1. SANKEN (The Institute of Scientific and Industrial Research), Osaka University, Mihogaoka 8-1, Ibaraki-shi, Osaka 567-0047, Japan
2. Graduate School of Engineering, Osaka University, Mihogaoka 8-1, Ibaraki-shi, Osaka 567-0047, Japan
3. Department of Media Engineering, Graduate School of Engineering, Tokyo Polytechnic University, 1583 Iiyama, Atsugi, Kanagawa 243-0297, Japan
4. Department of Electrical and Electronic Engineering, National Institute of Technology, Oita College, 1666 Maki, Oita 870-0152, Japan