[*
]University of Electro- Communications
Graduate School of Information Systems
Chofugaoka 1-5-1, Chofu, Tokyo 182-8585, JAPAN
Tel : +81 424 43 5620 / Fax : +81 424 89 6070
[**
]Senshu University
School of Network and Information
Higashimita 2-1-1, Tama, Kawasaki, Kanagawa 214-8580,
JAPAN
Tel & Fax : +81 44 911 0570