• Proceedings of the Korean Institute of Building Construction Conference
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• 2014.11a
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• pp.5-6
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• 2014

For estimating compressive strength of concrete, non-destructive test has conducted generally. It used experimental equation to calculate compressive strength from construction. This study investigated experiment to apply non-destructive test, based on fresh property, compressive strength and ultrasonic pulse velocity of high performance concrete. And it conducted to compare various proposed equation.

• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.6
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• pp.173-179
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• 2008

This paper aims to calculate age coefficient of ultrasonic pulse velocity by non-destructive test. When concrete compressive strength is measured by non-destructive test, rebound test hammer method is applied to estimate age coefficient depending on the course of time after concrete casting, but ultrasonic pulse velocity method is not applied in the process. Although it is necessary to consider age coefficient with change of ultrasonic pulse velocity of concrete depending on aging, there have been little attempts to apply that method. The experiments were conducted to calculate aging effects which will be applied to establish the formula of measuring concrete strength. As a result of experiments, it was found that ultrasonic pulse velocity showed radical changes depending on concrete hardening in comparison with initial standard values. So, it was concluded that age coefficient must be applied to calculate strength. In conclusion, age coefficient of ultrasonic pulse velocity of concrete was suggested on the basis of experimental results.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.20 no.44
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• pp.393-399
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• 1997

This study is concerned with reliability technology. In order to achieve the quality level of items for consumer's satisfaction, tests for the item's reliability are essential. This article deals with a method and real field application to plan reliability testing. Especially the environmental conditions and methods such as screening test for electronic components will be shown. As well, we will explore methods and field applications with respect to mechanic destructive tests and non destructive tests.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.10b
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• pp.737-742
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• 1998

Non-destructive field tests of the concrete has achieved increasing acceptance for the evaluation of existing concrete structures. But the application of this test has not still accomplished to guarantee perfectly the durability of the concrete bridges in Korea. As two major testing methods, this paper recommends the proper empirical relationship between the rebound number together with the ultrasonic pulse velocity and the core strength. Also, this paper recommend the relationships as the aging and as the element.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.4 no.2
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• pp.29-33
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• 2008

As the measures of nuclear power plant utilities and manufacturers to reduce the defects of tube expansion region during manufacturing steam generators, many types of NDEs(Non-Destructive Examinations) are conducted to inspect the expansion region. The expansion region of tube is subject to degrade because of stress concentration induced by tube expansion, sludge pile and high temperature. So the inspections for tube expansion region have been reinforced. Liquid penetrant test, helium leak test, Bobbin profile test and hydraulic test are performed to confirm the integrity of tube expanded by hydraulic expansion method. Liquid penetrant test and helium leak test are used to inspect seal weld region on tubesheet end part. Bobbin Profile test is used to inspect fully the expanded region of steam generator tube. Hydraulic test finally verifies the integrity of seal weld region on tubesheet end part.

• Electronics and Telecommunications Trends
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• v.33 no.3
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• pp.59-69
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• 2018

Terahertz (THz) imaging and spectroscopy have been developed as non-destructive testing methods for various industrial applications. However, they have not been widely adopted in real applications owing to a high system price and the large size of conventional THz time-domain spectroscopy systems, which are based on ultrashort optical pulse lasers. Recently, various types of compact THz emitters and detectors have become available. As a result, THz non-destructive test (NDT) systems have become viable solutions. Herein, we briefly review the recent advances in THz NDT techniques adopting continuous-wave THz systems, including our recent results of a THz-based waterproof test system and an electrical connection inspection system for car manufacturing.

• Proceedings of the KSME Conference
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• 2001.06a
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• pp.483-488
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• 2001

Until now, the tensile properties of materials can be obtained just in accordance with conventional tensile testing methods which are described in several standards such as ASTM (American Society for Testing and Materials) standard and BS (British Standard). For some cases including on-service facility materials, however, the standard testing methods cannot be applicable due to the destructive testing procedure and specimen size requirement. Therefore, simple, non-destructive and advanced indentation technique was proposed. This test measures indentation load-depth curve during indentation and analyzes the mechanical properties related to deformation and fracture. In this paper, the research trend of non-destructive evaluation of tensile properties using AIS (advanced indentation system) and its application fields are reviewed and discussed.

• Journal of Welding and Joining
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• v.17 no.6
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• pp.100-107
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• 1999

In this paper, we deal with the speckle noise reduction and parameter estimation of ultrasonic NDT(non-destructive test) signals obtained during weld inspection of piping. The overall approach consists of three major steps, namely, speckle noise analysis, proposition of wavelet domain AR(autoregressive) model and flaw detection by proposed model parameter. The data are first processed whereby signals obtained using vertical and angle beam transducer. Correlation properties of speckle noise are then analyzed using multiresolution analysis in wavelet domain. The parameter estimation curve obtained using the proposed model is classified a flaw in weld region where is contaminated by severe speckle noise and also clear flaw signal is obtained through CA-CFAR threshold estimator that is a nonlinear post-processing method for removing the noise from reconstructed ultrasonic signal.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.10a
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• pp.685-691
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• 2002

Air exclusion test which is the way to assess the quality of the concrete is a part destructive test for minor damaging and accurate measurement. it has been well known but the test process is complexed, so it has been well known in foreign country but it is not usable in our country. For this experiment, it analyze its special quality through the inspection for the factor which effect to the result or accuracy for the Air exclusion test, and it examine through the experiment for the Non destructive test and cylinder compressive test which is different from the air exclusion test. We suggest the suitable classified table for the domestic concrete condition through the comparative analysis against the overseas result that has been suggested before.

• Geomechanics and Engineering
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• v.25 no.4
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• pp.317-330
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• 2021

This paper reports the results of advanced data analysis involving artificial neural networks for the prediction of the unconfined compressive strength of granite using only two non-destructive test indexes. A data-independent site-independent unbiased database comprising 182 datasets from non-destructive tests reported in the literature was compiled and used to train and develop artificial neural networks for the prediction of the unconfined compressive strength of granite. The results show that the optimum artificial network developed in this research predicts the unconfined compressive strength of weak to very strong granites (20.3-198.15 MPa) with less than ±20% deviation from the experimental data for 70% of the specimen and significantly outperforms a number of available models available in the literature. The results also raise interesting questions with regards to the suitability of the Pearson correlation coefficient in assessing the prediction accuracy of models.