1. Venture Business Laboratory, Oita University, 700 Dannoharu, Oita-city, Oita 870-1192, Japan
2. Faculty of Engineering, Oita University, 700 Dannoharu, Oita-city, Oita 870-1192, Japan
3. Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8508, Japan