• Transactions of Materials Processing
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• v.26 no.4
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• pp.222-227
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• 2017

In order to respond to environmental regulations and increased demand for fuel economy, the demand for lightweight car bodies has grown. Hydroforming of aluminum is one possible solution as it eliminates the need for additional welding to develop closed cross-sectional parts. However, the low formability of aluminum is a limitation of its application. On the other hand, the ductility of materials can be improved at higher temperatures, and hot metal gas forming has been widely applied in the production of lightweight vehicle parts. In this study, aluminum alloy for pipe extrusion was developed by controlling the Mg:Cr:Mn ratio based on AA5083. Mechanical properties of the developed material were examined by tensile test and were applied to a forming simulation. Cold forming simulation for preforming and non-isothermal hot forming simulation for hot metal gas forming were carried out to validate process conditions. A prototype of the sidemember was manufactured under the given process condition. Finally, thickness distribution was compared with finite element analysis results.

• Textile Coloration and Finishing
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• v.35 no.3
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• pp.137-150
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• 2023

This paper investigated the applicability of polyester yarn coating using ther- moplastic polyester elastomer (TPEE) to replace polyvinyl chloride (PVC) coated yarn for blinds fabric. For this purpose, suitable TPEE for yarn coating was selected by measuring thermal and rheological properties and the yarn coating process conditions were investigated by changing variables such as extrusion temperature, die and nipple dimensions, take-up speed, and core yarn denier. TPEE coated yarns with a diameter of 0.3 and 0.4 mm were prepared, respectively. Tensile properties and cross-section uniformity revealed by a scanning electron microscopy (SEM) of the TPEE coated yarn were analyzed. Among several candidates, TPEE having a melt index of 35 and melting temperature of 153℃ was the most suitable for replacing PVC, and the opti- mum coating conditions for the TPEE coating yarn were a head temperature of 170℃ and core yarn denier of 420 denier. The selected TPEE coated yarns have enough ten- sile strength and uniformity to replace present PVC coated yarns, certified by SEM photograph.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.10a
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• pp.254-258
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• 2009

In this paper, the low frequency vibration forming system is developed for micro-patterns formation on the metal substrate. many researchers have studied about micro-forming technologies such as micro deep drawing, press forming, forging, extrusion etc. for the formation of precise micro-patterns on the surface of metal substrates, multi-step forming process must be used to improve qualifies of the deformed patterns. Since the low frequency vibration forming system could easily deform the surface of metal substrates, several steps of multi-step forming process should be removed by using the low frequency vibration forming system. In order to find optimal process conditions, we have carried out low frequency vibration forming process with varying the vibration frequency from 110Hz to 500Hz.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1992.03a
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• pp.11-26
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• 1992

In this research, a numerical algorithm has been developed, which can be applied to the large deformation and large displacement contact problems between angle change have been proposed considering the change in geometric shape and rate of contact force. A set of linear simultaneous equations is constructed by adding the geometric shape change and contact conditions to the original stiffness matrix. A new method to determine time increment has been proposed based on Euler method, in which the condition to prevent the contact bodies from penetrating and overrunning each other has been taken into consideration. Practical application to contact problem is extrusion in which bodies are sliding along the contact boundary.

• Korean Journal of Microbiology
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• v.30 no.4
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• pp.269-277
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• 1992

Several insertion mutants of Escherichia coli in the ant gene, coding for $Na^{+}$ $H^{+}$ antiport activity, showed littel, if any, reduction in the antiport activity. $Na^{+}$ dependent transport activity also remained at wild type level. These facts led to the idea that E. coli has evolved at least two distinct systems for extrusion of $Na^{+}$ The antiport activities were studied under various conditions to reveal different properties of these systems. For convenience these activities are referred to as major and minor activities. The distinguishing properties of the two systems include : kinetics (Km, Vm) at pH 7.8, competition pattern between $Na^{+}$ and Li$^{+}$ , pH profiles, pattern of the change in kinetic parameters as a function of pH, and sensitivity to protease, chemicals and heat.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.704-709
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• 2004

The wear behavior and the mechanical property of Cu-$TiB_2$ composites were examined. Cu-$TiB_2$ composites were fabricated by hot extrusion and cold drawing with $TiB_2$ contents(1$\∼$5vol.$\%$) and the size of $TiB_2$ particles(10$\mu$m and 20$\mu$m). The pin-an-disk wear test was carried out under dry sliding wear conditions which loads varied with from 20N to 100N. At the time, counterpart wear material used SM45C. The experimental results showed that the friction coefficient and wear rate decreased with increasing the $TiB_2$ contents and decreasing the size of $TiB_2$ particle. Also, the depth of plastically deformed zone decreased with increasing the $TiB_2$ contents and decreasing the size of $TiB_2$ particle.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.495-496
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• 2006

The kneading process and formulations of feedstock obviously affect the quality of MIM products. In the present work, the rheological behaviour of the composite MIM feedstock, metal matrix (Cu) with few additions of ceramic powders $(Al_2O_3)$, was measured by a self-designed/manufactured simple capillary rheometer. Experimental results show that the distribution between powders and binder is more uniformly when blending time increased. Though high powder loading will increase the feedstock viscosity, the fluidity reveals relatively stable through the load curves of extrusion. Besides, the temperature-dependence of viscosity of the feedstock approximately follows an Arrehnius equation. Basing on Taguchi's method, the kneading optimization conditions and the rheological model of the feedstock were established, respectively.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.05a
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• pp.78-81
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• 2005

The aluminum Subframe for automobile was developed using hybrid process, i.e. extruforming and press forming. To achieve a $30\%$ weight reduction compared with convensional steel subframe keeping satisfactory performance, the design of cross-section of extrusion part was initiated, then forming simulation was performed and the final design was determined. In addition, we tried to estibilish proper aluminum welding conditions for good penetration depth and few pore defact, finally the prototype of aluminum subframe was assembled using MIG welding method.

• Transactions of Materials Processing
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• v.5 no.2
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• pp.97-104
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• 1996

It is very important to obtain the knowledge of loads and flow patterns in most processes because these information are the fundamental data of die design and process design. The objective of present study is to investigate loads and metal flow patterns for various process conditions in flat die extrusion of square-bars from circular billets. For analyzing the metal flow patterns of the billets photo etching is used on sections of split specimen. From this method metal flow patterns are analyzed for various area reductions friction factors and punch stroke through the process from initial-stage to final-stage. Experiments are carried out with hard solder billets at room temperature.

• Journal of the Korean Society of Food Science and Nutrition
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• v.46 no.6
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• pp.751-758
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• 2017

The objective of this study was to determine the effects of moisture content and screw speed on the physical properties of extruded soy protein isolate (SPI). Expansion index, water absorption index, texture, integrity index, color, and nitrogen solubility index of extruded SPI were analyzed to determine the relationship with extrusion conditions. Extrusion conditions were moisture content (40, 50, and 60%) at a fixed die temperature ($140^{\circ}C$) and screw speed (250 rpm). The other extrusion conditions were screw speed (150, 250, and 330 rpm) at a fixed moisture content (55%) and die temperature ($140^{\circ}C$). Specific mechanical energy (SME) input decreased as moisture content increased from 40 to 60%. However, SME input increased as screw speed increased from 150 to 330 rpm. Expansion ratio and piece density decreased as moisture content and screw speed increased, and specific length increased as moisture content and screw speed increased. The extruded SPI at 40% moisture content had higher water absorption index, texture, and color differences than those of the extruded SPI at other moisture contents (50 and 60%). however, the extruded SPI at 40% moisture content had lower integrity index and cutting strength than those of the extruded SPI at other moisture contents (50 and 60%). In conclusion, the physical properties of extruded SPI were more affected by moisture content than screw speed.