• Tunnel and Underground Space
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• v.22 no.5
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• pp.354-364
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• 2012

In order to evaluate the physical properties of rock which might serve as a database for both mining and civil works, a lot of laboratory tests for Jecheon limestones were conducted to find unit weight, absorption ratio, porosity, elastic wave velocity, uniaxial compressive strength, Young's modulus, poisson's ratio, tensile strength, shore hardness, friction angle and cohesion. On investigation of the mechanical properties of both the gray limestone and the clayey limestone distributed in the studied region, the clayey limestone turned out to have more weak mechanical properties which might come from low unit weight, high absorption ratio and high porosity of rocks. The failure criteria of Jecheon limestones were discussed by means of both Mohr-Coulomb criterion and Hoek-Brown criterion. Regression analyses of the physical properties obtained from a lot of laboratory tests were also conducted by means of both linear and multiple regression analyses.

• Journal of the Korean Recycled Construction Resources Institute
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• v.2 no.1
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• pp.10-18
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• 2014

This study carried out to evaluate the hydration heat analysis and fundamental characteristics such as air content, slump, compressive strength and dry shrinkage according to concrete with premixed cement, ternary concrete and OPC concrete for using concrete with premixed cement. The results of experiment are founded that concrete with premixed cement have sufficient performances such as workability, compressive strength and dry shrinkage. Also, the results of hydration heat analysis are founded that concrete with premixed cement have more performance than ternary concrete and OPC concrete at a point of view for the quality control such as thermal crack reducing and economic benefit. Therefore, it is desirable that concrete with premixed cement should be used to rise durability performance and convenience of maintenance.

• Current Research on Agriculture and Life Sciences
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• v.32 no.2
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• pp.85-89
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• 2014

This study uses turbidity and rheological measurements to examine the effects of the molecular weight (MW), substitution type and substitution degree of cellulose ether and water content on the cooking characteristics of rice noodles, the turbidity of the cooking solution, and the compression strength of the cooked noodles. When increasing the MW of cellulose ether and water content, the turbidity decreased, thereby improving the morphological stability of the rice noodles during cooking. Thus, when controlling the above factors effectively, the rice noodle cooking solution had a lower turbidity than with wheat noodles. Measuring the compression strength of the rice noodles using a rheometer was also effective for examining the pasting characteristics of the rice noodles and texture changes during cooking. As a result, the water content and MW of cellulose ether were found to affect the pasting characteristics and texture of the rice noodles more than the other factors examined.

• Applied Chemistry for Engineering
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• v.16 no.4
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• pp.549-555
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• 2005

To evaluate the posterior and anterior restoration of polymeric dental restorative composite (PDRC), PDRC was prepared using a silica filler treated by heat at various temperatures. Compressive strength (CS) and diametral tensile strength (DTS) values were investigated to study the effect of a heat-treated silica on the mechanical properties of PDRC using the recommended dental specifications. Both the particle size and specific volume of silica were decreased upon increasing the heat treatment temperature. CS and DTS values of PDRC containing a heat-treated silica showed 1.2 and 1.3 times, respectively, higher than that of the PDRC containing a neat silica. Also, it was found that the lower heat treatment temperature, the better mechanical properties of PDRC were observed because there was less agglomeration between silica particles. Specially, PDRC using a silica treated at $600^{\circ}C$ showed superior mechanical strength.

• The Korean Journal of Food And Nutrition
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• v.9 no.4
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• pp.466-471
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• 1996

In order to investigate the compression characteristics on the some vegetables-cucumber, garlic, ginger, potato, and radish-compression force, distance, and time were measured with a Struct-O-Graph and correlations between them were investigated. Force-distance and distance-time curves were showed simply and reflection points were showed rarely. The time to rupture point was long of 11.7sec at the compression speed of 60mm/min and of 6.16sec at the compression speed of 120mm/min in potato, and short of 9.65, 4.55sec at the different compression speed in garlic, respectively. The rupture force was large of 16.64~20.00N at the different compression speed in potato and radish, and the sample at rupture point was showed crushing behavior under probe. These phenomena were suggested because compression strength of sample was different. In the result of regression analysis for force-time and distance-time to the rupture point, the correlation coefficients were above 0.96, and difference of among samples was small. The slopes of force-time were large of 1.772~3.385 in cucumber and small of 1.743~3.338 in potato, and the slopes of distance-time were obtained with reverse results.

• Journal of the korean academy of Pediatric Dentistry
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• v.29 no.3
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• pp.362-370
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• 2002

During the last two decades, many new filling materials and material groups have been developed. the number of available restoratives has increased dramatically, especially during the last 5 years. Ormocers are a new class of materials which are still under development with regard to dental applications. However, in the chemical literature these materials have been known for a long time and used for producing scratch resistant coatings on plastic spectacle lenses. It is a combination of inorganic and organic materials. 'Ormocer' is an abbreviation for 'Organically Modified Ceramics'. These compounds are also known in the literature as 'Ormosils' (organically modified silicates). Their chemistry is comparable to that of silicones and organic polymers. The purpose of this study was to determine of compressive strength and flexural strength of a ormocer (Admira) and to investigate the effects of water absorption in comparison with three composite resins(Z-100, Tetric Ceram, Surefil) and one compomer(Dyract AP). The following results were obtained ; 1. Admira had the lower compressive strength than Surefil, but no statistically difference with other materials at 1 day(p>0.05). 2. Admira had the lower flexural strength than all other materials at 1 day. From 2 days, Admits showed lower flexural strength than three composite resin(p<0.05). 3. There was not statistically significant difference of compressive and flexural strengths between hybrid composite resin group(Z-100, Tetric Ceram) and Packable resin group(Surefil) for experimental period(30 days)(p>0.05). 4. All five materials showed an increase in compressive and flexural strength till 2 days and showed a decrease from 7 days in water(p<0.05). 5. Each materials had the statistically similar behavior of compressive and flexural strengths over time(p>0.05).

• Applied Chemistry for Engineering
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• v.10 no.7
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• pp.1066-1072
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• 1999

The physical properties of polymer concrete were investigated for development of high-performance construction materials. Various specimens of polymer concrete were prepared using unsaturated polyester resin as the polymer-binder with the various dosage of calcium carbonate as microfiller (5~20 wt %) and fine aggregate(10~50 wt %). For the evaluation of the physical properties of polymer concretes, tests such as compressive strength, flexural strength, water absorption test, hot water immersion test, acid resistance test and pore size distribution analysis were conducted. As a result, it is concluded that compressive and flexural strengths of polymer concretes increased up to 4 times than those of conventional cement concrete. Whereas the compressive and flexural strengths of polymer concretes tested after hot water immersion, compared with those of polymer concretes tested before hot water immersion, decreased about 67%, 47%, respectively. By hot water immersion, total pore volume and porosity(%) of polymer concretes were remarkable increased due to decomposition of polymer binder. And also, it is showed that water absorption(%) and weight loss(%) of polymer concrete specimens by acid immersion, compared with those of ordinary portland cement concrete, decreased about 1/100, 1/27, respectively.

• Journal of the Korea Concrete Institute
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• v.22 no.3
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• pp.375-380
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• 2010

In this study, physical properties of cement blended with Finex-slag powder(OPC-FS) were investigated by the measurement of flowability, compressive strength, hydration heat, and $Ca(OH)_2$ content. In addition, those properties of the cement blended with blast furnace slag(OPC-BFS) were also measured for comparison. It was found that OPC-FS and OPC-BFS showed similar trend in the rheological properties. In the blended cement pastes with the $4,000\;cm^2/g$ Blaine value the flowability of OPCFS was better than that of OPC-BFS. The initial 3 day mortar compressive strength and the hydration heat of paste of OPC-FS was a bit higher, compared with OPC-BFS. Accordingly $Ca(OH)_2$ produced in the cement hydration was decreased very rapidly.

• Journal of the Korea Concrete Institute
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• v.13 no.1
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• pp.69-76
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• 2001

Foamed concrete for cast-in-site, which shows excellent lightweight, thermal insulation, noise insulation, constructability and cost efficiency, has been applied as thermal insulation or filling material for On-dol. However, the technology is too insufficient to obtain the high level of quality, and serious problems often occur in quality control at sites. It, thus, is necessary to establish the proper and reasonable quality control method for ensuring the required quality, based on the investigation on the physical properties and their reciprocal relation. This study aims to settle the quality control method in case of applying FA foamed concrete replacing 40% by weight with fly-ash as the filling material for On-dol. The results of the study include the correlation among flow, as-placed density and foam ratio of fresh foamed concrete, the correlation between physical properties before hardening and after 28-day, provision of an equation to estimate 28-day compressive strength early with 7-day compressive strength, and suggestion of quality criteria for the revision of KS on foamed concrete for cast-in-site.

• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.3
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• pp.69-78
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• 2011

As recent concrete products changed to pursue high class, high quality, and high strength, as translucent concrete was developed to meet esthetic effects and exhibition purpose of structures. This study aims at introducing fabrication methods of various shapes of translucent concrete and evaluating feasibility of using mineral admixture such as fly ash, ground granulated blast furnace slag and granulated glass throughout experimental tests. As the result, it was found that compressive strength of translucent concrete block at 28 days is 32.2MPa and higher elastic modulus and Poisson's ratio than ordinary concrete block, which means that translucent concrete is widely applicable to structural purpose. Application of fly ash as a replacement of cement showed lower strength of 85 to 96% than Portland cement. In the meanwhile, ground granulated blast furnace slag showed 82 to 96% depending on the amount of replacement. The use of granulated glass as replacement of optical fiber was not applicable due to invisibility of light in concrete.