1. Research and Development Group; Center for Technology; Innovation-Mechanical Engineering; Hitachi, Ltd. 832-2, Horiguchi, Hitachinaka, Ibaraki 312-0034 Japan
2. Research and Development Group; Center for Technology; Innovation-Electronics; Hitachi, Ltd. 1-280, Higashi-koigakubo, Kokubunji, Tokyo 185-8601 Japan