The present invention pertains to radiation sources that mimic radiation environment encountered by packaged semiconductor devices. The spindle motor is mounted on a driving circuit board which is mounted in a traverse module. The joint cover 20 is provided with a joint groove portion 21 that covers a top surface 12c of the convex portion 12 in the course of construction, and a lower edge portion 23 extending from the lower end of the joint groove portion 21 and brought into contact with the surface of an external wall panel 30B in the course of construction. The method further comprises the steps of displaying a selection of an Internet symbol mode if the demand for an input of the functional key corresponds to a demand for an input of the symbols, and displaying a symbol corresponding to the key corresponding to the key input section if the key corresponding to the key input section is inputted.