• Journal of the Korean GEO-environmental Society
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• v.20 no.5
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• pp.47-55
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• 2019

This study aims to provide basic data for soil packaging differing in accordance with the strength characteristics of mixed soil, using E.S.B. (Eco Soil Binder), an eco-friendly hardening agent, based on the type of soil. The soil used in this study is weathered granite soil readily collected in and around Korea, and is classified into SW, SP and SC according to soil classification systems. The test piece for the unconfined compressive strength test has dimensions of 50 mm in diameter and 100 mm in height, with the mix ratio of E.S.B. proportional to the weight of mixed soil changed from 5% to 10%, 15%, 20%, 25%, and 30%, where compactness of 90% and 100% were applied according to each condition to analyze the unconfined compressive strength characteristics at material ages of 3, 7, and 28 days. Also, the ratio of soil packaging standard strength and unconfined compressive strength was calculated to determine the optimal E.S.B. mix ratio, whereby the field applicability of the unconfined compressive strength using the estimation equation of ACI209R was evaluated.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.5 no.1
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• pp.1-12
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• 1985

This study is conserned for the optimum design of reinforced concrete slab-beam-column structures with multi-storys and multi-bays by Direct Method. Flexural and shear strength, sectional size, and steel ratio etc., were considered as the design-constraints and the cost function was taken as to objective function. They became high degree nonlinear problems. Using SLP as an analytical method of nonlinear optimal problems, an optimal algorithm was developed in this study and the algorithm was applied to the optimization of reinforced concrete structure system of 5 storys. The result converged to a optimal solution with 3 to 5 iterations, and proved that economical design could be possible when compared with conventional designs.

• Korean Journal of Food Science and Technology
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• v.35 no.4
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• pp.617-622
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• 2003

Experimental designs were applied to optimize the mixture ratio for the extrudate made by soymilk residue and corn grits. Nine candidate points were examined for their significance on extrudate using the modified distance design. Bending force, expansion ratio, bulk density, water solubility index (WSI), water absorption index (WAI) and color $(L^*,\;a^*,\;b^*)$ were the significant factors improving the extruded cereal production, and these values were applied to the mathematical models. Results showed that bending force, expansion ratio WSI, WAI and color $(L^*,\;b^*)$ increased with increasing the corn grits, whereas bulk density tended to decrease. The statistical study showed that the fitted models were adequate to describe the contour plot and all responses. Optimum mixture ratio allowing to maximize the two responses (expansion ratio and $b^*$) and minimize the response (WAI) were examined with a numerical optimization methods. The numerical optimization method was obtained as 53.18% : 46.19% (corn grits : soymilk residue).

• Journal of the Korea Institute of Construction Safety
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• v.6 no.1
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• pp.12-18
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• 2024

High-rise, large-scale, and diversification of buildings are possible, and the reduction of concrete cross-sections reduces the weight of the structure, thereby increasing or decreasing the height of the floor, securing a large number of floors at the same height, securing a large effective space, and reducing the amount of materials, rebar, and concrete used for designating the foundation floor. In terms of site construction and quality, a low water binder ratio can reduce the occurrence of dry shrinkage and minimize bleeding on the concrete surface. It has the advantage of securing self-fulfilling properties by improving fluidity by using high-performance sensitizers, making it easier to construct the site, and shortening the mold removal period by expressing early strength of concrete. In particular, with the rapid development of concrete-related construction technology in recent years, the application of ultra-high-strength concrete with a design standard strength of 100 MPa or higher is expanding in high-rise buildings. However, although high-rise buildings with more than 120 stories have recently been ordered or scheduled in Korea, the research results of developing ultra-high-strength concrete with more than 130 MPa class considering field applicability and testing and evaluating the actual applicability in the field are insufficient. In this study, in order to confirm the applicability of ultra-high-strength concrete in the field, a preliminary experiment for the member of a reduced simulation was conducted to find the optimal mixing ratio studied through various indoor basic experiments. After that, 130 MPa-class ultra-high-strength concrete was produced in a ready-mixed concrete factory in a mock member similar to the life size, and the flow characteristics, strength characteristics, and hydration heat of concrete were experimentally studied through on-site pump pressing.

• Journal of the Society of Disaster Information
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• v.20 no.1
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• pp.20-31
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• 2024

Purpose: Research and development of high-strength concrete enables high-rise buildings and reduces the self-weight of the structure by reducing the cross-section, thereby reducing the thickness of beams and slabs to build more floors. A large effective space can be secured and the amount of reinforcement and concrete used to designate the base surface can be reduced. Method: In terms of field construction and quality, the effect of reducing the occurrence of drying shrinkage can be confirmed by studying the combination of low water bonding ratio and minimizing bleeding on the concrete surface. Result: The ease of site construction was confirmed due to the high self-charging property due to the increased fluidity by using high-performance water reducing agents, and the advantage of shortening the time to remove the formwork by expressing the early strength of concrete was confirmed. These experimental results show that the field application of ultra-high-strength concrete with a design standard strength of 100 MPa or higher can be expanded in high-rise buildings. Through this study, we experimented and evaluated whether ultra-high-strength concrete with a strength of 130 MPa or higher, considering the applicability of high-rise buildings with more than 120 floors in Korea, could be applied in the field. Conclusion: This study found the optimal mixing ratio studied by various methods of indoor basic experiments to confirm the applicability of ultra-high strength, produced 130MPa ultra-high strength concrete at a ready-mixed concrete factory similar to the real size, and tested the applicability of concrete to the fluidity and strength expression and hydration heat.

• Journal of the Korea Concrete Institute
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• v.27 no.4
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• pp.419-426
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• 2015

The purpose of this study is to investigate experimentally the optimum mix design and site application case of soil mixing wall (SMW) method which is cost-effective technique for construction of walls for cutoff wall and excavation support as well as for ground improvement before constructing LNG storage tank typed under-ground. Considering native soil condition in site, main materials are selected ordinary portland cement, bentonite as a binder slurry and also it is applied $1,833kg/m^3$ as an unit volume weight of native soil, Variations for soil mixing wall are as followings ; (1) water-cement ratio 4cases (2) mixing velocity (rpm) 3levels (3) bleeding capacity and ratio, compressive strength in laboratory and site application test. As test results, bleeding capacity and ratio are decreased in case of decreasing water-cement ratio and increasing mixing velocity. Required compressive strength (1.5 MPa) considering safety factors in site is satisfied with the range of water-cement ratio 150% below, and test results of core strength are higher than those of specimen strength in the range of 8~23% by actual application of element members including outside and inside in site construction work. Therefore, optimum mix design of soil mixing wall is proposed in the range of unit cement $280kg/m^3$, unit bentonite $10kg/m^3$, water-cement ratio 150% and mixing velocity 90rpm and test results of site application case are satisfied with the required properties.

• Journal of the Korean GEO-environmental Society
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• v.9 no.1
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• pp.47-54
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• 2008

In this study, the effect of water content condition was investigated on the Mohr-Coulomb shear strength parameters which are commonly used as the input data in the soil slope analysis. For the purpose, a series of direct shear test was conducted in different water content conditions on the two types of weathered soils and a dam core material, obtained from the domestic slope construction sites and the dam construction site, respectively. The comparisons between the values of the Mohr-Coulomb ${\phi}_{peak}$ and $c_{peak}$, estimated from the relationships between the normal stress and the peak shear stress for the samples in the four different water content conditions (i.e., dry side, optimum, wet side, and saturated), showed that overall, the values of $c_{peak}$ decreased gradually while those of ${\phi}_{peak}$ did not vary much with increasing the water content. A rough estimate for the varying ratio of the values of ${\phi}_{peak}$ and $c_{peak}$ indicated that the values of $c_{peak}$ decreased by every 25% of the $c_{peak}$ values in dry side, while those of ${\phi}_{peak}$ were constant, as the water content condition changed from dry, optimum, and wet to saturated, respectively.

• Journal of the Korean Society of Food Science and Nutrition
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• v.32 no.7
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• pp.1032-1038
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• 2003

The two-level full factorial and mixture design were used to screen ingredient type and to investigate the effects of ingredients on properties of surimi gel from jack mackerel using measurements of breaking forces, deformation values and color. The addition of starch decreased breaking force significantly (p<0.05), but did not affect deformation. The bovine plasma protein (BPP) among non-muscle proteins increased a breaking force and deformation value. However, the dried egg white increased slightly a breaking force, and decreased greatly a deformation value. The breaking force of gel was increased, but deformation value did not change significantly (p<0.05) with adding BPP. The whiteness of gel was slightly improved with the addition of corn starch and BPP. At 78% moisture, the optimum ratios of ingredients were 89.5∼90.0% for alkali surimi, 4.6∼6.0% for corn starch and 4.3∼5.4% for BPP to obtain above 110g for a breaking force, 4.2 mm for a deformation, and 22.5 for a whiteness.

• Applied Chemistry for Engineering
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• v.7 no.3
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• pp.565-572
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• 1996

The optimum loading of carbon black was studied for the rubber compounds of natural rubber(NR), butadiene rubber(BR), and styrene-butadiene rubber(SBR) with different amount of oil. The optimum loading of carbon black was determined by the volume ratio of carbon black and L factor of Lee's theory. The optimum loading of carbon black was confirmed by the examination of physical properties of the rubbers. The optimum loading amounts of carbon black for the each rubber compound were 60 phr for NR, 57 phr for BR, 65 phr for SBR-A, 70 phr for SBR-B, and 76 phr for SBR-C, respectively. The optimum loading of carbon black was increased by 5 phr for every increment of 20 phr of oil content. It was revealed that the optimum loading amount of carbon black determined by L factor is closely related to the tensile strength of the rubber compounds. The optimum loading amount of carbon black was observed at the amount which shows the maximum value of tensile strength.

• Magazine of the Korea Concrete Institute
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• v.9 no.1
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• pp.165-172
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• 1997

Lightweight foamed concrete is a concrete which is lighter than conventional concree by mixing ptetoamed foam in cement slurry. The objectives of this study are to develop optimal prefoarneti lightweight foamed concrete with high lightness. high flowability and enough strength fol special use of structural application by using the polymer foam agent. By mixing the admixtures such as silica-fume and fly-ash and the industrial by-product such as styrofoam for the purpose of practical use of industrial waste, lightweight foamed concrete shich has better lightness. flowability and strength than the conventional prefoamed lightweight foamed concrete is developed. This paper presents extensive data on characteristics of compressive strength and flowability of the concrete manufactured with the different factors in mix design and also presents optimum mix proportion.