VLBI Phase Referencing and Astrometry with KVN and KaVA

Phase referencing is an important tool to study weak radio sources, especially in mm-VLBI (Very Long Baseline Interferometry) which are usually too faint to be observed using conventional VLBI. VLBI astrometry is a unique method to measure the position and to identify radio emitting regions of a radio source with unprecedented angular resolution. In order to evaluate the phase referencing and astrometric capabilities of KVN and KaVA, several observations have been conducted and analyzed. I will present the observational results and discuss constraints and requirements for high precision VLBI astrometry.