• Journal of Welding and Joining
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• v.26 no.4
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• pp.44-49
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• 2008

Generally, wear plate is steel plate having improved surface contact strength and impact strength by surface hardening which is welded using materials with good corrosion resistance, wear resistance and thermal resistance property. CFP GMAW(Compound Filler Plate Gas Metal Arc Welding) is the cladding method using GMAW with the CFP, which is bound with waterglass, on the substrate. It has advantages of reducing compound powder loss, uniform penetration, and preventing hardness decrease. To develope mass production technique of CFP GMAW process for production of high quality wear plate, the method for controling shallow penetration and increasing productivity is required. In this study, twin torch method applied to CFP GMAW process for increasing productivity. And the method was developed by controling penetration control, CFP dry time, gas formation flux and water glass concentration. As a result, applying twin torch method to CFP GMAW process was possible and high quality wide bead could be made without overlap joint.

• Journal of the Korean Chemical Society
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• v.48 no.5
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• pp.504-509
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• 2004

The reaction of Cu metal with mixed alkali metal polyselenide flux ($KNaSe_x$) produced large plate-like crystals of $KCu_4Se_3$. The structure of $KCu_4Se_3$, determined with X-ray single crystal diffraction techniques, is tetragonal (P4/mmm, a=4.013(1))${\AA}$, c=9.712(1))${\AA}$, z=1, R=6.7%). The structure is composed $[Cu_4Se_3]_n^{n-}$double layers which are made of fused anti PbO-type Cu2Se2 layers. Temperature variable resistivity measurement on single crystal of $KCu_4Se_3$ shows metallic behavior ranging from $1.8{\times}10^{-4}{\Omega}{\cdot}cm$ (at 300 K) to $1.0{\times}10^{-6}{\Omega}{\cdot}cm$ (at 20 K).

• Journal of the Korean Chemical Society
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• v.39 no.5
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• pp.371-378
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• 1995

The triazacrown compound, 1,7-dioxa-4,10,13-triazacyclopentadecane trihydrobromide salt (Na3O2-3HBr) was synthesized. And this compound was used to synthesize the new ion exchanger, which combined with Merrifield peptide resin. This new ion exchanger had a capacity of 3.2 meq/g dry resin. And the distribution coefficients of alkali and alkaline earth metal ions on this ion exchanger in the various concentrations of hydrochloric acid were determined. The ion exchange behaviors of alkali and alkaline earth metal ions in the various hydrochloric acid concentrations are, also, discussed.

• Journal of the Korean Magnetics Society
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• v.3 no.1
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• pp.1-6
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• 1993

Electronic and magnetic proper tis of the rare-earth transition metal compound, $LaCo_{13}$, are investigated by performing self-consistent local density functional LMTO (linearized muffin-tin orbital) band structure calculations for both paramagnetic and ferromagnetic phases of $LaCo_{13}$. The calculated magnetic moments for the two types of Co atoms, Co I and Co II, are 1.34 and $1.65{\mu}_{B}$, respectively. The average magnetic moment of Co atoms in the ferromagnetic phase of $LaCo_{13}$ is estimated to be $1.60{\mu}_{B}$, which is in fairly good agreement with the experimental values, $1.56~1.68{\mu}_{B}$.

• Journal of Environmental Science International
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• v.23 no.7
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• pp.1269-1275
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• 2014

Ecotoxicity assessments with the physiochemical water quality items and the bioassay test using Daphnia magna were conducted for 18 selected effluents of 6 industrial types (metal processing, petroleum refining, synthetic textile manufacturing, plating, alcohol beverage manufacturing, inorganic compound manufacturing) being detected toxicity from industrial effluent in Ulsan city, and the interrelationship between total toxic unit (${\Sigma}TU$) and concentrations of Water Quality Conservation Act in Korea were investigated. The average toxic unit(TU) of effluents for 6 industrial types displayed the following ascending order: petroleum refining (0.2) < synthetic textile manufacturing (0.6) < alcohol beverage manufacturing (0.9) < metal processing (1.3) ${\leq}$ inorganic compound manufacturing (1.3) < plating (3.0). These values were less than effluent permission standard. Based on the result of substances causing ecotoxicity, the correlation analysis was not easy because most of heavy metals were not detected or were less than effluent permission standard. Toxicological assessment of industrial effluent was suitable for the evaluation of the mixture toxicity for pollutant. The whole effluent toxicity test using a variety of species was needed for the evaluation of industrial wastewater.

• Tribology and Lubricants
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• v.10 no.4
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• pp.43-50
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• 1994

In order to elucidate the effects of co-existing additives (S$_{8}$, TBP: Tri butyl phosphate, ZnDTP: Zinc-dialkyl dithiophosphate) and the role of reacted surface film on the friction behavior of MoDTP (molybdenum dialkyl dithiophosphate), a friction experiment using a dual circular pipe edge surface type friction tester and XPS (X-ray photoelectronic spectrum) surface analysis were conducted. Friction reduction with MoDTP lubricant was proved to be greatly influenced by co-existing additive species. It was dependent on the properties of the film formed through the reaction between the additive and the surface. Phosphate film reduced the friction coefficient of MoDTP through suppression of diffusion of Mo compounds towards the metal substrate. On the other hand, sulfate film, which is inherently rich in lattice defects, did not lead to any appreciable friction reduction with MoDTP since the diffusion of the Mo compound towards the metal substrate was not effectively suppressed. With ZnDTP additive, the sulfide film formed through decomposition greatly influenced the lubricating performance of MoDTP. As such, properties of surface films formed from additives were proved to yield significant influence on the lubrication performance of MoDTP.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.425.2-425.2
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• 2014

$TiO_2$ possesses great photocatalytic properties but absorbs only UV light owing to high band gap energy (Eg = 3.2 eV). By narrowing the band gap through doping a metal ion, the photocatalytic activity can be enhanced in condition of the light of a higher than 365 nm wavelength. Main purpose for this study is to evaluate the activities of metal doped $TiO_2$ for degrading the volatile organic compounds (VOCs); p-xylene is chosen in the VOC removal test. Vanadium is selected in this study because an ionic radius of vanadium is almost the same as titanium ion and vanadium can be easily doped into $TiO_2$. V-doped $TiO_2$ was synthesized by sol-gel methods and compared with pure $TiO_2$. Pure TiO2 powder and V-doped $TiO_2$ powder were coated on glasses by spray coating method. UV-Visible spectrophotometer was used for the measurement of the band gap changes. VOC concentration degradation level was tested with using various UV light sources in an enclosed chamber. Catalytic activities of prepared samples were evaluated based on the experimental results and compared with coated pure $TiO_2$ sample.

• Progress in Superconductivity
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• v.7 no.2
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• pp.179-183
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• 2006

As a material for SFCL(Superconducting Fault Current Limiter), BSCCO tube with metal stabilizer is a promising candidate, assuring the stability and large power capacity, For the application, the proper soldering technique, which overcome the difficulties of the joining between BSCCO and metal stabilizer, is required. In this study, after soldering In-Bi solder and In-Sn solder with BSCCO superconductor, welding properties between BSCCO and solders were investigated. Because ceramic materials is difficult to weld, Ag electro-plating on BSCCO 2212 is used for intermetallic layer. To find out the best welding condition for superconductor, soldering is tested in the maximum temperature from $155^{\circ}C\;to\;165^{\circ}C$ in the reflow oven. By investigating the composition and thickness of IMC (lntermetallic Compound) created in the reaction of Ag with solder, we analyzed the welding properties of High-Tc superconductor from a micro point of view.

• Journal of Welding and Joining
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• v.25 no.5
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• pp.51-57
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• 2007

The present work was aimed to examine the variation of microstructure and mechanical properties by annealing($100{\sim}620^{\circ}C$, $2{\sim}8hr$) in A3003 Al alloy welded pipes. The A3003 Al alloy pipes with 34 mm in external diameter and 1.3 mm in thickness were manufactured by high frequency induction welding with the V shaped convergence angle $6.7^{\circ}$ and power input 50 kW. The tensile and yield strength decreased with increasing the annealing temperature remarkably, but elongation increased remarkably. Vickers hardness in welds decreased with increasing the annealing temperature remarkably. The primary intermetallic compound of $Al_{12}(Fe,\;Mn)_2Si$ was precipitated in welds as the same base metal. In a certain experimental condition, the welds line in A3003 alloys disappeared at $450^{\circ}C$ for 2 hr because of the same mechanical property and structure between welds and base metal.

• Proceedings of the KIEE Conference
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• 1994.07b
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• pp.1364-1366
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• 1994

In this paper, the monolayers of the polymers which polyion-complexed with PAA at the air-water interrace can be transferred on to solid substrates such as porous fluorocarbon membranes filter and quartz crystal microbalance. The properties of the monolayers and the LB films investigated by ${\pi}-A$ isotherms, FT-IR, DSC, deposition ratio, QCM, and SEM will be discussed. In addition, it was attempted to investigated the surface characterics of polymer/metal compound LB films in the air/water interface.