1. Extreme Energy-Density Research Institute, Nagaoka University of Technology, Nagaoka, Niigata 940-2188, Japan
2. Department of Electrical, Electronics and Information Engineering, Nagaoka University of Technology, Nagaoka, Niigata 940-2188, Japan
3. Department of Innovative Electrical and Electronics Engineering, National Institute of Technology, Oyama College, Oyama, Tochigi 323-0806, Japan