• Proceedings of the Materials Research Society of Korea Conference
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• 2010.05a
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• pp.40.1-40.1
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• 2010

Recently high strength steel sheets with high formability for automotive parts have been being developed to meet the demands for passenger safety and weight reduction of car body. Among these high strength steels, dual-phase steels are regarded as one of the attractive steels due to their excellent mechanical properties including high strength and ductility. However, to be successfully applied to automotive parts they should be corrosion resistant enough to satisfy the required quality of car maker. This also requires their feasibility for galvannealed production including hot dip galvanizability. In this study has been placed on understanding the effects of heat-treatment(austenizing and isothermal treatment) on the microstructures and mechanical properties of a 0.06C-0.03Si-2.0Mn high strength steel for cold forming. The microstructure and phase distribution were examined with eth aids of SEM, EBSD, TEM etc.. Through the study the production of 590MPa grade DP GA steels with good formability and galvaniability were shown to be possible.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.281-286
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• 2003

This study presents the results of investigations with the object to determine the resistance to sulfuric acid for some kinds of cements containing 0%-70% of slag powder. The specimen is immersed 5% H$_2$SO$_4$ solution after the 28th days, is measured chemical analysis, XRD, SEM and etc after the immersed 35th days and is measured the erosion depth after the immersed 168th days. The results of experiment are founded out that alumina cement containing slag power was excellent at a point of view for the sulfuric acid resistance and the erosion depth was suitable to the evaluated method of the sulfuric acid resistance in the stead of the evaluated method of weight loss.

• Proceedings of the KSME Conference
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• 2000.11a
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• pp.219-224
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• 2000

A research for development of composite body panel is in progress for lightening tare. Low specific weight LPMC (Low pressure molding compound) has advantages such as lightweight and resistance to dent and corrosion. In this study, tensile, bending and impact tests for the LPMC and SPRC35 (High tension steel plate) were carried out and compared. Although mechanical properties of SPRC35 are better than the LPMC, the LPMC satisfies basic requirements for car body panel. The high temperature exposed LPMC were degraded due to fiber-matrix debonding and deterioration of resin.

• Proceedings of the KWS Conference
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• 2007.11a
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• pp.363-365
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• 2007

Titanium and its alloys have excellent corrosion resistance, high strength to weight ratios and high temperature creep properties, which make them using many various fields of application. Responding to these needs, welding processes for titanium are also being used including TIG, MIG, resistance welding, plasma arc welding, diffusion welding, electron beam welding and laser welding. In this study, It is possible to get sound beads without humping bead and spatter with the decrease of peak power according to increase of pulse width and change of welding speed for heat input control at pulsed Nd:YAG laser welding of titanium plates for Lap welding.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2001.04a
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• pp.189-196
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• 2001

Recent days composite bridge deck is gaining attraction due to many advantages such as light weight, high strength, corrosion resistance, and high durability. In this study, composite sandwich deck models of hat, box, and triangular section type were fabricated by VARTM process. For those models, three point flexural test was carried out both in strong and weak axis. The experimental results are compared with each other to determine efficient section type. Also finite element analysis was performed and compared with experiments to verify analysis model. It has been demonstrated that composite sandwich deck can be used as bridge deck in the new construction and rehabilitation work.

• Korean Journal of Materials Research
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• v.23 no.2
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• pp.112-115
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• 2013

One of the most important characteristics of Mg alloys is the high ratio of strength to weight. This is why there is a high demand for applications with these alloys in the transportation industries to reduce the fuel consumption and to save energy. In addition, magnesium (and its alloys) is of considerable interest as a structural material, especially in the aerospace and automotive industries thanks to its low density. However, its major drawback is its high sensitivity to corrosion. Therefore, its use requires the application of a surface treatment. This study used a die-casted AZ91D Mg alloyand all the samples were annealed (in $120^{\circ}C$). The surface microstructure and phase distribution in thin-walled AZ91D magnesium components cast on a hot-chamber die-casting machine were investigated by optical microscopy and scanning electron microscopy. The reflectance differences in the bulk state comparison with the annealing state are caused by hydrogenation presence of the Mg layer under an oxidation surface layer.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2016.11a
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• pp.115.2-115.2
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• 2016

Al alloys are being used widely for automobile, aerospace and mechanical components because of their high strength ratio to weight. However, still they suffer from abrasion or corrosion owing to insufficient resistances to friction or mechanical impact and chemical attack. Plasma electrolytic oxidation (PEO) method is one of the promising surface treatment methods for Al alloys which can render better hardness than aluminum anodic oxide (AAO) films prepared by conventional anodizing method in acidic solutions. In this presentation, some basic nature of PEO film formation and growth process on Al alloys will be presented based on the experimental results obtained and discussed in view of dielectric breakdown and reformation and the role of various anions in film breakdown and reformation of PEO films.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05b
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• pp.181-184
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• 2005

When concrete structures are exposed under marine condition for a long time, the steel in concrete is corroded due to the ingression of chlorides in the seawater. Because the damages of corrosion resulting from the chloride ion are very serious, many researches have been performed. However evaluation on chloride attack of concrete structures are not fully examined, recently. Therefore, the objective of this paper is to study the applicability of colormetric method. For the purpose of this, reaction mechanism of colormetric method were investigated, and the colormetric method is applied for marine concrete structures. According to the test results, the diffusion coefficient by colormetric method is not so different to the value of chloride concentration profile test. It is confirmed that the colormetric method is useful tool for estimating the chloride of concrete structures in situ. The average chloride amount of colored parts indicates 0.9kg/$m^{3}$ per concrete unit weight.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05b
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• pp.325-328
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• 2005

Fiber Reinforced Polymers are recognized as the alternative materials for solving the problem due to the excellent corrosion-resistant property, light-weight and higher strength than steel. Glass fiber is superior to other fibers from the economical point of view but the mechanical property is not. For this reason, researches to improve the mechanical property of glass fiber reinforced polymer rebar has been conducted and it emerged as a solution to make the bar as a hybrid type with carbon fibers. This paper presents results of experimental program to investigate the scattering effectiveness of carbon fibers in glass FRP bar.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2000.10a
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• pp.67-74
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• 2000

Recently western countries are now beginning to use ACM (Advanced Composite Material) in the construction industry. Compared with conventional construction materials, ACM possesses many advantages such as light-weight, high-strength, corrosion resistant properties, etc. Among other fabrication process of ACM, pultrusion is one of the promising one for civil infrastructure application. In this paper, the structural characteristics of pultruded glass fiber reinforced composite structural member of angle and tube type were studied. Experiments for compression were performed for those members along with finite element buckling analysis with ABAQUS. The experimental and analytic results were compared each other and they were also compared with predicted values using coded formulae.