The present invention provides a technique of improving wear resistance of a Sialon sintered body. A fingerprint comparing unit identifies the input fingerprint via the fingerprint reader unit by comparing with the fingerprint database recorded in the database unit and a user recording unit records the input fingerprint input by the fingerprint reader unit. The topology uses a bank of 1-bit DAC elements, whose outputs are summed to produce a multi-level analog output. The drain system includes a plug having plug bodies sized and shaped to be inserted into the openings to effectively close a bottom of the grain compartment.