Mohammad Khalilzadeh - Phd student of Mathematical Sciences Department of Brunel University, West London,uk
Amin Malayeri - Bachelor student of Industrial Engineering Department of Sharif University of Technology, Iran

Quality Function Deployment (QFD) is a well-known and customer-oriented design tool that systematically tr anslates the Voice of the Customer (VOC) into the Design and Engineering Requirements (DRs). QFD is widely used to achieve higher customer satisfaction level by integrating marketing, design engineering, manufacturing, and other related functions of an organization. Most of the existing approaches and models for QFD planning seldom consider the innate imprecision and uncertainties in the customer requirements (CRs), which are usually expressed in natural language, as well as design processes, such as ill-defined or incomplete understanding of the relationships between a given set of customer requirements and design requirements, and the complexity of interdependence among DRs. For dealing with the imprecision and uncertainties in all stages of QFD planning, we apply the fuzzy environment including fuzzy AHP method for determining the relative importance weights of customer requirements, and fuzzy relationships between CRs and DRs as well as among the DRs. A fuzzy mathematical model is formulated to determine the systematic fulfilment level of each DR for increasing the customer satisfaction under the constraints such as cost and resource limitations, technical difficulty and market competition. An illustrative example is also given to illustrate how the proposed fuzzy model and optimization route can be applied to help QFD team and decision makers in a company to maximize overall customer satisfaction level.

QFD, Fuzzy AHP, Fuzzy numbers, Fuzzy linear programming, customer satisfaction