1993 - Present
Professor
Graduate School of Information Sciences, Tohoku University
1988 - 1993
Professor
Department of Information Engineering and
Research Institute of Electrical Communication, Tohoku University
1976 - 1988
Associate Professor
Department of Electrical Communications and
Research Institute of Electrical Communication, Tohoku University
1977 - 1978 (on leave)
Research Visiting Mathematician
Carnegie-Mellon University
at Pittsburgh, U. S. A.