1. Department of Applied Physics, Okayama University of Science, 1-1 Ridai-cho, Kita-ku, Okayama 700-0005, Japan
2. Department of Maritime Technology, National Institute of Technology, Toyama College, 1-2 Ebie-Neriya, Imizu, Toyama 933-0293, Japan
3. Department of Electrical and Control Systems Engineering, National Institute of Technology, Toyama College, 13 Hongo, Toyama 939-8630, Japan