Abstract
Pressure vacuum measurement technique using acoustic impedance change of ultrasonic transducers was studied. The sensor has been setup using two air-coupled ultrasonic transducers, one as a transmitter and the other as a receiver, and put it into vacuum chamber and measured pressure versus ultrasonic amplitude. The result confirms that the standard deviations of four repeat measurements were from 0.0093 to 0.3325 at pressure 6.66 kPa to 202.65 kPa(about two atmosphere), and the relative percents were 0.018% and 0.164% at pressure 133.32 kPa and 202.65 kPa, respectively.
초음파 변환기의 기체 음향임피던스 변화를 이용해서 압력진공 측정기술을 연구하였다. 상용화된 한 쌍의 500 kHz 공중 초음파 변환기(air-coupled ultrasonic transducer)를 진공용기에 넣고 초음파 진폭을 측정하였다. 그 결과 6.66 kPa에서 202.65 kPa (약 2기압)까지 4회 반복 측정값으로부터 계산된 표준편차는 0.0093에서부터 0.3325 사이에 있었으며, 표준편차를 압력으로 나누어서 백분율로 나타낸 값은 133.32 kPa에서 0.018%이었고 202.65 kPa에서는 0.164%이었다.