• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2013.05a
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• pp.179-179
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• 2013

Surface resistance of electro-deposited copper with its thickness, current density and surface roughness was determined by using a 4-point probe analyzer. The copper was prepared electrochemically on 316 stainless steel substrate in copper sulfate solution at the condition of $1A/dm^2$, 298 K, and 6.5 cm-electrode distance. The surface resistance of the copper sheet in the range of $0.93-0.97{\Omega}$ increased with the copper thickness in the range of $21-70{\mu}m$. The surface resistance in the range of $0.963-1.009{\Omega}$ also increased with current density in the range of $0.5-2A/dm^2$. The increased surface resistances corresponded to 11% for thickness and 25% for current density, respectively.

• Journal of Ceramic Processing Research
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• v.19 no.6
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• pp.455-460
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• 2018

Chromium plating is a common surface treatment technique extensively applied in industry due its excellent properties which include substantial hardness, abrasion resistance, corrosion resistance, surface color, and luster. In this study, the effect of PTFE on corrosion behavior of Cr-P plating, low carbon steel substrates are electroplated in Cr(III) baths without and with PTFE. Trivalent chromium carbon plating was electroplated from trivalent chromium sulfate-based baths with different PTFE dispersion contents. The study focused on the microstructure, PTFE content, roughness, and corrosion resistance of the Cr-P-PTFE composite plating. Scanning electron microscopy and atomic force microscopy images showed a smoother plating and a decrease in the surface roughness of the electrodeposited. The results demonstrate that PTFE eliminates the cracks within plating by reducing internal stress. Therefore, the corrosion resistance of Cr-P-PTFE composite platings were better than that of Cr-P alloy platings.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.4
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• pp.721-728
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• 1994

The objective of this research is to analyze whether the ground granulated blast furnace (GGBF) slag, by-product of industry in domestic iron-foundary, can be useful as a mineral admixture for concrete by investigating physical and chemical property. In addition, according to making an fundamental experiment on mortar and concrete mixed with GGBF slag to some grade, examining the consistency, the compressive strength and the resistance to sulfate attack of concrete and mortar, the acquired results are that the compressive strength was increased and the resistance to sulfate attack was predominant.

• Journal of Ocean Engineering and Technology
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• v.23 no.5
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• pp.54-60
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• 2009

Exposed to various environments, concrete confronts degradation by a lot of physical and chemical reaction. Though so many experiments and theorizations on the single condition of concrete degradation have been carried out by constant studies, the truth for now is that there are few studies on the compound phenomenon of degradation related with marine environments. Accordingly, this study measured the degree of degradation in the change of external shape, the change of unit weight and compressive strength, ultrasonic velocity test, and the change of length, etc. after exposing the specimen of cement mortar to the environment between 0 cycle and the maximum of 300 cycles under the condition of aquatic curing, freezing and thawing, and compound degradation, using mineral admixture effective for concrete degradation as a binder. The result indicated that the case of adding mineral admixture showed greater resistance than that of using OPC only, and specifically, the specimen with the additive of slag powder and three component system showed very excellent resistance to freezing and thawing, and compound degradation.

• Journal of the Korea Institute of Building Construction
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• v.19 no.1
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• pp.31-38
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• 2019

In this study, amine derivatives and ion exchange resins were selected to actively control penetration ions ($SO{_4}^{2-}$, $Cl^-$) as the element technology of repair materials for concrete structures in drainage environments. Ions ($SO{_4}^{2-}$, $Cl^-$) adsorption performance and corrosion resistance of calcium hydroxide solution with amine derivative and ion exchange resin were confirmed by ion chromatography and potentiostat analysis. As a result of the experiment, it was confirmed that the amine derivative is excellent in the adsorption of chlorine ion and the ion exchange resin is excellent in the adsorption of sulfate ion. It has been confirmed that corrosion resistance can be increased by proper combination of two materials in the calcium hydroxide solution containing sulfate ion and chloride ion simulating sewage environment.

• Journal of the Korean Applied Science and Technology
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• v.23 no.2
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• pp.169-176
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• 2006

Acrylic adhesives for automobiles protection were prepared by emulsion polymerization. Monomers used were n-butyl acrylate(BA), acrylonitrile (AN), butyl methacrylate(BMA), glycidyl methacrylate(GMA), and acrylic acid (AA). Emulsifiers used were sodium lauryl sulfate and polyoxyethylene lauryl ether, which are an anionic emulsifier and a nonionic emulsifier respectively. Potassium persulfate was used as an initiator and polyvinyl alcohol was used as a stabilizer. Emulsion polymerization was carried out in a semi-batch reactor at $70^{\circ}C$ and agitation speed was kept at 200 rpm. Water resistance, heat resistance, acid resistance, alkali resistance and smoke resistance were examined. As a result, when each 0.03 mole of GMA and AA was introduced, the adhesion properties and various above mentioned resistances of the prepared adhesives were satisfied the standard for automobiles.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.7
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• pp.113-119
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• 2019

Concrete structures built on reclaimed land are combined with chemical erosion such as chlorine and sulfate ions from seawater. Chloride attack deteriorates the performance of the structure by corroding reinforcing bars. In addition, the waste water treatment structure has a problem that the concrete is deteriorated by the sulfate generated inside. Therefore, in this study, the characteristics and chemical resistance of low heat cement concrete used in wastewater treatment structures constructed on reclaimed land were evaluated. As a result of the experiment, the target slump and air content were satisfied under all the mixing conditions. The slump of low heat cement (LHC) concrete was higher than that of ordinary portland cement (OPC) concrete, while the air content of LHC concrete was smaller than that of OPC concrete with the same mix proportion. As a result of compressive strength test, OPC concrete showed higher strength at younger age compared to 28 days. In contrast, LHC concrete exhibited higher strength than OPC concrete at the age of 56 days. As a result of chlorine ion penetration tests, LHC-B concrete showed chlorine ion penetration resistance performance of the "very low" level at the age of 56 days. As a result of chemical resistance evaluation, when the LHC concrete is applied without epoxy treatment, chemical resistance is improved by about 18% compared to OPC concrete. In testing chemical resistance, the epoxy coated concrete exhibited less than 5% strength reduction when compared to sound concrete.

• Journal of the Korean Ceramic Society
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• v.44 no.11
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• pp.633-638
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• 2007

The setting time of alkali activated slag cement tends to be much faster than ordinary Portland cement, and its compressive strength had been higher from the 1 day but became lower than that of the cement on the 28 days. According to the results of the surface observation, weight loss, compressed strength, and erosion depth tests on the sulphuric acid solution. It has been drawn that alkali activated slag cement has a higher sulphate resistance than ordinary Portland cement, and in particular, the alkali activated slag cement added 5 wt% alumina cement has little deterioration on the sulphuric acid solution. The reason why the alkali activated slag cement has higher sulphate resistance than other hardened cement pastes is that it has no $Ca(OH)_2$ reactive to sulphate ion, and there is little $CaSO_4{\cdot}2H_2O$ production causing volume expansion, unlike other pastes. And it is supposed that $Al(OH)_3$ hydrates with high sulphate resistance, which is produced by adding the alumina cement increases the sulfate resistance.

• The Korean Journal of Pesticide Science
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• v.7 no.1
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• pp.12-17
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• 2003

Potato blackleg disease caused by Erwinia carotovora subsp. atroseptica (Eca) has been a serious problem in Korea. Bactericidal activities of twelve bactericides including antibiotics, copper compounds and oxolinic acid were examined in vitro. Streptomycin, streptomycin sulfate, and oxolinic acid effectively controlled the pathogen at 0.02 mM. However, the pathogen developed resistance to the applied bactericides after 72 hours of incubation. Activity of copper compounds such as copper hydroxide, copper oxide and copper sulfate was lower than that of antibiotics. However, the pathogen did not develop resistant to them. Combinations of streptomycin (0.016 mM, 9.3 ppm) + copper oxide (1.2 mM, 171.6 ppm)/copper hydroxide (1.5 mM, 146.3 ppm); streptomycin sulfate (0.005 mM, 7.0 ppm) + copper oxide (1.2 mM, 171.6ppm)/copper hydroxide (1.5 mM, 146.3 ppm) were found to be effective for the control of E. carotovora subsp. atroseptica.

• The Journal of the Korean Society for Microbiology
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• v.5 no.1
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• pp.27-31
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• 1970

Nalidixic acid and six other drugs were studied for in vitro effectiveness against 200 strains of Escherichia coli isolated recently from healthy persons and bactericidal activity of ampicillin against one respective strain of Escherichia coli and Salmonella typhi isolated were also studied. The resutlts obtained by the plate dilution method showed the following percentage of resistance: kanamycin, 2.5%; streptomycin, 12.0%; ampicillin, 13.5%; tetracyclin, 15.5%; chloramphenicol, 17.5%; colistin sulfate, 19.5%. No strains were resistant to nalidixic acid, clearly indicating that nalidixic acid is the most effective drug tested. Ampicillin, measured by test-tube diltion method, was highly bactericidal against Salmonella typhi at the concentration of 2.5mcg/ml and against Escherichia coli at 5mcg/ml.