A device includes two optical fibers bonded to a body. An ultrasonic emitter may generate an ultrasonic beam and receive an echo of the ultrasonic beam off a liquid surface inside a tank. The correction period is separated into a reset period and a detection period. Also included are a work hour calculator, an allocation engine, a schedule preparation engine, a time tracking system, and a time imbalance calculator. The blast of air is directed laterally between the outer ring-shaped label and the adjacent ring-shaped label of the pack of ring-shaped labels, so that the adjacent ring-shaped label is blown off the outer ring-shaped label. The camera device captures a number of consecutive images of the motion scene, calculates characteristic values of the plurality of consecutive images, and stores the characteristic values.