1. Associate Professor, Institute of Rural Environment and Engineering, Shinshu Univ., 8304 Minamiminowa, Nagano 399-4598, Japan. E-mail: jsuzuki@shinshu-u.ac.jp
2. Deputy General Manager, Overseas Civil Engineering Division, Shinshu Corporation, 2-3, Shibaura 1-choume, Minatoku, Tokyo 105-8007, Japan.
3. Research Associate, Institute of Rural Environment and Engineering, Shinshu Univ., 8304 Minamiminowa, Nagano 399-4598, Japan.
4. Professor, Institute of Rural Environment and Engineering, Shinshu Univ., 8304 Minamiminowa, Nagano 399-4598, Japan.