• Journal of Korean Institute of Industrial Engineers
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• v.5 no.1
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• pp.1-6
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• 1979

This paper discusses an application of discrete variable Servo Theory to the analysis of the effectiveness of production-inventory control system which uses exponential smoothing as a specific forecasting technique by establishing a new model which consists of such three departments as production planning, production, and inventory. The objective of the new production-inventory model is to keep the production to the optimal level of minimum production cost in production planning problem for obtaining, the stability of inventory subject to demand variation. On this basis, the dynamic characteristic of the system with the change of the parameters is clarified by the numerical analysis. The results of the numerical analysis show the effect that is obtained by the simultaneous stability of production and inventory as soon as possible.

• Korean Management Science Review
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• v.30 no.1
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• pp.1-14
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• 2013

We conduct the future studies suggested by Park and Seo [3]. They considered a seat inventory control problem in which flights depart sequentially during a similar time-interval and passengers purchase available seats depending on individual customer choice behavior. Customer choice behavior can lead to one among a horizontal shift, a diversion-up, and a booking loss when a desired fare class is unavailable. We investigate how seat availability calculation method, booking limit control mechanism, seat inventory capacity, number of booking class, type of seat demand influence on revenues in an airline industry through thorough computer simulation experiments.

• Industrial Engineering and Management Systems
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• v.4 no.2
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• pp.145-157
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• 2005

There are a lot of raw materials, work-in-processes and finished goods in manufacturing industry. Here, the less stock of materials and work-in-processes manufacturing industry has, the worse the rate of the production is. Inversely, the more manufacturing industry has, the more expensive the cost to support them is. Thus, it is important for us to balance them efficiently. In general, inventory problems are to decide appropriate times to produce goods and to determine appropriate quantities of goods. Therefore, inventory problems require as more useful information as possible. For example, there are demand, lead time, ordering point and so on. In this paper, we deal with an optimal ordering policy on both way substitutable two-commodity inventory control system. That is, there is a problem of how to allocate the produced two kinds of goods in a factory to m areas so as to minimize the total expected inventory cost. The demand of each area is probabilistic, and we adopt the exponential distribution as a probability density function of demand. Moreover, we provide numerical examples of the problem.

• Journal of Korean Institute of Industrial Engineers
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• v.3 no.1
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• pp.39-47
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• 1977

Most of the current literature on inventory theory has been devoted to the study of single stage models. A class of inventory problems which is of great interest is the multistage inventory system which involves a series and hierarchical sequence of stations. This study analyzes some aspect of the series type and multi-stage inventory system, using the fixed cycle ordering which bas a modificatory control function in the system equations. The objective of this study is to clarify the dynamic behavior of the system. The author has derived the theoretical formulas of variation of ordering quantity and stock fluctuation of each stage due to power spectral density function. Influence of parameters such as, (1) intensity of autocorrelation of demand sequence ($\lambda$), (2) forecasting exponential smoothing factors of each stage (${\alpha}_1,\;{\alpha}_2,\;{\alpha}_3$) and (3) production control factor of the 3rd stage ($\gamma$), as operators of the system on the variation of ordering quantity and stock fluctuation of the system. is also clarified. As a result of this study, the relations between the variation of ordering quantity, stock fluctuation and the parameters of the system, have been found. The principles and the theorical analysis presented here will be applicable to more complex type of discrete control systems in constructing the specific condition of the system to minimize inventory variances.

• Journal of the Korea Safety Management & Science
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• v.6 no.3
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• pp.141-152
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• 2004

Supply chains for agricultural commodities with their various constraints such as production lead time, seasonal production, and methods of storage are limited in the extent to which techniques like Just-in-Time (JIT) inventory management can be applied. It is beyond the ability of producers to control harvest time and many agricultural products are perishable so that they can incur exceptional losses in storage if they are not handled correctly. This is a source of additional costs and inefficiency in supply chain management. The purpose of this study is to reduce or eliminate such sources of loss and inefficiency and to identify success factors for the JIT inventory management system where it can be applied for agricultural products. Where JIT techniques can be applied in supply chain management for agricultural products, costs such as transportation, inventory, and storage losses can be reduced with concurrent increases in efficiency. In the paper, some of the problems associated with applying JIT inventory control methods in supply chain management for agricultural commodities will be reported through a series of case studies.

• Proceedings of the Safety Management and Science Conference
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• 2004.05a
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• pp.191-201
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• 2004

Supply chains for agricultural commodities with their various constraints such as production lead time, seasonal production, and methods of storage are limited in the extent to which techniques like Just-in-Time (JIT) inventory management can be applied. It is beyond the ability of producers to control harvest time and many agricultural products are perishable so that they can incur exceptional losses in storage if they are not handled correctly. This is a source of additional costs and inefficiency in supply chain management. The purpose of this study is to reduce or eliminate such sources of loss and inefficiency and to identify success factors for the JIT inventory management system where it can be applied for agricultural products. Where ]IT techniques can be applied in supply chain management for agricultural products, costs such as transportation, inventory, and storage losses can be reduced with concurrent increases in efficiency. In the paper, some of the problems associated with applying ]IT inventory control methods in supply chain management for agricultural commodities will be reported through a series of case studies.

• The Journal of Society for e-Business Studies
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• v.3 no.2
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• pp.203-217
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• 1998

Supply chain management is defined as "an integrative philosophy to manage the total flow of a distribution channel from the supplier to the ultimate user". There are many differences between traditional systems and supply chain management systems, There are so many advantages applying SCM concept in inventory management field from the viewpoint of information sharing. While each firm try to optimize the inventory individually in traditional systems, SCM focus on optimizing the channel-wide-inventory making effort to reduce the inventory interrelatedly, The more complex your network of suppliers, manufacturers, and distributors, the more you are likely to gain operational efficiencies by attending on inventory management. The inventory stockpiles at the various sites, including both incoming materials and finished products, have complex interrelationships. Efficient and effective management of inventory throughout the supply chain significantly improves the ultimate service provided to the customer. The purpose of this thesis is to develop the integrated inventory management system for the control of channel-wide inventory on the intranet by applying SCM concept.

• Journal of Institute of Control, Robotics and Systems
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• v.21 no.11
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• pp.1076-1080
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• 2015

An inventory control system was developed for a distribution system consisting of a single multiproduct warehouse serving a set of customers and purchasing products from multiple vendors. Purchase orders requesting multiple products are delivered to the warehouse in a process. The receipt of customer orders by the warehouse proceeded in order intervals and in order quantities that are subject to random fluctuations. The objective of warehouse operation is to minimize the total cost while maintaining inventory levels within the warehouse capacity by adjusting the purchase order intervals and quantities. An adaptive model predictive control algorithm was developed using a periodic square wave model to represent the material flows. The adaptive concept incorporated a stabilized minimum variance control-type input calculation coupled with input/output stream parameter predictions. The effectiveness of the scheme was demonstrated using simulations.

• Journal of the military operations research society of Korea
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• v.8 no.2
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• pp.37-55
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• 1982

The whole blood inventory control model is developed, shown to provide an accurate representation of actual blood bank operations in Korea. The main difference of the blood bank situations between Korea and the United States is that about 50 percent of all bloods demanded, crossmatched, and held for a particular patient are eventually found not to be required for that patient in case of U.S. while in Korea the crossmatch test is not so significant and almost successful. Accordingly, the model in this paper is focused in seeking the minimum inventory level where neither shortage nor outdating bloods begin to occur, while the Jennings' model, developed in 1970 at MIT OR Center, is the inventory level somewhere between the inventory level 'band' where both shortage and outdating occur.

• Journal of Korean Society for Quality Management
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• v.18 no.2
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• pp.9-17
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• 1990

This paper deals with a FOQ( ; fixed-order quantity) model for spare-part inventory control. In a spare-part inventory problem, stock depletion arises not from external market demand but from internal demand resulting from failures of parts in use. The problem differs from the classical inventory problem in that the demand for a failed part never arises more during stockout period, since the unit remains inoperative when stockout occurs until the failed part is replaced by new one. In the problem under consideration, n identical units are operating simultaneously and failed one is replaced immediately by new one if on-hand spares remain. In order to replenish spares, an order with quantity Q is placed whenever the number of on-hand spares falls to levels. The average annual cost of operating the spare-part inventory system is derived under the assumption that both lifetime of a part and replenishment lead-time distributions are exponential.