• Design & Manufacturing
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• v.6 no.2
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• pp.90-95
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• 2012

The sheet metal forming proceccing is very important and indispensable in the automotive industry because the accuracy of prsee worked parts is directly related to the automotive quality. But when making mold it is difficult and expensive to modify mold. mold design technology is a critical technology in press plastic working. When design the mold there are lots of variables in press plastic working according to worked material, mold materials, conditions of heat treatment, clearance and so on. Abrasion of mold depends on these kind of conditions and sheared surface which is crucial for quality of product also depends on them. In this study, we conduct research on abrasion loss of mold according to 8, 10 and 12% of clearance for thickness of 1.0mm of worked material out of mold design variables of the products whose worked materials are high carbon steel and carbon tool steel by a practical experiment and perform a comparative evaluation of difference of abrasion loss mold with the alloy tool steel (STD11) and Tungsten Carbide (WC).

• Proceedings of the KWS Conference
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• 2002.10a
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• pp.714-719
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• 2002

In The Great Hanshin-Awaji Earthquake, the general yield brittle fractures were observed in beam-column connections of steel building frames. Among many influencing factors which affect the general yield brittle fracture, it can be considered that fracture toughness has substantial effects. Some studies are making clear the required toughness for the base metal and the weld metal, but general values are not proposed. Moreover, it seems that it is also important to pay attention to the toughness decrease in the weld heat affected zone (weld HAZ), because the toughness decrease occurs in the HAZs of mild steel. In this paper, the relationship between toughness of simulated HAZs of "the rolled steels for building structures (SN)" and the weld heat-input limit of the SN steel are investigated, in an attempt to provide the required toughness for HAZs. The relationships between the increase of the hardness value and toughness, and changes of microstructure after weld heat-input are also discussed. The main results are summarized as follows. 1) The SN400B can keep its toughness at higher heat-inputs compare to the SN490Bs. 2) The steel grade, which becomes harder than other steel grades at the same heat-input, has smaller absorbed energy and smaller limit of heat-input. 3) The weld heat-input limit of the SN400B and the SN490B are proposed separately for some required toughness values.

• Computers and Concrete
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• v.21 no.5
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• pp.539-546
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• 2018

Making a transverse opening in concrete beams in order to accommodate utility services through the member instead of below or above of that, sometimes may be necessary. It is obvious that inclusions of an opening in a beam decreases its flexural and shear strengths. Fabricated steel bars are usually used to increase the capacity of the opening section, but details of reinforcements around the opening are dense and complex resulting in laborious pouring and setup process. The goal of this study was to investigate the possibility of using steel fibers in concrete mixture instead of complex reinforcement detailing order to strengthen opening section. Nonlinear finite element method was employed to investigate the behavior of steel fiber reinforced concrete beams. The numerical models were validated by comparison with experimental measurements tested by other investigators and then used to study the influence of fiber length, fiber aspect ratio and fiber content on the shear performance of SFRC slender beams with opening. Finally, it was concluded that the predicted shear strength enhancement is considerably influenced by use of steel fibers in concrete mixture but the effect of fiber length and fiber aspect ratio wasn't significant.

• Journal of Korean Association for Spatial Structures
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• v.10 no.4
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• pp.103-111
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• 2010

Most of apartments, buildings and venues today were built without consideration of earthquake when there was no mandate for an earthquake-resistant design. To reinforce such construction, a compressive method of steel plate is widely used. In spite of continuous researches on the compressive method of steel plate, it has not been systematically evaluated for the effects of various factors affecting the structural behavior of beam and its effect on intensity and failure. Therefore, this study aims to determine the flexural behavior of beam due to Anchor conjugation through the materials obtained by making load test for the Anchor conjugated steel plate while the anchor is set as variable.

• Corrosion Science and Technology
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• v.23 no.2
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• pp.139-144
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• 2024

Recently, due to the rapid spread and continuation of COVID-19, customer demand for health and hygiene has increased, requiring the development of new products that express antiviral and antibacterial properties. In particular, viruses are much smaller in size than bacteria and have a fast propagation speed, making it difficult to kill. POSCO has developed eco-friendly PCM color coated steel sheets with excellent antiviral properties by introducing inorganic composite materials to the color coating layer on the surface of Zn-Al-Mg alloy plated steels. The virus is not only destroyed by adsorption of metal ions released from the surface of the coating film, but is also further promoted by the generation of reactive oxygen species by the reaction of metal ions and moisture. As a result of evaluating the developed products under the International Standard Evaluation Act, the microbicidal activity was 99.9% for viruses, and 99.99% for bacteria and 0% fungi. In particular, excellent results were also shown in the durability evaluation for life cycle of the product. The developed product was applied as a wall of school classrooms and toilets and ducts for building air conditioning, resulting in excellent results. Developed products are being applied for construction and home appliances to practice POSCO's corporate citizenship.

• Design & Manufacturing
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• v.18 no.2
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• pp.23-28
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• 2024

The automobile industry is a wide range of related industries, including parts manufacturing and vehicle assembly, press processing is an essential element in making automobiles. Press processing is a processing method for metal sheets that has relatively high dimensional and shape precision and is suitable for mass production. It refers to processing by attaching a special tool, a mold, to a press machine. Recently, the automobile industry is attempting to reduce the weight of automobiles in order to reduce carbon emissions due to global warming, and the use of high-strength steel sheets, which are lighter than general structural steel sheets, is a natural trend. Shear processing is required to use high-strength steel, and the shape of the shear surface created by shear processing has a significant impact on the quality of the automobile. Therefore, various methods are being attempted to improve the share surface during shear processing. Among them, shaving processing is a method of shearing the primary shearing area again, and it is difficult to obtain an accurate answer because complex deformation occurs in the microscopic shear area. Therefore, in this study, the effect of machining allowance on shaving processing was analyzed using the finite element method using high-strength steel plate (SPFH590), and the differences were compared and examined through actual experiments under the same conditions.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.10a
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• pp.162-168
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• 2008

Recently surround molding parts using stainless steel are applied to international and domestic high grade vehicles, but there are great difficulties in die manufacture because of springback and twist after forming process. To solve this problem, finding the method of reduction springback is very important. In this study the springback which might happen during making a die that produce stainless steel surround molding parts is predicted and the geometry of die which satisfy the tolerance between product and panel after forming and springback will be suggested using automatic die compensation module.

• Journal of Welding and Joining
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• v.25 no.2
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• pp.55-61
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• 2007

Flash butt weldability of 590MPa dual phase steel is carried out under micro metallographical examination and macro mechanical property tests. The objective of present study is to investigate the cause that brings on bond line fracture, and is to improve mechanical properties of the flash butt welded joint. The joint of flash butt welding has a superior tensile property, but has bad formability due to oxide formed at bond interface. The HAZ softening in the weld joint does not show. It was found that mechanical properties were increased with optimizing welding parameters and making application of oil dripping and post-weld heat treatment.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.1
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• pp.125-132
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• 2002

Recently, ULSAB(Ultra Light Steel Auto Body) concept is getting more attention due to various benefits in automotive body design. One of the ULSAB efforts is making a door with TWB(Tailor Welded Blanks). In TWB, two or more patches of steel panels are welded together before stamping process. In this research, domains and thicknesses of the patches in a front door structure are determined by a series of optimization schemes composed of topology, size and shape optimization and DOE(Design of Experiments) scheme. A door is designed to have better performances compared to exiting structure considering static stiffness and natural frequency. The final design is discussed and compared to the existing design.

• Proceedings of the KWS Conference
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• v.43
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• pp.150-152
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• 2004

This study was aimed at evaluation of residual stress of steel pipe structures. The production process of pipes was complex (at first bending was done by roll forming or press forming and welding was final process of making of steel pipes). So there could be effected high residual stresses in steel pipes. In order to evaluate the changes of residual stress the locations of measurement were selected carefully. Measurements of residual stress were done for various kinds of pipes (shapes in circular and square). For the evaluation of residual stress, hole-drilling method (ASTM E837 was applied. The results showed that along the weld Eine high tensile stress were measured as effected, and high tensile stresses were measured where large plastic deformation developed. Through these efforts, experimental results could be more effectively assisted by numerical method.