1. Department of Computer Science and Engineering, University of Aizu , Tsuruga Ikki-machi, Aizu-Wakamatsu, Fukushima 965-8580, Japan
2. Earth and Planets Laboratory, Carnegie Institution for Science , 5241 Broad Branch Road, NW, Washington, DC 20015, USA
3. Department of Physics, Nagoya University , Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8602, Japan
4. Kagoshima University, Graduate School of Science and Engineering , Kagoshima 890-0065, Japan
5. National Astronomical Observatory of Japan , Mitaka, Tokyo 181-8588, Japan