1. NTT Communication Science Laboratories, NTT Corporation, Atsugi, Kanagawa 243-0198, Japan
2. Taipei City Hospital, Taipei 106, Taiwan
3. Medical Institute of Developmental Disabilities Research, Showa University Karasuyama Hospital, Tokyo 157-8577, Japan
4. School of Engineering, Tokyo Institute of Technology, Yokohama, Kanagawa 226-8503, Japan
5. CREST, JST, Atsugi, Kanagawa 243-0198, Japan