1. Graduate School of Information, Production and Systems, Waseda University 1 , 2-7 Hibikino, Wakamatsuku, Kitakyushushi, Fukuoka 808-0135, Japan
2. Department of Information Electronics, Faculty of Engineering, Fukuoka Institute of Technology 2 , 3-30-1 Wajirohigashi, Fukuoka-shi, Fukuoka 811-0295, Japan