A secure association may be established between a first device and a second device for providing secure communication. The control mechanism includes a plurality of motor-gear groups and at least one control switch. A suitable refractory metal-silicon-nitrogen material to be used is TaSiN which provides a wide range of resistivity by changing the ratio of Ta:Si:N. A branch pipe is provided for directly introducing a part of gas discharged from the temperature controller to a temperature sensor inside the machine cover.