A locking device for mounting a heat sink to a CPU mounted on a printed circuit board, includes a back plate mounted below the circuit board and having a plurality of fasteners extending upwardly beyond the circuit board, and a plurality of retainers. A compression member, whose one surface crosses an axial direction of the rotary shaft is inclined continuously between a top dead center and a bottom dead center and is disposed in the cylinder to be rotated by the rotary shaft, compresses a fluid sucked from the suction port to discharge the fluid via the discharge port. The notch filter further includes a defected ground plane connected to at least one or more additional metal via stubs partially extending into the semiconductor substrate. As a result, the passive safety of an occupant is considerably increased and, in particular, the a consequences of an injury are kept to a minimum or are prevented altogether. A rod is slidably disposed within the opening.