How to Apply Human-Centered Design Process (HCDP) to Software Development Process?

This is a position paper of research related to usability and software engineering. Important problem to develop software with high usability is that it is difficult to apply human centered design process to software development process. To solve this, we propose three issues, they are 1) clarification of "demand" and evaluation process about user requirements, 2) how to fill gaps between software engineers and usability experts about HCD, 3) solution of twin peaks problem (gap between requirements and architecture). For these issues, it is necessary to discuss detail targets.