Satoru Izumi Kazuhiro Yamanaka Yoshikazu Tokairin Hideyuki Takahashi Takuo Suganuma Norio Shiratori Ubiquitous supervisory system based on social contexts using ontology. 141-163 2009 5 Mobile Information Systems 2 http://dx.doi.org/10.3233/MIS-2009-0078 db/journals/mis/mis5.html#IzumiYTTSS09