1. Department of System Cybernetics, Graduate School of Engineering, Hiroshima University, Higashihiroshima, Japan
2. Graduate School of Advanced Science and Engineering, Hiroshima University, Higashihiroshima, Japan
3. Graduate School of Health Sciences, Junshin Gakuen University, Fukuoka, Japan
4. Department of Cardiovascular Surgery, Hiroshima University Hospital, Hiroshima, Japan