• KEPCO Journal on Electric Power and Energy
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• v.8 no.2
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• pp.93-96
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• 2022

The boiler tubes of thermal power plants are exposed to harsh environment of high temperature and high pressure, and the deterioration state of materials rapidly increases. In particular, parent material and welds of the materials used are subjected to a temperature change and various constraints, resulting in deformation and its growth, resulting in frequent leakage accidents caused by tube failure. The power plant checks the integrity of boiler tubes through non-destructive testing as it may act as huge costs loss and limitation of power supply during power station shutdown period due to boiler tube leakage. However, the current non-destructive testing is extremely limited in the field to detect micro cracks. In this study, the ability of metal magnetic memory technique to detect flaws of size that are difficult to inspect by the visual or general non-destructive methods was verified in the early stage of their occurrence.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.04a
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• pp.385-390
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• 1998

Non-destructive field tests of the concrete has achieved increasing acceptance for the evaluation of existing concrete structures. 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 to fit the old concrete bridges in Korea.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.04a
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• pp.799-804
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• 2000

The joint treatment of concrete is one of the technical problems in top down construction method. Joints created wit the top down construction result in serous weakness from the aspects of both structural and water-barrier function. Several case studies for the insepction of top down construction joints of column in SRC structure using radar and infrared thermography method. The advantages and limitations of these methods for non-destructive inspection in top own construction joints are investigated.

• Journal of Industrial Technology
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• v.23 no.A
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• pp.63-68
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• 2003

Non-destructive method by tomography for safety diagnosis of civil engineering and building structures is tried. There are traveltime tomography that uses traveltime and fullwave tomography that uses the initial shock and seismic amplitude. But these methods have difficulty and weak points in accuracy and selection of initial value. In this study, corrected inversion method which is able to solve the two difficulty and this method is applied to theoretical pier model to calculate tomography.

• 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.

• Magazine of the Korean Society of Agricultural Engineers
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• v.34 no.E
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• pp.60-69
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• 1992

The research significance of the paper is to identify the major properties of synthetic lightweight concrete that are affected by ASR expansion and to determine the extent and magnitude of the loss in these properties. Emphasis is also given to the use of non-destructive testing techniques ; Such as dynamic modulus of elasticity and ultrasonic pulse velocity, to examine whether these methods could be used to identify the initiation of expansion and the internal structural damage caused by ASR.

• Journal of the Korean Wood Science and Technology
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• v.46 no.1
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• pp.93-99
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• 2018

It is necessary to review the non-destructive indexes in order to estimate the bending strength performance of the domestic larch lumber. In this study, MOEs (modulus of elastic) the larch lumber (cross-section $89{\times}120mm$) were evaluated through non-destructive methods such as the ultra-sonic method, longitudinal vibration method, and non-destructive bending method. The non-destructive measurement method which best represented the static MOE was determined and applied as the MOR(modulus of rupture) estimation index. The MOE that was measured through the longitudinal vibration method showed the highest correlation with the static MOE. The MOR was highly related to the static MOE. Therefore, the non-destruction MOE measured through the longitudinal vibration method was used to estimate the MOR of the lumber.

• 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.

• Journal of Biosystems Engineering
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• v.40 no.2
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• pp.153-158
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• 2015

Purpose: The research presented in this paper applied the chemometric analysis to the near-infrared spectral data from line-scanned hyperspectral images of beef and fish meals in animal feeds. The chemometric statistical models were developed to distinguish beef meals from fish ones. Methods: The meal samples of 40 fish meals and 15 beef meals were line-scanned to obtain hyperspectral images. The spectral data were retrieved from each of 3600 pixels in the Region of Interest (ROI) of every sample image. The wavebands spanning 969 nm to 1551 nm (across 176 spectral bands) were selected for chemometric analysis. The partial least squares regression (PLSR) and the principal component analysis (PCA) methods of the chemometric analysis were applied to the model development. The purpose of the models was to correctly classify as many beef pixels as possible while misclassified fish pixels in an acceptable amount. Results: The results showed that the success classification rates were 97.9% for beef samples and 99.4% for fish samples by the PLSR model, and 85.1% for beef samples and 88.2% for fish samples by the PCA model. Conclusion: The chemometric analysis-based PLSR and PCA models for the hyperspectral image analysis could differentiate beef meals from fish ones in animal feeds.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.05a
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• pp.777-782
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• 2001

Occurrence of crack in the Half-loc of rubble mound breakwater under T.T.P (Tetrapod) can cause serious problems in structural safety. There, probing of such cracks in marine structures is an important process in evaluating the overall integrity of structures. Ultrasonic, SASW(Spectral-Analysis-of-Surface-Waves)and Impect-Echo methods were used for the inspection of pilot concrete and SFC (Steel Fiber Concrete) block in this study. The advantage and limitations of these methods for non-destructive inspection in concrete blocks are investigated. As a result, it has been verified that these methods proved to present effective solution for detecting the crack of the pilot concrete block.