1. Postdoctoral Research Fellow, Advanced Research Laboratories, Tokyo City Univ., 8-15-1 Todoroki, Setagaya-ku, Tokyo 158-0082, Japan (corresponding author).
2. Associate Professor, Dept. of Civil Engineering, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8552, Japan.
3. Project Leader, Omron Social Solutions Corporation, Nishikusatsu 2-2-1, Kusatsu City 525-0035, Japan.