1. a Division of Electronic and Information Engineering, Faculty of Technology, Tokyo University of Agriculture and Technology , 2-24-16 Naka-machi, Koganei-shi, Tokyo , 184 , Japan
2. b Control and Power System Works, Mitsubishi Electric corporation , 1-1-2 Wadasaki, Hyougo-ku, Kohbe-shi, Hyougo , 652 , Japan