• Proceedings of the KSME Conference
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• 2003.11a
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• pp.1109-1114
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• 2003

The initial crack often occurs on the bonded interface and it is the general cause of the interface fracture. It is very significant to establish the measurement method of interfacial crack by applying the ultrasonic technology into the interface of bonded dissimilar materials. In this paper, the interfacial crack length was measured by ultrasonic attenuation coefficient in the Al/Epoxy bonded dissimilar materials of double-cantilever beam(DCB). The energy release rate, G, was obtained by the experimental and Ripling's equation measurement of compliance. The experimental results represent that the relation between interfacial crack length for the ultrasonic attenuation coefficient and energy release rate is increased proportionally. From the experimental results, a measurement method of the interfacial crack length by the ultrasonic attenuation coefficient was proposed and discussed.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.340-345
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• 2003

In this paper, the ultrasonic attenuation coefficient was measured by variation of crack length for double-cantilever beam(DCB) specimen. The energy release rate, G, was obtained by the experimental measurement of compliance. The experimental results represents that the relation between crack length for the ultrasonic attenuation coefficient and energy release rate is increased proportionally. From the results of experiments, the measurement method of crack length by the ultrasonic attenuation coefficient was proposed and discussed.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.4
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• pp.386-393
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• 2004

In this paper, the ultrasonic attenuation coefficient was measured by variation of crack length for double-cantilever beam(DCB) specimen. The energy release rate, G, was obtained by the experimental measurement of compliance. The experimental results represents that the crack length for the ultrasonic attenuation coefficient and energy release rate is increases proportionally From the experimental results, we proposed a detecting method of the crack length by the ultrasonic attenuation coefficient and discussed it.

• International Journal of Automotive Technology
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• v.5 no.4
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• pp.303-309
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• 2004

In this paper, an interfacial crack length has been detected by using the ultrasonic attenuation coefficient on the adhesively bonded double-cantilever beam (DCB) joints. The correlations between energy release rates which were investigated by experimental measurement, the boundary element method (BEM) and Ripling's equation are compared with each other. The experimental results show that the interfacial crack length for the ultrasonic attenuation coefficient and energy release rate increases proportionally. From the experimental results, we propose a method to detect the interfacial crack length by using the ultrasonic attenuation coefficient and discuss it.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.2
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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%.

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.1
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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.

• Journal of the Korean Institute of Telematics and Electronics
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• v.25 no.1
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• pp.49-55
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• 1988

To provide a quantitative parameter of evaluating diagnosis of the liver diseases accurately, the ultrasonic attenuation coefficient was estimated from liver phantoms, 15 normal human livers and 30 liver disease patients. Two kind of phantoms(No.1: 1552m/s, No.2: 1562m/s) which have velocity (1560m/s) similar to that in human liver were constructed and their ultrasonic attenuation coefficients were determined. In this paper the spectral-shift approach and spectral-difference approach were used for estimating ultrasonic attenuation coefficient, \ulcornerdB/Cm.MHz). These two approaches were utilized to esitmate for 15 normal humans without any liver disease and 30 liver disease patients. The results indicate that the two types of phantoms produce the value of near the suggested value of 0.5 and the attenuation coefficients of hepatoma, normal liver, corrhosis, fatty liver and hepatitis show decreasing value in order named, suggesting that the present study can be of clinical value incorrelating the estimated attenuation coefficidents with the liver diseases.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.25-30
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• 2004

In this paper, the compensation of interfacial scatter due to adhesive layer and adherend thickness ratio variation was applied to improve measuring precision by calculating ultrasonic attenuation coefficient in the Al/Epoxy dissimilar bonded components. The optimum condition of theoretical value and experimental measuring accuracy by the ultrasonic method in the Al/Epoxy dissimilar bonded components have been investigated. From the experimental results, we proposed a measurement method of the interfacial crack lengths by the ultrasonic attenuation coefficient and discussed it.

• Korean Journal of Materials Research
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• v.3 no.6
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• pp.585-592
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• 1993

The effects of grain size and microstructure on the ultrasonic attenuation was investigated with SCM440 steel quenched and tempered at various temperatures. The ultrasonic attenuation was primarily due to the grain boundary scattering and the ultrasonic attenuation coeffecient increased with increasing grain size. In the meantime, it was found that the ultrasonic attenuation coefficient decreased with increasing tempering temperature. The dependence of ultrasonic attenuation coefficient on the frequency of ultrasonic wave had linear relationship on a log-log scale and was proportional to the Roney's equation.

• Journal of Biomedical Engineering Research
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• v.5 no.1
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• pp.39-46
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• 1984

In order to improve the performance of ultrasonic diagnostic equipment, it is important to development the signal processing considering the ultrasonic properties of biological medium and propagation mechanism in tissue. Attenuation coefficient is not only important factor to analyze propagation properties, but also it is significant to estimate it in view of tissue characterization, so we show one of the method to estimate attenuation coefficient of biological tissue and the results of estimation.