• Journal of Chest Surgery
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• v.18 no.1
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• pp.7-12
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• 1985

The frequency of intraventricular conduction disturbance [IVCD] following right ventriculotomy and right atriotomy approach for ventricular septal defect [VSD] closure was compared in various conditions. Of the 170 isolated VSD patients, 114 patients were repaired via right ventriculotomy and 56 patients were repaired via right atriotomy. The results were as follows; 1. The frequency of IVCD was 45.6% in right ventriculotomy, and 21.2% in right atriotomy group [P<0.01]. The frequency of IVCD following transverse ventriculotomy and vertical ventriculotomy was not significantly different. 2. The frequency of IVCD in subarterial VSD following right ventriculotomy and right atriotomy was not significantly different. But the frequency of IVCD in perimembranous VSD was 50.8% in right ventriculotomy and 27.5% in right atriotomy group [P<0.01]. 3. The frequency of IVCD was higher in groups with larger VSD and it was more significant in right ventriculotomy group. 4. The frequency of IVCD was higher in patch graft closure and it was more significant in right ventriculotomy group. 5. Overall frequency of IVCD was lower in right atriotomy than right ventriculotomy group.

• Proceedings of the Acoustical Society of Korea Conference
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• autumn
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• pp.219-222
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• 2001

Nondestructive nonlinear acoustic method in two dimensions is suggested as a useful tool for detecting defects in a composite layer-structured material. Spectrum level changes in fundamental and harmonic frequencies are observed in the presence of a layer type defect compared with in the absence of such a defect. It is proposed in this study that such spectrum changes we due to the mode conversion. The layer type defect makes different normal modes due to different boundary conditions in the thickness direction for the Lamb waves propagating in a layer-structured material. Specifically, the normal mode with the fundamental frequency in the case of the water-layer gap is converted to the normal mode with the second harmonic frequency in the case of the air-layer gap.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.7
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• pp.1295-1297
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• 2008

Large-sized flat-panel displays are widely used for PC monitors and TV displays. In this paper, frequency domain pre-filter algorithms are presented for detection of defects in large-sized Thin Film Transistor-Liquid Crystal Display(TFT-LCD) panel surfaces. Frequency analysis with 1-D, 2-D FFT methods for extract the periodic patterns of lattice structures in TFT-LCD is performed. To remove this patterns, frequency domain band-stop filters were used for eliminating specific frequency components. In order to acquire only defected images, 2-D inverse FFT methods to inverse transform of frequency domain images were used.

• The Journal of the Acoustical Society of Korea
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• v.14 no.2
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• pp.92-100
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• 1995

In this study, the bearing defects were modeled and the vibration of ball bearing faults was presented for the defective pattern. The vibration signal was measured for the single and multiple defected ball bearing at the various defect positions and rotation speed, and then the signal components using the HFRT(high frequency resonance technique) were analyzed by FFT. The experimental data analysis has shown that the frequencies generated in the single or multiple defected ball bearings appear with the characteristic defect frequency and harmonics of ball pass frequency peak. Signal processing by HFRT makes it possible not only to detect the presence of a defect but also to diagnose the defect part of the bearing.

• Proceedings of the KIEE Conference
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• 1991.11a
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• pp.112-114
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• 1991

This paper describes an application of neural network to diagnose defect of induction motor and investigates possibility to construct defect diagnosis system to be operated without special knowledge. For defect diagnosis, frequency spectrum of vibration is utilized. Learning method of applied neural network is back propagation.

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.5
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• pp.108-117
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• 2004

In this paper, a measuring NDT(nondestructive testing) system using RUS(Resonant Ultrasound Spectroscopy) was built for nondestructive evaluation of the flaw in a ceramic Ferrule. The principle of RUS is that the mechanical resonant frequency of the materials depends on density, and the coefficient of elasticity. The RUS system is the measuring which is to exite specimen and to inspect the difference of natural frequency pattern between acceptable specimen and specimen which has some defects. RUS system is configured of spectrum analyzer, power amplifier, PZT sensor and support frame. For defect evaluation by the RUS, we performed to measure natural frequency of Ferrule, both acceptable and cracked. In the case of Ferrule, the resonant frequency of cracked-Ferrule existed to higher frequency band than acceptable-Ferrule.

• International conference on construction engineering and project management
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• 2013.01a
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• pp.7-13
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• 2013

Recently, defect management have been considered as one of the major issues for more large-sized and complicated in domestic construction industry. However, the defect management have not been performed systematically because of special manpower, excessive amount of documents, 2D based inspection work, unclear traditional checklists, complicated work process and difficulty in communicating construction information. Therefore, the construction field manager could not performed the quality inspection and defect management work on time as well as the reliability of recorded quality and defect factors was decreased. The primary objective of this study is develop a Construction Defect Management Application CDMA) using a mobile (smartphone). The application can be sharing a huge information and communication technology based on RFID (Radio-Frequency Identification), BIM (Building Information Modeling) which enables field mangers to efficiently gather the information of defection in construction on-site.

• Journal of the Korean Society for Nondestructive Testing
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• v.27 no.3
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• pp.246-254
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• 2007

The scanning laser source (SLS) technique is a promising new laser ultrasonic tool for the detection of small surface-breaking defects. The SLS approach is based on monitoring the changes in laser-generated ultrasound as a laser source is scanned over a defect. Changes in amplitude and frequency content are observed for ultrasound generated by the laser over uniform and defective areas. The SLS technique uses a point or a short line-focused high-power laser beam which is swept across the test specimen surface and passes over surface-breaking or subsurface flaws. The ultrasonic signal that arrives at the Rayleigh wave speed is monitored as the SLS is scanned. It is found that the amplitude and frequency of the measured ultrasonic signal have specific variations when the laser source approaches, passes over and moves behind the defect. In this paper, the setup for SLS experiments with full B-scan capability is described and SLS signatures from small surface-breaking and subsurface flaws are discussed using a point or short line focused laser source.

• Journal of KIISE:Computing Practices and Letters
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• v.14 no.6
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• pp.604-608
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• 2008

The TFT-LCD image allows non-uniform illumination variation and that is one of main difficulties of finding defect region. The SQI (self quotient image) has the HPF (high pass filter) shape and is used to reduce low frequency-lightness component. In this paper, we proposed the TFT-LCD defect-enhancement algorithm using characteristics of the SQI, that is the SQI has low-frequency flattening effect and maintains local variation. The proposed method has superior flattening effect and defect-enhancement effect compared with previous the TFT-LCD image preprocessing.

• Proceedings of the KIEE Conference
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• 2001.04a
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• pp.102-104
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• 2001

This paper presents a numerical analysis of the eddy current testing for pipe with axi-symmetric defect according to frequency changes using the finite element method(FEM). The defects used in this analysis are inner and outer axi-symmetric type. In order to obtain the behaviors of the signals by changing the frequency, the defects with different depths are modeled and analyzed using FEM. It is important to choose proper frequency because of the effect of skin depth in eddy current testing. This paper describes signal characteristics of each defects as frequency is changed.