The present invention provides a blade sharpening and edge uncurling device for sharpening dull blades. The memory apparatus using the portable recording medium comprises an upper outer case, a lower outer case, a drive device for driving the recording medium, an inner bottom case fitted onto the lower outer case, a top cover for covering the upper part of the inner bottom case, a power source unit disposed in the inner bottom case, and a holder for fitting the drive device to the inner bottom case. A receiver is coupled to the waveguide to detect a propagated wave and provides a first output signal proportional to the transit time of the propagated wave for determining fluid density. A tag identification system may identify tags within a predetermined range of the current position and the control system may execute an action based on an identified tag whose tag information comprises a telepresence robot action modifier.