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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
Journal of the Korean Society for Nondestructive Testing
Journal Basic Information
Journal DOI :
The Korean Society for Nondestructive Testing
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Volume & Issues
Volume 10, Issue 2 - Nov 1990
Volume 10, Issue 1 - May 1990
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A Study on the Distance and Object Recognition Applying the Airborne Ultrasonic Sensor
Han, E.K. ; Park, I.G. ;
Journal of the Korean Society for Nondestructive Testing, volume 10, issue 1, 1990, Pages 10~17
Recently, object recognition ultrasonic sensor is being used with automatization of industrial machine. Points which characterize the object can be deleted by measuring the propagation time of ultrasonic impulse and azimuth which gives its maximum amplitude, and from these points shape, position and orientation of the object are deduced. A new measuring method is adopted, where the distance to the object is calculated by sound reflection time which is measured from O-cross point of sound wave, and azimuth is measured by angle indicating maximum amplitude. The measuring accuracy of 1.0mm for distance and
for azimuth have been accomplished. By rotational scanning of sensor the characteristic point of an object can be known and it gives the information of its shape, position and orientation. Experimental results showed that the object of some complicated shape can be recognized, which suggest its applicability to robot.
Development of New Ultrasonic Transducer for Coarse-Grained Materials
Kim, B.G. ; Lee, J.O. ; Lee, S. ;
Journal of the Korean Society for Nondestructive Testing, volume 10, issue 1, 1990, Pages 18~23
In materials with the large grain size, ultrasonic waves are highly attenuated by the grain boundary acting as scattering centers due to discontinuity of elastic constant. In this study, the improved probes were developed so that they minimized the effect of grain scattering in order to detect deep flaws in coarse grained materials. As the result, the developed ultrasonic transducers showed the better sensitivity and signal to noise ratio when compared with the commercial probes in testing the interior of coarse grained material.
A study on the effect of ultrasonic beam skewing based on theoretical model approach in CCSS
Lee, S.L. ; Lim, H.T. ; Lee, Y.S. ;
Journal of the Korean Society for Nondestructive Testing, volume 10, issue 1, 1990, Pages 24~28
Centrifugally Cast Stainless Steel generally shows similar structure to the weld in austenitic stainless steel in the point of casting. When examining this material ultrasonically, the beam does not generally propagate straightforward but rather deviates from its original direction and this phenomenon called skewing is originally caused by anisotropic material. In order to calculate the beam skewing effect theoretically, work has been performed based on a model approach which has regarded material itself as having been composed of multi-layered columnar dendrite structure and the result was compared with the one from experiment. The result from both theory and experiment showed good correlation and ultrasonic beam showed the least skewing with around 45 degree incident angle.
A Study on the Disbonding Detection of Al/Al Honeycomb Sandwich Structures by Ultrasonic Methods
Cho, K.S. ; Lee, J.S. ; Chang, H.K. ; Lee, S.H. ;
Journal of the Korean Society for Nondestructive Testing, volume 10, issue 1, 1990, Pages 29~37
In this study the disbonding tests of adhesively bonded Al/Al honeycomb structures were performed by ultrasonic methods. Ultrasonic C-scan squiter method and ultrasonic surface wave attenuation measuring method were applied for the detection of skin/core disbonding. The bonding quality of Al/Al honeycomb structures could be well evaluated by properly controlled ultrasonic parameters.
Ultrasonic Detection of Small Crack in Studs[Bolts] by Time Difference of Thread Signals(TDTS)
Suh, D.M. ; Park, D.Y. ; Kim, C.K. ;
Journal of the Korean Society for Nondestructive Testing, volume 10, issue 1, 1990, Pages 38~46
It is difficult to detect such flaws as stress - corrosion cracking or corrosion wastage(loss of bolt diameter) in the threads. In many cases the critical size of a flaw is very small(1-2 mm order). This paper describes how it is possible to discriminate small flaw indications in threads using the time difference or thread signals(TDTS) by a signal-conditioning technique.
A Study of Measurement of In-plane Displacement by CW Laser Speckle Photography and Image Processing
Kim, K.S. ; Na, G.D. ; Kim, T.H. ; Chung, N.K. ; Kim, C.W. ;
Journal of the Korean Society for Nondestructive Testing, volume 10, issue 1, 1990, Pages 47~55
This paper presents experimental results which explore the capability of a CW laser speckle photography for tile measurement of in-plane displacement at high temperature. The serious restrictions on the application of the method seem to be the ambient air turbulence and the change of surface texture caused by the oxidation, as they tend to decorrelate the double exposured speckle patterns. In order to assess only the effect of air turbulence, a ceramics-coated stainless steel plate is heated in air and Ar-laser specklegrams are made with combination of temperature and lateral translation displacement. The slight reduction in visibility of Young's fringes is observed at
. The analyses of Young's fringes are carried out by a image processing system using a TV-camera and computers, and the result agrees well with the micrometer reading. Futhermore, uncoated stainless steel and Hastelloy X plates are tested and the effect of oxidation is also evaluated. The experimental results demonstrate that a CW laser speckle photography is applicable at temperatures up to
Fatigue Behavior of Glassy Polymers by Ultrasonic NDE
Lee, O.S. ; Rho, E.H. ;
Journal of the Korean Society for Nondestructive Testing, volume 10, issue 1, 1990, Pages 56~64
It is well-known that the defects (existing in structures) and the material degradation(caused by the fatigue load) generally initiate the failure of structures. The NDE such as ultrasonic technique which can be used to detect the size and the orientation of defects has been utilized to estimate the life and stability of structures. However, only few experimental reports made by using the ultrasonic technique have been published for the case of fatigue estimation of materials and structures. The purpose of this study is, thus, to derive the relationship between ultrasonic attenuation and fatigue behavior of Polycarbonate and PMMA through ultrasonic characterization. It is also attempted to offer NDE experimental procedure which may be useful to predict fatigue life.
A Study on Comparison of Acoustic Emission, Ultrasonic Testing and Crack Gauge Method in 3-point Bending Testing
Han, E.K. ; Kim, K.S. ; Park, J.S. ;
Journal of the Korean Society for Nondestructive Testing, volume 10, issue 1, 1990, Pages 65~72
Comparison of acoustic emission, ultrasonic testing and crack gauge in 3-point bending testing have been studied. As the results, COD is indirectly assumed by strain gauge rate and grid pitch width when crack gauge grid is out. Acoustic emission is qualitatively able to measure crack growth by total count but ultrasonic testing has a difficulty in measuring it because of echo height fluctuation according to the change and pressure of UT. probe.
A Study on the Crack Depth Measurements of Concrete by Tone-burst Flaw Detect Method
Han, E.K. ; Park, I.G. ; Park, J.S. ; Lee, S.H. ;
Journal of the Korean Society for Nondestructive Testing, volume 10, issue 1, 1990, Pages 73~83
Recently, research on the non-destructive testing of concrete has been rapidly increasing in relation with the quality, reliability, durability, and uniformity of concrete used in architectural structures. In this paper, the most important problem is the attenuation phenomena on throughing the side of concrete by ultrasonic wave, and applied tone-burst to decrease the attenuation in minimum. As the result, the correlation between crack-depth and propagation-time, maximum-spectrum and out-amplitude, in-frequency and maximum-spectrum are found to be excellent. The coefficient of each are +0.975, +0.847, -0.718. The merit of tone-burst through this experiment is that the start of reception wave is very excellent.
AE Source Location by the Discrimination of Wave Propagation Paths in Cylindrical Vessels
Yoon, D.J. ; Kim, Y.H. ; Kwon, O.Y. ;
Journal of the Korean Society for Nondestructive Testing, volume 10, issue 1, 1990, Pages 84~90
By discriminating the wave propagation paths in cylindrical vessels, a technique for AE source location has been proposed. This method is based on the path difference between several propagating directions from a source to a sensor. One sensor can receive multiple waveforms sequentially including a direct arrival and several others propagated through the circumferential direction. An wave front normally propagates in all directions and as many waveforms can reach the sensor until the signal faded out by attenuation. Only the first four arrivals suffice the condition for calculating the source location. The proposed method was examined for an actual cylindrical vessel by the source location experiment using simulated AE sources. The test showed very promising results and the method can be utilized for a simple AE source location without multi-channel instruments.
Welding Residual Stress Measurement by Barkhausen Noise Method
Lee, S.S. ; Ahn, B.Y. ;
Journal of the Korean Society for Nondestructive Testing, volume 10, issue 1, 1990, Pages 91~95
Welding residual stress was measured by Barkhausen noise method. The calibration experiment was done for the quantitative analysis. The specimen for the calibration experiment must has the same thermo-mechanical history as the actual material to be tested. The Barkhausen noise were analysed by the pulse-height distribution. The results show that the distribution and magnitude of welding residual stress from Barkhausen noise method are in good agreement with those from blind hole method.