1. a Department of Electronics and Informatics Toyama Kenritsu University Kosugi, Toyama 939-03, Japan
2. b Department of Electronic Engineering The University of Electro-Communications Chofu, Tokyo 182, Japan
3. c Department of Electronics and Informatics Toyama Kenritsu University Kosugi, Toyama 939-03, Japan
4. d Department of Electronic Engineering The University of Electro-Communications Chofu, Tokyo 182, Japan