• 한국자동차공학회논문집
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• 제12권1호
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• pp.130-137
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• 2004

The ultrasonic attenuation coefficients were measured by interfacial crack length in the adhesive components of double-cantilever beam(DCB). The energy release rate, G, was obtained by the experimental measurement of compliance. The numerical analysis by the boundary element method(BEM) and Ripling's equation was investigated. The experimental results represent that the relation between interfacial crack length for the ultrasonic attenuation coefficient and energy release rate is increased proportionally. A measurement method of the interfacial crack length by the ultrasonic attenuation coefficient was proposed and discussed.

• 한국자동차공학회논문집
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• 제14권2호
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• pp.67-75
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• 2006

In this paper, the compensation of ultrasonic scattering on interface crack depending on thickness variations of A1/Epoxy bonded dissimilar components was applied to improve measuring accuracy by using ultrasonic attenuation coefficient. The optimum conditions of theoretical value and experimental measuring accuracy by the ultrasonic method in A1/Epoxy bonded dissimilar components have been investigated. From the experimental results, the measurement method of interfacial crack lengths by using ultrasonic attenuation coefficient was proposed and discussed. After the ultrasonic scattering compensation depending on thickness variations of bonded dissimilar components was carried out, the measuring accuracy of interfacial crack length was improved by 5%.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 추계학술대회논문집
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• pp.720-725
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• 2000

A new ultrasonic pulse-echo technique was developed and described for vibration measurement of the suspension assembly in hard disk drives. The method is based upon the difference in magnitude of two consecutive reflection waves from a moving object(suspension), while the traditional ultrasonic vibrometer uses the phase shift of the reference wave and the reflection wave. A cone-shape delay line is designed to access the small structure. A simple mathematical model is presented and analyzed with experimental results to show the feasibility of the method. The advantages of this ultrasonic vibration measurement method are relatively high resolution, low cost, and ease of implementation comparing with the Laser Doppler vibrometer.

• 비파괴검사학회지
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• 제2권1호
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• pp.5-9
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• 1982

Experiments were performed according to ultrasonic attenuation measurement and comparison method of DAC curve to analyze the difference between PSI and 2nd ISI ultrasonic testing results. Smaller error was found by comparison method of DAC curve, and that method was more useful practically.

• 한국정밀공학회지
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• 제4권1호
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• pp.65-73
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• 1987

In recent days, the application of ultrasonics has been increased in the field of engineering and medicine. The ultrasonic hardness tester to apply the principle of contact compliance method is entirely different from hardness tester in the past and in the practical use, the more pre- cisive measurement is required because it has a slight change of hardness value due to the difference of resonance frequency. Therefore, in this study, as one type of applicative transducers which can detect the optimum pressure load, ring type load cell was used in the measurement of ultrasonic hardness. From experimental results, it was compared ultrasonic hardness testing method with the other hardness testing methods. Also, the measurement error of ultrasonic hardness tester could be measured within .+-. 0.5 HRC F.S. in the case of 3.0Kg pressure load.

• Journal of Electrical Engineering and Technology
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• 제13권2호
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• pp.981-988
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• 2018

In order to acquire an accurate TOF, this paper proposes a method that produces TOF by using a mathematical model for the envelope of the received signal obtained from a system dynamic model of ultrasonic transducer. The proposed method estimates the arrival time of the received signal retrospectively by comparing its wave form obtained after triggering point with its mathematical envelope model. Experimental result shows that the error due to variation of triggering point can be dramatically decreased by implementing the proposed method.

• 대한기계학회논문집
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• 제18권4호
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• pp.816-825
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• 1994

The purpose of this study is to develop the non-destructive material evaluation method of aluminum alloy base metal matrix composite(MMC) by ultrasonics. Five aluminum base MMC specimens were fabricated in which the fractional ratios of fiber were changed from 0% to 31%. Relations among acoustic properties, microstructural features and elastic constant were compared. The ultrasonic velocity method was useful for nondestructive elastic constant measurement of composite materials, since the method had as same accuracy as conventional strain measurement method. Furthermore, velocity, attenuation and backscattering behaviors for each specimen also related to fractional ratio of fiber and these relations could utilize ultrasonic non-destructive evaluation of fiber structure in MMC.

• 한국전자통신학회논문지
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• 제12권1호
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• pp.53-60
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• 2017

현재 대부분의 초음파를 이용한 거리 측정 기술은 송신부로부터 수신기까지 초음파가 진행하는 시간 즉, TOF(: Time of Flight)를 측정하여 그 동안 음파가 진행한 거리를 산출하는 방법을 활용한다. 이 경우 거리 측정 정확도를 높이기 위해서는 정확한 TOF의 측정이 필요하다. 본 논문은 정확한 TOF를 산출하기 위해 초음파 송수신기의 수학적 모델을 이용하여 수신된 파형의 수학적 모델을 얻어내고 이를 바탕으로 TOF를 산출하는 방식을 제안한다. 이 방식은 트리거링 후부터 수신된 파형를 이미 얻어진 수학적 모델과 최소자승법을 이용하여 비교하여 초음파 신호가 수신기에 도달한 시점을 역으로 추정하는 방식이다. 제안된 방법을 사용할 경우 트리거링 시점의 변동에 의한 영향을 줄일 수 있음을 실험을 통하여 확인하였다.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2002년도 유체기계 연구개발 발표회 논문집
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• pp.378-386
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• 2002

Multi-path ultrasonic Sow measurement system uncertainty is determined by assigning an expected error of each component of flow measurement and then defining the total flow measurement uncertainty as square root of the sum of squared values of the individual error. Sources of uncertainty for flow measurement are geometry, transit time and velocity profile integration uncertainty. A theoretical uncertainty model for multi-path ultrasonic transit time flowmeter configured with parallel 5 chords, is derived from and calculated by dry calibration method.

• 비파괴검사학회지
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• 제9권2호
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• pp.61-66
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• 1989

Welding residual stress was measured by ultrasonic birefringence technique. Acoustoelastic constant was taken by averaging the values in the literature. The initial birefringence from prefered orientation of grains was measured. The EMAT transducers were used to remove couplant effect. The results show that the distribution and magnitude of welding residual stress from ultrasonic measurement are in good agreements with those from semi destructive hole drilling measurement.