• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.4
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• pp.159-165
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• 2008

In this paper the signal analysis of eddy current test using transmit-receive(T/R) pancake coil of ECT array probe using electromagnetic finite element method(FEM) is performed. For characteristics analysis, the notch defect is used. The depth of defect is 40[%] of steam generator tube thickness, and inside defect and outside defect are used as simulation examples. The signal analysis is performed according to the variation of receive coil position. The receive coil is positioned $0[^{\circ}]$, $30[^{\circ}]$, $60[^{\circ}]$, $90[^{\circ}]$ of circumferential position of transmit coil. To obtain e electromagnetic characteristics of robes, the governing equation is derived from Maxwell's equations, and the problem is solved using the 3-dimensional finite element method. The signal magnitude of inside defect is bigger than that of outside defect, and the signal difference can be seen according to the variation of position of receive coil. The experimental signal and numerical signal of ASME standard tube show similar results. The results in this paper can be helpful when the ECT signals from ECT array probe are evaluated and analyzed.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.44 no.4
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• pp.128-135
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• 2021

WDM(Wavelength Division Multiplexing) is called a wavelength division multiplexing optical transmission method and is a next-generation optical transmission technology. Case company F has recently developed and sold PLC(Planar Lightwave Circuit), a key element necessary for WDM system production. Although Chinese processing companies are being used as a global outsourcing strategy to increase price competitiveness by lowering manufacturing unit prices, the average defect rate of products manufactured by Chinese processing companies is more than 50%, causing many problems. However, Chinese processing companies are trying to avoid responsibility, saying that the cause of the defect is the defective PLC Wafer provided by Company F. Therefore, in this study, the responsibility of the PLC defect is clearly identified through estimating the defect rate of PLC using the sampling inspection method, and the improvement plan for each cause of the PLC defect for PLC yeild improvement is proposed. The result of this research will greatly contribute to eliminating the controversy over providing the cause of defects between global outsourcing companies and the head office. In addition, it is expected to form a partnership with Company F and a Chinese processing company, which will serve as a cornerstone for successful global outsourcing. In the future, it is necessary to increase the reliability of the PLC yield calculation by extracting more precisely the number of defects.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.4
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• pp.521-527
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• 2013

This study provides the elastic stress intensity factors, K, for circumferential and longitudinal surface cracked straight pipes under single or combined loads of internal pressure, bending, and torsion based on three-dimensional (3D) finite element (FE) analyses. FE results are compared with two different types of defect assessment codes (API-579-1 and RCC-MR A16) to prove the accuracy of the FE results and the differences between the codes. Through the 3D FE analysis, it is found that the stress intensity factors are sensitive to the number of elements, which they were believed to not be sensitive to because of path independence. Differences were also found between the FE analysis results for crack defining methods and the results obtained by two different types of defect assessment codes.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.17 no.1
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• pp.39-47
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• 2004

In this paper, the defects of two-dimensional anisotropic elastic bodies are identified by using the boundary element method. The use of numerical models that contain only boundary integral terns reduces the dimensionality of the problem by one. This advantage is particularly important in problems such as crack mechanics. Avoiding domain meshing is also particularly advantageous in the solution of inverse problems since it overcomes mesh perturbations and simplifies the procedure. In this paper, nondestructive approaches for the existing isotropic materials are extended to analyze the elastic bodies made of anisotropic materials such as composites. After verifying that the proposing boundary element model is in good agreement with numerical results reported by other investigators, the effect of noise in the measurements on the identifiability is studied with respect to different design parameters of layered composites. Sample studies are carried out for various layup configurations and loading conditions. The effects of the layup sequences in detecting flaw of composites is explored in this paper.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2000.10a
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• pp.153-157
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• 2000

This paper presents possible defects when welded blank hydroforming and focus on wrinkling, and the die design to prevent this defect An explicit finite element code, PAM-STAMP, is used to simulate welded blank hydroforming process. The numerical results are compared to the experimental results in the aspect of deformed shape. An automobile subframe is taken as an example to carry out finite element analysis.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1992.04a
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• pp.65-70
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• 1992

This study deals with the finite element analysis of the monotonic behavior of reinforced concrete beams and beam-column joint subassemblages. It is assumed that the behavior of these members can be discribed by a plane stress field. Concrete and reinforcing steel are represented by separate material models which are combined together with a model of the interaction between reinforcing bar and concrete through bond-slip to discribe the behavior of the composite reinforced concrete material. To discribe the concrete behavior, a nonlinear orthotropic model is adopted and the crack is discribed by a system of orthogonal cracks, which are rotating as the principal strain directions are changed. A smeared finite element model based on the fracture mechanics principles are used to overcome the numerical defect according to the finite element mesh size. Finally, correlation studies between analytical and experimental results and several parameter studies are conducted with the objective to estabilish the validity of the proposed model and identify the significance of various effects on the local and global response of reinforced concrete members.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.32 no.12
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• pp.1063-1071
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• 2008

This paper provides a failure pressure evaluation model for local wall-thinned elbows. In this study, parametric finite element analyses are performed on the elbows containing local wall-thinning defect at their intrados and extrados, and the failure pressures are obtained from the analysis results by applying a local failure criterion that was validated by real-scale pipe tests. An evaluation model including the effects of thinning depth, length, circumferential angle, thinning location, and elbow geometries on the failure pressure is derived based on the evaluated failure pressures. The proposed model agrees well with the results of finite element analyses and reasonably estimates the dependence of failure pressure on the wall-thinning dimensions and elbow geometries. Also, the comparison with experimental data demonstrates that the proposed evaluation model can accurately predict the failure pressure of local wall-thinned elbows.

• Journal of Advanced Marine Engineering and Technology
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• v.24 no.4
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• pp.405-413
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• 2000

This paper present study on the application of sound pressure and vibration signals to detect the presence of defects in a rolling element bearing using a statistical analysis method. The well established statistical parameters such as the crest factor and the distribution of moments including kurtosis and skew are utilized in this study. In addition, other statistical parameters derived from the beta distribution function are also used. A comparison study on the performance of the different types of parameter used is also performed. The statistical analysis is used because of its simplicity and quick computation. Under ideal conditions, the statistical method can be used to identify the different types of defect present in the bearing. In addition, the results also reveal that there is no significant advantages in using the beta function parameters when compared to using kurtosis and the crest factor for detecting and identifying defects in rolling element bearings from both sound and vibration signals.

• Advances in materials Research
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• v.12 no.4
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• pp.273-286
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• 2023

The fracture mechanics make it possible to characterize the behavior with cracking of structures using parameters quantifiable in the sense of the engineer, in particular the stress field, the size of the crack, and the resistance to cracking of the material. Any structure contains defects, whether they were introduced during the production of the part (machining or molding defects for example). The aim of this work is to determine numerically by the finite element method the stress concentration factor Kt of a plate subjected to a tensile loading containing a lateral form defect with different sizes: a semicircle of different radii, a notch with different opening angles and a crack of different lengths. The crack propagation is then determined using the extended finite element technique (X-FEM). The modeling was carried out using the ABAQUS calculation code.

• Proceedings of the Zoological Society Korea Conference
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• 1996.10a
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• pp.153.1-153
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• 1996

No Abstract, See Full Text