test and the logistic regression estimation.

• 전기학회논문지
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• 제58권11호
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• pp.2162-2167
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• 2009

A Low cost and variable speed brushless motor drive system with single switch per phase is presented. The motor drive is realized with a novel two-phase flux-reversal-free switched reluctance motor and a split AC two switch converter. The strategy of the controller and the converter for its realization are described. Comparisons between a split AC converter, asymmetric converter, split DC converter, single controllable switch converter, and N+1 converter are performed for its device rating, cost, switching losses and conduction losses, and converter efficiency. The split AC converter is analyzed and simulated to verify the characteristics of the converter circuitry and control feasibility and the simulation results are presented. The efficiency with various loads is numerically estimated and experimentally compared from viewpoint of subsystem and system in details. The focus of this paper is to compare the presented motor drive system to the asymmetric converter system throughout experiments and demonstrate single switch per phase converter having comparable efficiency as the asymmetric converter system.

• 한국병원경영학회지
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• 제26권2호
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• pp.17-26
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• 2021

Purposes: This study aims to identify factors affecting dental university hospitals' profitability and understand recent their business condition. Methodology: Data from 2016 to 2019 was collected from financial statement, public open data in 8 dental university hospitals. For the study, multiple regression test with stepwise selection was applied. Findings: First of all, 9 out of 19 independent variables were selected by stepwise selection. As a result of multiple regression test with selected independent variables and the dependent variable(operating profit margin ratio), the factors affecting hospitals' profitability were the number of dental unit chair, hospital location, debt ratio, total capital turnover ratio, employment cost rate, material cost rate, management expense rate, the number of patient per a dentist. Practical Implication: To improve dental university hospitals' profitability, hospitals specifically analysis and manage their cost such as employment, material and management cost and seek effectiveness by managing the proper number of patient per a dentist.

• 무역학회지
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• 제45권2호
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• pp.17-29
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• 2020

This study analyzed that the effects of AEO MRA benefit on decreasing of trade cost and the strategies for expanding of trade. It uses the system GMM for effective solutions of endogenous matter with lagged dependent variable. In terms of the result of analysis, AEO MRA has a positive effect on decreasing of trade cost, especially this study proved the result of previous study AEO MRA expanded the trade through improving the time required for customs clearance and deregulation of non-tariff barriers. In conclusion, this study proposes the policy fo AEO MRA by analyzing the trade cost of AEO MRA by using the system GMM.

• Journal of Periodontal and Implant Science
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• 제26권3호
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• pp.689-699
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• 1996

The purpose of this research is to determine elements affecting the out-of-pocket cost of woman. The sample consisted of 1907 women living Iksan city. The survey was conducted by means of questionnaires. The model used in the analysis of out-of-pocket cost was the Andersen-Newman model, while the analysis techniques used were stepwise multiple regression and path analysis. The number of independent variables used in the analysis was 28 in total, ie 19 predisposing components, 6 enabling components, and 3 need components. In this study, the amount of variance by the model was 17 percent. Number of restricted activity days caused by oral disease, perceived susceptibility of dental disease, having a regular dental care, dental treatment costs, education level and income were found to have significant major effects on out-of-pocket cost. Number of restricted activity days caused by oral disease was the most important variable affecting out-of-pocket cost of woman. Also out-of-pocket cost shows larger effect due to enabling components than frequency of dental utilization.