**Ya-Chuan Ko 1,2**


Received: 21 August 2019; Accepted: 23 September 2019; Published: 27 September 2019

**Abstract:** In order to make people's lives more convenient and enhance living standards, the composition of a product usually includes more than one component. However, a product is created by the joint endeavor of people from various territories and therefore one of the important considerations is making a product merge into consumers' daily lives rather than simply fulfilling its functions. There might be conflicts with people's existing life patterns or existing values, which should be taken into consideration during the manufacturing process. This study is an investigation of the process of assembly by considering the assembly operations and the assembly operating time. By determining the relationship between components, the assembly concept of most components was analyzed. A fuzzy comprehensive evaluation was carried out during the evaluation of the degree of complexity of user operations. Depending on the ranking of membership, the most appropriate assembly was determined and this serves as a reference for designers to select the optimal product assembly. By recording the consumer usage models, the optimal assembly and usage model of product design were also proposed. The goal of this study is to find the balance between assembly evaluation and user usage model by the process in order to allow designers to determine the new assembly concepts that meet consumer usage models. A case study of four bedside stereos was carried out by implementing the proposed approach in order to determine the evaluation principle of assembly. The purpose of this is to enhance the balance between assembly design and user operation complexity for making efficient decisions. A product design can comply with the spirit of concurrent engineering and the quality of a product design can be enhanced.

**Keywords:** assembly design; usability and operation complexity; fuzzy theory
