Ultrasonic Wave & Magnet


Kyungwon Industry manufactures ultrasonic sonar sensor and ultrasonic sensor based on ultrasound, piezocermic technology

Ultrasonic wave

Refers to the sound wave with frequency of 20 kHz or higher, sound waves that are inaudible for humans.
Ultrasonic sonar sensor and ultrasonic sensor work by emitting this sound waves.

Ultra-low sound wave(~ 20Hz), Audible sound wave(20Hz ~ 20 kHz), Ultrasonic wave(20 kHz ~ 1 GHz)

Ultrasonic Intensity

The higher the frequency is, the higher the intensity (I) it obtains even with a small amplitude (A), and a relatively higher acceleration (α) is generated.

Key Features of Ultrasonic Wave

1) Highly directional : The higher the frequency is, the better the straightness of the sound wave.

2) Reflection and transmission : The larger the acoustic impedance (Z) difference between the media is, the larger the ultrasonic wave reflection is at the interface; on the contrary, less difference means larger transmittance.
By this feature, after ultrasonic sonar sensor emit the sound wave, wait for it to be reflected back for calculating distance based on the time required.

Materials ρ (kg/m3) c (m/s) Z (106kg/m2s)
air 1.3 330 0.00043
water 1000 1500 1.5
copper 7700 5850 45
rubber 950 1500 1.5

3) Acoustic matching layer : It is inserted between the media with different acoustic impedances to increase the transmittance of the ultrasonic wave.

- To increase the transmittance by inserting the junction layer M between media 1 and 2

a). Set the matching material with acoustic impedance ZM to make the identical albedo (r) for the media M-1 and M-2.

b). Set the matching material with acoustic impedance ZM to make the identical albedo (r) for the media M-1 and M-2.

4) Cavitation :

- Refers to the phenomenon in which ultrasonic wave accelerates the liquid, forming bubbles in parts with low pressure.

- Bubbles repeatedly contract and expand through continuous compression and decompression of the ultrasonic wave, grow to the threshold, and explode.

Bubble Size Failure Time Generated Temperature Generated Pressure
Single-digit ㎛ – double-digit ㎛ Single-digit ㎲ 5000 K 1000 MPa

Ultrasonic Applications

The ultrasonic wave is used in various areas, including medium transmission, reflection, and energy concentration. Its applications are divided into industrial, medical, and military. Ultrasonic sonar sensor and Ultrasonic sensor are representative products.