1. Faculty of Systems Science and Technology, Akita Prefectural University, Honjyo, 015-0055, Japan,
2. Department of Mechanical Engineering, Iwaki Meisei University, Iino 5-5-1, Chuohdai, Iwaki 970-8551, Japan
3. Department of Electrical Engineering, Kyushu Institute of Technology, Sensuicho 1-1, Tobata-ku, Kitakyushu 804-8550, Japan