1. Faculty of Economics, Kanagawa University, Yokohama-shi, Kanagawa, Japan
2. Department of Health Sciences, Oita University of Nursing and Health Sciences, Oita City, Oita, Japan
3. Department of Information Science, Okayama University of Science, Okayama-shi, Okayama, Japan
4. Department of Information Sciences, Tokyo University of Science, Noda-shi, Chiba, Japan