1. Hitachi, Ltd., Information & Telecommunication Systems Company, IT Platform Division Group 292; Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa, 244-0817 Japan
2. Faculty of Information Science and Technology; Ritsumeikan University; Nozihigashi, Kusatsu, Shiga 525-8577 Japan
3. Graduate School of Natural Science and Technology; Kanazawa University; Kakuma, Kanazawa 920-1167 Japan