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Due to the rapid growth of electronic commerce via the Internet, there is a need to streamline the supply chain in order to reduce product distribution costs and shorten delivery lead times. Among these, the role of distribution centers that connect physical and commercial distribution has become more important. Improvement in work efficiency in the distribution centers has also become an important theme. Aware of such problems, we focus on order picking operations where products are collected based on the customer order since it is one of the most labor-intensive activities in the distribution center. We consider methods to shorten the average traveling distance of order-picking operators from two perspectives: 1) Improving the floor layout of the distribution center, and 2) introducing better management rules to determine the storage position of products. In the first half of the paper, the mathematical model to evaluate the average traveling distance of the picker is proposed. The model proposed assumes that the width of the aisle and the size of the shelf are sufficiently small, and obtains the value of the traveling distance analytically. In addition, improvement measures are considered from the two perspectives stated above, and are evaluated by comparing with the case in conventional Traditional Layout with horizontal and vertical aisles. In the second half of the paper, two improvement measures combining the two perspectives are proposed based on the results of the first half of the paper. Both measures move the accumulation point of products to the center of the lower side of the floor. In addition, the first measure adopts the addition of a diagonal aisle on the floor and classbased management to determine the storage position of products. The second measure executes class-based storage in an area where the work floor is divided using diagonal straight lines, which means being equidistant from the accumulation point of products. As a result, this paper clarifies that the two improvement measures proposed in the second half of the paper shorten the average traveling distance by 25% or more compared to case in conventional Traditional Layout. [ABSTRACT FROM AUTHOR]

It is very important to increase the productivity of picking operations in e-commerce in order to satisfy customer demand in the shortest possible time. There are two work methods for shipping, order picking and inverse order picking, that are commonly used in distribution centers. An inverse order picking system has two major tasks before shipping. One is picking the total amount of each item from the shelves, and the other is properly placing items into the correct container based on the customer that ordered them. This placement operation is also called “sorting”. In a traditional sorting method, the workers place items into the container by type one at a time. When there are many different types of items, workers must walk long distances because the route the worker must walk is decided based on each type required to fill the order. In this paper, we propose a sorting method that consolidates multiple types of apparel items. Walking time is reduced by consolidating items together. However, the selection time increases because worker must choose the items required, sorting them out from multiple items. Therefore, it is not easy to determine which sorting method is best. In this paper, we reveal the effect of make-span and total working time, such as walking time and blocking time using simulation. The simulation approach is effective in modeling blocking. The experimental results indicate that the sorting method needs to be selected according to situation and purpose. [ABSTRACT FROM AUTHOR]