• 비파괴검사학회지
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• 제28권3호
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• pp.263-272
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• 2008

Many technical methods are used for nondestructive testing field for solid materials. Among those, ultrasonic inspection methods are widely used and one of the popular methods involves the extraction of an appropriate set of features followed by the use of a neural network for the classification of the signals in the feature space. This paper describes an approach which uses LMS method to determine the coordinates of the ultrasonic probe followed by the use of SAFT with centroid technique to estimate the location of the ultrasonic reflector. The method is employed for classifying UT-NDE signals from the steam generator tubes in a nuclear power plant. The classification results are presented for the ultrasonic signals from cracks and deposits within steam generator tubes.

• 비파괴검사학회지
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• 제9권2호
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• pp.67-72
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• 1989

In nuclear power plants, nondestructive examinations(NDE) plays an important role in ensuring the integrity and reliability operation. As the number of plants and operational time increased, manual handling of voluminous data associated with PSI/ISI(preservice/inservice inspection) could result in many errors or mistakes in writing the examination plan or other reports. Several new approaches to process the data have been attempted and DBMS(Data Base Management System) has been well known concept with a faster and more accurate data processing. This paper proposes an application program, called NDTSYS designed with DBMS in micro computer. The program could be used for a tool to add new records to a data base, change existing records, delete records and request reports with the data base. It would be helpful to the user who manage the PSI/ISI data with minimal time and effort.

• 비파괴검사학회지
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• 제36권2호
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• pp.155-159
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• 2016

Eddy current testing (ECT) is an important nondestructive testing technology for the inspection of flaws in conductive materials. However, this widely used technology is not suitable for inspecting lamination when a conventional pancake coil is used because the eddy current (EC) generated by the pancake coil is parallel to the lamination and will not be perturbed. A new method using a rectangular coil placed vertical to the work piece is proposed for lamination detection. The vertical sections of the rectangular coil induce ECs that are vertical to the lamination and can be perturbed by the lamination. A parametric study of a rectangular coil by finite element analysis was performed in order to examine the capability of generating vertical EC.

• 비파괴검사학회지
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• 제22권6호
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• pp.599-608
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• 2002

The mechanical properties of mullite $(3Al_2O_3\;2SiO_2)$ environmental barrier coatings are determined using a laser-based ultrasonic system. The waveforms generated by a laser source in mullite coatings in the $1-20{\mu}m$ thickness range are evaluated theoretically using the integral transform technique. It is shown that the laser source generated the two lowest order SAW modes in these systems. Experimental waveforms are generated using a 600ps pulsed Nd:YAG microchip laser and detected using a stabilized Michelson interferometer. The dispersion curves for the generated modes are extracted from the experimental data and the mechanical properties of the coatings are obtained by minimizing the error between the measured and calculated velocity values. The waveforms generated in mullite coatings agree well with theory and laser-based ultrasonics is shown to provide an effective tool for the nondestructive evaluation of ceramic coatings.

• ETRI Journal
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• 제44권5호
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• pp.816-825
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• 2022

Nondestructive testing, which can monitor a product's interior without disassembly, is becoming increasingly essential for industrial inspection. Computed laminography (CL) is widely used in this application, as it can reconstruct a product, such as a printed circuit board, into a three-dimensional (3D) high-magnification image using X-rays. However, such high-magnification scanning environments can be affected by minute vibrations of the CL device, which can generate motion artifacts in the 3D reconstructed image. Since such vibrations are irregular, geometric corrections must be performed at every scan. In this paper, we propose a geometry calibration method that can correct the geometric information of CL scans based on the image without using geometry calibration phantoms. The proposed method compares the projection and digitally reconstructed radiography images to measure the geometric error. To validate the proposed method, we used both numerical phantom images at various magnifications and images obtained from real industrial CL equipment. The experiment results confirmed that sharpness and contrast-to-noise ratio (CNR) were improved.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2003년도 춘계학술대회 논문집
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• pp.73-78
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• 2003

Ultrasonic measurement is one of important technologies in the lift-time maintenance of nuclear poler plant. Ultrasonic inspection system is consisted of the operator, equipment and procedure. The reliability of ultrasonic inspection system is affected by its ability. The performance demonstration round robin was conducted to quantify the capability of ultrasonic inspection for in-service. The small number of teams who employed procedures that met or exceeded ASME Sec. XI Code requirements detected the piping of nuclear power plant with various cracks to evaluate the capability of detection and sizing. In this paper, the statistical reliability assessment of ultrasonic nondestructive inspection data using Monte Carlo simulation is presented. The results of the probability of detection (POD) analysis using Monte Carlo simulation are compared to these of logistic probability model. In these results, Monte Carlo simulation was found to be very useful to the reliability assessment f3r the small hit/miss data sets.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2006년도 정기 학술대회 논문집
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• pp.232-239
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• 2006

Guided wave techniques have been used for pipeline inspection because of the long range inspection capability of guided waves. One of main concerns of these technique is how ones decide the axial interval of sensors when they are utilized for pipeline inspection. This question is related to the characteristic of cylindrical guided wave propagation, especially wave attenuation. Thus, attenuation of fundamental longitudinal guided wave propagating liquid-filled steel pipes is numerically investigated in the paper. Several liquids such as water, diesel oil, castor oil etc. are considered for the filing materials in the pipes. Sink is considered for numerical models for abandoning standing wave modes; hence, the attenuation dispersion curves become much simpler. Those attenuation calculations can be utilized for guided-wave-based nondestructive testing of pipelines when one inspects pipelines, using monitoring sensors, which are installed outside pipes.

• 한국생산제조학회지
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• 제9권6호
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• pp.9-18
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• 2000

This study includes noise automatic inspection system for washing machine auto-transmission one of modern home necessary. We effort to find and certificate sound noise source by sound power and sound intensity, and apply to frequency analysis in vibration related sound noise. still more we have been studying to data acquisition and programming for MS VisualBasic version 5.0. System component is below. 1) Pentium PC or data acquisition. 2) DSO for noise acquisition. 3)S/W for comparison and decision. 4) I/F Board for data communication. Wave form data through the DSO are converting to ASCII code data. The ASCII code through binary converting S/W. Finally we will making noise monitoring system and automatic inspection system.

• 한국공작기계학회논문집
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• 제16권6호
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• pp.37-42
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• 2007

The purpose of this research is stability estimation of plant structure through classification and recognition about welding flaw in SWP(Spiral Welding Pipe). And, In this research, we used nondestructive test based on ultrasonic test as inspection method, and made up 2-axes inspection robot in order to control of ultrasonic probe on the SWP surface, and programmed to image processing and probabilistic neural network(PNN) classifying code by MATLAB programming. Through this process, we proved efficiency on the system of SWP stability Estimation.

• 한국정밀공학회지
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• 제20권3호
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• pp.82-88
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• 2003

The nondestructive internal quality evaluation of agricultural products has been strongly required from the needs for individual inspection. Recently, the ultrasonic wave has been considered as a solution fur this problem, and an ultrasonic system was constructed for the ultrasonic NDE of fruits and vegetables in our previous work. In this paper, the practical applicability of our ultrasonic system is tested fur the inspection of internal defects (central cavity) in Atlantic potato. Sound speed and RMS of transmitted ultrasonic wave signal were measured and classification algorithm using 2 dimensional stochastic analysis. was presented. Experimental results showed greater value of sound speed and RMS (root mean square) of transmitted signal in normal samples than in abnormal samples with cavity. Also a stochastic method to distinguish normal and abnormal showed fault detection rate less than 5%.