1. Information Engineering, Niigata University, Niigata-shi, Niigata-ken 950-2181, Japan
2. Graduate School of Information Science, Nara Institute of Science and Technology, Ikoma-shi, Nara-ken 630-0101, Japan
3. Nagahama Institute of Bio-Science and Technology, Nagahama-shi, Shiga-ken 526-0829, Japan