[1] P and I Laboratory, Tokyo Institute of Technology
[2] Tokyo Institute of Technology, Tokyo
[3] Prec. and Intelligence Laboratory, Tokyo Institute of Technology
[4] AT and T Bell Laboratories, Crawford Hill, NJ
[5] Japan Society of Applied Physics, Inst. Electronics, Info. Commun. E.
[6] P and I Laboratories, Tokyo Institute of Technology
[7] Inst. Electronics, Info. Commun. E.