• Journal of Korean Society of Industrial and Systems Engineering
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• v.35 no.2
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• pp.196-203
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• 2012

When manufacturing die casting mold, generally, the casting layout design should be considered based on the relation between injection system, casting condition, gate system, and cooling system. Also, the extent or the location of product defects were differentiated according to the various relations of the above conditions. High-qualified products can be manufactured as those defects are controled by the proper modifications or the changes of die casting mold with the conditions. In this research, the proper manufacturing method was derived intensively for reducing the defect of the internal porosity of steering wheel housing which is very complicated to achieve a good mold design. The method was also derived for minimizing and for guaranteeing the product quality through the analysis of the casting problem and the deduction of alternative plans.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.3
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• pp.107-114
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• 2001

The durability of head/disk interface is an important issue for hard disk drives. Currently, there are several means of assessing the performance and integrity of the head/disk interface. In this work Track Average Amplitude(TAA) signal was used to analyzed the head/disk interface with respect to variations in disk velocity, slider pre-load and preformed scratch on the disk. Particularly, TAA variation due to disk defect in the form of a scratch was investigated.

• Journal of Electrical Engineering and Technology
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• v.5 no.4
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• pp.666-671
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• 2010

Multi-layer perceptron neural networks have been constructed to classify four types of defects in steam generator tubes. Three features are extracted from the signals of the eddy current testing method. These include maximum impedance, phase angle at the point of maximum impedance, and an angle between the point of maximum impedance and the point of half the maximum impedance. Two hundred sets of these features are used for training and assessing the networks. Two approaches are involved to train the networks and to classify the defect type. One is the conjugate gradient method and the other is the Broydon-Fletcher-Goldfarb-Shanno method which is recognized as the most popular algorithm of quasi-Newton methods. It is found from the computation results that the training time of the Broydon-Fletcher-Goldfarb-Shanno method is much faster than that of the conjugate gradient method in most cases. On the other hand, no significant difference of the classification performance between the two methods is observed.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.2
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• pp.140-145
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• 2001

The tape carrier package(TCD) is one of the most important components in a liquid crystal display(LCD) module. It has a role to transmit electrical signals from a printed circular board(PCB) to a display panel. If TCP is damaged under mechanical shock, the signals can not be transmitted to the panel and as a result, some dead lines are generated on the panel. This kind of phenomenon is commonly called as 'line defects'. In this paper, new structural design concepts of TCP are proposed to guarantee its reliability by using Taguchi's approach and dynamic FE-analysis. The line defects problem of TCP module is solved by replacing the original TCP with the newly designed one.

• Journal of Korea Foundry Society
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• v.22 no.6
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• pp.293-298
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• 2002

The effects of alloying elements added on the microstructure and high temperature oxidation behavior of the electro-slag remelted Fe-22Cr-5Al alloy were investigated. The amount of casting defect was makedly reduced by the electro-slag remelting. The electro-slag remelted ingot had a directionally solidified structure and cleaner surface than that of air-melted one. The high temperature oxidation reststance was greatly improved by the addition of Be and Zr.

• Proceedings of the KIEE Conference
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• 1987.11a
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• pp.311-315
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• 1987

This paper describes the automatic visual inspect ion system of fabric defects based on pattern recognition techniques. To extract features for detection of fabric defects, four different techniques such as SGLDM. GCM, decorrelation method, and Laws' texture measure were investigated. From results of computer simulation, it has been found that GCM and decorrelation techniques provide good features. By employing a simple statistical pattern recognition technique, theaccuracy of classification of defect and nondefect was more than 90%. Some experimental results arm also presented.

• Proceedings of the KIEE Conference
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• 1988.07a
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• pp.959-962
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• 1988

This paper describes an automatic visual inspection system for fabric defects based on pattern recognition techniques. The inspection for fabric defects can be separated into three sequences of operations which are the detection of fabric defects[1], the classification of figures of fabric defects, and the classification of fabric defects. Comparing projections of defect-detected images with the predefined complex, the classification accuracy of figures of fabric defects was found to be 95.3 percent. Employing the Bayes classifier using cluster shade in SGLDM and variance in decorrelation method as features, the classification accuracy of regional figure defects was found to be 82.4 percent. Finally, some experimental results for line and dispersed figures of fabric defects are included.

• Proceedings of the Korean Society of Computer Information Conference
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• 2018.07a
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• pp.387-388
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• 2018

본 논문은 스마트 공장의 표면 결함 검사 시스템에서 사용할 수 있는 VVC, VOV 영상의 특징 활용에 관한 연구를 내용으로 다루었습니다. 본문에서는 VVC와 VOV 특징에 대하여 원리를 소개하고, 실험에서는 이들 특징을 사용한 표면 결함 검사의 결과를 제시하였습니다.

• Journal of Surface Science and Engineering
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• v.48 no.6
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• pp.349-353
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• 2015

In this paper, arc thermal spray coating was conducted onto the SS400 steel using Inconel 625 wires in order to improve the durability of marine steel structures, and then investigated cavitation damage behavior of Inconel 625 coating layer in sea water. For the Inconel 625 coating layer, surface hardness appeared similar to that of existing high velocity oxy-fuel coating technology with 380~480 HV, but the porosity of about 6 % was larger relatively. During the cavitation experiment, pit damages were originated and grown at the rough surface and pore defect area of Inconel 625 coating layer. And, after the 72 hours of experimental time, weight loss of Inconel 625 coating layer exhibited gradually increasing tendency due to surface damage effect of the undercut.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.5 no.4
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• pp.347-352
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• 2005

PD(Partial discharges) are small electrical sparks that occur within the electric insulation of cables, transformers and windings on motors. PD analysis is a proactive diagnostic approach that uses PD measurements to evaluate the integrity of this equipment. Recently, several diagnostic algorithms for classifying the type of PD and locating the defect position have been developed. In this work, a new PD recognition system is proposed, which utilizes approximate coefficients of wavelet transform as a feature vector, furthermore, introduces bank of Elman networks to recognize the various PD phenomena. In order to verify the performance of the proposed scheme, it is applied to the simulated PD data.