1. Department of Computational Intelligence and Systems Science, Tokyo Institute of Technology, Yokohama 226-8502, Japan
2. Applied Informatics, Faculty of Science and Engineering, Hosei University, Koganei 184-8584, Japan
3. Department of Home Electronics, Faculty of Creative Engineering, Kanagawa Institute of Technology, Atsugi 243-0292, Japan
4. Human Technology Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8568, Japan