Applied Soft Computing 10 (2010) 1108–1118 Contents lists available at ScienceDirect Applied Soft Computing journal homepage: www.elsevier.com/locate/asoc Inventory replenishment model using fuzzy multiple objective programming: A case study of a high-tech company in Taiwan He-Yau Kang a , Amy H.I. Lee b,∗ a Department of Industrial Engineering and Management, National Chin-Yi University of Technology, No. 35, Sec. 1, Chung Shan Rd., Taiping, Taichung 411, Taiwan b Department of Industrial Management, Chung Hua University, Non. 707, Sec. 2, WuFu Rd., Hsinchu 300, Taiwan article info Article history: Received 29 April 2008 Received in revised form 30 October 2009 Accepted 27 November 2009 Available online 23 December 2009 Keywords: Fuzzy multiple objective programming Replenishment Quantity discounts Multiple suppliers abstract The progress in high technology has led to the wide use of thin film transistor-liquid crystal display (TFT- LCD). The evolution of the manufacturing technology of TFT-LCD keeps increasing the size of TFT-LCD since a larger TFT-LCD allows a larger display application and an improved productivity. However, as the size of TFT-LCD increases, the size of TFT-array substrates and color filter substrates has to increase simul- taneously. This leads to a more complicated inventory problem of large-sized substrates. Therefore, this paper considers a color filter replenishment problem in TFT-LCD manufacturing with the consideration of storage space, yield rate, quantity discounts and multiple suppliers. We first formulate the color filter replenishment problem as a fuzzy multiple objective programming, and then a fuzzy multiple objective programming with assigned weights for objectives based on experts’ opinions is proposed. An example with four cases is given to illustrate the practicality for empirical investigation. The results demonstrate that both methods are effective tools for inventory management of color filters for multi-periods. In addition, the methods can be applied or modified for managing inventory in general. © 2009 Elsevier B.V. All rights reserved. 1. Introduction The spread of flat panel displays (FPDs) is inescapable in the digital era and is quickly becoming the preferred choice in many applications of human–machine interface. Because of their low weight, slender profile, low power consumption, high resolution, high brightness and low radiance advantages, the use of FPDs has been expanding from portable appliances to notebooks and desk- top monitors and even to large screen digital televisions. Among the industry, thin film transistor-liquid crystal display (TFT-LCD) is the primary FPD technology and represents more than 80% of the FPD market. A statistics data indicated that global TFT-LCD market will increase to US$56 billion in 2009 [16]. In the fabrication of TFT-LCD panels, color filter substrates, one of the most expensive raw materials, are usually purchased from color filter manufacturers, and sufficient amount of them must be available in the plant to maintain a smooth production flow. In addition, the size and the unit cost of color filters increases as the generation of TFT-LCD increases through technology progress, and the storage of these large-sized color filters and the high holding cost become important issues that must be tackled. To summarize, in order to reduce cost and to ensure product availability, the inven- ∗ Corresponding author. Tel.: +886 3 5186582. E-mail address: amylee@chu.edu.tw (A.H.I. Lee). tory management of color filters is especially important in TFT-LCD manufacturing. The purpose of this research is to construct a color filter’s inven- tory model with the consideration of storage space, yield rate, quantity discounts and multiple suppliers. The objective of this model is to minimize total cost, maximize yield rate and fix the replenishments to a desired number over the planning horizon. A fuzzy multiple objective programming (FMOP) model is first pro- posed. Next, we extend the model by considering the opinions of experts on the importance of various objectives by develop- ing a fuzzy multiple objective programming with assigned weights for objectives (FMOP-W). To determine the importance of various objectives, fuzzy analytic hierarchy process (FAHP) and extent anal- ysis method (EAM) is applied to incorporate experts’ opinions. The results of the two methods can both satisfy the decision-makers’ desirable achievement level of multiple objectives in a fuzzy envi- ronment. The remaining of this paper is organized as follows. Section 2 introduces the manufacturing process of TFT-LCD and reviews some recent related works. In the subsequent section, the prob- lem under consideration and the assumptions are described. The construction of the algorithm is presented next. A numerical exam- ple with four cases is presented to examine the practicality of the proposed algorithms. The results of the FMOP and FMOP-W meth- ods are compared for different cases. Some concluding remarks are made in the last section. 1568-4946/$ – see front matter © 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.asoc.2009.11.035