A method for sensing mechanical quantities such as force, stress, strain, pressure and acceleration is disclosed. The invention includes one or more user devices and a prediction system server having a sentiment rating module, a user proficiency ranking module, a content creation module, and a database. Thus, even when the number of the friction plates is increased, a total gap between the clutch piston and the pressure-receiving plate can be set freely without giving consideration to the falling-off of the Belleville spring. An outfeed part enables banknotes ordered externally via a banknote ordering means to be dispensed from a second storage device. Seed information can be received for use with the algorithm to provide a new secret key, and preliminary trigger information can be used to poll a group of appliances to request key information to determine any duplication of appliances. An anodic oxide film is formed on at least the cooling medium passage forming groove on the joining surface, and the plurality of metal plates are integrally joined each other by a friction agitation joining method.