• Journal of Electrical Engineering and Technology
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• v.2 no.3
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• pp.342-345
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• 2007

This paper presents an engineering approach to derive the optimum price levels of transacted power. In this paper, with the assumption that power import is possible through the system connection in Northeast Asia regions, the upper price limit of imported power deserving economic efficiency was derived with respect to the time and amount of power import. The proposed approach was demonstrated based on the data from the National Power Development Planning in 2004 with the WASP model.

• Journal of Nutrition and Health
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• v.43 no.5
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• pp.533-542
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• 2010

The objective of this study is to provide basic information and policy implications needed to balance the supply and demand for dietitian by projecting supply and demand for dietitian. The data from the Ministry of Health Welfare and Family on the number of licensed nutritionist, resident registration data of the Ministry of Public Administration and Security, and health insurance qualification data of the National Health Insurance Corporation were used to examine the current status of supply. To project the supply of nutritionist workforce, the in-out moves method and demographic method were used. The ratios of nutritionist to population and GDP, and that of other countries were applied as the demand projection method. According to the study results, the projection on the imbalance of supply and demand for dietitian by year 2021 differs depending on the method used. First, according to the results based on age-adjusted population ratio, there is an oversupply of 1,643 dietitians in year 2010, and 2,076 dietitians in year 2020. Second, although the projection on the imbalance of the supply and demand for dietitian differs depending on whether the GDD is calculated in won(￦) or dollar($). it is expected that there will be an oversupply in general. Third, as to the scenario using the nutritionist ratio in foreign countries, the oversupply of dietitian is likely in Korea, under any scenario, when comparing the nutritionist supply projection with the demand projection based on the nutritionist ratio in the United States. However, the projection of the supply and demand varies in each scenario when the European nutritionist ratio is applied. Under European 'scenario 1', an oversupply is expected, whereas under 'scenario 2', a shortage of supply is expected. A careful approach is required in interpreting the supply and demand projection using criteria of other countries, because dietitian assumes different roles and functions in each country. Although a slight oversupply of nutritionist workforce is projected, it does not cause a major problem as the demand for diet therapy is expected to rise due to aging and the increase of chronic diseases, and as the demand for clinical dietitians in hospitals increases. Accordingly, the demand for dietitians will rise and, in this context, the oversupply of nutritionist will not incur much problem. However, the nutritionist qualification is much too open in Korea, and this has a negative effect on the quality of the nutritionist workforce. Therefore, it is important that the nutritionist qualifications and requirements are reinforced in the future, enhance the quality level of the nutritionist supply, and maintain the balance between the supply and demand.

• Journal of Korean Institute of Industrial Engineers
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• v.30 no.2
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• pp.146-158
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• 2004

This paper considers a continuous-review two-echelon inventory control problem with one-to-one replenishment policy incorporated and with lost sales allowed where demand arrives in a stationary Poisson process. The problem is formulated using METRIC-approximation in a combined approach of pricing and (S-l, S) inventory policy, for which a heuristic solution algorithm is derived with respect to the corresponding one-warehouse multi-retailer supply chain. Specifically, decisions on retail pricing and warehouse inventory policies are made in integration to maximize total profit in the supply chain. The objective function of the model consists of sub-functions of revenue and cost (holding cost and penalty cost). To test the effectiveness and efficiency of the proposed algorithm, numerical experiments are performed with two cases. The first case deals with identical retailers and the second case deals with different retailers with different market sizes. The computational results show that the proposed algorithm is efficient and derives quite good decisions.

• Journal of Korean Society for Quality Management
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• v.40 no.4
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• pp.441-452
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• 2012

Purpose: In this paper, we have considered a problem of newsvendor model in an environment of random yields in quality and customer balking behavior, in which only the mean and the variance of the demand are known. In practice, the distributional information of the demand is very limited and only the mean and variance are guessed by experience. In addition, due to the customers balking behavior occurring when the available inventory level decreases, the product's demand becomes a function of inventory level so that the classical newsvendor's optimal order quantity is no longer optimal. Methods: We have developed an optimal order quantity model that enables us to incorporate the random yield of a product and the customer balking information such as a threshold inventory level of balking and the corresponding probability of a sale during the balking. Results: We illustrated the concepts developed here through simple numerical examples and showed the robustness of our model in a various setting of parameters. Conclusion: This paper provides a useful analysis showing that our distribution-specific and distribution-free approach to the optimal order quantity in the newsboy model can act as an effective tools to match supply with demand for these product lines.

• The Journal of Korean Institute for Practical Engineering Education
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• v.2 no.1
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• pp.8-16
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• 2010

Confronted with serious problems in nurturing IT engineers such as a mismatch in supply and demand of IT workers, shortage of globally competitive IT professionals, and insufficient education and training of university graduates, the Ministry of Information and Communication has decided to adopt a new approach in national IT engineering education, based on supply chain management (SCM) in manufacturing. SCM weighs improving competitiveness of the supply chain as a whole via a long-term commitment to supply chain relationships and a cooperative, integrated approach to business processes. These benefits of SCM are believed to provide useful insight into a more effective IT education and industry orientation. On the basis of the SCM literature, a framework for industry-oriented practical IT higher education is designed, and then applied in the field of computer-software engineering in Korea.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.1
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• pp.25-33
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• 2008

This paper presents a new approach of a evaluation of location marginal prices(LMPs) considering demand response resources in the competitive electricity market. The stabilization of the electric power supply and demand balance has been one of the major important activities in electric power industry. Recently, much attention is paid to the demand-side resources which are responsive to incentives or time-varying prices and existing power system planning and operation activities are incorporated with the so-called demand response resources. In this paper, we first present an analytical method for calculation of LMPs considering demand response resources and then break down the LMPs into three components. In this study, we assume that Korean power system consists of two major regions, one which is the metropolitan and the other is non-metropolitan region. In the case study, we have considered several LMPs cases with different use of locational demand response resource and we can obtain a locational signal to demand response resources. Also, the economics of demand response resources are evaluated, compared with the increase of transmission line capacity and of generation capacity.

• Journal of Intelligence and Information Systems
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• v.22 no.4
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• pp.45-67
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• 2016

Given the recent development of smart devices, users are producing, sharing, and acquiring a variety of information via the Internet and social network services (SNSs). Because users tend to use multiple media simultaneously according to their goals and preferences, domestic SNS users use around 2.09 media concurrently on average. Since the information provided by such media is usually textually represented, recent studies have been actively conducting textual analysis in order to understand users more deeply. Earlier studies using textual analysis focused on analyzing a document's contents without substantive consideration of the diverse characteristics of the source medium. However, current studies argue that analytical and interpretive approaches should be applied differently according to the characteristics of a document's source. Documents can be classified into the following types: informative documents for delivering information, expressive documents for expressing emotions and aesthetics, operational documents for inducing the recipient's behavior, and audiovisual media documents for supplementing the above three functions through images and music. Further, documents can be classified according to their contents, which comprise facts, concepts, procedures, principles, rules, stories, opinions, and descriptions. Documents have unique characteristics according to the source media by which they are distributed. In terms of newspapers, only highly trained people tend to write articles for public dissemination. In contrast, with SNSs, various types of users can freely write any message and such messages are distributed in an unpredictable way. Again, in the case of newspapers, each article exists independently and does not tend to have any relation to other articles. However, messages (original tweets) on Twitter, for example, are highly organized and regularly duplicated and repeated through replies and retweets. There have been many studies focusing on the different characteristics between newspapers and SNSs. However, it is difficult to find a study that focuses on the difference between the two media from the perspective of supply and demand. We can regard the articles of newspapers as a kind of information supply, whereas messages on various SNSs represent a demand for information. By investigating traditional newspapers and SNSs from the perspective of supply and demand of information, we can explore and explain the information dilemma more clearly. For example, there may be superfluous issues that are heavily reported in newspaper articles despite the fact that users seldom have much interest in these issues. Such overproduced information is not only a waste of media resources but also makes it difficult to find valuable, in-demand information. Further, some issues that are covered by only a few newspapers may be of high interest to SNS users. To alleviate the deleterious effects of information asymmetries, it is necessary to analyze the supply and demand of each information source and, accordingly, provide information flexibly. Such an approach would allow the value of information to be explored and approximated on the basis of the supply-demand balance. Conceptually, this is very similar to the price of goods or services being determined by the supply-demand relationship. Adopting this concept, media companies could focus on the production of highly in-demand issues that are in short supply. In this study, we selected Internet news sites and Twitter as representative media for investigating information supply and demand, respectively. We present the notion of News Value Index (NVI), which evaluates the value of news information in terms of the magnitude of Twitter messages associated with it. In addition, we visualize the change of information value over time using the NVI. We conducted an analysis using 387,014 news articles and 31,674,795 Twitter messages. The analysis results revealed interesting patterns: most issues show lower NVI than average of the whole issue, whereas a few issues show steadily higher NVI than the average.

• IE interfaces
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• v.21 no.4
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• pp.444-455
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• 2008

In the present manufacturing environment, the appropriate decision making strategy has a significance and it should count on the fast-changing demand of customers. This research derives the optimal levels of the decision variables affecting the inventory related performance in multi-stage supply chain by using simulation and genetic algorithm. Simulation model helps analyze the customer service level of the supply chain computationally and the genetic algorithm searches the optimal solutions by interaction with the simulation model. Our experiments show that the integration approach of the genetic algorithm with a simulation model is effective in finding the solutions that achieve predefined target service levels.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2004.05a
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• pp.441-445
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• 2004

In this paper, we deal with an inventory model of a multi-stage, serial supply chain system where a single product type and nonstationary customer demand pattern are considered. The retailer and suppliers place their orders according to an echelon-stock based replenishment control policy. We assume that the suppliers can access online information on the demand history and use this information when making their replenishment decisions. Using a reinforcement learning technique, the inventory control parameters are designed to adaptively change as the customer demand pattern is altered, in order to maintain a given target service level. Through a simulation based experiment, we verified that our approach is good for maintaining the target service level.

• Management Science and Financial Engineering
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• v.1 no.1
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• pp.39-66
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• 1995

This article presents a new model called the periodic square wave(PSW) to describe the material flow of periodic processes involving an intermediate buffer. The material flows into and out of the intermediate buffer are assumed to be periodic square shaped. By using this model, It is proved that the classical economic lot size model with finite supply rate, the so-called EPQ model, can be applicable to the arbitrary periodic demand case. This new model relaxes the original assumption of the constant demand. It is shown, as a unique application example, that the explicit solution for determining both upstream and downstream economic lot size can be obtained with the aid of the PSW model. The PSW model provides more accurate information on analyzing the inventory and production system than the classical approach, without losing simplicity and increasing the computational burden.