• Korean Journal of Materials Research
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• v.27 no.10
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• pp.513-517
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• 2017

An optimum route to fabricate a hybrid-structured W powder composed of nano and micro size powders was investigated. The mixture of nano and micro W powders was prepared by a ball milling and hydrogen reduction process for $WO_3$ and W powders. Microstructural observation for the ball-milled powder mixtures revealed that the nano-sized $WO_3$ particles were homogeneously distributed on the surface of large W powders. The reduction behavior of $WO_3$ powder was analyzed by a temperature programmed reduction method with different heating rates in Ar-10% $H_2$ atmosphere. The activation energies for the reduction of $WO_3$, estimated by the slope of the Kissinger plot from the amount of reaction peak shift with heating rates, were measured as 117.4 kJ/mol and 94.6 kJ/mol depending on reduction steps from $WO_3$ to $WO_2$ and from $WO_2$ to W, respectively. SEM and XRD analysis for the hydrogen-reduced powder mixture showed that the nano-sized W particles were well distributed on the surface of the micro-sized W powders.

• Journal of the Korean institute of surface engineering
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• v.27 no.2
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• pp.65-73
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• 1994

Effects of deposition parameter on the ionic conductivity and structural change of the Lithium borosili-cate solid electrolyte films, prepared by rf sputtering using 7$LI_2O-3B_2O_3-1SiO_2$ single phase target and also a mosaic target enriched with $LI_2O$, were analyzed by measuring AC impedance and IR absorption spectra for the films. Thed solid electrolyte film deposited from the single phase target exhibited very low ionic conductivi-ty of $10^{-10}{\Omega}^{-1}cm{-1}$ at room temperature, a result of low $Li^+$ ion content(7.52 at%) in the film. The $Li^+$ con-ductivity for the films deposited from the mosaic target, however, significantly increased to $10^{-7}{\Omega}^{-1}cm{-1}$ due to both an increased $Li^+$content (14.75 at %) and a structural change of the films. The increased ionic conduc-tivity of the film appears to be associated with an easiness of ionic mobility by structural change of glassy film from a some close packed network structure to a open one. These structural changes of film were found to be closely related to the increase in the peak intensity at~$960cm^{-1}$ of IR absorption spectra for the glassy films. With increasing either argon pressure from 3 to 21 mtorr or rf power from 2 to 3 W/$cm^2$, the $Li^+$ conduc-tivity for the films significantly increased to an order of $10^{-6}{\Omega}^{-1}cm{-1}$ due to an increase in openness of film structure, as confirmed by both an increase in the IR absorption peak intensity at ~$960cm^{-1}$ and a resultant reduction of activation energy for mobility of $Li^+$ ion.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.3
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• pp.103-110
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• 2018

The long-term flexural behavior of reinforced concrete (RC) beams strengthened with an iron based-shape memory alloys (Fe-SMAs) by a near-surface mounted (NSM) method was evaluated. The pre-strained values of 2% and 4% and introduced prestressing force by an activation of a shape memory effect of the Fe-SMA strengthening material were considered as experimental variables. Deflections at the center of the RC beams were measured for six months after the 1 tonf concrete weight was loaded on the beam. Experimental results show that the deflections decreased because of the increased flexural stiffness of beams strengthened with the Fe-SMA strips. On the contrary, with increased pre-strained values, the deflection increased due to stiffness reduction of the strengthening material. It was confirmed that the specimens incorporating the prestressed force showed the deflection reduction of about 30%, compared to the ones without the prestressed force.

• Applied Chemistry for Engineering
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• v.3 no.4
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• pp.686-693
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• 1992

In order to investigate the mechanism of dissolutin of nickel from a matte composed essentially of heazlewoodite and ferronickel, the leaching in an aqueous solution of hydrochloric was carried out at $50-90^{\circ}C$, 0.5-3.ON HCl, and with the particle sizes between $100-160{\mu}m$ and $400-500{\mu}m$. The leaching rate of heazlewoodite was much rapider than that of ferronickel, and the two components were simultaneously dissolved with different reaction rates. Within the experimental range, NiS, an intermediate, was not formed. However a possibility to form a thin layer of NiS on particle surface upon saturating the reaction mixture with $H_2S$ was not excluded. At the initial stage, the activation energy was about 10 kcal/g mol. The reaction occurred at the particle surface, and consequently the particle size decreased with time. The rate of dissoultion for nickel was linearly proportional to the concentration of HCl up to 1.0N.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.26 no.2
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• pp.158-165
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• 2017

This study investigated spraying factors applicable to stripper usage. Cyclodextrine, as environment-friendly material, was included in the stripper composition. An efficient spray technology was applied for the Photoresist strip. For industrial applications, stripping requires a temperature below $50^{\circ}C$, a strip time within 50 s, and chemically stable activation. Spraying factors were organized considering many conditions-orifice diameter, working pressure (inlet speed), spray distance, and spray angle. For commercial practicability, the flow rate was limited to 3 L/min. The nozzle parameters were nozzle orifice diameter of 1.8-2.2 mm, spray distance of 40-60 mm, and injection speed of 0.7-1.2 m/s. Through the thermal spray movement of the fluid, the thermal boundary layer for a chemical reaction just above the ITO-glass surface and momentum region for sufficient agitation (above 4 m/s) was achieved.

• Applied Chemistry for Engineering
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• v.10 no.6
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• pp.814-821
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• 1999

The specific capacitance characteristics of the electric double layer capacitors(ELDC) which were made of phenol based activated carbon fiber(ACF) electrodes. Also the effect of aqueous electrolytes on the cell performance has been investigated with respect to different specific surface areas of electrodes and different kinds of aqueous electrolytes. It has been shown that larger surface area and pore size, higher conductivity of electrodes, and higher ion mobility of electrolytes have better specific capacitances. It has been found that heat treatment at $1200^{\circ}C$ and $CO_2$ post-activation at $900^{\circ}C$ of the electrode are effective to improve the specific capacitance over 145F/g and 165F/g, respectively. The EDLC showed high efficiency and long cycle life over 30000 cycles.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.13 no.4
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• pp.253-262
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• 2015

Radionuclide deposited on the surface of several internal and external systems in a nuclear power plant is created by the activation of corrosion products from nuclear reactor structural materials and fission products. Especially, the constant contact between water and the surface corrodes the inside where primary system makes coolants and corrosion products mixed. Also, these are circulated along the systems. For comparing models, CRUDTRAN, DISER, MIGA-RT and CPAIR codes are analyzed to predict the quantity of radionuclide and corrosion product of primary reactor that are used at the stage of designing. The corrosion products behavior of domestic PWR primary system was predicted by using CRUDTRAN. This study aims to increase the reliability of corrosion product evaluation model by comparing the actual values and calculated values with the data of a Westing House-type Nuclear Power Plant.

• Korean Journal of Materials Research
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• v.23 no.12
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• pp.732-736
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• 2013

AlN epilayers were grown on a c-plane sapphire substrate using hydride vapor phase epitaxy (HVPE). A series of AlN epilayers were grown at $1120^{\circ}C$ with V/III ratios 1.5, 2.5 and 3.5, and the influence of V/III ratio on their properties was investigated. As the V/III ratio was increased, the surface roughness (RMS roughness), Raman shift of $E_2$ high peaks and full-width at half-maximum (FWHM) of symmetrical (002) & asymmetrical (102) of the AlN epilayers increased. However, the intensities of the Raman $E_2$ high peaks were reduced. This indicates that the crystal quality of the grown AlN epilayers was degraded by activation of the parasitic reaction as the V/III ratio was increased. Smooth surface, stress free and high crystal quality AlN epilayers were obtained at the V/III ratio of 1.5. The crystal quality of AlNepilayers is worsened by the promotion of three-dimensional (3D) growth mode when the flow of $NH_3$ is high.

• Korean Journal of Veterinary Research
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• v.52 no.2
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• pp.89-97
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• 2012

Mycobacterial cell-wall skeleton (CWS) is an immunoactive and biodegradable particulate adjuvant and has been tried to use for immunotherapy. The CWS of Mycobacterium bovis bacillus Calmette-Guerin (BCG-CWS) was studied as an universal vaccine vehicle for antigen conjugation, to develop potentially effective and safe vaccine. Although a variety of biological activities of BCG-CWS have been studied, the effects of BCG-CWS on spleen cells are not fully elucidated. Using MTT assay and trypan blue exclusion test, we found that BCG-CWS significantly enhanced the viability and proliferation of cells. Multiple clusters, indicating proliferation, were observed in BCG-CWS-treated spleen cells and surface marker staining assay revealed that BCG-CWS promoted the proliferation of $CD19^+$ B lymphocyte rather than $CD4^+$ or $CD8^+$ T lymphocyte. In addition, BCG-CWS up-regulated the expression of anti-apoptotic molecules such as bcl-2, bcl-xL. BCG-CWS increased the surface expression of CD25 and CD69 as well as IL-2 production of spleen cells, suggesting increased activation. Furthermore, BCG-CWS enhanced the antigen-specific cell proliferation and interferon-gamma production of spleen cells. Taken together, these results demonstrate the immunostimulatory effects of BCG-CWS on spleen cells via multiple mechanisms, providing valuable information to broaden the use of BCG-CWS in clinical and research settings.

• Applied Chemistry for Engineering
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• v.16 no.4
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• pp.570-575
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• 2005

In this study, we have manufactured electrodeless ultraviolet lamp which has a long life and a high degree of efficiency than the existing electrode UV lamp used in sewage effluent sterilization disinfection. First, we investigated change of UV intensity and temperature of lamp by activation materials. The best results for the dose response experiments were 250 minutes stabilizing to UV intensity of $300{\mu}W/cm^2$ and surface temperature $200{\sim}250^{\circ}C$ in Hg/Ind's weight ratio 95/5. When electrodeless UV lamp emits light for prolonged hours, surface temperature of lamp increases. therefore, temperature change is studied using a duplex lamp for cooling in actual sewerage process. Also, manufactured electrodeless UV lamp showed sterilization efficiency of more than 99.9% as result that experiment manufactured electrodeless UV lamp by E-coli. for sterilization disinfection of sewage effluent.