1. Department of Bioinformation Sciences, Faculty of Information Sciences, Hiroshima City University , 3-4-1 Ozuka-Higashi, Asa-Minami-Ku , Hiroshima, 731-3194, Japan
2. Department of Bioinformation Sciences, Graduate School of Information Sciences, Hiroshima City University , 3-4-1 Ozuka-Higashi, Asa-Minami-Ku , Hiroshima, 731-3194, Japan