• Transactions of Materials Processing
• /
• v.24 no.5
• /
• pp.332-339
• /
• 2015

In the current paper, a cold forging sequence was developed to manufacture a precisely cold forged H/Lower, which is used as the air back unit in commercial automobiles. The preform shape of the H/Lower influences the dimensional accuracy and stiffness of the final product. The shape factor (SF) ratio and shape of the tools are considered as the design parameters to achieve adequate backward extrusion height and maintain appropriate thickness variations. The optimal conditions of the design parameters were determined by using an artificial neural network (ANN). To experimentally verify the optimal preform and tool shapes, the experiments of the backward extrusion of the H/Lower were executed. The process design methodology proposed in the current paper, can provide a more systematic and economically feasible means for designing the preform and tool shapes for cold forging.

• Speech Sciences
• /
• v.8 no.2
• /
• pp.181-191
• /
• 2001

The acoustic quality of a vowel is known to be mostly determined by the frequencies of the first formant(Fl) and the second formant(F2). The perceptual(or psychological) dimensions of vowel perception were examined in this study. Also the relationships among perceptual dimensions, acoustical dimensions(Fl & F2), and articulatory gestures of vowel were discussed. Using multi-dimensional scaling(MDS) technique, the experiment was performed in order to identify the perceptual dimensions of the perception of Korean vowel. In the experiment 8 Seoul standard speakers performed the similarity rating task of 10 synthesized Korean vowels. Two-dimensional MDS solution based. on the similarity rating scores was obtained. The results showed that two perceptual dimensions, D1 and D2 were correlated strongly with F2 and F1(r = -.895 and .878 respectively), and were so interpreted as 'vowel advancement' and 'vowel height' respectively. The relationship between the perceptual dimensions of vowel and the articulatory positions of tongue suggested that perception may be directly linked to production. Further research problems were discussed in the .final section.

• Journal of the Korean Society for Precision Engineering
• /
• v.11 no.1
• /
• pp.129-137
• /
• 1994

A rigid-viscoplastic finite element method has been used for modeling superplastic stretch/blow process design to improve thickness distribution. Punch velocity-time relationship of the stretch forming and pressure-time cycle of the blow forming for a given strain rate are calculated. A superplastic material is assumed to be isotropic and a plane-strain line element based on membrane approximation is employed for the formulation. The effects of the width, corner radius and height of the punch during stretch forming are examined for the final thickness distribution, and the process design to improve thickness distribution can be established.

• International Journal of CAD/CAM
• /
• v.3 no.1_2
• /
• pp.31-40
• /
• 2003

In this paper, first order slice height calculation in Laminated Object Manufacturing (LOM) of free form surfaces is done with two different considerations: that a) the cutter trajectory is oriented in the direction of local absolute maximum more in number when compared to the case where the cutter trajectory is contained in the normal vertical section (NVS). However, it would help in achieving higher form accuracy of the final part because it would be a form of worst-case check. For the second proposed strategy, least number of slices results, thereby reducing overall build time drastically.

• Proceedings of the KWS Conference
• /
• 2006.05a
• /
• pp.304-306
• /
• 2006

Positioning the workpiece accurately and preventing the weld distortion, tack welding is often performed before main welding in the construction of welded structures. The weld bead size of the tack weld is determined according to the workpiece thickness, weld length, weld joint type etc. However, this tack weld deteriorates the final weld bead profile, so that the grinding process is usually adopted for the uniform weld bead profile. In this study, an experimental method for the selection of optimal welding condition was proposed in the fillet weld which was done over the tack weld. This method uses the response surface analysis in which the leg length and the reinforcement height of weld bead were chosen as the quality variables of weld bead profile. The overall desirability function, which was combined desirability function for the two quality variables, was used as the objective function for getting the optimal welding condition. From the result, it was revealed that a uniform weld bead can be obtained by adopting the optimal welding condition which was determined according to the method proposed.

• Proceedings of the KSRS Conference
• /
• 2008.10a
• /
• pp.212-215
• /
• 2008

The final product generated from the KOMPSAT-2 Terminal for Polar System, K2PS, is an ellipsoid projected image. This leaves a relief displacement on the image by process of which the height value of subject area is constant. In this paper, orthorectification using the SRTM was used to remove such artifacts, and thereafter, the additional product that could be generated from the K2PS was discussed.

• Proceedings of the International Microelectronics And Packaging Society Conference
• /
• 2003.11a
• /
• pp.94-98
• /
• 2003

The microstructure of Sn1.8Bi0.8Cu0.6In alloys was evaluated at various aging time. The bumps of Sn1.8Bi0.8Cu0.6In alloys after reflowed at $250^{\circ}C$ were well-formed and had 260um height. The craters on the bumps, however, were observed. Intermetallic compounds formed on the interface between so]der and Cu/Ni UBM were consist of $(Cu,Ni)_6Sn_5$. As aging goes on up to 1000hours, the composition of Ni changed from $6.63\%$ at initial stage(as-reflowed) to $13.47\%$ at final stage(1000hours aging ). In addition, after 500hours aging, the floating of IMC to the solder was observed.

• Transactions of Materials Processing
• /
• v.6 no.4
• /
• pp.329-337
• /
• 1997

Forging of an inner pulley for compressor clutch assembly of car air conditioner is investigated in this study. In cold forging of inner pulley, the design requirements are to keep the same height of the inner rib and the outer one, and to make uniform the hardness distribution in the forged product. Using the rigid-plastic finite element simulation. we design the optimal process conditions, which has a performing operation. Also the final product configuration of forging has to be designed again in view of the metal flow involved in the operation, derived from the finite element simulations. The forged pulley is investigated by checking the hardness distribution and it is noted that the distribution has improved to be even and high enough for industrial application.

• Transactions of Materials Processing
• /
• v.16 no.4 s.94
• /
• pp.223-228
• /
• 2007

The profile ring rolling process of Ti-6Al-4V alloy was investigated by finite element(FE) simulation and experimental analysis. The process design of the profile ring rolling includes geometry design and optimization of process variables. The geometry design such as initial billet and blank sizes, and final rolled ring shape was carried out with the calculation method based on the uniform deformation concept between the wall thickness and ring height. FEM simulation was used to calculate the state variables such as strain, strain rate and temperature and to predict the formation of forming defects during ring rolling process. Finally, the mechanical properties of profiled Ti-6Al-4V alloy ring product were analyzed with the evolution of microstructures during the ring rolling process.

• Journal of the Semiconductor & Display Technology
• /
• v.4 no.3 s.12
• /
• pp.5-9
• /
• 2005

The bonding structure of organic materials such as fluorinated amorphous carbon films was classified into two types due to the chemical shifts. The electrical properties of fluorinated amorphous carbon films also showed very different effect of two types notwithstanding a very little difference. Fluorinated amorphous carbon films with the cross-link break-age structure existed large leakage current resulting from effect of the electron tunneling. Increasing the cation due to the electron-deficient group increased the barrier height of the films with the cross-link amorphous structure, therefore the electric characteristic of the final materials with low dielectric constant was also improved. The lowest dielectric constant is 2.3 at the sample with the cross-link amorphous structure.