Apparatuses and methods for low power combined self-refresh and self-correction of a Dynamic Random Access Memory array. The variable valve operating device includes a rocking cam, a rocking cam support member, a valve, a rocking position changing unit, and a lock unit that can fix the rocking cam support member so as not to move during a valve-opening period of the valve. Tension in the seat belt webbing is transmitted to the elongated member. The instantaneous frequency is defined by the speed the instantaneous phase is changed in the complex plane by the in-phase and quadrature-phase control signals; the instantaneous frequency is linearly changed between initial and instantaneous frequencies over the whole duration of the chirp signal; the initial and final instantaneous phases of the chirp signal are identical.