• Journal of the Society of Cosmetic Scientists of Korea
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• v.41 no.2
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• pp.113-119
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• 2015

The measurement of hydration level in the surface layer of the skin, stratum corneum (SC), gives important information on the biophysical properties and function of the skin barrier such as softness, flexibility, and healthiness of the skin. But it is difficult to measure a consistent hydration level from a sample to another sample due to individual variations and environmental changes. The aim of this study was to evaluate objective hydration after using various products in the SC. The SC Hydration was measured by capacitance (Corneometer$^{(R)}$, C+K, Germany) on the ventral site of forearm from 40 healthy volunteers. The skin surface was chronologically measured immediately after application of the test products and 3 and 6 hours later. We analyzed the averages of five measurements of each site and used the hydration increase rate for correction on untreated site variation. We found that most polyols including glycerol and butylenes glycol influenced directly the hydration increase rate in the SC previously. In this study, glycerol was used to prepare the standard products from 0 to 20 percents and applied to the same volunteers. The individual standard curve showed linear relation to glycerol concentrations. Based on the the standard curve, hydration of SC was converted into hydration increase rate to glycerol concentrations. The converted glycerol concentrations of products were repetitive and reproducible. In addition, the individual standard curve was used to relate the skin type of each individual. These results suggest that the hydration of the SC standardized regardless of external variation and individual skin condition can explain detailed skin state variation. Further studies will be conducted with other ingredients such as surfactants, lipids and aqueous materials, and with other methods for noninvasive measurement.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.10c
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• pp.19-24
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• 1998

In this study, blended cement with low blaine(2000, 3000$\textrm{cm}^2$/g) blast-furnace slag power by 10-70wt.% was investigated through the measurement hydration heat, physical properties. The experiment results indicated compressive strength was decreased as low blaine slag blended, but hydration heat was reduced significantly and flow of the cement paste was increased.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.525-528
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• 2006

This study performed an experimental test to derive the characteristics of compressive strength, het of hydration and creep of roller compacted concrete. The main variable of strength test are cement content and fly ash content. The heat of hydration test was performed using MARUTO CH-50-CA and dreep test was carried out according to KS F 2453.

• Preventive Nutrition and Food Science
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• v.17 no.1
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• pp.87-91
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• 2012

Three oat cultivars and one oat breeding line were evaluated for chemical, hydration and pasting properties. Protein, starch and ${\beta}$-glucan levels ranged 11.13~14.37, 56.37~64.86 and 3.44~4.76%, respectively. The oat cultivars Daeyang and Seonyang contained higher ${\beta}$-glucan levels of 4.76 and 4.35%. The Daeyang variety had a higher water absorption index (WAI) of 2.83~3.35 (g/g), but a lower water solubility index (WSI) of 8.67~11.08%. Daeyang and Seonyang cultivars showed higher peak and trough viscosity, but lower breakdown and setback, indicating that they easily swell, and thus could possibly provide the desirable viscosity of an oat product. The ${\beta}$-glucan levels were correlated positively with WAI, peak and trough viscosity, and negatively to WSI, breakdown and setback viscosity.

• Advances in concrete construction
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• v.5 no.3
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• pp.289-301
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• 2017

The synergistic interactions of supplementary cementitious materials (SCMs) with ordinary portland cement (OPC) in multi-blended systems could enhance the mechanical and durability properties of concrete and increase the amount of cement that can be replaced. In this study, the characteristics of the hydration products as well as paste microstructure of blended cement containing 20% coal fly ash, 10% rice hull ash and 10% sugar mill lime sludge in quaternary blended system was investigated. Portlandite content, hydration products, compressive strength, pore size distribution and microstructural architecture of hydrated blended cement pastes were examined. The quaternary blended cement paste showed lower compressive strength, reduced amount of Portlandite phases, and higher porosity compared to plain hardened cement paste. The interaction of SCMs with OPC influenced the hydration products, resulting to the formation of ettringite and monocarboaluminate phases. The blended cement paste also showed extensive calcium silicate hydrates and calcium aluminate silicate hydrates but unrefined compared to plain cement paste. In overall, the expected synergistic reaction was significantly hindered due to the low quality of supplementary cementitious materials used. Hence, pre-treatments of SCMs must be considered to enhance their reactivity as good quality SCMs can become limited in the future.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.489-492
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• 2008

Adiabatic temperature rise and autogenous shrinkage experiments were performed for three silica-fume included mass concrete mixtures and a reference mixture without silica-fume, in order to investigate the influence of silica-fume on the hydration heat and autogenous shrinkage properties of mass concrete, and to examine applicability of silica-fume to mass concrete. It was revealed from the experiment that, for mass concrete, the rate of hydration was hardly increased while the maximum adiabatic temperature rise decreased about 5$^{\circ}$C by the addition of silica-fume, and the amount of autogenous shrinkage was almost the same regardless of silica-fume replacement. These facts imply that silica-fume can enhance the resistance of mass concrete to temperature cracking as well as the durability.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2008.11a
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• pp.31-36
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• 2008

This study aims to examine the effects of thickness of the concrete members and curing temperature on the properties of low heat concrete through heat of hydration analysis. Type of the members that was analyzed in the experiment is ternary mixture of ordinary portland cement, blast-furnace slag incorporating ratio(20%) and fly ash incorporating ratio(30%), which formed a mat foundation. Thicknesses of the concrete members were 1, 2 and 3(m) and three levels of curing temperatures were 10, 20 and 30(℃). They were applied to analyze the effects on the temperature and thermal cracking index. As a result, for temperature history, temperature difference between the central area and the surface tended to decrease as the thickness of the concrete members get thinner. For the temperature cracking index, on the other hand, the risk of cracking tended to decrease as the curing temperature gets higher and as the thickness gets thinner.

• Journal of the Korean Ceramic Society
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• v.34 no.7
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• pp.738-746
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• 1997

MgO clinker and two kinds of dolomite clinkers with different microstructures and CaO contents were used as starting materials, and the effects of Fe2O3 addition on the properties of MgO and dolomite were investigated in the range of 2 to 8 wt% of Fe2O3 content. Secondary phases contributed to densification of MgO-Fe2O3 and dolomite-Fe2O3 were magnesioferrite and dicalciumferrite, respectively. Sinterabilities of MgO-Fe2O3 and dolomite-Fe2O3 were directly proportional to the amount of secondary phases. Also, sinterability of dolomite itself was dependent on the microstructure of starting material including distribution of CaO and MgO as well as the addition amount of Fe2O3. The flexural strength of MgO-Fe2O3 content was almost constant. The hydration resistance of dolomite with large size of MgO and discontinuous distribution of CaO was higher than that of dolomite with small size of MgO and continuous distribution of CaO. Also, the minimum content of Fe2O3 to prevent they hydration of dolomite was about 4wt%. As increasing Fe2O3 content, the penetration resistance of MgO-Fe2O3 was improved by the increment of magnesioferrite. On the other hand, the penetration resistance of dolomite-Fe2O3 was decreased because of the increment of dicalciumferrite having low melting point.

• Journal of the Korean Recycled Construction Resources Institute
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• v.12 no.1
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• pp.33-39
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• 2024

In this study, the basic properties of cement paste with varying replacement ratio of micro-silica and fumed silica were analyzed to determine the suitability of nanomaterials for use as concrete admixtures. Referring to the ultra-high strength mix, the fluidity of cement paste was evaluated according to the nanomaterial replacement rate and the compressive strength characteristics were compared and analyzed. The related properties of the reactive nanomaterials to the cement hydrate were analyzed using SEM and EDS to observe the microstructure and identify the components of the hydration product. The reactive nanomaterials used in this study had tap densities between 0.061 and 0.264 g/cm³, which were lower than SF. Micro silica exhibited excellent compressive strength properties with increasing replacement ratio, but fumed silica, unlike micro white, obtained excellent compressive strength at replacement ratio of 0.01~0.1 %. The same trend was observed in the hydration characterization.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.10a
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• pp.725-728
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• 1999

The bridge slab of express railway was designed for high strength concrete (design strength 400kgf/$\textrm{cm}^2$). In case the slab is made with the concrete using type I cement, used much amount of cement can cause cracks through concrete by hydration heat or dry shrinkage. In this study we targeted to solve above problems using type III cement. We could decrease the cement ratio in concrete using type III cement than type I cement. The concrete using type III cement showed good workability and compressive strength, and showed better properties in hydration heat and dry shrinkage than that using type I cement