• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.8
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• pp.466-469
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• 2016

In this study, in order to develop composition ceramics for Acoustic Emission (abbreviated as AE) sensor application, the PZT system ceramics was fabricated by conventional solid state reaction method. When x=0.48, the density, electromechanical coupling factor($k_p$), piezoelectric coefficient $d_{33}$ and piezoelectric voltage constant $g_{33}$ of the maximum values of $7.857g/cm^3$, 0.51, 190[pC/N], 52[$10^{-3}mV/N$] were obtained, respectively, suitable for AE sensor.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.4
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• pp.601-607
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• 2012

The magnetic abrasive polishing (MAP), for online monitoring with AE sensor attachment, was performed in this study. To predict the surface roughness after the magnetic abrasive polishing of NAK80, the signal data acquired from the AE sensor were analyzed. A dimensionless coefficient, which consisted of average of AErms and standard deviation of AE signal, was defined as a characteristic of the MAP and a prediction model was obtained using least square method. A neural network, which had multiple input parameters from AE signals and polishing conditions, was applied for predicting the surface roughness. As a result of this study, it was seen that there was very close correlation between the AE signal and the surface roughness in the MAP. And then on-line prediction of the surface roughness after the MAP of the NAK80 was possible by the developed prediction model.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.97-101
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• 2000

The AE measurement is one of the most convenient methods for detecting contacts between slider disk. The AE method has been widely used in the investigation of the tribology of sliding interfaces due to the convenience of using AE sensor. In this study, we examined the relationship between the AE signal and the flying height of a slider. We tried to know the influence of the disk velocity on the AE rms signal by using the AE measurement system. The experiment also gives the relationship between the take-off velocity and the disk surface state. To investigate the behavior of the slider further, the variances of the AE signal are analyzed. The results about a subambient pressure slider indicate that the increase in the magnitude of AE rms signal does not necessarily mean the slider/disk contacts.

• Journal of the Korean Society for Nondestructive Testing
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• v.16 no.3
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• pp.155-161
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• 1996

For the condition monitoring of the journal bearing in rotating machinery, a system for their diagnosis by acoustic emission(AE) was developed. AE has been used to detect abnormal conditions in the bearing system. It was found from the field application study as well as the laboratory experiment using a simulated journal bearing system that AE RMS voltage was the most efficient parameter for the purpose of current study. Based on the above results, algorithms and judgement criteria for the diagnosis system was established. The system is composed of four parts as follows: the sensing part including AE sensor and preamplifier, the signal processing part for RMS-to-DC conversion to measure AE ms voltage, the interface part for transferring RMS voltage data into PC using A/D converter, and the software part including the graphic display of bearing conditions and the diagnosis program.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1994.10a
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• pp.371-376
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• 1994

This paper presents an on-line modeling method approach for the machine condition. the machine condition is continuously monitored with a sensor such as, a vibration, a current, an acoustic emission (AE) sensor. In this study, neural network modeling by radial basis function is designed for analysis a prediction error. An on-line learning algorithm is designed using the RLS(recursive least square) estimation and the existing clustering method of Kohonen neural network. Experimental results show that the proposed RBNN modeling is suitable for predicting simulated data.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.8
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• pp.780-788
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• 2009

AE technique was applied to the static structural test of the composite wing structure to evaluate the structural integrity and damage. During the test, strain and displacements measurement technique were used to figure out for static structural strength. AE parameter analysis and source location technique were used to evaluate the internal damage and find out damage source location. Design limit load test, the 1st and 2nd design ultimate load tests and fracture test were performed. Main AE source was detected by an sensor attached on skin near by front lug. Especially, at the 1st design ultimate test, strain and displacements results didn't show internal damage but AE signal presented a phenomenon that the internal damage was formed. At the fracture test, AE activities were very lively, and strain and displacements results showed a tendency that the load path was changed by severe damage. The internal damage initiation load and location were accurately evaluated during the static structural test using AE technique. It is certified from this paper that AE technique is useful technique for evaluation of internal damage at static structural strength test.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.4 no.2
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• pp.31-37
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• 1995

This study is focused on the prediction of appropriate tool life by clarifying the correlation between progressive tool wear and AE signal. when rcutting SM45C by End mill in machining center. First of all, end mill have a problem that position of sensor sticking because it is revolution tool, but I think that it can be bained specific character according to sticking Sensor in the Vise. Consequently, the following results have been obtained; 1. Each cutting speed of feed rate over 0.1mm had a tendency to increase linearly according to the RMSAE 2. The level of AE signal at the same cutting area was more sensitive to depth of cut tharn the variation of feed rate 3. In the range of cutting duringqr about 75minqr atqr cutting speed 27m/min flankqr wear turns up aboutqr 0.21mm, aboutqr 0.29mm in the caseqr of about 65minqr at 33/min, qr hereby RMSAE increased rapidly at 0.2mm flank wear, also AE-HIT and CUM-CNTS.

• Proceedings of the KIEE Conference
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• 1999.07e
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• pp.2335-2337
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• 1999

In this paper, using AE (Acoustic Emission) sensor the electrical and emitted-sound signals are measured by treeing breakdown in the epoxy resin, and the corresponding frequency spectrum of the AE signals are analyzed. We also examined the relationship between partial discharge magnitude and pulse number of AE signals to diagnose the deterioration of the electrical insulation due to treeing breakdown. From these results, a frequency band of AE signals through treeing breakdown was set to about 230 [kHz], and it appeared that pulse number of AE signal was proportional to partial discharge magnitude.

• Journal of the Korea Concrete Institute
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• v.13 no.2
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• pp.107-113
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• 2001

This study was conducted preliminarily to develop the crack source location technique for plain concrete beam using acoustic emission(AE). Before the main experiment, the test of virtual An source location was achieved in plain concrete block. The sensor layout was mutually compared between triangular layout and rectangular layout. As the results of test, AE source location by triangular layout was evaluated more effective than that by rectangular layout. The specimen to apply he source location technique was man in total nine specimens (each three in 40 %, 50%, 60% of W/C ratio) which the experiment variable was the compressive strength level(W/C ratio). The bending loading method is selected by cyclic loadings to evaluate the degree of concrete damage. It is seen that Kaiser effect and Felicity effect exists through analysis of AE parameters in coming failure experiment. As a result of analyzing the felicity ratio(FR) values, it is shown that this values can be used for evaluating the degree of concerto damage. AE activity is started highly at the 70% of failure load without the compressive strength level. Thus considered by a index in constructing the system of the failure warning at application of the field structure. And the results compared the real cracking location with the source location has perceived by AE monitoring before it is appeared the primary crack by visual observation.

• Proceedings of the KIEE Conference
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• 1999.07e
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• pp.2338-2340
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• 1999

In this paper measurements of AE (Acoustic Emission) signals caused by corona discharge were performed to analyze the electrical deterioration in oil. We also examined the relationship between discharge magnitude and peak-to-peak value of AE signals to diagnose the deterioration of liquid dielectrics. From these results, Vpp(peak to peak value) of AE signals was proportional to corona discharge magnitude. The main frequency band of AE signals in oil appeared to 130[kHz].