• 한국경영과학회지
• /
• 제41권2호
• /
• pp.1-16
• /
• 2016

Yield management, which originated from the U.S. service industry, uses pricing techniques and information systems to make demand management decisions. Demand uncertainty is an important factor in the area of demand management. A key strategy to reduce the effects of demand uncertainty is substitution. The most generally known type of substitution is inventory-driven substitution, in which consumers substitute an out-of-stock product by buying a similar or other type of product. Another type of substitution is the price-driven substitution, which occurs as a result of price changes. In this research, we consider two market segments that have unique perishable products. We develop yield management optimization models with stochastic demand based on the newsvendor model where inventory-driven and price-driven substitutions are allowed between products in the two market segments. The most significant contribution of this research is that it develops analytical procedures to determine optimal solutions and considers both types of substitution. We also provide detailed theoretical analysis and numerical examples.

• Journal of applied mathematics & informatics
• /
• 제42권2호
• /
• pp.379-390
• /
• 2024

This study proposes a fuzzy inventory model for managing large-scale production, incorporating cost considerations. The model accounts for two types of expenditure scenarios-parametric and exponential. Uncertainty surrounds holding costs, setup costs, and demand rates. The approach considers a supply chain system with a complex manufacturing process, factoring in transportation costs based on the quantity of goods and distance between the supplier and retailer. The initial crisp model is then transformed into a fuzzy simulation, incorporating specific fuzzy variables affecting inventory costs. The proposed method significantly reduces overall inventory costs for the entire supply chain. Retailer demand is linked to inventory levels, and vendor/distributor storage deteriorates over time. The fuzzy condition assumes hexagonal variables for all associated factors. The study employs the signed distance method for defuzzification to determine the optimal order quantity with hexagonal fuzzy numbers. Mathematical examples are provided to illustrate the practicality of the proposed approach.

• 대한산업공학회지
• /
• 제2권1호
• /
• pp.93-100
• /
• 1976

Given a fixed production process and facility capacity, the ability to respond to market fluctuations in terms of changes in production, work force, and inventory is the major task of production management. The costs involved are primarily payroll (regular and overtime), inventory carrying, and hiring and firing. The magnitude of these costs is usually a significant portion of the operating costs of the firm and consequently a small percentage saving due to astute aggregate scheduling can mean substantial absolute saving. At least three demonstrably optimal techniques have been developed for solving this aggregate scheduling problem. These three optimal are apparently LDR, PPP, and SDR. By combining these three different approaches, another optimal solution was obtained by me. I call this CDR (Combined Decision Rule). This approach appears to be useful. This approach may be generalizable to aggregate scheduling involving a short term resources.

• 산업경영시스템학회지
• /
• 제36권3호
• /
• pp.43-50
• /
• 2013

In this paper, the single-period inventory problem, what is called newsboy problem, has been revisited with two different conditions, uncertain supply and risk-averseness. Eeckhoudt et al. [5] investigated the effect of risk-averseness of a newsboy on the optimal order quantity in a stochastic demand setting. In contrary to Eeckhoudt et al. [5] this paper investigates the effect of risk-averseness in a stochastic supply setting. The findings from this investigation say that if ${\alpha}^*$ represents the optimal order quantity without risk-averseness then the risk-averse optimal order quantity can be greater than ${\alpha}^*$ and can be less than ${\alpha}^*$ as well.

• 품질경영학회지
• /
• 제24권1호
• /
• pp.44-49
• /
• 1996

This paper deals with a (Q, r) spare-part inventory model with gamma leadtime. In the model, if the inventory level falls to a reorder point r, a replenishment order quantity Q is ordered. Assumming that the number of operating units is one and the lifetime of a unit follows an exponential distribution, we derive the expected cost rate and suggest a procedure to obtain the optimal pair of (Q, r) minimizing the cost rate. A numerical example is presented to explain the model.

• 한국경영과학회지
• /
• 제12권1호
• /
• pp.1-9
• /
• 1987

This paper considers (S -1, S) inventory models which have wide applications in reparable spare parts inventory systems and multi-echelon systems. We assume a discrete compounds Poisson demand and order size dependent delivery times ; when the replenishment order size is n, we assume the delivery time distribution is arbitrary with finite mean $b_{n}$ . On the basis of the fact the outstanding orders follow a certain queueing process, we introduce the results of Fakinos (1982). We develop the efficient recursive formulae to find the optimal $S^{*}$ under several performance measures as a function of the decision variable S. The results of this paper can be applied to the multi-echelon systems such as MEETRIC.C.

• 한국경영과학회지
• /
• 제40권1호
• /
• pp.21-33
• /
• 2015

This paper develops an analytic model for minimizing the cost of distributing items by truck from one supplier to many customers under Milk run logistics strategy. The model derives formulas for not only inventory and transportation costs but also costs associated with carbon emission trading scheme. In addition, monetary investment for reducing carbon emissions is considered. We analyze how to determine optimal shipment size and carbon emission reduction investment. The purpose of this work is to evaluate the effects of carbon emission trading scheme on the Milk run logistics strategy in terms of how much to reduce carbon emissions and/or inventory and transportation costs. We analytically show that it is possible to reduce carbon emissions while reducing inventory and transportation costs by introducing cap-and-trade carbon emission trading scheme under certain conditions.

• 한국경영과학회:학술대회논문집
• /
• 한국경영과학회/대한산업공학회 2003년도 춘계공동학술대회
• /
• pp.1-7
• /
• 2003

This paper considers an Integrated one-vendor multi-buyer production-inventory model where the vendor manufactures multiple products In lot at Her associated finite production rates In the model. It is allowed for earth product to be shipped In lot to the buyers before the whole product production is not completed yet. Each product lot is dispatched to the associated buyer In a number or shipments. The buyers consume their products at fixed rates. The objective is to the production and shipment schedules in the Integrated system. which minimizes the mean total annual cost per unit time. The mean total annual cost consists or production setup cost inventory holding cost and shipment cost. For the model, an Iterative optimal solution procedure with shipment consolidation policy incorporated is derived. It is then tested through numerical experiments to show how efficient and effective He shipment consolidation policy is.

• 품질경영학회지
• /
• 제14권2호
• /
• pp.21-27
• /
• 1986

This paper deals with a continuous review (s,S) spare part inventory system. The distributions of service life of each part and the replenishment lead time are assumed to be exponential. Assuming that there is never more than a single order outstanding, we obtain the average annual cost of operating the inventory system. If the length of stockout period is small enough to be neglected compared to the length of operating period, the optimal operating policy variables minimizing the cost rate can be calculated iteratively. For the case of one-for-one ordering (that is, s=S-1), an exact cost rate, and a closed form decision rule minimizing the cost rate are obtained for a more general situation in which more than one order is allowed to be outstanding and the distribution of the replenishment lead time is general.

• 산업경영시스템학회지
• /
• 제44권4호
• /
• pp.220-226
• /
• 2021

In supply chain, there are a variety of different uncertainties including demand, service time, lead time, and so forth. The uncertainty of demand has been commonly studied by researchers or practitioners in the field of supply chain. However, the uncertainty of upstream supply chain has also increased. A problem of uncertainty in the upstream supply chain is the fluctuation of the lead time. The stochastic lead time sometimes causes to happen so called the order crossover which is not the same sequences of the order placed and the order arrived. When the order crossover happens, ordinary inventory policies have difficult to find the optimal inventory solutions. In this research, we investigate the lead time distribution in case of the order crossover and explore the resolutions of the inventory solution with the order crossover.