Graduate of the University of Tokyo: undergraduate (1954), Doctoral course (1959, Dr. of Science); Bell Laboratories, MTS (1961-1964); University of Tokyo: Lecturer (1964-66), Associate Professor (1967-1977), Professor (1978-1991); Retired from the University of Tokyo at 60; Professor of Tokyo University of Science (1991-2001); Special Adviser (2001-2015)