• Proceedings of the KIEE Conference
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• 1996.07c
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• pp.1935-1937
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• 1996

This paper deals with ACSR(Aluminum Conductor Steel Reinforced) inner corrosion detection using a detector which automatically runs on an ACSR transmission line and inspects the inner corrosion of the conductor by utilization of the nondestructive eddy current test. And the relationship between the corrosion grades and the tensile strength can be estimated by means of this test. According to corrosion appearance and development of ACSR, the impedance change of the eddy current coils is theoretically verified. And then specifications And performances of the detector are described. Experimental procedures and desirable test results are reported. In conclusion, this detector can realize the nondestructive detecting of an ACSR inner corrosion. Upgrading the maintenance effciency and improving the reliability of transmission line would be expected by this nondestructive test method.

• Journal of the Korean Society for Nondestructive Testing
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• v.5 no.1
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• pp.9-23
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• 1985

Boshin-Kak Bell, which is one of the largest bells, is located at Chong-Ro Square in the center of Seoul. The bell has been struct early morning and late evening for time-report since the 14th century in Lee Era. Therefore Boshin-Kak Bell has been an intimate old friend of Seoul citizen more than 500 years. Unfortunately, motal large cracks were found inside this bell in the horizontal and vertical directions in 1979. The present paper has investigated the propagated bell-crack by ultrasonic flaw detecting method, and the stress level, bell vibration and weight measurement by electric wire resistance strain gauge method. The results indicate that they are useful for further study of Korean bell by nondestructive test.

• 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.

• Journal of the Korean Wood Science and Technology
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• v.32 no.3
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• pp.8-14
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• 2004

Nondestructive evaluation (NDE) technique method using a resonance frequency mode was carried out for woodceramics produced at different carbonizing temperatures (600℃, 800℃, 1000℃, 1200℃, 1500℃) at the phenol resin impregnation rate of 70%, for three kinds of species (Pinus densifora, Pinus koraiensis, Larix leptolepis), respectively. There was a poor relationship between density and static bending MOR. However, close correlations were found between dynamic MOE_d and static bending MOR, and between static MOEs and MOR. Especially, the correlation coefficient was highest between MOE_d and static bending MOR. Therefore, the MOE_d using the resonance frequency mode is useful as a NDE method for predicting the MOR of woodceramics produced at different carbonizing temperatures.

• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.3
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• pp.199-207
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• 2008

As infrastructures are being deteriorated, nondestructive evaluation of existing structures and construction quality control are increasingly demanded. The importance of predicting compressive strength of concrete structure is also gradually increasing in construction industry. The estimation of concrete compressive strength is a critical factor of the construction management and quality control. This study has been conducted using Schmidt hammer test and Impact echo method, which are nondestructive test methods for the comparison of the concrete compressive strength. It is focusing to examine the relationship between compressive strength of concrete and rebound number by Schmidt hammer test result by Impact echo method. It was found that concrete compressive strength and rebound number have a close correlation.

• Earthquakes and Structures
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• v.3 no.3_4
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• pp.519-532
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• 2012

Using nondestructive testing techniques to evaluate the length or depth of an existing foundation is an important issue with potential high application values. One of these is to evaluate whether the foundation is broken after severe earthquakes. In this aspect, academic research related to nondestructive evaluation for caisson foundations is rarely reported. The objective of this paper is to study the feasibility of using Sonic Echo method to evaluate the depth of caisson foundations. Two types of caissons, simple cylindrical caisson and compound caisson with chambers, were studied for their responses to the Sonic Echo tests. The study was carried out in numerical simulation with finite element method and experimental way with in-situ tests. A bridge system which spans over Sofong Brook in Taiwan was selected for the tests in situ. The bridge system is still under construction and therefore the effect of different construction stages on the testing results may be studied. In this paper, the parameters to be varied for the studies include the testing locations and the existence of chamber plates, the bottom plate and the top plate. Finally some preliminary conclusions can be reached for a successful test.

• Journal of the Korean Society for Nondestructive Testing
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• v.12 no.4
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• pp.18-25
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• 1993

This paper is to aim the microdefect evaluation of If package into a quantitative from NDI's image processing of ultrasonic wave. (1) Automatically repeated discrimination analysis method can be devided in the category of all kind of defects on IC package, and also can be possible to have a sampling of partial delamination. (2) It is possible that the information of edge section in silicon chip surrounding can be extractor by the partial image processing of IC package. Also, the crack detection is possible between the resin part and lead frame.

• Journal of the Korean Society for Nondestructive Testing
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• v.11 no.2
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• pp.7-14
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• 1991

The integral model for the eddy current phenomena has been suggested. The model could lift the limitations of the previously well-known analytical model of eddy current theory. The model could be applied to two-dimentional, arbitary shaped defects. The computer programs have been developed in order to calculate the eddy current signal with the suggested integral method. The eddy current signals by the model calculations have been shown similar patterns to the actual experimental data from the real defects in the calibration standard tubes.

• Journal of the Korean Society for Nondestructive Testing
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• v.24 no.2
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• pp.125-135
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• 2004

This paper describes the calculation technique for guided wave propagation with a semi-analytical finite element method (SAFEM) and shows some results of numerical calculation and guided wave simulation for plates, pipes and railway rails. The SAFEM calculation gives dispersion curves and wave structures for bar-like structures. Dispersion curve software for a pipe is introduced, and also dispersion corves for a rail are given and experimentally verified. The mode conversions in a plate with a defect and in a pipe with an elbow or a defect are shown as examples of our guided wave simulations.

• Journal of information and communication convergence engineering
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• v.5 no.4
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• pp.324-327
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• 2007

In this paper, the p-n junction depth with nondestructive method by using scanning electron microscopy (SEM) is determined and conformed. By measuring the critical short circuit current on the p-n junction which induced by electron beam and calculating generation range, the diffusion depth can be obtained. It can be seen that values destructively measured by constant angle lapping and nondestructively by this study almost concur. As this result, it is purposed that diffusion depth of p-n junction can be easily measured by nondestruction. This nondestructive method can be recommended highly to the industrial analysis.