Reverberation mapping (RM) of Active Galactic Nuclei (AGNs) is the primary method to determine AGN broad line region (BLR) sizes and black hole (BH) masses. Most objects in the current H beta RM sample are low-to-intermediate luminosity AGNs with only a few objects larger than L5100=10^45 erg/s. Here we present the latest result from our 6-year Seoul National University AGN Monitoring Project (SAMP).  With hundreds of nights of regularly sampled spectroscopic/photometric observations, we successfully measure H beta lags and BH masses for ~ 30 objects at the luminosity range of L5100 ~ 10^44.0 ~ 45.5 erg/s.  This sample enables us to test the H beta size-luminosity relation at the high-luminosity regime, and investigate how the departure from the size-luminosity relation correlates with AGN properties, .e.g, Eddington ratios. We will also briefly show other key results, including velocity resolved H beta lags and BLR stratification based on lags of multiple emission lines, and discuss the implication of these realists on the BLR properties of high luminosity AGNs.