Affiliation: | a Department of Socio-Information, Okayama University of Science, 1-1 Ridaicho, Kita-ku, Okayama 700-0005, Japan b Graduate School of Environmental Science, Okayama University 1-1-1 Tsushima-naka, Kita-ku, Okayama 700-8530, Japan c Department of Information Science, Okayama University of Science, 1-1 Ridaicho, Kita-ku, Okayama 700-0005, Japan |