1. Graduate School of Engineering, Fukuoka Institute of Technology, Fukuoka, Japan. E-mails: ryui1010@gmail.com, shinji.t.sakamoto@gmail.com
2. Fukuoka Prefectural Fukuoka Technical High School, Fukuoka, Japan. E-mail: matuo-k7@fku.ed.jp
3. Department of Information and Communication Engineering, Fukuoka Institute of Technology, Fukuoka, Japan. E-mails: makoto.ikd@acm.org, barolli@fit.ac.jp
4. Department of Languages and Informatics System, Technical University of Catalonia, Barcelona, Spain. E-mail: fatos@lsi.upc.edu