Ultrasound means a wave with a frequency of 20 Khz or more, has a property of penetrating water, and is widely used in the medical field such as an ultrasonic diagnosis device and an ultrasonic treatment device.
The most representative application of ultrasound in the medical field is an ultrasound imaging device using transmission and reflection properties of ultrasound.
It is a device that obtains a cross-sectional image of the human body by visualizing the time and intensity of ultrasound waves being reflected while passing through the body and passing through each organ.

A shock wave occurs when air is compressed in a very short time, or when an object such as an aircraft or a bullet moves through the air at the speed of sound or faster.
Pressure waves in a gas are usually transmitted at a constant speed, such as sound, in both the compressed and expanded parts, but if the pressure changes rapidly, the expansion part gradually changes and the compression part changes rapidly, and the waveform is distorted. It is felt as a sudden increase in pressure, density, or speed.
In electrical engineering, an impulse voltage or current is sometimes called a shock wave. Impulse current or voltage refers to the generation of very high energy for a very short time (several ns to us).