• ETRI Journal
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• v.38 no.4
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• pp.746-756
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• 2016

Owing to the intermittent power generation of renewable energy sources (RESs), future wireless cellular networks are required to reliably aggregate power from retailers. In this paper, we propose a distributed power allocation (DPA) scheme for base stations (BSs) powered by retailers with heterogeneous RESs in order to deal with the unreliable power supply (UPS) problem. The goal of the proposed DPA scheme is to maximize our well-defined utility, which consists of power satisfaction and unit power costs including added costs as a non-subscriber, based on linear and quadratic cost models. To determine the optimal amount of DPA, we apply dual decomposition, which separates the master problem into sub-problems. Optimal power allocation from each retailer can be obtained by iteratively coordinating between the BSs and retailers. Finally, through a mathematical analysis, we show that the proposed DPA can overcome the UPS for BSs powered from heterogeneous RESs.

• New & Renewable Energy
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• v.1 no.3 s.3
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• pp.35-41
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• 2005

This paper analyses the economics of grid-connected photovoltaic systems. With the 2003 cost of photovoltaic systems, under prevailing capital market conditions, with a system lifetime of 30 years, and under the best climatic conditions, it appears that the cost of production of grid-connected electricity could be of 0.21 US $/kWh, and under medium climatic conditions, European locations, Switzerland, Japan and South Korean could be of 0.28$/kWh. If the lifetime if the system goes up, due to future technological improvements, to a very large value such as 50 years, these costs can be lowered by 10-20%. Competitiveness of grid-connected photovoltaic electricity, while it still cannot be taken for granted, is a possibility, especially if major technological advances further lowers the costs of photo cells and increases their lifetimes.

• Korean Journal of Child Studies
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• v.17 no.1
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• pp.275-288
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• 1996

The purposes of this study were to investigate children's prosocial behavior by age and sex and to examine the relationship between children's prosocial moral reasoning and prosocial behavior by costs and types of tasks. The subjects were 300 3th-and 6th-graders enrolled in elementary schools in Seoul. The revised form of Prosocial Moral Dilemmas including costs and types of tasks was used. The tasks of prosocial behaviors included time-cost tasks, money-cost tasks and physical strength-cost tasks. For data analysis, the paired t-test, two-way ANOVA, and Pearson's Correlations were used. Major findings were as follows; (1)There was age difference in children's prosocial behavior. 6th-graders performed at a higher level than 3th-graders. Sex differences weren't significant. In low- and high-cost tasks and in time-, money-, and physical strength-cost tasks, there were (2) Scores on high-cost behavior tasks were higher than on low-cost tasks. (3) Children's prosocial moral reasoning was positively related to prosocial behavior; in low- and high-cost tasks, and in time-, money-, and physical strength-cost tasks.

• IE interfaces
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• v.24 no.4
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• pp.341-350
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• 2011

This paper considers a problem of locating both distribution centers and retailers in a zone-dependent two-level distribution network where either a distribution center or a retailer should be located in each zone. Customer demands of each zone should be satisfied directly from either its own distribution center or its own retailer being supplied from a distribution center of another zone. The objective of the proposed problem is to minimize total cost being composed of distribution center/retailer setup costs and transportation costs. In the analysis, the problem is proved to be NP-hard, so that a branch-and-bound algorithm is derived for the problem. Numerical experiments show that the proposed branch-and-bound algorithm provides the optimal solution efficiently for some small problems.

• Journal of Korean Society for Quality Management
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• v.33 no.3
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• pp.135-148
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• 2005

This paper considers a six sigma project for reducing the project costs through project risk management. The project follows a disciplined process of five phases: define, measure, analyze, improve, and control. A risk management process map is used to identify process input and output variables. Seven key process input variables are selected by using C&E diagram and X-Y matrix and finally four vital few input variables are selected by the related statistical analysis. The optimum alternatives of the vital few input variables are obtained by the method of PUGH matrix. The process is running on control plan and we obtained substantial project cost reductions in early stage of the control phase.

• Proceedings of the KIEE Conference
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• 1999.07f
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• pp.2537-2539
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• 1999

In order to widen the radius of electric vehicle (EV) travel recharging points must be provided in sufficient numbers and at convenient places. The cost of providing side an infrastructure is at preset, not well documented and this lack of information acts as a detersent to prospective insestors in EV technology. This paper acts as a preliminancy investigation into the cost of infrastructure is the different situation i.e for the private owner, the fleet owner or for the public. It provides an overview of the items required and this relative costs. Cost will however, vary from country to country and application to application, and this paper two acts purely as guide to the type of equipment and its relative costs.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.5
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• pp.871-881
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• 2010

In the uniform price electricity market or bilateral electricity market, the energy transactions in which the network is not considered and ISO's system operation costs which ISO try to minimize are settled separately. In this paper, transmission loss, one of the ISO's system operation costs, was dealt. The conventional marginal loss allocation method gives economic signals but three aspects have to be considered; excessiveness, arbitrariness and cross-subsidy. In this paper, marginal loss compensation efficiency method was suggested which consider those aspects of the conventional marginal loss allocation method. Also the characteristics of the marginal loss compensation efficiency were analyzed in the appendixes. And simple 2-bus system and IEEE 14 bus system were used to explain these characteristics.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.09a
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• pp.199-201
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• 2003

The monitoring effectiveness not only depends on the effectiveness of the network, but also the costs of the network. Generally the costs of the monitoring network are mainly on the equipment and personnel; the implementation and maintenance; the observation and sample connection; the sample analysis; and the data storage and processing. The cost of the monitoring network can be expressed as a function of monitoring frequency because the monitoring method can be an automatic or a manual measurement. To determine the sampling frequency of subsidiary groundwater monitoring stations, time series data of national groundwater monitoring stations were used. The proposed optimal sampling frequency for subsidiary groundwater monitoring station is about 7 to 20 days and the average frequency is about 2 weeks.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.15
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• pp.6177-6180
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• 2014

Background: Our study objectives were to evaluate the medical economics of cervical cancer prevention and thereby contribute to cancer care policy decisions in Japan. Methods: Model creation: we created presence-absence models for prevention by designating human papillomavirus (HPV) vaccination for primary prevention of cervical cancer. Cost classification and cost estimates: we divided the costs of cancer care into seven categories (prevention, mass-screening, curative treatment, palliative care, indirect, non-medical, and psychosocial cost) and estimated costs for each model. Cost-benefit analyses: we performed cost-benefit analyses for Japan as a whole. Results: HPV vaccination was estimated to cost $291.5 million, cervical cancer screening $76.0 million and curative treatment $12.0 million. The loss due to death was $251.0 million and the net benefit was -$128.5 million (negative). Conclusion: Cervical cancer prevention was not found to be cost-effective in Japan. While few cost-benefit analyses have been reported in the field of cancer care, these would be essential for Japanese policy determination.

• THE INTERNATIONAL COMMERCE & LAW REVIEW
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• v.14
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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.