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This paper proposes a new inventory control technique for dual-channel supply chains. In dual-channel supply chains, both a retail channel and a direct channel via a website exist. In previous studies, Takahashi et al. (2011) proposed a new inventory control technique for dual-channel supply chains by using a switching point that starts and stops for production and delivery. However, using a linear function for switching, reductions in inventory cost and lost sales costs can be expected. Therefore, in this paper, the authors propose an inventory control method using linear functions for dual-supply chains and and prove its effectiveness using numerical experiments and comparing results with those of a previous study conducted by Takahashi et al. (2011). [ABSTRACT FROM AUTHOR]

In this paper, we conduct a case study of a company that collects and processes used home appliances and sells them as new recycled resources based on the Home Appliance Recycling Law. The target company earns sales by selling multiple resources to multiple sales destinations with different selling prices. There are various restrictions on such sales, which creates complexity. Due to this complexity, the sales amount cannot be maximized using only the intuition and experience of employees. Therefore, we propose a model that maximizes the sales amount obtained from selling each resource. As a result, using the proposed model, different sales amounts and sales destinations of each resource were obtained, achieving better results. Specifically, compared to the current total sales amount, 3.6% better results are expected. Furthermore, as a sensitivity analysis, experiments were conducted in which the credit constraints of each sales destination were varied. It was found that risk management can be performed without affecting the objective function value by setting credit appropriately. [ABSTRACT FROM AUTHOR]

In the area of materials stock-flow analysis, the cumulative graph is an effective method to visualize and analyze flow patterns and embedded problems, leading to identifying ways to improve material flows in production and service systems. However, since the conventional approach of cumulative flow graphs assumes a tandem flow shoptype one-way flow, the graph cannot be used in complicated flow patterns where each stage is comprised of parallel processes and materials flow back-and-forth between these stages. This paper proposes a method to apply a cumulative flow graph to the case of such parallel flow pattern, where a single stage is comprised of a main system and a subsystem, and materials repeatedly flow between these systems before finally flowing out from the process. For the purpose of identifying fundamental problems in the material flow, the method proposed focuses on depicting stock quantity in each system on the cumulative flow graph. The paper finally applies the method proposed to the actual case of a physical distribution system comprised of the main and secondary warehouses, and the validity of the method proposed is discussed and clarified using practical examples. [ABSTRACT FROM AUTHOR]

The control and maintenance of inventories are vital for many companies because the effective management of inventories can provide better customer service and improve profitability. In recent years, the number of different stock keeping units (SKUs) that must be delivered is exploding. Meanwhile, due to the spread of the electronic commerce, filling customer orders within a 24-hour period is becoming the new standard in many industries, which means that an increasing number of SKUs has to be delivered more frequently and faster. We consider a warehouse configured with a forward area, where items are stored in cases for easy retrieval by an order picker, and a reserve area, where items are stored by the case for picking and replenishing stocks in the forward area. Based on real data, this paper studies the setting of order-up-to level and reorder level in (s,S) policy and determining the proper maintenance intervals (PMIs) in order to reduce stockouts and excessive stock in a distribution center. Order-up-to and reorder levels should be decided after comprehending the trade-off between inventory space and emergency replenishment. Furthermore, we show maintenance at PMIs can lead to cost savings. Such improvements would allow the distribution center to reduce stock-outs and excessive stock, and to increase productivity. [ABSTRACT FROM AUTHOR]

In most studies dealing with inventory problems, lead time is treated as fixed. However, in several practical situations, the lead time can be reduced at an added cost, which is called a "crashing cost". By shortening the lead time, we can lower the safety stock, save inventory space, reduce the stock-out loss, and improve the customer service level. In fact, there are some studies that consider lead time reduction. Pan et al. (2002) proposed the crashing cost, which is assumed to be a function of both the order quantity and the reduced lead time. Ouyang et al. (2001) and Lee (2005) proposed the backorder rate, which is assumed to be dependent on the amount of shortages. There are no inventory models that consider both crashing cost in the Pan et al. (2002) and backorder rate in the Lee (2005). In this paper, we present an inventory model in which the order quantity, reorder point, and lead time are regarded as decision variables. The crashing cost is represented as a function of both the reduced lead time and the order quantity, and the backorder rate is assumed to be dependent on the amount of shortages. We develop an algorithm to find near optimal solutions and give numerical examples to demonstrate the effectiveness of our proposed model. Furthermore, a sensitivity analysis is also conducted to identify situations where shortening lead time is valuable. [ABSTRACT FROM AUTHOR]