• Transactions of Materials Processing
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• v.9 no.4
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• pp.339-347
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• 2000

For the successful forming of tailored blank, it is important to control the deformation of the stretch flange mode, which is strong1y dependent upon the location of weld line and blank shape. In order to investigate the effects of tailored blank design factors on the stretch flange forming, we made the model die which can simulate stretch flange mode. Taguchi method was employed to analyze the sensitivity of blank design factors for the forming of tailored blank. From the results of experiment S/N ratios were calculated and using Variance Analysis, significance of parameters and optimal condition of each factors were extracted. Based on these analyses, the weld line height and the strength ratio and the arc center height were selected as effective parameter. The analysed result was practically applied for Side outer panel stamping process.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.575-576
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• 2006

Recently, the demand of high-productivity injection mold increases since the consumption of packaging grows in the world. Stack mold is composed of more than two molds and it has very high productivity and economic efficiency. In advanced country, stack mold which has $4Level{\times}96cavity$ was developed already but, in occasion of domestic mold industry, there is no study of stack mold. In this study, stack mold which has $2Level{\times}4cavity$ is developed for securing the technique of manufacturing high-productivity mold.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.10a
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• pp.23-27
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• 2005

Generally, when the injection molds are made in advanced nations, the improvement of a quality and production rate is obtained by using CAE. In this paper, the methodology which is possible to reduce the cycle time of injection molding process is studies by using the cooling analysis with CAE(Moldmax). In case of changing the cooling system design with the analysis result of CAE, the manimum reduction of the cycle time runs into 30 percent. Finally, the average reduction of the cycle time is 17.8 percent.

• Transactions of Materials Processing
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• v.1 no.1
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• pp.75-86
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• 1992

Coated sheet steels have been increasingly used in automotive industry for improving corrosion resistance. One of the arised concerns is frictional behavior of coated sheet steel in stamping process. But analyses of the frictional behavior are complex and difficult. A tensile strip test has been developed for evaluating friction under the condition which simulate the stretching of sheet. Tests are conducted under different die radius and lubrication conditions. Electro-galvanized steel sheets show a lower coefficient of friction than bare steel sheets whose coated layers have been chemically removed. The coefficients of friction are independent of die radius.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.5 no.4
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• pp.79-85
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• 2006

Multi-filament hydrostatic extrusion was developed as a fine wire manufacturing process and wire forming experiments were conducted. Also, single wire stretch forming process was proposed in the possibility of obtaining long wire with constant cross-section. In the multi filament extrusion since the workpiece, die and forming facility are in the macro forming circumstance, fine wire and fine hole structure with less than a few micrometer can be easily obtained. Although stretch forming does not use a die in order to avoid the friction problem between the workpiece and the die, it is necessary to have high level of technology to maintain cross-sectional shape and measure in longitudinal direction.

• Transactions of Materials Processing
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• v.31 no.1
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• pp.23-28
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• 2022

Although the hole expansion test is currently the most commonly used method to evaluate the stretch flangeability of HSS, it has been criticized due to its poor repeatability and reproducibility for test results. This paper focuses on the development of a new measurement method to investigate the stretch flangeability of HSS. Two materials (DP590, DP980) were investigated with a hole expansion test and a developed test method. Test results showed that the developed test method could be used as one stretch flangeability test to help identify relevant parameters of the shearing process to avoid edge cracking.

• Transactions of Materials Processing
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• v.32 no.2
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• pp.61-66
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• 2023

The quality of the sheared surface affects the stretch flangeability of steel sheet. The quality of sheared surface is influenced by several process factors such as die clearance, shape of cutting edge, use of counter punch, and shear. In this paper, the influence of these shearing process factors on the stretch flangeability of the HSS (DP980) was analyzed through a shearing and a stretch flangeability test. When the die clearance was 10%, the effect of these shearing process factors on the stretch flangeability was the greatest, and the use of an acute angle blade was found to be more advantageous in the stretch flangeability than a right angle blade. It was found that the stretch flangeability was improved when active bending was applied during shearing.

• The Korean Journal of Nuclear Medicine
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• v.31 no.4
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• pp.427-432
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• 1997

Re-188 is useful candidate for therapeutic radionuclide because it has a physical half life of 17 hours, contains beta emissions suitable for therapy(maximum energy 2.12MeV) and emits a gamma ray that is suitable for quantitative diagnostic scanning(155keV). To use Re-188 as a radionuclide compound of angioplasty balloon radiotherapy, we investigated the labelling method and biodistribution of Re-188-DTPA We postulated that labeled Re-188-DTPA is preferable because it would be excreted via urinary system more easily than other compounds. To label Re-188 with DTPA, 1ml of 222MBq(6mCi) of Re-188 was added to DTPA solution(DTPA 20mg, $SnCl_2{\cdot}2H_2O$ 10mg, pH 3.5) and boiled at $100^{\circ}C$ for 120min in water bath. pH was adjusted to 5 with 2.3% sodium acetate. Labeling efficiency was measured using TLC-SG(acetone, saline). We evaluated biodistribution of Re-188-DTPA in sacrificed mice at 10 and 60 minutes after injection. We acquired images of kidneys, and drew time-activity curves in normal dogs and rats and calculated Tmax and Tl/2 in rats. The labelling efficiency was 95.7% on average. Labelling of Re-188-DTPA was.stable(90% after 5hours) in vitro at room temperature. According to time-activity curves of dogs and rats, it took 15 to 20 minutes after injection for Re-188-DTPA to be washed out through kidneys. In conclusion, Re-188-DTPA was successfully labeled, Re-188-DTPA was stable in vitro and was excreted early via kidneys in animals. We could recommend Re-188-DTPA as radionuclide of potential use in angioplasty balloon radiotherapy.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.30 no.3
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• pp.225-231
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• 2008

This study evaluated whether there is a difference between a conventional titanium distraction device and a TiN-coated device in terms of implant osseointegration after horizontal distraction osteogenesis in narrow alveolar bone. Four adult mongrel dogs, each weighing $9{\sim}10kg$, were used in this study. The lower premolars were extracted and horizontal distraction was performed with conventional titanium distraction devices (group 1) or TiN-coated devices (group 2). After an 8-week consolidation period, the implants were installed, and the dogs were sacrificed after another 8 weeks. The osseointegration around the implants was evaluated histomorphologically. There was one failure in experimental group 1 because of fracture of the device. Direct bone contact was achieved and there were no significant differences between the control group and experimental groups 1 and 2 in terms of osseointegration around the implants at 8 weeks. In summary, intraoral distraction osteogenesis is a good option for augmenting severely atrophied alveolar ridges, and the TiN-coated device may be useful because of its advantages, which include surface hardness, corrosion resistance, and reduced bacteria.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.27 no.3
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• pp.159-167
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• 2021

The need for biodegradable plastic continues to increase, improvement of physical properties is necessary for actual use in the market. In this study, composite film was produced by adding peroxide additives to bioplastic according to concentration to investigate changes in the melt index, elongation, morphology, and TGA of the composite film. The addition of peroxide compatibilizer showed superior elongation of film and TGA compared to those of control. The added amount of compatibilizer affected the extrusion process, and it was revealed that adding an appropriate amount of peroxidizer is important. Analysis of the composite film's morphology revealed a heterogeneous dispersion sequence due to different rates of crystallization depending on the resin, and surface physical properties were best in the group added with 4% peroxide. The results above showed that the test group added with 4% peroxide compatibilizer was superior in the production of composite biodegradable film.