1. Graduate School of Engineering, Hiroshima University, Higashihiroshima, 1-4-1, Higashihirohima 739-8527, Japan
2. Hiroshima University, Higashihiroshima, 1-4-1, Higashihirohima 739-8527, Japan Currently: Okayama Prefectural Bureau, Uchiyamashita, 2-4-6, Kita-ku, Okayama 700-8570, Japan