• Korean Management Science Review
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• v.6 no.2
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• pp.89-96
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• 1989

본 논문에서는 제품의 유효기간이 짧고, 그 수요분포가 정규분포 함수로 주어지는 다품목 생산롯트의 크기를 결정하는 문제가 다루어진다. 총 생산량의 제약하에 2기간 동안의 생산재고 비용을 최소화하는 조건으로부터 적정 기초 재고수준과 롯트 크기를 구하는 효율적 해법이 제시된다. 특수 형태의 하나로 단일품목의 경우에 대한 최적 조건식도 아울러 주어진다.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.24 no.63
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• pp.55-64
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• 2001

최근의 생산환경 변화에 따라 기업은 경쟁력 강화 및 매출 신장을 목적으로 고객의 구매비용에 대하여 일정기간 외상을 허용하고 있으며, 또한 경쟁기업간에 제품 수요 증대를 통한 경쟁우위를 위하여 고객의 구매비용에 따라 차별적으로 신용기간이 적용되는 경우를 흔히 볼 수있다. 본 연구는 이와 같이 구매비용에 따라 차둥적으로 신용기간이 허용되는 상황에 대한 재고모형을 분석하였고, 최적재고정책 결정을 위한 해법을 개발하였다.

• Proceedings of the Korea Society for Simulation Conference
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• 2003.06a
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• pp.167-175
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• 2003

본 연구는 (s, S) 재고시스템의 최적 재고정책을 수립하는 문제를 시뮬레이션을 통하여 분석하고자 한다. 이러한 목적으로 재고관리비용에 대한 파라미터 (s, S)의 민감도를 퍼터베이션 분석법으로 구하고 확률 최적화 기법을 적용하여 단위 기간에 평균 재고관리비용을 최적으로 하는 재고정책을 발견하였다. 민감도의 추정에는 IPA법과 SPA법을 표본경로의 주문 사건 변동에 따라 조건적으로 결합하여 사용하였다. 시뮬레이션 결과 s와 S의 최적정책 추정치를 상당히 정확한 값으로 얻었으며 이러한 결과는 보다 일반적인 재고관리 문제의 분석에 도움을 줄 것으로 기대한다.

• The Journal of the Convergence on Culture Technology
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• v.8 no.6
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• pp.655-660
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• 2022

This paper analyzes the problem of the economic order quantity (lot size) of a retailer in a two-stage supply chain consisting of a supplier, a retailer(distributor), and a customer. In this two-stage supply chain, the supplier permits the retailer to defer payment for a certain fixed period of time for the purchase cost to be paid by the retailer as a price differentiation strategy with his competitor. In addition, in the case of customer goods such as food and grain, it is common to see that end-customer demand is generally depend on the level of inventory displayed by the retailer. From this perspective, this paper analyzes the inventory problem of retailers under the assumption that the supplier may allow a certain period to suspend payments for the purchase of goods and the end customer demand is a function of the retailer's inventory level increasing with size. In this regard, we need to analyze how much the length of the grace period for product purchase costs affect the retailer's lot-sizing policy. Therefore, we formulate the retailer's annual net profit and analyze the effect of the length of credit period on the retailer's inventory policy numerically.

• Environmental and Resource Economics Review
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• v.22 no.4
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• pp.643-670
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• 2013

This study analyzed the impact of crude oil inventory while gasoline price adjusts to international crude oil price(WTI) fluctuations. We mainly focused on asymmetric relationship between crude oil and petroleum product prices and added oil inventory as an variable, using the error correction model which is based on Borenstein et al.(1997). This paper selected the sample period from January 1988 to December 2012, analyzed the asymmetry of each intervals and the influence of crude oil inventory to the degree of asymmetry changes, both full period and five years period respectively. The results showed that when considering crude oil inventory, existence and degrees of time amount asymmetry varies.

• Journal of Navigation and Port Research
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• v.39 no.3
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• pp.261-266
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• 2015

Many of previous studies suggested that working capital management is an important component of firm's financial decision and efficient working capital management affects firms' profitability and it's value. Recently, Korean shipping firms have been suffering from financial distress by recession of shipping economy. In this point of view, this study tries to investigate the relationship between working capital management and shipping firm's profitability, using panel data on 46 Korean shipping firms for the period of 2004-2013. As result of panel regression, it proved that average payment period, inventory turnover, cash conversion cycle and operating cycle are significantly associated with firms profitabilities such as profit margin ratio and operating profit ratio, and the manager of shipping firm can increase firms profitability by more efficient working capital management. There are strong positive relationships between average payment period and operating cycle and firm's profitability. These results suggest that managers can create firm's value by increasing average payment period and operating cycle. Otherwise inventory turnover and cash conversion cycle have negative relationships with firm's profitability. It means that managers can increase firm's profitability by reducing these variables.

• KDI Journal of Economic Policy
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• v.28 no.1
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• pp.117-144
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• 2006

This study is to analyze the existence of the real buffer effect that reflects the effect of beginning-of-period inventory stocks effect on the demand for fixed investment, and the financial buffer effect indicates the substitution effect between end-of-period inventory stock and the source of financing for fixed investment. I use panel data of 361 Korean listed non-financial firms during 1990-2003. After the crisis, it also observed whether the relationship between inventory stocks and fixed investment has altered or not. I review the theoretical connection between inventory stock and fixed investment through the paper by Bo(2004) and estimate the investment model by the method of GMM-SYS. The results show negative relation between end-of-period inventory stock and fixed investment in the whole period and each period classified, also it confirms that the relation between fixed investment and end-of-period investment is significantly negative. It can be interpreted through two aspects that firms not only use inventory stock as a buffer in response to unexpectedly high demand, but also utilize inventory stock as a source of financing for fixed investment. The results imply that firm's decision-making is much correlated with production-and-inventory stock adjustment, decision-making about fixed investment, and decision-making about financial affairs.

• Journal of the Korea Safety Management & Science
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• v.11 no.3
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• pp.113-119
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• 2009

본 연구는 공급자(supplier), 중간분배자(retailer/distributor) 그리고 고객(customer)으로 구성된 2 단계 공급사슬을 대상으로 공급자가 수요 증대를 목적으로 중간분배자에게 일정기간 동안 제품대금에 대한 지불 연기를 허용한다는 가정 하에 중간분배자의 최적 재고정책 결정을 위한 재고 모형을 다루었다. 소비성 상품의 경우, 고객의 수요는 일반적으로 상품 진열대에 진열되어있는 상품의 재고량에 많은 영향을 받는 것으로 알려져 있다. 따라서 본 연구에서는 이와 같은 상황을 고려하여 고객의 수요가 중간분배자의 재고량에 영향을 받는다는 가정 하에 재고 모형을 설계하였고, 모형 분석을 통하여 이익을 최대화하는 경제적 주문량 결정 방법을 제시하였다. 또한 예제를 통하여 제시된 해법을 적용하고, 그 타당성을 보였다.

• Korean Journal of Construction Engineering and Management
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• v.9 no.1
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• pp.187-198
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• 2008

There are usually plenty of material inventories in a construction site. More inventories can meet unexpected demands, and also they may have an economical advantage by avoiding a probable escalation of raw material costs. On the other hand, these inventories also cause negative aspects to increase costs for storing redundant inventory as well as decreasing construction productivity. Therefore, a proper method of deciding an optimal level of material inventories while considering dynamic variations of resources under uncertainty is very crucial for the economical efficiency of construction projects. This research presents a stochastic modelling method for construction operations, particularly targeting a work process involving on-site fabrication of raw materials like iron-rebar process (delivery, cut and assembly, and placement). To develop the model, we apply the concept of factory physics to depict the overall components of a system. Then, an optimal inventory management model is devised to support purchase decisions where users can make timely actions on how much to order and when to buy raw materials. Also, optimal time lag, which minimizes the storage time for pre-assembled materials, is obtained. To verify this method, a real case is applied to elicit an optimal amount of inventory and time lag. It is found that average values as well as variability of inventory level decreased significantly so as to minimize economic costs related to inventory management under uncertain project condition.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2004.10a
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• pp.578-581
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• 2004

본 연구에서는 수요가 정규분포의 형태를 따르는 N차 시리얼(serial) 시스템을 대상으로 한다. 최상위 노드는 상위의 공급자로부터 받고자 하는 물량을 제한 없이 받을 수 있으며 하위 노드로 이러한 물량을 공급하게 된다. 최하위 노드에서는 고객의 직접적인 수요가 발생하고 만족시키지 못한 수요는 다음 기간으로 이월된다. 이러한 환경 하에서 전체시스템에서 발생하는 재고유지 비용(holding cost)과 재고이월 비용(backorder cost)의 합을 최소화하는 각 노드별 최적의 기초 재고 수준(base stock level)을 결정하는 문제를 다룬다. 본 논문에서는 모의실험과 계층 재고(echelon stock)의 개념을 통해 수요 분포 내의 적절한 분위수(quantile)를 결정하는 접근방법으로 각 노드의 기초 재고 수준을 구하는 방안을 제시하고자 한다.