• Journal of the Korean Ceramic Society
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• v.44 no.1 s.296
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• pp.23-31
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• 2007

To examine the effects of chemical admixture on the fluidity and strength development of high chloride cement, experiments were conducted in which lignosulfonate (LS), naphthalenesulfonate (NS), and polycorboxylate (PC) were each added in standard and excessive amounts, and the results were as follows. 1. Because adding KCl to NS causes a decrease in flow, adding PC is better in maintaining high cement fluidity. 2. When cement contained much chloride comes in contact with water, hydration begins 4 h after contact and securing workability becomes difficult, but by adding PC, workability can be secured to 10 h. 3. The bound water ratio and compressive strength in aging 3 days occupy $70\sim80%$ of those in aging 28 days, and the early compressive strength increases not only by adding KCl, but also by chemical admixture. 4. Although compressive strength development is excellent in NS, PC, if NS is added excessively, hydration becomes slow and while the pore structures become slightly minute, the strength development decreases due to severe setting retardation.

• Journal of the Korean Applied Science and Technology
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• v.33 no.4
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• pp.795-801
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• 2016

This study is on the denitrification process using the sodium alginate and $CaCl_2$ as a flocculant. Removal techniques of nitrate nitrogen from waste water are reverse osmosis, ion exchange, electro dialysis and biological method etc. We tried to remove nitrate nitrogen with flocculation and sedimentation method in the present study. Calcium alginate is expected to form a chelate bond with nitrate nitrogen in the solution. So the effects of flocculantt component, flocculation reaction time, molar ratio of the flocculant, flocculant injection rate are studied to determine the best removal rate of nitrate nitrogen. In addition, we tried to determine the nitrate nitrogen removal mechanism by analyzing the structure and component ratio of the configuration after the agglutination precipitate by FE-SEM and EDS. As a result, the nitrate nitrogen removal mechanism is turned out to form calcium-nitro-alginate, and the best mole ratio of flocculating agent is 1 : 1, the injection rate of the flocculant was up to 2%, the removal rate of the nitrate nitrogen to be 56.7% in the synthetic wastewater.

• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.1
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• pp.35-44
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• 2015

Two main parameters were examined such as CSA content and polymer-binder ratio to find effects on the strength, water absorption, chloride ion penetration depth, carbonation depth, length change and chemical resistance of polymer-modified mortar with CSA and EVA polymer powder (EVAPP). As results, compressive, flexural, tensile, adhesive strengths, and length change of the polymer-modified mortar with CSA and EVAPP increases with increasing CSA content and polymer-binder ratio, although the water absorption, chloride ion penetration depth, and carbonation depth decrease with increasing polymer-binder ratio and CSA content, and also the chemical resistance decreases. Such strength and durability development is attributed to the high tensile strength of EVA polymer and the improved bond between cement hydrates and aggregates because of the addition of EVAPP and CSA.

• Journal of the Korean Ceramic Society
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• v.29 no.3
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• pp.241-251
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• 1992

The effects of slip composition and processing conditions on the fabrication of ceramic heat exchanger cores by doctor blade process were investigated. Since the effects of those two variables were inter-dependent, the effects of binder system, binder plus plasticizer, were extensively studied for a limited range of processing conditions and a pre-determined ceramic composition. The content of binder system and the ratio of binder to plasticizer were identified as main variables to affect densities and mechanical properties of green sheets, compressive properties and bond strengths of laminates, and shrinkages and their anisotropy of sintered laminates. However, sintered densities and water absorptions of laminates were not influenced by either the content of binder system or the ratio of binder to plasticizer, when the debinded laminates had a relatively high density (relative density of >55% in this study).

• Journal of the Korean Society of Safety
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• v.4 no.1
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• pp.91-98
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• 1989

Today, the conception of building architecture is changing the conception that it is a kind of product and the operator of construction try to produce excellent building through developing efficiency and materials of building component. This study improves the problematic point of the extenor tile setting, through making on experiment on the method of it and purposes doing to do the exterior tile setting of good quality as it selects out of the most conformable the method. The experimental materials choose the tile of 60$\times$108mm size which are using frequently in the exterior tile setting and mortar is made from sand of Han river and potland cement, which apply the volume mixing of the ratio 1：3. The water cement ratio (W/C)is made up 62％ The methods of tile setting utilise the method of the tile setting and laying the method of the tile improved setting and laying, the method ol the pressing adhesion, the method of the improved pressing adhesion and the method of setting adherent (the method of VIBRATOR).

• Proceedings of the Korean Institute of Building Construction Conference
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• 2011.11a
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• pp.109-110
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• 2011

Gypsum is an important building material used to provide fire resistance to constructions by reducing their temperature rises. As the hardened gypsum is exposed to fire, evaporation of both the free water and the chemical bond water is easier than that in the cement extruding panel. The purpose of this study is to investigate the utilizability of alpha-hemihydrate gypsum to prevent spalling failure of cement extruding panel exposed to fire. This paper reports the fire-resistance property of a controled general cement extruding panel(C100), and gypsum-cement extruding panels(C50A50, A100) according to replacement ratio of alpha-hemihydrate gypsum. As a results, it is found that A100 and C50A50 are more effective to prevent the explosive spalling failure under standard fire condition than C100.

• Journal of The Korean Society of Agricultural Engineers
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• v.60 no.3
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• pp.123-133
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• 2018

The purpose of this paper is to propose an experimental method to evaluate the resistance of abrasion about 24 MPa, 27 MPa, and 30 MPa compressive strength. These strength are used in the design and construction of concrete hydraulic structures in Korea. The mixing ratios of the ready mixed concrete strengths were investigated countrywide and set the representative mixture proportion ratios of the nine mixed types of OPC, FA and BFS. After making and curing the test specimens, the underwater abrasion test was performed. ASTM C 1138 International Standard was used to fabricate the test equipment, and the surface abrasion resistance of the specimen was tested using the test equipment. In the case of OPC, the 30% abrasion resistance improvement effect was observed at 72 hours as the water-binder ratio decreased. That was reason the coated cement bond strength of the specimen was strong. In the case of BFS and FA, it was improved by 9.9% and 3.8%, respectively, at 72 hours as the water-binder ratio decreased. It was due to the characteristics of the latent hydraulic and pozzolanic reactions. Generally, the relative abrasion resistance of concrete can be evaluated at 24 hours. However, in case of low strength (under 24 MPa), the surface mortar layer wears much faster at the first 12 hours, so it can be considered to evaluate the relative abrasion loss rate at this point.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2014.11a
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• pp.11-12
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• 2014

In this study, fundamental properties of concrete mixed with fiber has been analysed. Compressive strength, tensile strength and plastic shrinkage has been tested to conduct the optimum addition ratio of fiber. Effect to control press concrete's cracking has been tested. The following results could be made as the conclusion. For the flowability, slump decreased about 41-79% when all types of fiber used in the concrete. When the addition ratio of fiber is 1.2%, the slump of concrete decreased about 45%. For the strength properties. all the specimens with different addition ratio of fiber shown higher compressive strength comparing with Plain. Comparing with Plain, cracking decreased when the fiber added. Especially, when NY fiber used in the concrete, the plastic shrinkage did not occurred. In addition, Latex modified concrete(LMC) has improved superior physical and chemical properties. The properties of latex, combined with the low water-cement ratio, produce a concrete that has improved flexural, tensile, and bond strength, lower modulus of elasticity, increased freeze-thaw resistance, and reduced permeability compared to conventional concrete of similar mix design.

• Journal of the Korea Concrete Institute
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• v.20 no.5
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• pp.635-642
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• 2008

In recent years, epoxy-coated reinforcing bars have been widely used in order to prevent the corrosion of ordinary reinforcing bar. However, they have a bad balance between performance and cost. Especially, they have a brittleness properties, low bond strength to cement concrete and no good bend-ability in the field. The purpose of this study is to evaluate the tensile properties and adhesion of hybrid-type anti-corrosion polymer cement slurry (PCS). PCSs are prepared with four types polymer dispersions using fly ash and silica fume, and tested for proper coating thickness, tensile properties, adhesion to steel plate and bend-ability. From the test results, the viscosity of PCS is effected by polymer dispersion types, and is a little decreased by using fly ash. The coating thickness of PCS has a proper thickness at polymer-binder ratio of 100%. It is apparent that the coating thickness has various values according to viscosity of PCS, water-binder ratio and polymer-binder rato. PCS has a good various anticorrosion properties and physical properties such as tensile strength, adhesion and bend-ability. It is also recommended that proper coating thickness to reinforcing bar is in the ranges of 150 to $250{\mu}m$ for bond strength, adhesion and bend-ability. It is also expected that the coated reinforcing bar using PCS is widely used instead of epoxy coated reinforcing bar in the industrial field.

• Archives of Pharmacal Research
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• v.16 no.2
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• pp.134-139
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• 1993

The molecular structure of acemetacin, 1-(4-chlorobenzoyl)-5-methoxy-2-methyl-1H-indole-3-acetic acid carboxymethyl ester, was determined by single cystal X-ray diffraction analysis. The compound was recrystallized from a mixture of acetone and water in triclinic, space group P1, with a=7.796(1), b=10.245(2), c=13.542(3)$\AA,\;\alpha=97.35(1),\;\beta=96.34(1),\;\gamma=107.06(1)^\circ$, and Z=2. The calculated density is 1.422; the observed value is $1.42\;g/cm^3$. The structure was solved by the direct method and refined by full matrix least-squares procedure to the final R value of 0,037 for 2960 independent reflections. There are water molecules, which are thought to be co-crystallized during the evaporation procedure, with the ratio of one water per compound molecule in the crystal. The conformation of the compound is found to be very similar to that of indomethacin. The molecules are stabilized by three O-H.....O type intermolecular hydrogen bonds between the oxygen of water molecule and those of the compound.