“…In the time domain, the magnitude of a signal for a certain time is analyzed. In the frequency domain, the distribution of each frequency is analyzed [ 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 ]. Additionally, in the time–frequency domain, the vibration and amplitude of the frequency according to a certain time are analyzed.…”