1 Electrical, Systems, and Control Engineering Program, Graduate School of Advanced Science and Engineering, Hiroshima University, Higashi-Hiroshima, Hiroshima, 739-8527, Japan.
2 Electrical, Systems, and Control Engineering Program, Graduate School of Advanced Science and Engineering, Hiroshima University, Higashi-Hiroshima, Hiroshima, 739-8527, Japan. sozu@bsys.hiroshima-u.ac.jp.
3 New Business Producing Division, Maxell Ltd., Yokohama, 240-0005, Japan.
4 Center for Exploratory Research, Research and Development Group, Hitachi. Ltd., Tokyo, 185-8601, Japan.
5 Department of Rehabilitation, Hibino Hospital, Hiroshima, 731-3164, Japan.
6 Department of Neurosurgery, Center for Brain, Mind and KANSEI Sciences Research, Hiroshima University, Hiroshima, 734-8553, Japan.
7 Electrical, Systems, and Control Engineering Program, Graduate School of Advanced Science and Engineering, Hiroshima University, Higashi-Hiroshima, Hiroshima, 739-8527, Japan. tsuji-c@bsys.hiroshima-u.ac.jp.