Affiliation: | a The University of Tokyo, School of Engineering, Department of Mechanical Engineering, 7-3-1, Bunkyo-ku, Hongo, Tokyo 113-8656, Japan b The Nippon Signal Co., Ltd., Visionary Business Center, Sunshine 60, 3-1-1, Higashi-Ikebukuro, Toshima-ku, Tokyo 170-6019, Japan |