• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1994.06a
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• pp.1-9
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• 1994

Three recent developments made at Rensselaer in sheet material forming processes are briefly reviewed in this paper. These advances represent three broad disciplines of Process Simulation, Forming Processes, and Computer-Aided Measurement Methods. The first development deals with simple and quick computer simulation of 2D sheet forming process without depending on popular finite element analysis methods. An analytical method based on a thin shell theory accounts for bending and unbending effects, and is capable of simulating practical sheet metal forming processes under the plane strain condition. The second area is concerned with innovative methods to improve formability of sheet materials by temperature gradient forming. The drawing limit is increased by such an improved temperature gradient forming process. The third and final area deals with a totally new experimental technique to capture 3D geometry data and measure strain distributions of sheet metal parts using a digital 35mm SLR camera.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.05a
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• pp.199-202
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• 2009

In roll forming process, a sheet metal is continuously progressively formed into a product with required cross-section and longitudinal shape, such as a circular tube with required diameter, wall-thickness and straightness, by passing through a series of forming rolls in arranged in tandem. Tn this process, each pair of forming rolls installed in a forming machine play a particular role in making up the required cross-section and longitudinal shape of the product. In recent years, that process is often applied to the bumper rail in the automotive industries. In this study, a optimal Front Bumper Beam manufacturing technology, model deign and proper roll-pass sequences can be suggested by forming number of roll-pass and bending angle. And also effects of the process parameters on the final shape formed by roll forming defects were evaluated.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.10a
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• pp.293-295
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• 2007

The thixoforming process become important for forming automobile parts. But, the thixoforming process cannot still prevent to forming defects such as pores and shrinkage which reduce mechanical properties of automobile parts. Therefore, it is necessary to analyze the correlation between forming defects and mechanical properties. However, it is difficult to get data about relations between mechanical properties and forming defects in thixoformed aluminum alloy parts. In this study, three parts of aluminum thixoformed knuckle have been analyzed using tensile test and computer tomography(CT scan). Experimental results showed that the elongation properties of thixoformed aluminum parts were significantly dependent on size and number of forming defects.

• Journal of the Korean Society of Safety
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• v.15 no.3
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• pp.7-13
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• 2000

Forming characteristics of tailored blank are mostly effected by the welding method. Recently, laser welding is widely used for the tailored blank. However, tensile and forming characteristics vary due to welding conditions such as welding speed, heat flux etc. The objective of this paper is to evaluate the effect of welding speed on the tensile and forming characteristics of laser welded tailored blank. For this purpose, tailored blank specimens with different welding speed were prepared and tensile tests were performed. Also forming tests such as LDH and OSU test, were performed to evaluate the effect of welding speed on the forming characteristics. Finally, forming limit diagrams were obtained for different welding speed.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.06a
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• pp.97-98
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• 2007

• East Asian Economic Review
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• v.16 no.2
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• pp.205-225
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• 2012

I use panel data of sales by the foreign subsidiaries of the U.S. MNCs to examine whether trading blocs create more or less FDI and the impacts on FDI of the extended market size created by forming blocs. By employing a region-fixed effects model, I find that countries forming trading blocs attract more FDI, particularly from non-member countries, but that FDI does not always increase with the market size of the blocs. As the market size increases, FDI increases only for large blocs. However, these findings are sensitive to model specifications. A policy implication is that a country considering forming or joining a trading bloc with a view to attract FDI may want to form a trading bloc with a country or countries with a large market size.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.3
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• pp.283-288
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• 2012

Ultra-high-strength steels (UHSSs) are widely used for lightweight automobile parts, and the control of springback is very important in sheet-metal forming. The object of this study is to verify the effects of multi-stage forming process parameters for U-channel-type automobile parts made of UHSS. Finite element analysis is carried out to predict the formability and springback. The main parameters considered for the multi-stage forming process are the die angle, die radius, and punch-forming direction. It is shown that multi-stage forming is very effective for reducing springback, and that a small punch-forming angle and die radius reduce springback, whereas the die angle does not have a large effect.

• The Journal of Korean Obstetrics and Gynecology
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• v.20 no.2
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• pp.124-138
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• 2007

Purpose: This study was conducted to investigate the antimicrobial effects of the interior warming herbs on vaginal microbes. Methods: Staphylococcus aureus, Methicillin-resistant Staphylococcus aureus, Candida albicans and Gardnerella vaginalis were used for vaginitis-induced microbes. Lactobacillus gasseri, Streptococcus spp. and Escherichia coli HB101 were used for normal vaginal florae. And herbs for warming the interior (Zingiberis Rhizoma, Alpiniae Officinari Rhizoma, Aconiti Tuber, Anethi Fructus, Evodiae Fructus, Cinnamomi Cortex Spissus, Caryophylli Flos, Aconiti Tube, Zanthoxyli Pericarpium, Piperis Longi Fructus, Piperis Nigri Fructus) were used in this study. Antimicrobial activities were tested by the change of optical densities (OD) and colony test in vitro. Results: In the results of vaginitis-induced microbes, Anethi Fructus was decreased the OD values on MRSA and Gardnerella vaginalis and Aconiti Tuber was decreased on MRSA. There were no viable MRSA and Gardnerella vaginalis colony forming against Evodiae Fructus, Staphylococcus aureus and MRSA colony forming against Piperis Longi Fructus, Staphylococcus aureus colony forming against Piperis Nigri Fructus and MRSA colony forming against Zanthoxyli Pericarpium. In the results of normal vaginal florae, Zingiberis Rhizoma was decreased the OD values on Streptococcus spp. and all normal vaginal florae were showed viable colony forming against all experimental herbs. Conclusion: According to these results, we can suggest that some kinds of interior warming herbs have antimicrobial effects on vaginal microbes. So there might be needed to make furthermore studies to seek the herbs which have selective antimicrobial effect on pathologic vaginal microbes.

• Journal of the Korean Society for Precision Engineering
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• v.29 no.11
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• pp.1221-1227
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• 2012

As demands on micro-products increase significantly with raising functional integration and increasing complexity, microfoming attracts a lot of attention in the manufacture of micro-products. Since the conventional big forming systems are not adequate to achieve sufficient tolerances of micro-scale parts, it is necessary to reduce the scale of the forming equipment and devices. In addition, understandings on the size effects, which exist in the material behavior and process characterization of microforming processes, need to be expanded. In this study, a miniaturized forming system based on the ball screw and servo motor actuator was developed for the efficient micro-parts production. In addition, tensile tests and cylindrical upsetting experiments were performed to evaluate the performance of the microforming system and to investigate the flow stress and friction size effects in microforming processes.

• Transactions of Materials Processing
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• v.23 no.6
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• pp.376-379
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• 2014

During roll forming a sheet metal is continuously and progressively formed into a product of the required cross-section and longitudinal shape. An example product is a circular tube with a required diameter, wall-thickness and straightness. Roll forming occurs by passing the sheet through a series of forming rolls that are arranged in tandem. Each pair of forming rolls in the roll forming line plays a particular role in obtaining the required cross-section and longitudinal shape in the product. In recent years, that process is often applied to car body parts by automotive industries. In the current study, an optimal model design and proper roll-pass sequences as well as the number of forming rolls and bending angles were used to produce a sill side. The effects of the process parameters on the final shape formed by roll forming defects were evaluated.