1. Department of Engineering Synthesis, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
2. Central Research Laboratory, Hitachi, Ltd., I-280 Higashi-koigakubo, Kokubunji, Tokyo 185-8601, Japan
3. Department of Engineering Synthesis, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan and Research Fellow of the Japan Society for the Promotion of Science, 8 Ichibancho, Chiyoda-ku, Tokyo 102-8472, Japan