1. a Department of Industrial Engineering , University of Osaka Prefecture , Sakai, Osaka, 593, Japan
2. b Toyo Engineering Corporation , Akanehama, Narashino, Chiba, 275, Japan
3. c Rakuwa-Kai Medical Corporation , Rakuwa-Kai Otowa Hospital, Otowa Chinji-Cho, Yamashina-Ku, Kyoto, 607, Japan