Affiliation: | (1) Central Research Laboratory, Nihon Cement Co., Ltd, Koutou-ku, 135 Tokyo, Japan;(2) Department of Electrical Engineering, Nagaoka University of Technology, 940-21 Nagaoka, Niigata, Japan;(3) Research Institute of Electrical Communication, Tohoku University, Aoba-ku, 980 Sendai, Japan |