• Journal of Ocean Engineering and Technology
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• v.13 no.3 s.33
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• pp.57-67
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• 1999

Welding is widely applicable and reliable process and is mainly adopted for fabricating heavy structures. Recently, weld metal transverse cracks in butt and fillet weld joint is a serious problem, and they must be eliminated for improving weld joint reliability. The weld metal transverse crack susceptibility of butt and fillet joint was carried out by cantilever type tensile crack testing jig and CTS test. In this view of point, this study investigated the potential factors for weld metal transverse crack. The main results obtained were as follows: 1. The content o fdiffusible hydrogen in weld metal played an important role for weld metal transverse cracks. 2. From cantilever type tensile crack tests, it was pointed out that the higher the diffusible hydrogen content and tensile restraint, the more susceptible to weld metal transverse craking. 3. The TSN(thermal severity number) and diffusible hydrogen were important factors for determining weld metal transverse cracks in fillet weld joints.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.22 no.5
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• pp.812-817
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• 2013

This study demonstrates the diffusion bonding process between a tungsten carbide shank (K30) and tungsten carbide (DX5) for micro WC-PCD tool fabrication. A type of nickel alloy was used as the filler met alto improve the bond ability between K30 and DX5. The bonding pressure, time, and surrounding conditions were kept constant. In particular, the normal pressure was controlled precisely under buckling analysis. Diffusion bonding was performed at various operation temperatures (1170-1770 K) by using a specially designed jig. The microstructure on the localized bonded surface was analyzed using scanning electron microscopy and optical microscopy. In the case of diffusion bonding of WCat 1370-1770K, the filler metal melted completely and diffused between the two base metals, and they were bonded more tightly on both sides than at temperatures below 1370 K. Our results demonstrated the importance of sensitive temperature dependence of diffusion bonding.

• IE interfaces
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• v.25 no.1
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• pp.87-95
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• 2012

Very special and tentative considerations including emotional aspects are required to apply any new mechanism and methodologies for manufacturing fields due to several reasons. This study reviews the characteristics of manufacturing collaborations through specific cases applied digital engineering to enhance the collaboration performance in manufacturing domains. Two cases of collaboration related with automotive manufacturing process are analyzed to extract meaningful insights for better collaboration model suggestions. The first case deals the robot simulation to find out advance errors in jig and fixture design during the various welding process of body-in-whites. The effective communication protocol to share their idea and agreed schedules are essential for this collaboration. More severe requirement of collaboration between R&D and manufacturing departments are studied in the second case for e-coating process. The invisible barriers among different departments are lowered by the process application of Computer Aided Engineering which can make sure their own interesting effectively. Those technical and managerial suggestions can be used when the information system and standard process are sought to implement and update not only when innovation projects are executed.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.4
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• pp.761-769
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• 1994

Actual load acting on rail surface in the track is the combined mode loading due to the contact rolling load of the wheels. To investigate the fracture behavior on rail steel under combined modes I and II, fracture tests were performed by using the test jigs and fracture specimen which were designed by Richard. The analysis results of experimental fracture data were compared with various fracture criteria that have been introduced for determination of the crack propagation direction and the critical stress of fracture of a crack submitted to a mixed mode loading. From the results, it was shown that the actual crack propagation direction of rail steel agree with the crack propagation directions predicted by maximum tangential stress criterion and strain energy density criterion, and that fracture criterion follows principal strain criterion.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.22 no.1
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• pp.73-79
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• 1998

The development of a new material which should be continuously usable under severe environment of very high temperature has been urgently requested. The conventional thermal barrier coating(TBC) is a two layer coating, but a composition and a microstructure of functionally graded material(FGM) are varied continuously from place to place in ways designed to provide it with the maximum function of mitigating the induced thermal stress. The purpose of this study is to evaluate the heat-resistant characteristics by thermal shock of laser and furnace heating. The fracture behaviors of non-FGM(NFGM) and FGM were investigated based on acoustic emission(AE) technique during thermal shock test. Therefore, it can be concluded that FGM gives higher thermal resistance compared to NFGM by AE signal and fracture surface analysis.

• Journal of Institute of Control, Robotics and Systems
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• v.21 no.12
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• pp.1109-1114
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• 2015

This paper presents an improved learning-based visual inspection method for auto parts inspection in severe lighting changes. Automobile sunroof frames are produced automatically by robots in most production lines. In the sunroof frame manufacturing process, there is a quality problem with some parts such as volts are missed. Instead of manual sampling inspection using some mechanical jig instruments, a learning-based machine vision system was proposed in the previous research[1]. But, in applying the actual sunroof frame production process, the inspection accuracy of the proposed vision system is much lowered because of severe illumination changes. In order to overcome this capricious environment, some selective feature vectors and cascade classifiers are used for each auto parts. And we are able to improve the inspection accuracy through the re-learning concept for the misclassified data. The effectiveness of the proposed visual inspection method is verified through sufficient experiments in a real sunroof production line.

• Journal of Digital Convergence
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• v.10 no.9
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• pp.79-87
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• 2012

While the youth unemployment problem has come to extend over a long period of time, because of the promotion policy of youth inauguration of an enterprise, many youths have been considering the start-up to be an alternative of the working. But it is said that many youths who had started an enterprise through the start-up education and related programs were unsuccessful mostly and dashed to get a job or became the delinquent borrower. This article will examine the actual conditions of the youth unemployment and the present conditions of promotion policy of the youth start-up, analyse problems as a result of this examination, propose alternatives of policy to revitalize the youth start-up.

• Journal of the Society of Naval Architects of Korea
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• v.42 no.4 s.142
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• pp.330-340
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• 2005

Compressible two-phase flow is analyzed based on the arbitrary Lagrangian-Eulerian (ALE) formulation. For water, Tamman type stiffened equation of state is used. Numerical fluxes are calculated using the ALE two-phase Godunov scheme which assumes only that the speed of sound and pressure can be provided whenever density and internal energy are given. Effects of the approximations of a material interface speed are Investigated h method Is suggested to assign a rigid body boundary condition effectively To validate the developed code, several well-known problems are calculated and the results are compared with analytic or other numerical solutions including a single material Sod shock tube problem and a gas/water shock tube problem The code is applied to analyze the refraction and transmission of shock waves which are impacting on a water-gas interface from gas or water medium.

• Journal of the Korean Society for Nondestructive Testing
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• v.21 no.6
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• pp.642-649
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• 2001

Precision parts and instruments are tested to evaluate performance in development-process and product-step to prement a potential defect due to a failure design. In this paper, Environmental test technology, which is the basis of reliability analysis, is introduced with examples of test criterion, test method for products, encoder and traffic signal controller, and measuring instruments. Recently, as the importance of the environmental test technology is recognised. It is proposed that tranining of test technician and technology of jig design and failure analysis are very essential.

• The Journal of Korean Academy of Prosthodontics
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• v.39 no.2
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• pp.171-183
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• 2001

The purpose of this study was compare the fracture strength of the IPS Empress ceramic crown according to the occlusal depth (1.5mm, 2.0mm, 2.5mm) and axial inclination ($4^{\circ},\;8^{\circ},\;12^{\circ}$) of the upper first molar. After 10 metal dies were made for each group, the IPS Empress ceramic crowns were fabricated and were cemented with resin cement. The cemented crowns mounted on the testing jig were inclined 30 degrees and a universal testing machine was used to measure the fracture strength. The results of this study were as follows: 1. The fracture strength of the ceramic crown with 2.5mm depth and $8^{\circ}$ inclination was the highest (1393N). Crowns of 1.5mm depth and $4^{\circ}$ inclination had the lowest strength (1015N) 2. There were no significant differences of the fracture strength according to occlusal depth and axial inclination. 3. Most fracture lines began at the loading area and extended through proximal surface perpendicular to the margin, irrespective of occlusal depth. 4. There was positive correlation between the fracture strength and the fracture surface area of crowns.