1. Department of Physics, Faculty of Sciences, Kyushu University,
4-2-1 Ropponmatsu Chuo-ku, Fukuoka 810-8560
2. Tsukuba Space Center, National Space Development Agency of Japan,
2-1-1 Sengen, Tsukuba, Ibaraki 305-8505
3. Graduate School of Science, Hokkaido University,
Sapporo 060-0810