1. Department of Physics, Graduate School of Science, Osaka University, 1-16 Machikaneyama, Toyonaka, Osaka 560-0043
2. Department of Physics, Faculty of Science and Engineering, Konan University, 8-9-1 Okamoto, Higashinada-ku, Kobe 658-8501
3. Department of Computer Science and Electronics, Kyushu Institute of Technology, Fukuoka 820-8502