Low cost electronic ballast does not have a function of crest factor correction in those conventional arts, and so a life span of a fluorescent lamp using the electronic ballast decreases due to a high crest factor correction. The method includes: storing a plurality of reference disc unbalance values; measuring an RPM of the disc; comparing the measured RPM with a target RPM; and when the measured RPM reaches the target RPM, detecting a reference disc unbalance value among the plurality of reference disc unbalance values based on an elapsed time to reach the target RPM. Each cosmetics depiction has associated indicia. The pressurizing shoe is provided within the jacket at the position of the calender nip and presses the interior surface of the jacket radially outward to pressurize the calender nip.