• Journal of Soil and Groundwater Environment
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• v.17 no.6
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• pp.82-91
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• 2012

The heavy metal effects on the degradation of fluorene by Sphingobacterium sp. KM-02 was determined in liquid cultures. The results showed that 10 mg/L cadmium, copper, zinc, and lead not only affected the growth of KM-02 with fluorene but also the ability of growing or resting cells to degrade this compound. Growth and fluorene degradation were strongly inhibited by cadmium and copper at 10 mg/L, while the inhibitory effect of zinc and lead at the same concentration or at 100 mg/L were not significant. In contrast, arsenic did not affect degradation or growth, even at very high concentrations of 100 mg/L. Subsequent analyses additionally revealed that concentrations of arsenic remained unchanged following incubation, while those of cadmium and copper decreased significantly.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.374.2-374.2
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• 2016

Volatile organic compounds (VOCs) in the atmosphere are harmful materials which influence indoor air environment and human health. Titanium dioxide ($TiO_2$) is photocatalyst extensively used in degradation of organic compound. To improve the photocatalytic activity in the visible light region, doping with non-metals element or loading noble metals on the surface of $TiO_2$ is generally proposed. In this study, N- doped $TiO_2$ having photocatalytic activity in visible light region was attached noble metal such as Pt, Ag, Pd, Au by coupling method. Catalytic activities of Noble metal coupled $N-TiO_2$ powders were evaluated by the improvement of their photocatalytic activities and the degradation of VOC gas. A UV-Vis spectrophotometer was used to measure the diffuse reflectance spectra of coupled $N-TiO_2$ sample. The photocatlytic activities of as prepared samples were characterized by the decoloration of aqueous MB solution under Xenon light source (UV and visible light). To measure of decomposition VOCs, ethylbenzene was selected for target VOC material and the concentration was monitored under UVLED irradiation in a closed chamber system. Adjusting the initial concentration of 10~12 ppm, to evaluate the removal characteristics by using the coupled $N-TiO_2$.

• Laser Solutions
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• v.13 no.3
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• pp.19-26
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• 2010

In this study, fundamental experiment was conducted with various strength of UHSS (Ultra High Strength Steel) by $CO_2$ laser. And then, butt and lap joint laser welding with boron alloyed steel and Al-Si coated boron alloy steel have been done by changing laser beam feature, existence of gap and existence of coating layer to know welding characteristics of those materials. As a result, in case of fundamental experiment with various strength steel, hardening was found in the weld metal of all tested materials and softening was found at the heat affected zone of SGAFC 1180. In case of laser butt welding of UHSS, mechanical properties was improved by using small laser beam diameter and Al-Si coating layer caused fracture of weld metal. In case of laser lap welding of UHSS, Al-Si coating layer resulted in formation of intermetallic compound at the fusion boundary where fracture occurred. Al-Si coating layer caused lowering mechanical properties of weld metal.

• Journal of the Korean Ceramic Society
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• v.35 no.3
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• pp.219-230
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• 1998

Various interlayer materials have been tested for active metal(Cusil ABA) brazing of Si3N4/S. S316 joint. In general multilayer joint had higher strength(80-150 MPa) and better reliability than monolayered one. The joint with Cu(0.2)/Mo(0.3)/Cu(0.2mm) interlayer showed the highest bending strength of abou 490 MPa and the joint with Cu(0.2)/Mo(0.3mm) interlayer the best reliability (14.6 Weibull modulus). The stresses distributed in joint materials during 4-point bending test were estimated by CAE von Mises analysis; the estimated stresses were In good agreement with the measured data. In multilayer joint Cu was though to reduce the residual stresses induced by the difference in thermal expansion coefficient between the ceramic Mo and metal It apperared that a Cu/Mo was optimum interlayer material for Si3N4/S. S316 joint with high bending strength (420 MPa) and reliability. In addition the various shapes and types of compound were examined by EPMA in joining interface.

• Proceedings of the KIPE Conference
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• 2008.06a
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• pp.646-648
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• 2008

The multi-films of a metallic film and a transparent conducting oxide (TCO, indium-tin oxide, ITO) film were formed on the stainless steel 316 and 304 plates by a sputtering method and an E-beam method and then the external metallic region of the stainless steel bipolar plates was converted into the metal nitride films through an annealing process. The multi-film formed on the stainless steel bipolar plates showed the XRD patterns of the typical indium-tin oxide, the metallic phase and the metal substrate and the external nitride film. The XRD pattern of the thin film on the bipolar plates modified showed two metal nitride phases of CrN and $Cr_2N$ compound. Surface microstructural morphology of the multi-film deposited bipolar plates was observed by AFM and FE-SEM. The electrical resistivity of the stainless steel bipolar plates modified was evaluated.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.29-29
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• 1999

The synthesis of layered structures on the nanometer scale has become essential for continued improvements in the operation of various electronic and magnetic devices. Abrupt metal-metal interfaces are desired for applications ranging from metallization in semiconductor devices to fabrication of magnetoresistive tunnel junctions for read heads on magnetic disk drives. In particular, characterizing the interface structure between various transition metals (TM) and aluminum is desirable. We have used the techniques of MeV ion backscattering and channeling (HEIS), x-ray photoemission (ZPS), x-ray photoelectron diffraction(XPD), low-energy ion scattering (LEIS), and low-energy electron diffraction(LEED), together with computer simulations using embedded atom potentials, to study solid-solid interface structure for thin films of Ni, Fe, Co, Pd, Ti, and Ag on Al(001), Al(110) and Al(111) surfaces. Considerations of lattice matching, surface energies, or compound formation energies alone do not adequately predict our result, We find that those metals with metallic radii smaller than Al(e.g. Ni, Fe, Co, Pd) tend to form alloys at the TM-Al interface, while those atoms with larger atomic radii(e.g. Ti, Ag) form epitaxial overlayers. Thus we are led to consider models in which the strain energy associated with alloy formation becomes a kinetic barrier to alloying. Furthermore, we observe the formation of metastable fcc Ti up to a critical thickness of 5 monolayers on Al(001) and Al(110). For Ag films we observe arbitrarily thick epitaxial growth exceeding 30 monolayers with some Al alloying at the interface, possible driven by interface strain relief. Typical examples of these interface structures will be discussed.

• The Journal of Korean Academy of Prosthodontics
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• v.35 no.2
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• pp.365-372
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• 1997

This study was executed to measure the shear bond strength of Panavia EX and Panavia 21 when the Ni-Cr-Be alloy castings were cemented to the enamel surfaces with these cements. The cast metal plates of Ni-Cr-Be alloy were sandblasted and cemented to acid etched enamel surface with Panavia EX or Panavia 21. Their shear bond strength were measured with Instron Universal Testing machine. Within the limits of this study, following conclusions were withdrawn. 1. The mean shear bond strength were 26.85.7MPa, in Panavia EX and 28.35.2MPa, in Panavia 21. 2. t-Test revealed no statistical significance between two groups(.05 level) 3. Macroscopically, bond failures were revealed compound fracture at metal and enamel interfaces, in cases of both cements, as the cement attached partly on both metal and enamel surface.

• Journal of Korea Foundry Society
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• v.30 no.6
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• pp.241-246
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• 2010

The viscosity of foam metal is necessary to get the pores, but it is difficult to manufacture net-shape foam, because the fluidity decreases by increasing viscosity. In this study, the A356 alloy which has good fluidity and less defect was selected and fabricated to foam metal. To understand about effect of thickening agent on foaming and mechanical properties, quantity of thickening agent was changed. The pore size, porosity and distribution of foam metal were measured by i-solution program. And compression test were performed by UTM. In case of 3.0wt% Ca in thickening agent, it is found that most of foam consist of homogeneous shape, and the growth height had the highest value of 204 mm in the all fabricated foams. The porosity was 93% and compressive strength was 3.1 MPa. In the microstructure, the $Al_2Si_2Ca$ intermetallic compound and Ti were observed. The vickers hardness value rose with increasing viscosity value.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.409-414
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• 1999

The influence of ion beam energy and reactive oxygen partial pressure on the electrical and crystallographic characteristics of transition metal oxide compound(Cr0x) film was studied in this paper. Chromium oxide films were prepared onto the coverglass using Ion Beam Sputter Deposition(1BSD) technique according to the processing conditions of the partial pressure of reactive oxygen gas and ion beam energy. Crystallinity and grain size of as-deposited films were analyzed using XRD analysis. Thickness and Resistivity of the films were measured by $\alpha$-step and 4-point probe measurement. As results, according to the XRD, XPS and resistivity measurement, the deposited films were the cermet type films which has a crystal structure including amorphous oxide(a-oxide) phase and metal Cr phase simultaneously. The increasernent of the ion b m energy during the deposition process happened to decreasernent of metal Cr grain size and the rapid change of resistivity above the critical $O_2$ partial pressure.

• Journal of the Korea Concrete Institute
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• v.18 no.1 s.91
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• pp.57-64
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• 2006

The crack presented in concrete structures causes a structural defect, the durability decrease, and external damages etc. Therefore, it is necessary to improve durability through the effort to control the crack. Fluosilicic acid($H_2SiF_6$) is recovered as aqueous solution which absorbs $SiF_4$ produced from the manufacturing of industrial-graded $H_3PO_4$ or HF. Generally, fluosilicates prepared by the reaction between $H_2SiF_6$ and metal salts. Addition of fluosilicates to cement endows odd properties through unique chemical reaction with the fresh and hardened cement. Mix proportions for experiment were modulated at 0.45 of water to cement ratio and $0.0{\sim}2.0%$ of adding ratio of fluosilicate salt based inorganic compound. To evaluate correlation of concrete strength and adding ratio of fluosilicate salt based inorganic compound, the tests were performed about design strength(21, 24, 27 MPa) with 0.5% of adding ratio of fluosilicate salt based inorganic compound. Applications of fluosilicate salt based inorganic compound to reduce cracks resulted from plastic and drying shrinkage, to improve durability are presented in this paper. Durability was evaluated as neutralization, chloride ion penetration depth, freezing thawing resistant tests and weight loss according reinforcement corrosion. It is ascertained that the concrete added fluosilicate salt based inorganic compound showed m ability to reduce the total area and maximum crack width significantly as compared non-added concrete. In addition, the durability of concrete improved because of resistance to crack and watertightness by packing role of fluosilicate salt based inorganic compound obtained and pozzolanic reaction of soluble $SiO_2$ than non-added concrete.