1. Department of Information Engineering, Kagawa National College of Technology, Mitoyo, Kagawa 769-1192, Japan
2. Institute of Technology and Science, The University of Tokusihma, Tokushima, Tokushima 770-8506, Japan
3. Department of Electrical and Electronics Engineering, Numazu National College of Technology, Numazu, Shizuoka 410-8501, Japan
4. Interdisciplinary Graduate School of Engineering Science, Kyushu University, Fukuoka, Fukuoka 812-8581, Japan