1. Department of Engineering and Design, Shibaura Institute of Technology, 307 Fukasaku, Minuma-ku, Saitama 337-8570, Japan
2. Institute of Mathematics, University of Tsukuba, Tsukuba 305-8571, Japan
3. Institute of Mathematics for Industry, Kyushu University, 744 Motooka, Fukuoka 819-0395, Japan
4. Department of Education and Creation Engineering, Kurume Institute of Technology, 2228-66 Kamitsu, Kurume 830-0052, Japan
5. Department of Mathematics, Kobe University, Rokko, Kobe 657-8501, Japan