1. Kyoto University, Graduate School of Engineering, C1 Kyoto-Daigaku Katsura, Nishikyo-ku, Kyoto 6158540, Japan.
2. Corresponding author.
3. Shikoku Electric Power Co. Inc., Marunouchi 2-5, Takamatsu, Kagawa, 7608573, Japan.
4. Shikoku Research Institute Inc., Yashimanishimachi 2109, Takamatsu, Kagawa, 7610192, Japan.