Donghai Guan Weiwei Yuan Young-Koo Lee Andrey Gavrilov Sungyoung Lee 0001 Activity Recognition Based on Semi-supervised Learning. 469-475 2007 conf/rtcsa/2007 RTCSA https://doi.org/10.1109/RTCSA.2007.17 https://doi.ieeecomputersociety.org/10.1109/RTCSA.2007.17 db/conf/rtcsa/rtcsa2007.html#GuanYLGL07