1. Graduate School of Integrated Science and Technology, Shizuoka University, Hamamatsu, Shizuoka 432-8561, Japan
2. Faculty of Engineering, Shizuoka University, Hamamatsu, Shizuoka 432-8561, Japan
3. Graduate School of Science and Technology, Shizuoka University, Hamamatsu, Shizuoka 432-8561, Japan
4. Yamaha Advanced Material Research Group, Yamaha Motor Co., Ltd., Iwata, Shizuoka 438-8501, Japan