• Journal of the Korean Society of Manufacturing Process Engineers
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• v.9 no.6
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• pp.7-15
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• 2010

Recently, with the high performance and efficiency of machine, there have been required the multi-functions in various machine parts, such as the heat resistance, the abrasion resistance and the stress resistance as well as the strength. Fatigue crack growth tests were carried out to investigate the fatigue characteristics of high carbon steel (SM53C) experienced by high-frequency induction treatment. The Cam nose part of the Automobile's Cam shaft is strongly bumped with rocker arm or valve-lift. Therefore abnormal wear such as unfair wear and early wear occur in the surface. This abnormal wear causes a defect that bad timing open and close actions of the engine valve happen in the combustion chamber so the fuel gas will be combustion imperfect. Therefore, the cam shaft demands high hardness and wear resistance. In this study, high frequency heat treatment has been accomplished while wear test for material SM53C.

• Journal of Biosystems Engineering
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• v.20 no.4
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• pp.368-375
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• 1995

A computer vision system was built to generate images of a stationary egg. This system includes a. CCD camera, a frame grabber, and an incandescent back lighting system An image processing algorithm was developed to accurately detect surface holes and surface cracks on eggs. With 20W of incandescent back light, the detection rate was shown to be the highest. The Sobel operator was found to be the best among various enhancing filters examined. The threshold value to distinguish between the crack and the translucent spots was found to be linear with the average gray level of a whole egg image. Those values of both gray level and area were used as criteria to detect holes in egg and those values of both area and roundness were used to detect cracks in egg. For a sample of 300 eggs, this system was able to correctly analyze an egg for the presence of a defect 97.5% of the time. On the average, it took 59.5 seconds to analyze an egg image and determine whether or not it was defected.

• Proceedings of the KSR Conference
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• 2004.06a
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• pp.1084-1089
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• 2004

Recently, Orthotropic steel deck bridges, which have long span decks, have been regarded as one of economical as well as durable bridge types. However, Orthotropic steel deck bridge is used by a lot of welding, which may cause welding defect and deformation of connections. This kind of system happens some damages by the fatigue cracks of welding. The cross-connection of longitudinal rib and transversal rib is one of the weakest point because of the fatigue. The secondary stresses which are from the out-plane deformation of transversal rib and the torsion of longitudinal rib make the topical stress concentration phenomenon. But, it is principle that a Bulkhead Plate is not established in the domestic design standard. Therefore, it is estimated that a study for the installing of Bulkhead Plate is needed. This study with considering these circumstances proves efficiency of Bulkhead Plate and will be presented optimal design details through finite element analysis according to change the geometrical system of Bulkhead Plate and the cross-connection area of longitudinal and transversal rib

• Transactions of Materials Processing
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• v.15 no.4 s.85
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• pp.289-294
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• 2006

To reduce automobile parts weight, TWB(tailored welded blank) forming is widely used in panel forming. But products used TWB forming process have many defect, wrinkle, crack and springback. So study of TWB forming process character is very important. In this study one of the current problems of TWB forming was analyzed, especially for the try-out process of inner door panel without frame. A comparison was made between actual measurements and prediction of forming analysis for formability and springback. Also a new analysis die model which have additional plane on die surface was proposed to correct result of forming analysis. This proposed method overcomes the difference for TWB forming result between try-out and analysis.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.7
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• pp.578-583
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• 2001

The bushing for high voltage and large and power should endure weight of itself and force of pushing from contact with circuit breaker. Like this, epoxy mold bushing has to be strong without fault. However, the external circumstances and internal factors was caused by partial discharge, flashover and dielectric breakdown. Therefore, to remove external factor of defect and to prevent the internal cracks and cavity generated from the contraction on interface of Cu-Epoxy, we should form semi-conductive layer on Cu bar by carbon. Then, the PD properties and the insulation qualities of epoxy mold type bushing was able to improved by roles of cushions for the direction of diameter and by effects fo natural sliding like as separated from conductor for the direction of length. So, in this work, we could prove the method of semi-conductive layer in making the long conductor.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.233-236
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• 1997

In modem industry, the accuracy and the surface-finish requirements for machined parts have been becoming ever more stringent. Optical method in measurements is playing an important role in vibration measurement, crack and defect detection and surface topography with the advent of opto-mechatronics. In this study, the principle of the general confocal microscope is introduced for surface measurement, and the advanced confocal microscope that has better measuring speed than the traditional confocal microscope is developed. A study on improving the resolution of the advanced confocal microscope is followed. Finally, Software for data acquisition and analysis of various parameters in surface geometrical features has been developed.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.11
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• pp.2742-2748
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• 2000

In this study, the quantitative evaluation was performed by examination for gatigue crack origin in two prepared ductile irons specimens which have different microstructures using rotary bending fatigue tester, Series A has mixed microstructure. ferrite plus pearlite, and series B has bainitic microstructure. Obtained main results are as follows. The scatterings of fatigue strength were observed on σ(sub)α-Ν diagram of both specimen series, and it is observed that scatterings of series A were more serious. It is reasonable to evaluate the size of mesocrack range by means of √A(원문참조), where A means the area of mesocrack range including globular graphite nodule. As a result of reconsideration for the fatigue data by introduction of K(sub)α-Ν diagram, the scattrings of fatigue life were, remarkably. reduced. Therefore, it is more reasonable to evaluate of mesocrack range on fatigue life by parameter K(sub)α rather than σ(sub)α.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.650-655
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• 2010

The ground vibration which is induced by train leads defect and crack of neighborhood structure. Consequently, in order to reduce the train vibration, it is need to appropriate countermeasure. Wave-guide typed roadbed induce the train vibration to a channel wave forms using the difference of the track layer's stiffness. Therefore train vibration is restrictively attenuated along the longitudinal direction of the track. 5 kind of wave-guide typed roadbed structure is selected in this paper. A finite element, time history, linear spectrum, transfer function and damping ratio analysis are performed to evaluate the vibration reduction efficiency as the wave-guide roadbed.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.1058-1062
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• 1996

The assessments of weld defects by fracture mechanics are performed for design of welded Joints. In general, butt, T-type, and L-type welded joint are useful for welding structure. When linear weld defects are in welded joint, stress intensity factors for each joints are calculated by finite element method. Analysis results are shown for the fracture modes and characteristics of joint types. And they are founded for the weaken order of welded joints being T-type, butt, L-type.

• Journal of the Korean Society of Safety
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• v.20 no.1 s.69
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• pp.30-35
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• 2005

This study proposes construction of through transmission for weld defects detection of rail weld zone from ultrasonic signals. For these purposes, the ultrasonic signals for defects(porosity and crack) of weld zone in rails are acquired in the type of time series data and echo strength. 6 lines in the distance amplitude characteristics curve(DACC) indicated damage evaluation standard of weld zone in rails. The acquired ultrasonic signals agree flirty well with the mesured results of reference block and sensitivity block(defect location beam propagation distance, echo strength, etc). The proposed construction of through transmission in this study can be used for weld defects detection of rail weld zone.