1. Okeisha Co. Ltd., 90-7 Nishiminato-machi, Kokurakita-ku, Kitakyushu 803-0801, Japan
2. Faculty of Advanced Science and Technology, Kumamoto University, 2-39-1 Kurokami, Chuo-ku, Kumamoto 860-8555, Japan
3. Department of Earth System Science, Faculty of Science, Fukuoka University, 8-19-1 Nanakuma, Jonan-ku, Fukuoka 814-0180, Japan (e-mail: )