No abstract

The User requirements of many web-based services are dynamically and continuously changing even during the service time itself. For that reason, web service companies always keep trying to satisfy users' needs from the market.Requirements elicitation, among the processes in requirements engineering, is a process requiring high costs and time. Thus, a company planning to conduct the process wants to catch the points users don't satisfy in their needs by taking advantage of an effective process of requirements elicitation.In this paper, we propose value based requirements elicitation, so called, the Value Gap Model aiming to clarify need selection and focus on key factors to a requirements engineer who should take into account the value on behalf of users. To do that, the process, at first, recognizes a value gap between the value users currently have and the value a system understand as users' one, and then it figures out the components that a requirements engineer has to select and focus on in his or her requirements elicitation process. In order to focus on and invest effectively the resources of elicitation process, the proposed process finds the part where most of users feel unsatisfying so that it eventually elicits the valuable requirements from users.

In the automotive industry, being lightweight has become an important design factor with the enhancement of environmental regulations. As a result, many studies on the application of composite materials are in progress. Among them, interest in carbon materials, such as carbon sheet molding compound (C-SMC) and carbon-fiber-reinforced plastic (CFRP), which have excellent strength and stiffness, is increasing. However, CFRP is a material that makes it difficult to secure economic feasibility due to its relatively high manufacturing costs and limited mass production, despite its excellent mechanical strength and durability. As a result, many studies have been conducted on C-SMC as an alternative carbon composite material that can be easily mass-produced. In this regard, this study intended to conduct a study on evaluating the fatigue strength of C-SMC and CFRP among mechanical properties due to the lack of clear failure criteria for fatigue design. We investigated the tensile and fatigue strengths of C-SMC and CFRP, respectively. In the case of C-SMC, the mechanical strength tests were conducted for two different width conditions to evaluate the cutting effect and the machining methods to assess the effects of the edge conditions. To evaluate the fatigue failure assessment criteria, the stiffness drop and elastic modulus degradation criteria were applied for each fatigue test result from the C-SMC and CFRP. The results confirmed that the rationality of the failure criteria in terms of the stiffness drop and the application of the fatigue life prediction of C-SMC based on elastic modulus degradation demonstrated promising results.