• Journal of the Korean Society for Nondestructive Testing
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• v.21 no.4
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• pp.425-433
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• 2001

A correlation between fatigue damage and acousto-ultrasonic (AU) parameters has been obtained from signals acquired during fatigue loading of the single-lap joints of a carbon-fiber reinforced plastic (CFRP) laminates and A16061 plate. The correlation showed an analogy to those representing the stiffness reduction $(E/E_0)$ of polymer matrix composites by the accumulation of fatigue damage. This has been attributed to the transmission characteristics of acoustic wave energy through bonded joints with delamination-type defects and their influence on the change of spectral content of AU signals. Another correlation between fatigue cycles and the spectral magnitude of acoustic emission (AE) signals has also been found during the final stage of fatigue loading. Both AU and AE can be applied almost in real-time to monitor the evolution of damage during fatigue loading.

• Journal of the Korean Society for Precision Engineering
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• v.12 no.3
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• pp.92-100
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• 1995

This experimental study is mainly investigated on the mean cutting forces and AE(acoustic emission) parameters in order to detect and estimate the tool failure in the pachinig of SUS304 by face milling Mean cutting forces and AE parameters can detect the tool failure in face milling. Effective detection parameters are AE RMS, AE energy, AE count, AE duration, and z-direction mean cutting force. From the analysis of cutting tool failure detection, the tool failure of face milling is caused by sudden increasing of the cutting force.

• Structural Monitoring and Maintenance
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• v.1 no.1
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• pp.111-130
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• 2014

The increased use of carbon fiber reinforced polymer (CFRP) in retrofitting reinforced concrete (RC) members has led to the need to develop non-destructive techniques that can monitor and characterize the unique damage mechanisms exhibited by such structural systems. This paper presented the damage characterization results of six CFRP retrofitted RC beam specimens tested in the laboratory and monitored using acoustic emission (AE). The focus of this study was to continuously monitor the change in AE parameters and analyze them both qualitatively and quantitatively, when brittle failure modes such as debonding occur in these beams. Although deterioration of structural integrity was traceable and can be quantified by monitoring the AE data, individual failure mode characteristics could not be identified due to the complexity of the system failure modes. In all, AE was an effective non-destructive monitoring tool that can trace the failure progression in RC beams retrofitted with CFRP. It would be advantageous to isolate signals originating from the CFRP and concrete, leading to a more clear understanding of the progression of the brittle damage mechanism involved in such a structural system. For practical applications, future studies should focus on spectral analysis of AE data from broadband sensors and automated pattern recognition tools to classify and better correlate AE parameters to failure modes observed.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.4
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• pp.240-246
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• 2000

An in-process estimation of the ground surface roughness is a bottle-neck and an essential field in conventional grinding operation. We defined the dimensionless average roughness factor (D.A.R.F) that exhibits a roughness characteristics of ground surface. The D.A.R.F was composed easily of the absolute average and the standard deviation values which were the analytic parameters of the acoustic emission (AE) signal generated during the machining process. The theoretical equation between the surface roughness and the D.A.R.F has been derived from the linear regressive analysis and verified its availability through the experimentation on the surface grinding machine.

• Journal of Ocean Engineering and Technology
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• v.17 no.1
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• pp.47-54
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• 2003

In this study, the residual stress and the acoustic emission Charactreistics from fatigue crack propagation were investigated, bused on the welded material of STS316L. The residual stress of welding locations could be evaluated by ultrasonic parameters, such as L$_{CR}$ wave velocity and L$_{CR}$ wave frequency； the residual stress between base metal and weld metal was evaluated. In the fatigue tests, three types of signals were observed, regardless of specimen condition, base metal, and weld metal. Based on NDE analysis of AE signals by the time-frequency analysis method, it should also be possible to evaluate, in real-time, the crack propagation and final fracture process, resulting from various damages and defects in welded structural members.

• Proceedings of the KIEE Conference
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• 1992.07b
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• pp.973-975
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• 1992

The Acoustic Emission due to treeing progress in Crosslinked Polyethylene(XLPE) is studied by using the self developed automatic measuring system of acoustic emission. Tree progression and average pulse amplitude are almost in proportion to the rising of applied voltage but there is no proportionality relation between tree progression and pulse numbers. From now on, Skewness and kurtosis of average cycle, special property of $\phi$-a distribution characteristics can be confirmed as the useful parameters of treeing deterioration.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.13 no.4
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• pp.95-99
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• 2004

In this study, the leak detection technique of pressure vessel by using acoustic emission(AE) signal is suggested experimentally. The leak of pressure vessel is located at the welding line due to welding defects. we measured the AE signal using Rl5I sensor, and examined the AE parameters in leak condition. It is investigated that the mean value of AE signal is dependent on leak source location. So the absolute mean value of AE signal is adopted as dominant AE parameter. We proposed leak detection algorithm using AE signal mean value for monitoring the leak source location.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2003.10a
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• pp.289-294
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• 2003

The object of this study is to investigate the effect of compounded welding by using acoustic emission (AE) signals fur weld heat affected zone (HAZ) in tensile testing. This study was carried out a SM 490A high tension steel for electronic shielded metal are welding (SMAW), $\textrm{CO}_2$ gas arc welding and TIG welding. And correspondingly, the root openings are 3, 4 and 2.8mm. Data displays are based on the measured parameters of the AE signals, along with environmental variables such as time and load. These history plots give us useful and powerful information to analyze the results of material evaluation testing.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2003.04a
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• pp.363-370
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• 2003

The object of this study is to investigate the effect of compounded welding by using an acoustic emission (AE) signals and doing a source location for weld heat affected zone (HAZ) through tensile testing. This study was carried out a SM 490A high tension steel for electronic shielded metal arc welding (SMAW), $CO_2$ gas arc welding and TIG welding. Data displays are based on the measured parameters of the AE signals, along with environmental variables such as time and load. These history plots are displays showing the chronological course of the test. Also, source location gives the X- and Y-coordinates of the AE source.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.11 no.3
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• pp.39-44
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• 2002

As laser cutting process is widely used in industry, an automated on-line process control system has become very important. In this paper, development of a laser cutting monitoring system, which is regarded as the fundamental step toward automation of the process, is presented. Acoustic emission and an artificial neural network were used for the monitoring system. With given process Parameters including laser power and scanning speed the system can predict the suitability of laser beam for the cutting or a stainless steel (STS304) plate.