Affiliation: | a Faculty of Engineering Science, Osaka University Toyonaka, Osaka 560 Japan b Research Development Division, Nissin Electric Co. Ltd., Umezu-Takase-cho, Ukyouku Kyoto 615 Japan c Faculty of Science, Kwansei-Gakuin University, Nishinomiya Hyogo 662 Japan d Kansai Electronics Research Laboratories, NEC Corporation, 2-9-1 Seiran Otsu, Shiga 520 Japan |