1. Department of Urban and Environmental Engineering, Kyoto University , Yoshida Hon-machi, Sakyo-Ku, Kyoto 606-8501, Japan Fax:
2. Department of Urban and Environmental Engineering, Kyoto University , Yoshida Hon-machi, Sakyo-Ku, Kyoto 606-8501, Japan
3. Technical Research Center, The Kansai Electric Power Company Incorporation , Hyogo, 661-0974, Japan