• 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 Korean Institute of Industrial Engineers
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• v.12 no.1
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• pp.49-53
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• 1986

A dynamic lot size model is developed for the deteriorating items. The amount of deterioration during a period is assumed to be proportional to the inventory at the end of the period. It is further assumed that deterioration rates can differ among periods. This new model is shown to be equivalent to the general one by simple transformation of some variables. A numerical example is given to illustrate the derived results.

• Journal of applied mathematics & informatics
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• v.6 no.2
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• pp.539-552
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• 1999

An order-level inventory model for a perishable product with a time-dependent demand is developed for a fixed planning pe-riod allowing backlogging in all cycles within the said period. The market demand is assumed to decrease exponentially as time elapses. The average system cost is derived and its optimization procedure is illustrated with a numerical example. Sensitivity of the optimal so-lution to changes in the values of different parameters of the system is also analysed.

• Journal of the Korean Operations Research and Management Science Society
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• v.5 no.1
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• pp.53-59
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• 1980

An order level inventory model is developed for deteriorating items. The demand during prescribed scheduling period is constant and deterministic in which the demand follows power pattern. Deterioration is assumed to be a constant fraction of the on hand inventory. The expression for the optimal order level is developed and an example is given to illustrate the model.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.25 no.1
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• pp.56-62
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• 2002

본 논문은 제품 공급자로부터 일정량의 덤이 제공되는 상황에서 퇴화성 제품의 경제적 주문량 결정에 대하여 연구한다. 공급자로부터 제공되는 덤의 크기는 주문량의 크기, 즉 거래단위에 따라 차별적으로 제공된다는 가정하에 최적주문 및 재고정책 결정을 위한 해법이 제시되며 예제를 통하여 덤의 크기에 따른 재고정책의 민감도를 계량적으로 분석한다.

• Journal of Korean Institute of Industrial Engineers
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• v.40 no.2
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• pp.233-239
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• 2014

This paper presents an extended EMQ model which determines an optimal production run length in an deteriorating production process. The production process is subject to a random deterioration from an in-control state to an out-of-control state and thus producing some proportion of defective items. Defective items produced are re-processed in the rework process to convert them into non-defectives. Through the mathematical modeling, an optimal solution minimizing the average cost per unit time as well as minimum average cost are derived. Numerical experiment is carried out to examine the behavior of the proposed model depending on model parameters.

• Journal of Korean Institute of Industrial Engineers
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• v.26 no.4
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• pp.384-391
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• 2000

Most of the previous works on classical location models are based on the assumption that the value(or utilities) of inventory remains constants over time. In this study a special case of location problem is studied for both ameliorating and deteriorating items in two-echelon supply-chain management such as agricultural and fishery products. The objective of this study is to determine the minimum number of storage facilities among a discrete set of location sites so that the probability for each customer to be covered is not less than a critical value. We have formulated this problem using stochastic set-covering problem which can be solved by 0-1 programming method. Also we developed a computer program and applied to a set of problems for fish culture storage and distribution centers and the sample results well show the impact of ameliorating and deteriorating rate on the location problem. For the further study, a graphical user-interface with visualization for input and output is needed to be developed.

• Journal of applied mathematics & informatics
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• v.4 no.2
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• pp.457-468
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• 1997

The present paper deals with an economic order quan-tity model for items deteriorating at some constant rate with demand changing at a known and at a random point of time in the fixed pro-duction cycle.

• Journal of Korean Institute of Industrial Engineers
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• v.14 no.2
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• pp.11-23
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• 1988

A periodic review inventory model for deteriorating items in which time is treated as a discrete variable is developed. The model is developed under deterministic but time dependent demands and instantaneous delivery. Deterioration is assumed to be a constant fraction of the on hand inventory and partial returns are allowed for the deteriorated items. The solution procedures for obtaining the optimal order quantities which maximize the total profit in the scheduling period are presented for the cases of back orders and lost sales. Finally, when the additional orders are allowed, an efficient solution algorithm determining the initial and additional order quantities and additional ordering time is developed. Some numerical examples are also presented to illustrate the results.

• Journal of Korean Institute of Industrial Engineers
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• v.7 no.2
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• pp.19-26
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• 1981

A special case of the probabilistic multi-location problem is studied in a two-echelon logistic system for deteriorating items. The objective is to determine the location of the minimum number of supply centers among a discrete set of location sites of supply centers, such that the probability each retailer being covered by some supply center is not less than a specified value. A logistic cost is introduced as performance measure of the system, and leads us to analyze the impact of deterioration rate on the location problem. The results obtained from numerical examples are discussed, which provides effective guidelines that can be used for the logistic managerial decisions.