• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2008년도 춘계 학술논문 발표대회
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• pp.21-25
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• 2008

It is the aim of this study to investigate the fire resistance design Guidelines for high-strength concrete structure for example compressive strength more than 40Mpa. It is well know that explosive spalling due to fire attack of high strength concrete is related to concrete failure. so, the purpose of this study introduce the fire A Studty on the Fire Resistance Design Guidelines for High-Strength Concrete Structures of AIK for the response of explosive spalling of high strength concrete.

• Journal of Welding and Joining
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• 제19권4호
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• pp.379-383
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• 2001

Resistance spot welding has been widely used in the sheet metal joining processes because of low cost, high productivity and convenience. Recently, automobile and aerospace industries are trying to replace partly steel sheets with aluminum alloy sheets. But in the case of dissimilar materials, to apply resistance spot welding has been known to be very difficult owing to the effect of melting temperature. On this study, an effort was made to apply spot welding of dissimilar sheet metals, 2024 aluminum alloy and zinc coated steel sheet, evaluate the spot weld quality with tensile-shear strength test and nondestructive evaluation technique, C-scan image methodology. In this study results, as the current below 11 kA, melting of materials is not achieved well. Also as the current exceeds to 13.5 kA, the more spatters happen at welded zone and tensile-shear strength lowered. So, the feasibility of C-scan image technique proposed in the study is found to be suitable evaluation method for resistance spot weldability.

• 반도체디스플레이기술학회지
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• 제10권4호
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• pp.43-46
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• 2011

In this study, we investigated the effects of the post Ar plasma treatment at different RF powers for various durations on electrical, structural, and optical properties of relatively thin Al-doped zinc oxide films. The sheet resistance was observed to decrease rapidly for the first 5min, beyond which the resistance apparently saturated. As the RF power increased, the grain size and the interplanar distance of (002) planes also increased. The observed decrease in sheet resistance was stated to be a consequence of Al and/or Zn interstitials as well as grain growth. It was also found that Ar plasma treatment increased the transmittance of Al-doped zinc oxide films in most of the visible light range below the blue light.

• Journal of Microbiology
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• 제44권3호
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• pp.255-262
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• 2006

Titanium and its alloys are technically superior and cost-effective materials, with a wide variety of aerospace, industrial, marine, and commercial applications. In this study, the effects of titanium ions on bacterial growth were evaluated. Six strains of bacteria known to be resistant to both metal ions and antibiotics were used in this study. Two strains, Escherichia coli ATCC 15489, and Pseudomonas aeruginosa ATCC 10145, proved to be resistant to titanium ions. Plasmid-cured p. aeruginosa resulted in the loss of one or move resistance markers, indicating plasmid-encoded resistance. The plasmid profile of p. aeruginosa revealed the presence of a 23-kb plasmid. The plasmid was isolated and transformed into $DH5{\alpha}$. Interestingly, the untransformed $DH5{\alpha}$ did not grow in 300 mg/l titanium ions, but the transformed $DH5{\alpha}$ grew quite well under such conditions. The survival rate of the transformed $DH5{\alpha}$ also increased more than 3-fold compared to that of untransformed $DH5{\alpha}$.

• 한국해양공학회지
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• 제10권2호
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• pp.98-105
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• 1996

A method is proposed to evaluate the elastic-plastic fracture resistance curve only with load displacement records without the crack length measurement in CT specimen. This method is based on the idea that the effect of plastic deformation and the crack growth can be measured only by using a load-displacement record. If we know the reference-load curve representing the hardening of specimen, then the crack extension can be calculated by the elastic compliance determined from the load ratio. The results of this proposed method were compared to those of the elastic-plastic fracture resistance curve for the ASTM standard unloading compliance method. The experimental results for two kinds of ductile materials showed that the proposed method well simulates the material J-R curves. This method is currently applied for CT specimens. but it can be extended to the other specimen geometries.

• Corrosion Science and Technology
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• 제15권6호
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• pp.259-264
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• 2016

With a specially designed electrochemical cell, the changes in impedance behavior for Inconel 600 and aluminide diffusion coatings under molten sulfate film with thermal cycles (from $800^{\circ}C$ to $350^{\circ}C$) were monitored with electrochemical impedance measurements. It was found that corrosion resistance for both materials increased with lower temperatures. At the same time, the state of molten salt was also monitored successfully by measuring the changes in impedance at high frequency, which generally represents the resistance of molten salt itself. After two thermal cycles, both Inconel 600 and aluminide diffusion coatings showed excellent corrosion resistance. The results from SEM observation and EDS analysis correlated well with the results obtained by electrochemical impedance measurements. It is concluded that electrochemical impedance is very useful for monitoring the corrosion resistance of materials under molten salt film conditions even with thermal cycles.

• Steel and Composite Structures
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• 제27권4호
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• pp.401-416
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• 2018

Composite beams with web openings are vulnerable to Vierendeel bending failure. The available methods provide quite conservative estimates of Vierendeel bending resistance. An alternative design method to compute the resistance was proposed in this study, based on quadratic nonlinear interactions of normalized shear force, axial force and Vierendeel bending moment. The interactions of the top and bottom Tee section must satisfy mutual conditions to prevent the Vierendeel failure. The normalized shear force and Vierendeel bending moment of the composite part were used instead in the top Tee interaction. The top Tee axial force was computed based on force equilibrium. Based on a rigid-plastic model, the composite resistance is estimated using an effective slab width of the vertical shear resistance. On using the proposed method, nonlinear reductions due to shear loads and axial forces are not required, in contrast to prior methods. The proposed method was validated against experiments from literature. The method limitations and accuracy as well as the Vierendeel behavior were investigated by finite element simulations, with varied composite beam parameters. The proposed design loads are less conservative than earlier estimates and deviate less from the simulations.

• 한국표면공학회지
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• 제31권4호
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• pp.209-216
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• 1998

It is well knownthat electroledd plating is the desirable surface treatment method which is being widely used to all kinds of material such as requiring corrosing resistance, wear resistance and conductivity, especially nonconductivity materials' surface plating. However, it is suggested that there are some problems that must be solved, for exaple, rate of plating, corrosion resistance, thickness of plating film etc. Therefore in this paper, when electroless nickel plating was performed on the PZT(Pb(Zr,Ti))with varying of solution composition such as NaOH, and $H_2NCH_2COOH$, the effect of the rate of plating and corrosion resistance were investigated.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 추계학술대회 논문집 학회본부
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• pp.457-461
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• 1996

An optimum design methodology for the power MOSFET's with a predetermined mask is proposed and verified by comparing with the results of MEDICI simulation and the data of commercially available devices. Optimization is completed by determining a doping concentration and a thickness of the epitaxial layer which satisfy a specific voltage and current rating requirements as well as a minimum on-resistance for the mask set. The commercial HEX-1 mask set with a die area of $40.4{\times}10^{-3}\;cm^2$ and a T0-220 package has the on-resistance of $1.5{\Omega}$ at 200 V/2.5 A rating while the M-1 mask from this study exhibits $0.6{\Omega}$ on-resistance at 200 V/6 A. The 60 % reduction in the on-resistance and 58 % enhancement in the current rating have been obtained by the proposed method.

• 한국미생물·생명공학회지
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• 제40권3호
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• pp.215-219
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• 2012

Although the antioxidant capacity of carotenoids and their role in regulating membrane fluidity have been well studied, their ability to confer resistance to hypoosmotic shock is poorly understood. In this work, we analyzed the effect of a mixture of carotenoid pigments obtained from an Antarctic microorganism belonging to the genus Pedobacter on liposomal resistance to hypoosmotic conditions. Intercalation of pigments into liposomal structures resulted in an improvement of membrane resistance by decreasing the percentage of calcein released in comparison to that by liposomes without pigments. Due to these properties, such pigments could be useful for biotechnological applications.