 24  8 pp. 431-440 (2005)       Construction of Ultrasonic Power Measurement System and Its Performance Evaluation   *,  *,   *,    (Moon Jae Jho*, Yong Tae Kim*, Yong Hyeon Yun*, Sung Soo Jung*) *     ( 2005 7 25 ; :2005 9 14 )           .     on/off                        .           ,   ,          .  1MHz, 5MHz, 10MHz, 15MHz 10 mW 10 W              5%  . :  , ,  ,  , :    (4.1) The precise measurement of ultrasonic power is important to the quality assurance and the safety of medical ultrasonic equipments. In the present work, a brief theory was introduced to determine the ultrasonic power from the time varying balance-indication due to the radiation force acting on an absorbing target and/or other causes such as buoyancy during the repetition of on/off behavior of ultrasonic irradiation. The developed automated system measuring the ultrasonic power was described in detail with the precise mechanical alignment tool, the electric signal generation network, the, control and measurement network, and the appropriate procedure. The ultrasonic power measured by the developed system was compared to the reference data calibrated by the other national metrology institute at 1 MHz, 5 MHz, 10 MHz, and 15 MHz over )e range 10 mW to 10 W. Their relative differences are within 5 %. Keywords'- Ultrasonic power, Radiation force, Absorbing target, Ultrasonic attenuation, Sound speed ASK subject classification Ultrasonic and Elastic Waves (4.1) I.  ,                    .      (  )       ,1MHz 15MHz    10mW 10W    . :   (ytkim@kriss.re.kr) 305-340   1     ( :042-868-5301. :042-868-5643)     (target)    (radiation force)    [1],  (hydrophone)         [2], -     ,    .                     ,    (    [5])  .             ,         .     