• Proceedings of the Korean Institute of Building Construction Conference
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• 2016.05a
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• pp.83-84
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• 2016

For the slip resistance test of shower room floor, the "O-Y Pull Slip Meter method (O-Y·PSM)" regulated under KS M 3510. This test method uses cooking oil as a substitute of soapy water, and thus it does not reflect the real condition. In this study, on 10 types of floor material samples, the Coefficient of Slip Resistance Bath (CSR·B) on bare foot between 10 types of body wash solution and 6 types of SDS solution was compared. The body wash solution is a mixture of soap and water in 1:20 ratio. As a result, SDS 0.1% solution was the most suitable for a substitute of soapy water in shower.

• Journal of the Korea Institute of Building Construction
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• v.11 no.1
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• pp.83-90
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• 2011

The purpose of this research is to investigate the effect of AFm formation on the stiffening process of cement paste. High and low alkali sulfate clinkers were used for the experiments. The flow and stiffening behavior of cement paste was investigated using modified ASTM C403 penetration resistance test and oscillatory shear rheology. X-ray powder diffraction (XRD) was used for phase identification associated with stiffening of the paste. It was found from the results that low alkali clinker mixture produced very strong premature stiffening whereas high alkali clinker mixture did not cause premature stiffening. This is because of the large amount of alkali sulfate present in the clinker. Addition of calcium and sodium chloride to the high alkali clinker mixture caused faster stiffening and set.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.577-580
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• 2006

As this study is to estimate resistance of cement mortars using crushed sand under chemical attacks. Besides tests have been carried out with cement mortars by river sand and crushed sand by fine sand, cement mortars mix various proportions of silica fume and fly ash(up to 15% and 50% by weight for cement) were prepared and immersed in pure water, sodium sulfate solution, magnesium sulfate solution, seawater for 28days, 60days, 90days and 180days. Test on the change in the weight and compressive strength of cement mortars according to the duration of immersion time and the content of silica fume and fly ash was performed.

• Journal of the Korean Recycled Construction Resources Institute
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• v.4 no.2
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• pp.149-156
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• 2016

It has been well known that concrete structures exposed to chloride and sulfate attack environments lead to significant deterioration in their durability due to chloride ion and sulfate ion attack. The purpose of this experimental research is to evaluate the long-term durability against chloride ion and sulfate attack of the alkali activated cementless concrete replacing the cement with ground granulated blast furnace slag. For this purpose, the cementless concrete specimens were made for water-binder ratios of 40%, 45%, and 50%, respectively and then this specimens were cured in the water of $20{\pm}3^{\circ}C$ and immersed in fresh water, 10% sodium sulfate solution for 28, 91, 182, and 365 days, respectively. To evaluate the long-term durability to chloride ion and sulfate attack for the cementless concrete specimens, the diffusion coefficient for chloride ion and compressive strength ratio, mass change ratio, and length change ratio were measured according to the NT BUILD 492 and JSTM C 7401, respectively. It was observed from the test results that the resistance against chloride ion and sulfate attack of the cemetntless concrete were comparatively largely increased than those of OPC concrete irrespective of water-binder ratio.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.11a
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• pp.519-522
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• 2005

As this study is to test effects of chemical attack on deterioration of cement mortars using in crushed sand. Besides tests have been carried out with cement mortars by river sand and crushed sand by fine sand, cement mortars mix various proportions of slica fume and fly ash(up to $15\%$ and $50\%$ by weight for cement) were prepared and immersed in pure water, sodium sulfate solution, magnesium sulfate solution, seawater for 28days. Test on the change in the weight and compressive strength of cement mortars according to the duration of immersion time and the content of slica fume and fly ash was performed.

• 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 Concrete Institute
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• v.16 no.1 s.79
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• pp.1-9
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• 2004

This paper represents the permeability of chloride ions and the corrosion performance in the concrete blended with granulate blast furnace slag exposed to chloride environment. An ordinary cement (type I ) and sulfate resisting cement(type V) were used for the experiment. The two cements were combined with $0\%$, $25 \%$, $40\%$, and $55\%$ of the granulated blast furnace slag. The accelerated permeability tests of chloride ions were performed in accordance with ASTM C1202, and the accelerated corrosion tests of steel were carried out by using the method of immersion/drying cycles. After water curing 28 days, 56 days and 91 days, these tests were conducted until 30 cycles. In every cycle, test specimens were wetted in $3\%$ NaCl solution for three days and dried again in $60^{\circ}C$ air for four days. As an experimental results, the diffusion coefficient of chloride ions of the ordinary cement Concrete Combined granulated blast furnace slag was much lower than that of non granulated blast furnace slag concrete. Moreover, the diffusion coefficient of chloride ions of sulfate resisting cement concrete was higher than that of ordinary cement concrete. On the basis of the results of accelerated corrosion tests, corrosion resistance of the concrete mixed with granulated blast furnace slag shows good to corrosion resistance, however, the concrete with sulfate resisting cement shows bad to corrosion resistance.

• Journal of the Korean Wood Science and Technology
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• v.14 no.2
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• pp.29-35
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• 1986

This study was carried out to examine the effect of aluminium sulfate addition to the alkali-acid catalyst phenolic resin for the manufacture of the kapur (Dryobalanops spp.) plywood on the reduction of phenolic resin spreading. On the manufacture of plywood, Adhesive Contents such as 50g/$m^2$, 75g/$m^2$ and 150g/$m^2$ were treated. The spreading adhesive content of 50g/$m^2$ and 75g/$m^2$ had been controlled to about 150g/$m^2$ added with the water in order to get sufficient spreading and controlled to pH 4.5 with aluminium sulfate [$Al_2(SO_4)_3$]. The results are summarized as follows: 1. Specific gravities of air dried plywood manufactured from each adhesive ranged from 0.77 to 0.86 and their moisture contents met the KS requirements. 2. In dry and wet shear strengths, 150 $P_{Al{\cdot}Ac}$ adhesive showed the highest and 75 $P_{Al{\cdot}Ac{\cdot}Am}$ adhesive indicated higher value than 150 $P_{Al{\cdot}Ac}$ adhesive. 3. In case of glue shear strength after boiling test, 150 $P_{Al{\cdot}Ac}$ adhesive was the best and adding of aluminium sulfate was not effective on reinforcement of boiling water resistance of phenolic resin, but met KS requirements. 4. 75 $P_{Al{\cdot}Ac{\cdot}Am}$ adhesive showed the good shear strength and met KS requirements. Therefore, adding of aluminium sulfate was very efficient for economical plywood manufacture.

• 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.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.3
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• pp.171-177
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• 2010

As concrete structures are exposed to chemical substances, damaged from salt, or progressed to the neutralization, the surface damage of the structures is generated timely fashion, resulting shortened service life. Especially, the sulfate erosion causes rapid surface defects, and the steel skeleton becomes corroded due to the water infiltration, generating stability deterioration of the concrete structure. In this study, the physical characteristics of the acid-resistant mortar with aluminosilicates was investigated in order to resolve problems of the acid resistance, one of the most serious problems of the cement type repair material. As the result of the experiment, the test specimen turned to exhibit almost equivalent physical characteristics with those of concrete sectional repair materials in terms of compressive and bending strengths. As both the cement sectional repair material and the test specimen were immerged in sulfuric acid solution to examine weight changes, the test specimens exhibited only 4% loss of their weights while the cement sectional repair materials reached at the level of 80% or above, proving the excellence acid resistant characteristics of the test specimens. Consequently, the physical characteristics of acid resistant mortar with aluminosilicates were revealed to be superior than those of concrete sectional repair materials. It can be utilized as a sectional repair material where the acidic erosion is anticipated.