  Initial performance of the UltraLo-1800 alpha particle detector at the 700 m
deep Yangyang underground laboratory in Korea is described. The ionization
detector uses Argon as a counting gas for measuring alpha events of a sample.
We present initial calibration results and low-activity sample measurements
based on the detector's pulse discrimination method and a hardware veto. A
likelihood analysis that shows a separation of a bulk component from a surface
component with a contamination depth from $^{210}$Po alpha particles using
simulated models is presented.
