1. a Department of Electrical Engineering, Faculty of Engineering , Hachinohe Institute of Technology , 88-1, Aza-Ohbiraki, Ohaza-Myoh, Hachinohe, Aomori, 037, Japan
2. b JES Co., Ltd. , 794-1, Aza-Hirusawa, Nakano, Kanazawa, Yokote, Akita, 019-13, Japan
3. c Department of Electronics Engineering, Faculty of Engineering , Tohoku University , Aza-Aoba, Aramaki, Aoba-Ku, Sendai, Miyagi, 980, Japan