• Journal of Korean Institute of Industrial Engineers
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• v.13 no.2
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• pp.65-77
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• 1987

Congestion occurs whenever users interfere with each other, while competing for scarce resources. In a congested market, such as a telecommunication service market, users of telecommunication services incur costs in using the service in addition to the price. The user's own time costs involved in learning to use the service, waiting for the service, and making use of the service are typically greater than the price of telecommunication services. A market equilibrium analysis is performed in which a method for user demand aggregation is developed. The effects of price changes on user demands and market demands for congested services are examined. It is found that total market demands may increase as the price for less-congested services increase under certain demand conditions. This suggests that a nonuniform pricing scheme for a congested service may improve the utilization of the congested system. The sign of price cross-elasticity for congested services is show to vary with demand conditions. A possible complementary property of congested services is found and the implication of such a property is discussed. It is argued that such a complementary property may lead to a cross subsidy in a market with congestion. Finally, comparisons between uniform pricing and nonuniform pricing policies are made. A specific numerical example is given to show that a nonuniform pricing policy may be Pareto superior to a uniform pricing policy.

• Journal of Satellite, Information and Communications
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• v.7 no.2
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• pp.13-17
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• 2012

In recent years, type of the car is changing. Instead of cars that use internal combustion engines, we will use mainly eco-friendly electric vehicles. However, the utilization of electric vehicles brings enormous increase of power consumption. Thus, efficient power management and intelligent power consumption is required. Demand response can be effective measures of power consumption. In this paper, we present demand response technology applications, communication method, PLC application and simulation result.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.23 no.60
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• pp.11-22
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• 2000

The main objective of this research is to analyze an order point and an order quantity of a distribution center and each branch to attain a target service level in multi-level inventory distribution system. In case of product item, we use the item with low volume of average monthly demand. Under the continuous review method, the distribution center places a particular order quantity to an outside supplier whenever the level of inventory reaches an order point, and receives the order quantity after elapsing a certain lead time. Also, each branch places an order quantity to the distribution center whenever the level of inventory reaches an order point, and receives the quantity after elapsing a particular lead time. When an out of stock condition occurs, we assume that the item is backordered. For considering more realistic situations, we use generic type of probability distribution of lead times. In the variable lead time model, the actually achieved service level is estimated as the expected service level. Therefore, this study focuses on the analysis of deciding the optimal order point and order quantity to achieve a target service level at each depot as a expected service level, while the system-wide inventory level is minimized. In addition, we analyze the order level as a maximum level of inventory to suggest more efficient way to develop the low demand item model.

• Women's Health Nursing
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• v.5 no.2
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• pp.222-229
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• 1999

These days, as the society has been in the trends of highly industrialized and the family has been downsized, there is remarkably increasing number of women who follow occupation. These changes have made it more difficult for the family to help post-partum mother, which had been performed in side of house. By the help of social believe that during at least 1 month after childbirth professional nursing program is indispensable for both maternity protection and physical-mental recuperation, now many post-partum care centers for post-partum mother have been in operation. Although these post-partum care center have in use for a long time, no study was performed before this study on the same subject. Data were analyzed using by SAS. The results of study are as follow : 1. The general features of the user of the post-partum care center. The predominant band of user's age is extended from 26 to 30. The users are mainly housewives and they are in higher level of incomes and educations. As for the feature of delivery methods, they performed the normal spontaneous vaginal delivery method by 58.0% and the Caesarean operation method by 42.0%. As for the sexuality for babies, 59.3% of infants are male, and 40.7% are female. The highest delivery order of users is first and admission after 1-3days delivery is highest. 2. The results for the investigation into the actual condition of the post-partum care center are as follow : About the main reason for entrance of the post-partum care center was found to be the needs for the better nursing programs for recuperation after childbirth. This demands are also supported by their husbands. The average length of stay in the post-partum care center is 17.6 days and the besides promised expense ; powdered milk, milk-suckers, disposable dippers, skin cares, body shape cares, entrophics, injections. The post-partum have private rooms for mother and infants. Over the half of average expense is 229 million won. They are paying accessory fees the post-partum care center have similar step organization : the nurses, the skin carers, the cleaners. Mostly both ways of feeding powdered milk and breast feeding are in use, and mother's milk is preserved in the night time to be given to infant by nurse in charge. 3. The results of the investigation on users' nursing demand to the post-partum care center and satisfaction are as follow : The ranking order of nursing demand of mothers who used the is that ; infant care demands, environmental demands, emotional and mental care demands, education and training demands. As much as 70% of the respondents have dissatisfaction in nursing program, The ranking order of service satisfaction of mothers who used appears to be higher following order ; satisfaction in infant care demand, satisfaction in physical nursing demand, satisfaction in emotional and mental nursing demand, satisfaction in education and training demand, satisfaction in environment nursing demand. The results of pearson correlation. between nursing demand and service satisfaction of mothers who used are found to be relative noticeable in the level of 0.05. only infant care. The 61.7% of the women who used the post-partum care center. are responding that they will reuse the same post-partum care center again.

• Environmental and Resource Economics Review
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• v.30 no.2
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• pp.237-268
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• 2021

As variable renewable sources rapidly increase due to the Energy Transition plan, integration cost of renewable sources to the power system is rising sharply. The increase in variable renewable energy reduces the capacity factor of existing traditional power capacity, and this undermines the efficiency of the overall power supply, and demand resources are drawing attention as a solution. In this study, we analyzed how much electric vehicle demand resouces, which has great potential among other demand resources, can reduce power supply costs if it is used as a flexible resource for renewable generation. As a methodology, a stochastic form of power system optimization model that can effectively reflect the volatile characteristics of renewable generation is used to analyze the cost induced by renewable energy and the benefits offered by electric vehicle demand resources. The result shows that virtual power plant-based direct control method has higher benefits than the time-of-use tariff, and the higher the proportion of renewable energy is in the power system, the higher the benefits of electric vehicle demand resources are. The net benefit after considering commission fee for aggregators and battery wear-and-tear costs was estimated as 67% to 85% of monthly average fuel cost under virtual power plant with V2G capability, and this shows that a sufficient incentive for market participation can be offered when a rate system is applied in which these net benefits of demand resources are effectively distributed to consumers.

• Journal of Korean Institute of Industrial Engineers
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• v.20 no.3
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• pp.55-63
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• 1994

Optional two-part tariffs are in growing use in telecommunication services markets. This paper considers the problem of designing profit-maximizing optional two-part tariffs for heterogeneous user groups. It is shown that, at an optimum, one of usage charges among a set of optional two-part tariffs should be made equal to marginal cost. It is also shown that, if demand curves cross, then one of usage charges at the optimum can be below marginal cost. An example with linear demand functions is given to illustrate the important features of optimal two-part tariffs.

• Journal of Korean Institute of Industrial Engineers
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• v.20 no.3
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• pp.117-124
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• 1994

In this paper an inventory model is presented for determining the ordering schedule in which the demand rate is changing linearly with time and the decay is assumed to be a constant rate of the on-hand inventory. An easy to use heuristic is developed to find the times and sizes of replenishments so as to keep the total of ordering, inventory carrying and deteriorating costs as low as possible. Solutions of the model to test problems show that our heuristic model outperforms other existing models in the literature without sacrificing the computational complexity. When there is no deterioration, the model developed is related to the corresponding model of nondeteriorating items.

• Journal of the Korean Professional Engineers Association
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• v.27 no.4
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• pp.46-55
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• 1994

Demand Side Management(DSM) is a system to reduce the investment cost for new power plant construction and expansion of supply facilities, power through the investment for the energy conservation and load management. In this study, the trend of the energy environment, the necessity and feasibility of DSM shall be investigated and analysed, so that this study will give a help to select and develope a proper DSM technologies for actual use.

• Proceedings of the IEEK Conference
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• 1998.06a
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• pp.737-740
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• 1998

Under the worldwide booming internet environment, there has been increasing demand for various multimedia services. Especially the demand for effective video services has been rapidly increased. In this paper, we describe the implementation of video service system for internet use based on H/263 video compression technique and UDP socket on the TCP/IP environment. In addition, by using the plug-in-play technique, the implemented system improved user interface for correct retrieval and easy usage.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.1533-1541
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• 2010

Multi-purpose freight car is applicable for both bulk freight and containerized freight to cope with the unbalance between demand and supply due to the demand variation by seasons or directions. In this paper, we suggested the advantages of introducing attachable container to railway freight transportation and possible freight items to use multi-purpose freight car. This results can be used to analyse the amount of attachable container and the feasibility of introducing multi-purpose freight car to railway.