• Proceedings of the Korea Concrete Institute Conference
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• 2005.05a
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• pp.371-374
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• 2005

The research reported in this paper provides the test results of eleven reinforced concrete beams strengthened with FRP composites. Three parameters were considered in this investigation: the amount of FRP composites, the types of bonding schemes(continuous sheets or strips), and the material types of FRP composites (Carbon or Glass). The experimental results indicated that because the rupture strain of FRP composites was relatively higher that the yield strain of steel bars, the RC beams strengthened with FRP composites failed due to concrete crushing before the FRP composites arrived at its rupture strain. The compatibility-aided truss model showed reasonable agreement between the predicted and experimental shear stress-strain curves of the beams throughout the entire loading history.

• Corrosion Science and Technology
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• v.9 no.2
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• pp.87-91
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• 2010

It is pointed out that non-wetting behavior of liquid Zn alloy occurs on high-tensile strength steels, which usually contain Si and Mn. There have been a lot of investigations to improve the above wettability of liquid Zn alloy with steels containing Si and Mn. Although those studies evaluated the wettability qualitatively by observation of the surface of steels galvanized by Zn or exfoliation test of Zn with substrate steels and so on, it is required to evaluate the wettability of liquid Zn with steels by measuring contact angle, work of adhesion, spreading velocity etc. which are usually used to assessment of general wetting behavior. In the present work, we evaluated the wettability of liquid Zn with steels containing Si and Mn by applying a sessile drop method to measure the change in contact angle and diameter of liquid Zn droplet wetted on steels.

• Steel and Composite Structures
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• v.12 no.2
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• pp.149-166
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• 2012

This paper presents an experimental investigation on the performance of 2.5 m long reinforced concrete (RC) T-beams strengthened in shear using epoxy bonded glass fibre fabric. Eighteen (18) full scale, simply supported RC T-beams are tested. Nine beams are used as control beam specimens with three different stirrups spacing without glass fibre reinforced polymer (GFRP) sheet and rest nine beams are strengthened in shear with one, two, and three layers of GFRP sheet in the form of U-jacket around the web of T-beams for each type of stirrup spacing. The objective of this study is to evaluate the effectiveness, the cracking pattern and modes of failure of the GFRP strengthened RC T-beams. The test result indicates that for RC T-beams strengthened in shear with U-jacketed GFRP sheets, increase the load carrying capacity by 10-46%.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2011.05a
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• pp.171-171
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• 2011

Atmospheric pressure- plasma enhanced chemical vapor deposition(AP-PECVD)Processes are recognized as promising and cost effective methods for wide-area coating on sheets of steel, glass, polymeric web, etc. In this study, $SiO_xC_y$ thin films were deposited by using AP-PECVD with a dielectric barrier discharge(DBD). The characteristic of $SiO_xC_y$ thin films were investigated as afunction of the HMDSO/O2/He flow rate. And the moisture permeability of $SiO_xC_y$ thin films was studied. The $SiO_xC_y$ thin films were characterized by the Fourier-transformed Infrared(FT-IR) spectroscopy and also investigated by X-ray photo electron spectroscopy(XPS), Auger Electron Spectroscopy(AES). The moisture permeability of $SiO_xC_y$ thin films was investigated by $H_2O$ permeability tester Detailed experimental results will be demonstrated through th present work.

• Proceedings of the KIEE Conference
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• 2005.10c
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• pp.101-103
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• 2005

전기강판으로 제작되어진 전기기기의 보다 정확한 수치적인 해석을 위해서는 회전자계(Rotating magnetic flux)에 따른 전기강판의 정화한 자계특성 측정이 필요하다. 이 논문에서는 개발되어진 2방향 자계인가 형 Single sheet tester를 이용하여 회전자계에 따른 전기강판의 자계특성을 측정하였다. 실험을 통하여 등방성 시료와 방향성 시료에 대하여 각각 1.6[T] 와 1.2[T]까지 측정할 수 있었다.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1023-1025
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• 2005

이방성 전기강판으로 제작되어진 전기기기의 보다 정확한 수치적인 해석을 위해서는 이방성 전기강판의 인가자계방향에 따른 정확한 자계특성 측정이 필요하다. 이 논문에서는 개발되어진 2방향 자계인가 형 싱글시트 테스터를 이용하여 이방성 전기강판의 인가자계방향에 따른 자계특성을 측정하였다. 실험을 통하여 방향성 전기강판의 rolling direction과 transverse direction에 대하여 각각 1.8[T]와 1.3[T]까지 측정할 수 있었다.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.05a
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• pp.320-323
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• 2008

In this study, a macroscopic approach was carried out to gain insight into the bending mechanism of metallic sandwich plates. Shear force-punch stroke curves for various clearances were analytically derived for mild steel (CSP 1N) sandwich plates with the total thickness of 3 mm and 0.5 mm face sheets. As the clearance increases, shear force of the inner structures and sensitivity of punch stroke decrease. These data are useful to derive a criterion of judgment for core shear failure and de-bonding failure during U-bending.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.05a
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• pp.396-399
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• 2008

A visco-plastic self-consistent (VPSC) polycrystal model has been applied to simulate texture simulation and anisotropic properties of DP steels during deep drawing process. In order to evaluate the strain path during deep drawing, a steady state was assumed in the flange part of deep drawn cup. The final stable orientations were strongly dependent on the initial location in the blank. The evolution of anisotropy of DP steel sheets has been demonstrated through comparison of plastic strain rate vector at the different plastic strain levels.

• Journal of the Korean Society for Precision Engineering
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• v.7 no.2
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• pp.28-38
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• 1990

The study is concerned with the theoretical and experimental investigation of axisymmetric fluid pressure-driven hydroforming of sheet metal by forming over the die cavity. The rigid-plastic finite element method is employed to calculate the stress and strain distribution. The effect of blank size and die radius is also studied in the finite element analysis. Experiments are carried out for hydroforming of cold-rolled steel sheets under various process conditions. The computational results are compared with the experimental results for the forming pressure vs. pole displacement relations and strain distributions. Comparison has shown that theoretical predictions by the finite element method are in good agreement with the experiment with the experimental observations. Thus, it is shown that the rigid-plastic finite element method is effectively used in the analysis of axisymmetric fluid pressure-driven hydroforming process.

• Journal of Surface Science and Engineering
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• v.34 no.4
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• pp.281-288
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• 2001

Phosphating treatments have been performed to improve paint adhesion and corrosion resistance of zinc and zinc alloy coated steels for a long time. In this work, the effects of the addition of chelate compound were studied to improve the stability of surface conditioning solution and properties of zinc phosphate films. The coalescence of colloidal Ti-compound and extraneous charged particles (alkaliearth metal cation such as $Mg^{2+}$ , $Ca^{2+}$ ) were suppressed by using a surface conditioning solution with chelate compound. Therefore, after surface conditioning solution containing chelate compound was left standing for one week at room temperature, the formation of a white sediment was decreased comparing to surface conditioning solution without chelate compound. The crystal size of phosphate film was fine and the whiteness value of phosphated zinc coated steel sheets was also high without the decrease of corrosion resistance and anti-patina. It was very effective to use chelate compound improving the stability of surface conditioning solution.