• Journal of the Korean Operations Research and Management Science Society
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• v.39 no.1
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• pp.83-100
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• 2014

Retail shops often experience purchase dependence in which some items are purchased together by customers due to their unknown interior associations. This paper develops an inventory model considering partial backordering under purchase dependence and compares the performance of the inventory model that ignores purchase dependence. Computational analyses show that purchase dependence should be incorporated as an important factor of inventory replenishment policy because the impact of purchase dependence can be more significant as the lost portion of the unmet demand orders increases and the item set is more correlated in terms of order demand.

• Journal of Digital Convergence
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• v.17 no.10
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• pp.103-113
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• 2019

The purpose of this study is to recognize the importance of sustaining the coal industry in spite of the declaration of new climate change regime. Due to the importance to have the ability to control the supply and demand for energy source, this study will present the ground supporting the need to save some fixed amount of coal to carry out this task. The relative quantity of fossil fuel like coal and oil consumed as an energy source is reduced due to the increasing portion of renewable energy sources. Nevertheless, we can verify the fact that the position as a main energy source in demand for and supply of electric power is still valid. And the optimal amount of coal storage is estimated through the average annual amount of demand derived from preceding studies. In this context, it is very urgent problem to maintain the coal industry as a industrial policy for the sustainable national economic growth through the coal storage policy and to determine the optimal amount of annual storage.

• Industrial Engineering and Management Systems
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• v.8 no.2
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• pp.72-79
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• 2009

The ultimate goal of inventory management is to decide the timing and the quantity of ordering in response to uncertain demands. Recently, some researchers have focused upon an impact of distortions in the information, e.g., customer order cancellation, on an economical inventory policy. The customer order cancellation is considered a kind of distortions in demands, because a demand that is eventually cancelled is equivalent to a phony demand. Also, there are some additional distortions in the inventory information. For instance, the procurement of suppliers may include some nonconforming items as a result of imperfect production and inspection by the suppliers, and/or damage in transit. The nonconforming item should be considered a kind of distortions in the inventory information, because the nonconforming item is equivalent to a phony stock. In this article, we consider an inventory model under the situation that customers can cancel their orders and the procurement of suppliers may include some nonconforming items. Then, we introduce the customer order reservation into the inventory model for the purpose of avoiding the costly backlogs, because the customer order reservation gives retailers a period to fulfill customer's requests. We formulate a periodic review (s, S) inventory model and investigate the economical operation under the situation mentioned above. Further, through the sensitivity analysis, we show the impact of these distortions and the effect of the customer order reservation on the inventory policy.

• The Journal of Asian Finance, Economics and Business
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• v.8 no.3
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• pp.675-682
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• 2021

The study analyzes the demand for residential space in the Untact Era. Residential space comprises six categories: the most necessary dedicated space (DS), most preferred south-facing space (SFS), largest space (LS), most necessary shared space (SS), most necessary infra-space (IS), and others. Results indicated the following: 1) All respondents had the highest preference for relaxing spaces except DS. 2) Differences were found between DS, SFS, and LS by age and SS; IS by residential area; and DS, SS, and IS by household size. 3) People aged 60+ preferred a living room while people aged 40-59 preferred a larger kitchen. Seoul citizens preferred gardens or parks in the complex or neighboring forests whereas local citizens preferred shared offices and medical centers. Households of three or more persons preferred a park/forest and two-person households preferred a honbap restaurant. The implications for housing policy are as follows. 1) Nature-friendly spaces are needed to alleviate a sense of isolation. 2) Changing demand for residential space should be reflected in housing policies. 3) The government's housing supply policy with the same residential space and structure must be changed to provide various residential spaces according to age, residential area, and household size.

• Industrial Engineering and Management Systems
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• v.11 no.2
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• pp.134-141
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• 2012

It is difficult to find an appropriate ordering policy for a many types of items. One of the reasons for this difficulty is that each item has a different demand trend. We will classify items by shipment trend and then decide the ordering policy for each item category. In this study, we indicate that categorizing items from their statistical characteristics leads to an ordering policy suitable for that category. We analyze the ordering policy and shipment trend and propose a new method for selecting the ordering policy which is based on finding the strongest relation between the classification of the items and the ordering policy. In our numerical experiment, from actual shipment data of about 5,000 items over the past year, we calculated many statistics that represent the trend of each item. Next, we applied the canonical correlation analysis between the evaluations of ordering policies and the various statistics. Furthermore, we applied the cluster analysis on the statistics concerning the performance of ordering policies. Finally, we separate items into several categories and show that the appropriate ordering policies are different for each category.

• Industrial Engineering and Management Systems
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• v.6 no.2
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• pp.106-118
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• 2007

This paper present a new optimization model to generate aggregate production planning by considering electric cost. The new Time Of Switching (TOS) electric type is introduced by switching over Time Of Day (TOD) and Time Of Use (TOU) electric types to minimize the electric cost. The fuzzy demand and Dynamic inventory tracking with multiple plant capacity are modeled to cover the uncertain demand of customer. The constraint for minimum hour limitation of plant running per one start up event is introduced to minimize plants idle time. Furthermore; the Optimal Weight Moving Average Factor for customer demand forecasting is introduced by monthly factors to reduce forecasting error. Application is illustrated for multiple cement mill plants. The mathematical model was formulated in spreadsheet format. Then the spreadsheet-solver technique was used as a tool to solve the model. A simulation running on part of the system in a test for six months shows the optimal solution could save 60% of the actual cost.

• International Journal of Highway Engineering
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• v.16 no.4
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• pp.97-110
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• 2014

PURPOSES: This study is to find the substantial shortcomings embedded in the government policies and practical administrative processes associated with the Korean Transportation Database (KTDB) and to propose preliminary approaches to overcome. METHODS: Administrative and socioeconomic issues on inefficiency in public and private investment and redemption was found from the literature review. Through the interview of sets of experts and practitioners, a set of faultiness embodied in the administrative procedure utilizing and managing KTDB was found and analyzed. RESULTS: This study found the erroneous administrative elements categorized into four groups: faulty socioeconomic data supporting local governors's optimistic will yielded overestimation of future traffic demand; faulty data incidentally introduced in KTDB burdened traffic demand analysis; unavoidable misuse of KTDB worsened the unstability of KTDB; and apathy to manage the KTDB data deviated systematic management. The proposed includes the alteration of the administrative and technical systems to overcome those shortcomings. CONCLUSIONS : Erroneous administrative elements associated with KTDB should be concerned prior to indicating subsequential faultiness in demand analysis.

• The Research Journal of the Costume Culture
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• v.5 no.3
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• pp.36-46
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• 1997

This study concerns the demand for Korean textile products in the USA, Japan, EU from 1997 to 2000. The conclusion from this study is that demand for Korean textile products in the USA, Japan, and the EU will steadily decline through to the year 2000. And with this conclusions, in order to rejuvenate the textile industry, we have to consolidate the system of production and proceed with the rationalization of management departments in the industry and the reduction of costs and develop new products. Also, the global policy strategy of the textile industry should be strongly promoted on order to make the textile industry a strong industry in the 21 century.

• Korean Management Science Review
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• v.25 no.1
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• pp.29-41
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• 2008

In the mobile communication service market, this study represents an attempt to forecast the subscribers of the IMT-2000 service market using the questionnaire of experts which is the qualitative technique is used. In this study, by using the substitution model of next generations among products in order to analyze the IMT-2000 demand of service, a demand was predicted. And by estimating the market demand prospect in which it becomes the important factor of the IMT-2000 service diffusion according to each bandwidth frequency the politically necessary approaching direction about the frequency was presented. It will be able to become the important part to not only the business carrier but also the policy maker to examine a prospect toward the subscriber of the IMT-2000 service. As a result, the market demand was exposed to be most big when the SKT 800MHz, and the KTF 800(900)MHz were used as the additional frequency. And it was likely to reach to the IMT-2000 number of subscribers to about 35.750 thousand peoples in the future at 2015.

• Health Policy and Management
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• v.23 no.1
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• pp.78-89
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• 2013

This study empirically analyze efficiency and productivity changes of public hospitals of Korea using data envelopment analysis/Window model and global Malmquist indices model. We use the ten-year data from 2001 to 2010 of 30 regional public hospitals listed database from the Association of Korean Regional Public Hospitals. The main focuses are to reveal whether the technical inefficiency are improved as time goes by, and efficiency and productivity are affected by environmental factors. The results can be summarized as follows. First, the efficiencies of public hospitals rise in trend as time passes. Second, regional public hospitals show the different average efficiencies according to their regional type, hospital type, operational type, medicaid type, and demand and supply conditions by Mann-Whitney U-tests. Third, technical efficiency changes mainly contribute to 4.4% annual average growth rate of productivity of regional public hospitals during that period. Our findings have some policy implications. It is confirmed that there exist some environmental inefficiencies, and those inefficiencies can not be overcome through just improving the inner management system. Thus, policy and institutional changes are necessary for regional public hospitals to improve efficiency and productivity overall.