A communication system includes a server and a plurality of terminals. The retaining devices can be a cap adapted to be disposed over a portion of a corneal implant insertion device. This provides a considerable savings in computational complexity for moderate output FFT sizes. Due to this configuration, the NOx storage reduction catalyst are inhibit from being poisoned by sulfur and high NOx removal percentage is maintained. The wedge member is formed so as to have an inclination towards an axial direction of the stator core and the elastic plate member has a structure undulating towards the axial direction.