Concurrent engineering design is widely used to shorten the time needed to introduce a new product and to enhance the quality of the design of the product. However, designers seldom consider the difficulty of assembling a product's components and modules in the concurrent development process. In fact, the concept of design for assembly is not new. Planning the execution of assembly operations and selecting the assembly sequence during product development will provide designers with interrelated information of design and manufacture that help reduce manufacturing problems. The designer should realize that a reasonable assembly sequence for a product has a significant effect on the efficiency of the entire assembly process. This research focuses on the enhancement of the contact relation matrix approach to the generation of assembly sequences in a product design procedure. A systematic and efficient assembly sequence assistance procedure is proposed to generate feasible assembly sequences and to find an optimal sequence to assemble the product. Compared to the complexity of other methods, this research proposes a modularized contact-rule reasoning approach to generating assembly sequences. The general approach of this research is to (a) develop a modular method for assembly sequence planning, (b) use matrix operations to facilitate the generation of assembly sequences, and (c) generate the assembly sequence of the designed product by searching for subassembly extraction rules. The assembly sequences are then created in the form of a hierarchical structure. The results will assist designers to consider and reduce some manufacture problems in advance that might occur in the process of generation of the recommended design alternative.

Product design is a creative decision-making process that aims to satisfy human needs by releasing good products that can appropriately meet the preferential requirements of customers. In the development of new products, the designer must identify the preference and attitudes of customers toward certain products, ascertain the factors that make products popular in the market, and devise optimum design plans for those products. Biking has become a popular activity due to its contribution to maintaining health. Bicycle-related clothing is known to play an important role in comfort level and safety. Unfortunately, there is hardly any research or designs that consider customer preferences in the bicycle-related clothing design process. Many manufacturers mainly focus on the improvement of the material properties of clothes instead of clothing design to meet the customer requirements. This study uses conjoint analysis in bicycle-related clothing design to provide designers with an efficient approach to identify customer preferences. The lifestyles of users are examined through a massive amount of collected data used to design an attitude measurement chart/questionnaire. Customer requirements are subsequently categorized through factor analysis, and critical requirement attributes are identified for conjoint analysis. Finally, conjoint analysis is used to obtain the optimal design combination for bicycle-related clothing that adheres to the preferences of customers.