• Journal of the Korean Society for Nondestructive Testing
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• v.14 no.2
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• pp.83-89
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• 1994

It is important for an ultrasonic testing to know the sound pressure field and the directivity of ultrasonic waves propagating in a solid. The directivity of ultrasonic wave is closely related to the sensitivity, the scanning pitch, the arrangement of angle probe, and the defect kind in ultrasonic testing. This paper describes on the directivity measurement of ultrasonic wave using ultrasonic wave visualization method. The directivity of the shear wave emitted from the angle probes were constant during propagation. The difference of directivity was existed between 2MHz and 4MHz angle probes. The centers of directivity were located backward from the incident poing and inside of the angle probe and were not changed during the wave propagation.

• Journal of the Korean Society for Nondestructive Testing
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• v.15 no.2
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• pp.378-385
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• 1995

The ultrasonic non-destructive testing uses the directivity of the ultrasonic pulse wave which propagates in one direction. The directivity is expressed as the relationship between the propagate direction and its sound pressure. The directivity of ultrasonic wave is closely related to determination of probe arrangement, testing sensitivity, scanning pitch and defect location and characterization. The paper measured the directivity of shear wave, which reflected from artificial defect located in weld metal zone in butt welded joint similar model made of pyrex glass by using visualization method. 2 MHz and 4 MHz angle probes were used to measure the directivity of reflection wave at the artificial defect. The directivity of shear waves reflected from the defect was different according to the probe position and the shape of butt welded joint. The difference of directivity of reflection wave was existed between 2 MHz and 4 MHz angle probes. The angle of reflection wave became equal to angle of incidence as increase of the height of excess metal.

• Journal of Welding and Joining
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• v.8 no.1
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• pp.12-22
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• 1990

우리나라와 선진 각국에서는 구체적인 부분까지 상당량을 규격(standard)으로 제정해 놓고 있다. 규격의 내용을 전반적으로 언급하기는 어렵기 때문에, 여기서는 범위를 좁혀 한 분야의 계통을 선택하여 설명하고자 한다. 즉, 강재의 맞대기 용접부에대하여, 사각탐촉자에 의한 탐상법을 예시적으로 선택하고 KS B 0896 규격을 중심으로 설명하는 내용이다. 이와 관련한 내용들은, 탐상장치의 성능시험, 거리진폭 특성곡선, 결함 및 탐상에 관한 사전준지, 결함의 탐상방법 등이며, 참고로 한국 일본 미국의 초음파 탐상시험에 관련된 규격명을 열거한다.

• Journal of Ocean Engineering and Technology
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• v.13 no.4 s.35
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• pp.45-54
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• 1999

Non destructive test is applied to revise mechanical strength and assume material strength or defect of material, equipment and structure, instead of fracture test. Especially, ultrasonic test has the characteristics such as an excellent permeability high-sensitiveness to fine defect and an almost exact measurement for position, size and direction of inner defect which differ from other non destructive tests. In this study, the program is developed to evaluate optimal testing condition, to distinguish obstacle echo and defect position. This program on the basic of Ray-Tracing model shows generation and processing of ultrasonic pulse. The simulation is compared with testing in the 3 cases of an oblique angle transducer like $45^{\circ},\;60^{\circ}\;and\;70^{\circ}$. The test result for all conditions is well compared with simulation result when relative not is within $0.1{\sim}7.2%$. And the course of several echos is simply assumed through simulation.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.9
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• pp.37-44
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• 2001

Ultrasonic testing has a characteristics such as excellent permeability, high-sensitivity to find defect and an almost exact measurement for position. size and direction of inner defect, which differ from other non-destructive testing. In the study, we developed program into optimal testing condition, to distinguish obstacle echo and defect position. This program shows generation and processing of ultrasonic pulse. We compared simulation with ultrasonic test in 45$^\circ$, 60$^\circ$and 70$^\circ$transducer. Test results were in accordance with simulation within 0.1~7.2%.

• Journal of the Korean Society for Nondestructive Testing
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• v.15 no.1
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• pp.291-298
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• 1995

An ultrasonic testing uses the directivity of the ultrasonic wave which propagates in one direction. The directivity is expressed as the relationship between the propagate direction and its sound pressure. This paper studied the directivity of shear waves emitted from angle probes and scattered from surface defects by using visualization method. These experimental results were compared with the theory which was based on the continuous wave. The applicability of continuous wave theory was discussed in terms of the parameter $d/{\lambda}$; where d is transducer or defect size and ${\lambda}$ is the wavelength. In the case of angle probes, the experimental results show good agreement with theoretical directivity on the principal lobe. When defect size was smaller than the wavelengths, clear directivity in the reflected wave was observed. In the case of the same ratio of defect size to wavelength, the directivity of reflected waves from the defect show almost the same directivity in spite of frequency differences. When the $d/{\lambda}$ is greater than 1.5, measured directivities almost agreed with the theoretical one.

• Journal of the Korean Society for Nondestructive Testing
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• v.23 no.5
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• pp.475-479
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• 2003

Traditional ultrasonic evaluation to detect micro/small surface cracks is the pulse-echo technique using the normal immersion transducer with high frequency, or the angle beam transducer with surface wave. It is difficult to make the automatic ultrasonic system that is to detect micro and small surface crack and position on the large structure like steel and ceramic rolls, because of the huge data of inspection and the ambiguous position data of transducer. The aim of this study using the high precision scanning acoustic microscope with 10MHz large aperture transducer was to display the real time A, B, C-scan for the automatic ultrasonic system in order to detect the existence and position of surface crack. The ultrasonic method with large aperture transducer was improved the scanning time and speed over 10times faster than traditional methods.

• Journal of the Korean Society for Nondestructive Testing
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• v.24 no.2
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• pp.180-185
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• 2004

Conventional ultrasonic examination to detect micro and small surface cracks is based on the pulse-echo technique using a normal immersion focused transducer with high frequency, or an angle-beam transducer generating surface waves. It is difficult to make an automatic ultrasonic system that can detect micro and small surface cracks and position in a large structure like steel and ceramic rolls, because of the huge data of inspection and the ambiguous position data of the transducer. In this study, a high-precision scanning acoustic microscope with a 10MHz large-aperture transducer has been used to assess the existence, position and depth of a surface crack from the real-time A, B, C scans obtained by exploiting the ultrasonic diffraction. The ultrasonic method with large aperture transducer has improved the accuracy of the crack depth assessment and also the scanning speed by ten times, compared with the conventional ultrasonic methods.