The measured operation time of a setting/operating device is corrected using a first corrected value table and a second corrected value table and the size of the setting/operating device is defined based on the corrected operation time. The first corrected value table defines, as a first corrected value, the corrected value corresponding to the operation time region defined so as to correspond to the size of the setting/operating device and the sliding resistance region defined by dividing the range taken by the sliding resistance (friction) of the valve stem of a regulating valve and the second corrected value table defines, as a second corrected value, the corrected value corresponding to the operation time region defined so as to correspond to the size of the setting/operating device and the supply air pressure region defined by dividing the range taken by a supply air pressure.