The core shift measurements for two-sided jets affected by Free-Free absorption using VLBA Takafumi Haga, Akihiro Doi, Yasuhiro Murata, Hiroshi Sudou, Seiji Kameno, Kazuhiro Hada and Hiroshi Nagai EPJ Web of Conferences, 61 (2013) 08004 Published online: 09 December 2013 DOI: 10.1051/epjconf/20136108004