• Proceedings of the Korean Institute of Building Construction Conference
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• 2016.10a
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• pp.56-57
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• 2016

Recently amongst Korea's construction companies there has been heightened interest in environment load reduction and resource recycling. As a result, the construction industry is examining recycled materials alternative to cement and blast-furnace slag (BS henceforth) cement, such as waste refractories and desulfurized plaster. This study analyzes the liquidity and intensity characteristics of mortar according to changes in replacement ratios of waste refractories and desulfurized plaster, used as industry by-products in mortar environments that use BS 3-type cements and circulated fine aggregate. As a result, the greater the increase in replacement ratios of desulfurized plaster, the greater the increase in liquidity and air quantity, as well as compression strength.

• Magazine of the Korean Society of Agricultural Engineers
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• v.17 no.1
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• pp.3685-3701
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• 1975

This study was conducted to investigate the strength of soil cements for varied molding water content and cement content(3,6,9,12%) in four cementstabilized soils(KY: sand, MH: sad, SS: sandy loam, JJ: loam). The eoperimental results obtainedfrom unconfined compressive strength tests are asfollows: 1. The optimum moisture content increased in accordance with the increase of the cement while maximum dry density didn't change uniformly. 2. The moisture content for maximum strength was higher than the optimum moisture content in the higher cement content. Moisture-density curves showed a dull peak in the higher cement contents, on the other hand, a sharp peak in the lower cement contents. 3. In molding the specimen with the approximate optimum moisture content, the maximum strength showed at the wet side of the optimum moisture content. 4. SS and JJ maybe used as cement-stabilized base of road to require 300PSI of compressive strength cured seven days, but MH and KY may be not adequate. 5. In soil cement, the better the grain size distribution was, the stronger the compressive strength was itn general. 6. The relation between 28-day strengh and 7-day strength in the cementstabilized four soils may be expressed as follows: q28=1.55q7+1.5 in which q28:28-day strength. q7:7-day strength.

• Resources Recycling
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• v.10 no.6
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• pp.43-52
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• 2001

This study was conducted to obtain granular crystalline gypsum that can be used as raw material for Plaster boards or cements from waste Plaster board. Gypsum could be Preferentially disintegrated to gypsum needle in $10\mu\textrm{m}$ or less size by hydration after the dehydration of crushed waste Plaster board. The finer the gypsum needle, it is easier to remove coarse impurities and to recover the gypsum needle. The optimum conditions for obtain the finer gypsum size were dehydration rate of 75~85%, solid concentration at hydration of 10~15%, agitation speed of 250~400 rpm, crushing size before dehydration of 2 cm or less. Gypsum of 98.21% grade was recovered with 99.0% yield as the undersize of 325 mesh wet screening followed by the dehydration-hydration process performed at the conditions of dehydration rate of 80%, solid concentration at hydration of 15%, agitation speed of 300 rpm, crushing size before dehydration of 2 cm or less. After the recrystallization of recovered gypsum, Plate-like gypsum of $151\mu\textrm{m}$ size with 99.49% grade was obtained as the oversize of 270 mesh in a wet screening.

• Restorative Dentistry and Endodontics
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• v.17 no.2
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• pp.421-430
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• 1992

The purpose of this study was to evaluate the bond strength between the composite resin and light - cured glass ionomer cement base / liners treated by the several methods. The light - cured glass ionomer cement(Vitrebond / Cavalite) were injected into cavites prepared in acrylic plates. One hundred and twenty specimens were uniformly prepared and devided into 3 groups. For the first group, primer was not applied to glass ionomer cement. For the second group, no application of primer was undertaken and light - curing procedure to uncured glass ionomer cement surface which was covered by bonding agent was undertaken. After bonding composite resin to light - cured glass ionomer surface, the specimens, were stored in $37^{\circ}C$, 100% humidity for 1 hour. The following results were obtained : 1. The omission of application of a primer did not produce a significantly poorer bond strength. 2. Light - curing technique to uncured glass ionomer cement which was covered by bonding agent did not produce a significantly poorer bonding strength. 3. The bond strength of Cavalite to composite resin was significantly higher than that of Vitrebond. 4. There was no significant difference between two different types of composite materials(Silux-Plus / Herculite XR) when it was applied to bond to glass ionomer cement.

• Nuclear Engineering and Technology
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• v.50 no.1
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• pp.151-158
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• 2018

The neutron powder diffractometer (NPD) is used to study a variety of technologically important and scientifically driven materials such as superconductors, multiferroics, catalysts, alloys, ceramics, cements, colossal magnetoresistance perovskites, magnets, thermoelectrics, zeolites, pharmaceuticals, etc. Monte Carlo-based codes are powerful tools to evaluate the neutronic behavior of the NPD. In the present study, MCNPX 2.6.0 and Vitess 3.3a codes were applied to simulate NPD facilities, which could be equipped with different optic devices such as pyrolytic graphite or neutron chopper. So, the Monte Carlo-based codes were used to simulate the NPD facility of the 5 MW Tehran Research Reactor. The simulation results were compared to the experimental data. The theoretical results showed good conformity to experimental data, which indicates acceptable performance of the Vitess 3.3a code in the neutron optic section of calculations. Another extracted result of this work shows that application of neutron chopper instead of monochromator could be efficient to keep neutron flux intensity higher than $10^6n/s/cm^2$ at sample position.

• Journal of Periodontal and Implant Science
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• v.39 no.4
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• pp.437-441
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• 2009

Purpose: The purpose of this report is to show three cases treated by an intergrated periodontal and restorative dentistry approach. Methods: Three patients with Miller Class Ⅰgingiva recessions associated with cervical lesions were enrolled for treatment. Two patients received a connective tissue graft and resin modified glass ionomer, and one patient was treated with a connective tissue graft, resin restoration. Keratinized gingiva and relative gingival recession were measured. Results: The mean reduction of relative gingival recession was 3.7 mm, and the mean keratinized gingiva increase was 2.5 mm. The percentage of root coverage was 80% in average. No signs of gingival inflammation or bleeding on probing were seen. The patients were satisfied with the final esthetics and had no more dentin hypersensitivity. Conclusions: This report indicates that teeth with Miller ClassⅠ gingival recession associated with cervical lesions can be successfully treated by a connective tissue graft combined with restorative dentistry. However, longitudinal randomized controlled clinical trials must be performed to support this approach.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.721-724
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• 2008

Recently, by-products for example of fly-ash, blast-furnace slag and etc are generally using in concrete. However a mount of by-products are mostly dropped into the land and sea. Expecially it is necessary to manage against London Dumping Convention which is prohibited for throwing the by-product into the sea. The purpose of this study is for the active use of the fly ash, which is a by-product of the combustion pulverizes coal thermal power plants, to compensate for the lack of landfill and for conservation of energy, by using fly ash as the supplementary cementitious material, and to prove its possibility as the related products of the cements.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.785-788
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• 2008

Ceramics manufactures in the nation produced more than 5,000 tons of waste pottery a year increasing industrial waste quantity. However, Almost researches were made to reduce environmental pollution and recycle waste ware. It is needed that they are used as recycled materials in order to prevent environmental pollution and gain economic profits. Therefore, the purpose of this study is to present the method of utilizing the recycled cements that are obtained from waste pottery. The test results that replacement of waste pottery powder by cement admixture at the level 10% had effect on the stripping strength(compressive strength). Also, When GBFS and WP used by cement admixture, WP is better than GBFS.

• Journal of the Korean Ceramic Society
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• v.36 no.1
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• pp.77-81
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• 1999

In order to investigate the effect of fineness on the properties of Portland cement, we prepared five kinds of portland cements with different Blaine values(2300, 2500, 3000, 3500, 45oo $\textrm{cm}^2$/g) and measured Ca(OH)2 analysis, hydration heat, the fluidity and the physical properties of them. According to the results, as the Blain value of cement is lower, the rate of hydration is delayed, and the hydration heat and the compressive strength are decreased. But the fluidity of cement paste is improved. Especially, the hydration heat of the cement with 2500$\textrm{cm}^2$/g of Blaine value is decreased about 15% compared with 3500 $\textrm{cm}^2$/g cement.

• Journal of the Korean Ceramic Society
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• v.51 no.2
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• pp.57-63
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• 2014

Bottom ash can be used as pelletizing seeds in unsintered artificial lightweight aggregates, so it can be called as 'cold-bonded aggregates'. In the present study, the mechanical and chemical characteristics of bottom ash aggregates cold-bonded with fly ash were investigated. The crushing strength and the water transfer characteristic of the aggregates, which may affect the strength gain of the concrete, were evaluated. Moreover, the degree of hydration and the hydration products of the aggregates were analyzed to verify the chemical stability of the aggregates. Compared to commercialized artificial lightweight aggregates manufactured by sintering process, cold-bonded fly/bottom ash aggregates had similar levels of water transfer characteristics, while having lower strengths. The calcium hydroxide in the aggregates was almost completely consumed after 28 days moist curing.