1. a Department of Administration Engineering , Keio University , 3-14-1 Hiyoshi, Kohoku, Yokohama, 223-8522, Japan
2. b Department of Economics and Business Management , Yamagata University , 1-4-12 Kojirakawa-cho, Yamagata-shi, 990-8560, Japan
3. c Department of Management Science and Engineering , Akita Prefectural University , 84-4 Tsuchiya-Ebinokuti, Yulihonjo, Akita, 015-0055, Japan