Two major experiments, AMoRE searching for neutrino-less double beta decay and COSINE searching for dark matter WIMPs (Weakly Interacting Massive Particles), are running in the YangYang underground Laboratory (Y2L). To understand their signals, it is necessary to know the backgrounds from their detector materials such as fasteners, crystals, cables, connectors, etc. By using two 100\% HPGe detectors at the Y2L, the trace levels of naturally occurring radioactivity from the material samples were measured and analyzed using efficiencies estimated with the Geant4\cite{geant4} simulation toolkit. In this report, we present radioactivity measurements of the samples together with improved efficiency calibration produced with a mixed source containing 10 known radioactive isotopes.