• Proceedings of the Korean Reliability Society Conference
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• 2001.06a
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• pp.235-238
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• 2001

It is well known that the reliability of materials of mechanical products is becoming more and more important not only for assurance of quality, but for international competition of products. In order to assure the reliability of materials or mechanical products nondestructive evaluation (NDE) techniques are playing more important roles. The existence of Internal defects in materials or mechanical parts is served as crack initiation site during the various loading condition. Historically, nondestructive evaluation (NDE) technique has been used almost exclusively for detecting microscopic discontinuities In materials or mechanical parts after they have been in service to expand the role of the NDE to include all aspects of materials production and application. Research efforts are being directed at developing and perfecting NDE techniques capable of monitoring (1) materials production processes (2) material integrity following transport, storage and fabrication and (3) the amount and rate of degradation during service. In addition, efforts are underway to develop technique capable of quantitative discontinuity sizing, permitting determination of response using fracture mechanics analysis, as well as techniques for quantitative materials characterization to replace the qualitative techniques used in the past. In this paper, the important role of NDE technology for reliability assurance of materials/mechanical parts is introduced.

• Journal of the Korean Society for Nondestructive Testing
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• v.24 no.5
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• pp.525-531
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• 2004

In this paper, the concept of infrared thermography(IRT), the principle of measurement of IRT and how to set up the IR camera for the nondestructive testing are described in detail. Also, its utilization and non-destructive testing(NDT) diagnosis are reviewed. By performing the periodic non-touched WDT through the estimation of thermal patterns related with the temperature for the surface targeted, IRT can be applied to the early prevention of the device failure. For the diagnosis utilization, thermal imaging patterns obtained from IRT for heated blocks with internal defects were estimated through the lion-destructive method and discussed the way of IRT estimation from the analysis of characteristics between material defects and thermal imaging patterns.

• Journal of the Korean Society for Nondestructive Testing
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• v.20 no.3
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• pp.221-230
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• 2000

The usefulness and limitations of the impact-resonance method, which is a nondestructive evaluation (NDE) method for concrete, are studied by both experimental and theoretical methods. For the experimental study, several concrete slab specimens with various inclusions embedded were fabricated, and tested by the impact-resonance method. Some of the inclusions have been detected and accurately located, but some have not. The reasons for the failure in the latter cases have been investigated theoretically by using finite element analyses, from which the primary factors determining the success of the method have also been identified. This study will serve to enhance the understanding of the underlying physics and to improve the usefulness of the impact-resonance method as applied to concrete NDE.

• Near Infrared Analysis
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• v.1 no.1
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• pp.31-35
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• 2000

Near-infrared reflectance spectroscopy(NIRS) was used to determine the humic acids in soil samples from the fields of different crops and land-use over Youngnam and Honam regions in Korea. An InfraAlyzer 500 scanning spectrophotometer was obtained near infrared relectance spectra of soil at 2-nm intervals from 1100 to 2500nm. Multiple linear regression(MLR) or partial least square regression (PLSR) was used to evaluate a NIRS method for the rapid and nondestructive determination of humic acid, fulvic acid and its total contents in soils. The raw spectral data(log 1/R) can be used for estimating humic acid, fulvic acid and its total contents in soil by MLR procedure between the content of a given constituent and the spectral response of several bands. In which the predicted results for fulvic acid is the best in the constituents. The new spectral data are converted from the raw spectra by PLSR method such as the first derivative of each spectrum can also be used to predict humic acid and fulvic acid of the soil samples. A low SEC, SEP and a high coefficient of correlation in the calibration and validation stages enable selection of the best manipulation. But a simple calibration and prediction method for determining humic acid and fulvic acid should be selected under similar accuracy and precision of prediction. NIRS technique may be an effective method for rapid and nondestructive determination for humic acid, fulvic acid and its total contents in soils.

• Journal of the Korean Society for Nondestructive Testing
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• v.31 no.5
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• pp.500-507
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• 2011

Acoustic emission(AE) signals during the polymerization shrinkage of composite resin subjected to the LED light exposure were detected through a wave guide method and a direct sensor attachment method. For PMMA, human tooth, stainless steel substrate, data of AE hits and amplitudes were compared. For the test using the wave guide, AE amplitudes decreased because of the attenuant wave. However, AE hits and 1st peak frequency distribution were not different according to the sensor attachments. Through the experiments, wave guide could be used for a nondestructive evaluation of the marginal disintegrative fracture of dental restoration.

• Journal of Biosystems Engineering
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• v.40 no.1
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• pp.67-77
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• 2015

Purpose: Fungal secondary metabolite (mycotoxin) contamination in foods can pose a serious threat to humans and animals. Spectroscopic techniques have proven to be potential alternative tools for early detection of mycotoxins. Thus, the aim of this review is to provide an overview of the current developments in nondestructive food safety testing techniques, particularly regarding fungal contamination testing in grains, focusing on the application of spectroscopic techniques to this problem. Methods: This review focuses on the use of spectroscopic techniques for the detection of fungi and mycotoxins in agricultural products as reported in the literature. It provides an overview of the characteristics of the main spectroscopic methods and reviews their applications in grain analysis. Results: It was found that spectroscopy has advantages over conventional methods used for fungal contamination detection, particularly when combined with chemometrics. These advantages include the rapidness and nondestructive nature of this approach. Conclusions: While spectroscopy offers many benefits for the detection of mycotoxins in agricultural products, a number of limitations exist, which must be overcome prior to widespread adoption of these techniques.

• Journal of Mechanical Science and Technology
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• v.17 no.3
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• pp.391-399
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• 2003

The thermo-acoustic emission (AE) technique has been applied for nondestructive characterization of composite laminates subjected to cryogenic cooling. Thermo-AE events during heating and cooling cycles showed a Kaiser effect. An analysis of the thermo-AE behavior obtained during the 1st heating period suggested a method for determining the stress-free temperature of the composite laminates. Three different thermo-AE types classified by a short-time Fourier transform of AE signals enabled to offer a nondestructive estimation of the cryogenic damages of the composites, in that the different thermo-AE types corresponded to secondary microfracturing in the matrix contacting between crack surfaces and some abrasive contact between broken fiber ends during thermal load cycles.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.1830-1835
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• 2005

It is important to estimate the distribution of intensity of a magnetic field for application of magnetic method to industrial nondestructive evaluation. Magnetic camera provides the distribution of a quantitative magnetic field with homogeneous lift-off and same spatial resolution. And it is possible to interpret the distribution of the magnetic field when the dipole model is introduced. This study introduces the numerical and experimental considering of the quantitative evaluation of several size and shapes of the cracks using the magnetic field images of the scan type magnetic camera.

• Proceedings of the KSME Conference
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• 2001.06a
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• pp.534-540
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• 2001

One approach to testing the suitability of an adhesive joint for a particular application is to build and test to destruct ion a representative sample of the joint. The nondestructive test will not measure strength directly but will measure a parameter which can be correlated to strength. It is therefore, essential that a suitable nondestructive test is chosen and that its results are correctly interpreted. In this paper, typical defects found in adhesive joints are described together with their significance. The limits and likely success of current physical nondestructive tests are described, and future trends outlined.

• Journal of the Korean Society for Nondestructive Testing
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• v.36 no.2
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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.