• 한국전산구조공학회:학술대회논문집
• /
• 한국전산구조공학회 2006년도 정기 학술대회 논문집
• /
• pp.89-96
• /
• 2006

Nondestructive evaluation using surface waves needs an analytical solution for the reference value to compare with experimental data. Finite element analysis is very powerful tool to simulate the wave propagation, but has some defects. It is very expensive and high time-complexity for the required high resolution. For those reasons, it is hard to implement an optimization problem in the actual situation. The developed engine in this paper can substitute for the finite element analysis of surface waves propagation, and it accomplishes the fast analysis possible to be used in optimization. Including this artificial intelligence engine, most of soft computing algorithms can be applied on the special database. The database of surface waves propagation is easily constructed with the results of finite element analysis after reducing the dimensions of data. The principal wavelet-component analysis is an efficient method to simplify the transient wave signal into some representative peaks. At the end, artificial neural network based on the database make it possible to invent the artificial intelligence engine.

• 소성∙가공
• /
• 제17권4호
• /
• pp.278-283
• /
• 2008

This paper concerns the die face design for a heat protect panel aided by the finite element forming analysis in order to eliminate the surface defect and to improve the surface quality. The CAE procedure of the stamping process is introduced in order to reveal the reason of surface inferiorities and to improve surface quality. Complicated shape of the product induces the surface inferiorities such as wrinkling due to the insufficient restraining force of the forming blank and the non-uniform contact of the blank with the tools. This paper proposes a new guideline for the die design which includes the modification of tool shapes and addition of the draw-beads on the tool surface for ensuring the increased the restraining force with the uniform contact condition. The effectiveness of the proposed design is verified by the forming analysis and is confirmed by the tryout operation in the press shop. The analysis and test results show that the modified process parameters such as tool shapes and draw-beads can reduce the tendency of wrinkling and improve surface quality.

• 한국기계가공학회지
• /
• 제3권3호
• /
• pp.64-70
• /
• 2004

The sub-surface stress field beneath the spur gear's contact surface in lubricated condition has been analysed. The surface pressure was obtained by the elasto-hydrodynamic lubrication analysis using the accurate geometric clearances around the contact region of the teeth. The sub-surface stress field was calculated by using the Love's rectangular patch solution. The analysis results show that the sub-surface stress distribution is quite dependent on the surface pressure distribution. The pattern of sub-surface stress field is similar to that of the external load. The depth where the maximum effective stress occurs is not proportional to the intensity of the external load.

• Tribology and Lubricants
• /
• 제29권4호
• /
• pp.228-234
• /
• 2013

This paper presents analysis of elastohydrodynamic lubrication (EHL) of ball bearings, in which surface roughness is considered. A lot of time is required to obtain a solution in the case of EHL analysis where surface roughness is considered, because the analysis requires a variety of analytic nodes. To save time, we use the full approximation scheme (FAS) among multilevel methods. We analyze the results of EHL and contact analyses in terms of pressure. We also compare the results for smooth and rough surfaces with respect to film thickness. We confirm that the film pressure decreases as compared to contact pressure because of the presence of lubricants between the ball and the raceway. Furthermore, in the case when surface roughness is considered, the film pressure increases because of contact asperities. Therefore, surface roughness should be considered when designing ball bearings.

• 한국공작기계학회논문집
• /
• 제12권5호
• /
• pp.46-52
• /
• 2003

End-milling have been used widely in industrial system because it is effective to a material manufacturing with various shape. Recently the end-milling processing is needed the high-precise technique with good surface roughness and rapid time in precision machine part and electronic part. The optimum surface roughness has an effect on end-milling condition such as, cutting direction spindle speed, feed rate and depth of cut, etc. Therefore this study was carried out to presume for mutual relation of end-milling condition to get the optimum surface roughness by regression analysis. The results shown that coefficient of determination($\textrm{R}^2$) of regression equation has a fine reliability of 87.5% and regression equation of surface rough is made by regression analysis.

• 대한치과보철학회지
• /
• 제38권3호
• /
• pp.328-335
• /
• 2000

Statement of the problem. Recently an innovative method of fabricating indirect restorations by gold electroforming has been developed. But the bond quality and strength of the gold coping to the porcelain is uncertain. Purpose of study. The purpose of this study is to analyze and evaluate the electroformed gold surface for mechanical bonding between the gold and the ceramic veneering. Methods/material. Electroformed disks were made using electroforming technique. And the surface of the electroformed coping was analyzed after sandblasting, heat-treatment, bonding agent application, opaque porcelain firing with scanning electron microscopy and energy dispersive x-ray analysis. Results. In the analysis with SEM, Sandblasting made the sharp edges and undercuts on the electroformed surface, and after bonding agent application, net-like structure were created on the electroformed surface. In the energy dispersive x-ray analysis it is confirmed that electroformed surface contains some impurities. Conclusion. With the use of sandblasting and bonding agent, electroformed surface seems to be enough to bond with veneering porcelain.

• Tribology and Lubricants
• /
• 제26권6호
• /
• pp.329-335
• /
• 2010

Recently, the End-milling processing is needed the high-precise technique to get a good surface roughness and rapid time in manufacturing of precision machine parts and electronic parts. The optimum surface roughness has an effect on end-milling working condition such as, cutting direction, spindle speed, feed rate and depth of cut, and so on. It needs to form the correlation of working conditions and surface roughness. Therefore this study was carried out to presume of surface roughness on end-milling working condition of Al7075 by regression analysis. The results was shown that the coefficient of determination($R^2$) of regression equation had a fine reliability of 87.5% and nonlinear regression equation of surface rough was made by multiple regression analysis.

• Bulletin of the Korean Chemical Society
• /
• 제32권2호
• /
• pp.389-398
• /
• 2011

Although the currently available surface spectroscopic techniques provide powerful means of studying atoms and simple molecules on surfaces, the identification of complex molecules and functional groups is a major concern in surface analysis. This article describes a recently developed method of surface molecular analysis based on reactive ion scattering (RIS) of low energy (< 100 eV) $Cs^+$ beams. The RIS method can detect surface molecules via a mechanism in which a $Cs^+$ projectile picks up an adsorbate from the surface during the scattering process. The basic principles of the method are reviewed and its applications are discussed by showing several examples from studies of molecules and their reactions on surfaces.

• 소성∙가공
• /
• 제26권3호
• /
• pp.162-167
• /
• 2017

The tensile surface residual stress in the multi-pass drawn wire deteriorates the mechanical properties of the wire. Therefore, the evaluation of the residual stress is very important. Especially, the axial residual stress on the wire surface is the highest. Therefore, the objective of this study was to propose an axial surface residual stress prediction model of the multi-pass drawn steel wire. In order to achieve this objective, an elastoplastic finite element (FE) analysis was carried out to investigate the effect of semi-die angle and reduction ratio of the axial surface residual stress. By using the results of the FE analysis, a surface residual stress prediction model was proposed. In order to verify the effectiveness of the prediction model, the predicted residual stress was compared to that of a wire drawing experiment.

• Steel and Composite Structures
• /
• 제18권6호
• /
• pp.1479-1492
• /
• 2015

This study evaluated the localized stress condition of the real corroded deck surface of an orthotropic steel bridge because severe corrosion damage on the deck surface and fatigue cracking were reported. Thus, a three-dimensional finite element (FE) analysis model was created based on measurements of the corroded orthotropic steel deck surface to examine the stress level dependence on the corrosion condition. Based on the FE analysis results, it could be confirmed that a high stress concentration and irregular stress distribution can develop on the deck surface. The stress level was also increased by approximately 1.3-1.5 times as a result of the irregular corroded surface. It was concluded that this stress concentration could increase the possibility of fatigue cracking in the deck surface because of the surface roughness of the orthotropic steel bridge deck.