• KCI Concrete Journal
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• v.14 no.3
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• pp.121-129
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• 2002

This study investigates experimentally into the design factors and quality variations having an effect on the properties of the combined high flowing concrete to be poured in the slurry wall of Inchon LNG in-ground receiving terminal. Especially, high belite cement and lime stone powder as cementitious materials and viscosity agent in order to improve self-compaction and hydration heat are used in this study. Water-cement ratio(W/C), fine aggregate volume ratio(Sr) and coarse aggregate volume ratio(Gv) as design factors of the combined high flowing concrete are applied to determine the optimum mix design proportion. Also quality variations for sensitivity test are selected items as followings. (1)Surface moisture(5cases) and (2)Fineness modulus of fine aggregate(5cases), (3)Concrete temperature(3cases), (4)Specific surface(3cases) and particle size of lime stone powder. As experimental results, water-cement ratio, fine and coarse aggregate volume ratio are shown as the optimum range 51%, 43% and 53% separately considering site condition of slurry wall. Also quality factors by sensitivity test should be controlled in the following ranges. (1) Surface moisture :to.67% and (2)Fineness modulus 2.6$\pm$0.2 of fine aggregate, (3)Concrete temperature l0-20t, (4) Specific surface 6,000$\textrm{cm}^2$/g and particle size 9.7$\pm$1.0${\mu}{\textrm}{m}$ of lime stone powder. Based on the results of this study, the optimum mix design proportion of the combined high flowing concrete are selected and poured successfully in the slurry wall of LNG in-ground tank.

• Journal of the Korea Institute of Building Construction
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• v.4 no.2
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• pp.129-136
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• 2004

High fluidity concrete(HFC) requires high dosage of superplasticizer to acquire sufficient fluidity, and high contents of fine powder and viscosity enhancing admixtures to resist segregation. The use of high amount of admixtures to make HFC at batcher plant in ready mixed concrete company is one of the reasons to raise the manufacturing cost of HFC. For this reason, new type of manufacturing method of HFC are described using both flowing concrete method and segregation reducing superplasticizer(SRS) in order to gain economical profit and offer the convenience for quality control.. As dosage of melamine based superplasticizer increases, it shows that fluidity and bleeding increase, while air contents and ratio of segregation resistance decrease. It also shows that addition of viscosity agent into superplasticizer reduce bleeding and improve segregation resistance of concrete. Dosage of AE agent into superplasticizer containing viscosity agent recovers loss of air contents during flowing procedure. Combination of proper contents of superplasticizer, viscosity agent and AE agent make possible to develope segregation reducing type superplasticizer. Compressive strength of high fluidity concrete applying flowing method with it is higher than that of base concrete. No differences of compressive strength between compacting methods are found. For the estimation of construction cost of high fluidity concreting using segregation reducing type superplasicizer, under same strength levels, although material cost of high fluidity concrete is somewhat higher than that of plain concrete due to segregation reducing type superplasticizer cost, labor cost and equipment cost of high fluidity concrete is cheaper than that of plain concrete. However, based on the strength differences, high fluidity concrete shows lower material cost, labor cost and equipment cost than that of plain concrete due to decreasing in size of member and re-bar caused by high strength development of concrete.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.5A
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• pp.531-541
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• 2009

The research analyzes and investigates conventional concrete, hydration heat, set, and mechanical properties by making high flowing self-compacting concretes of binary blend and ternary blend as one of evaluations about the properties of the hydration heat of high flowing self-compacting concrete with a strength of 30, 50, and 70 MPa. In addition, it estimates concrete adiabatic temperatures by calculating a thermal property value of powder obtained by measuring a heat evolution amount for powder used in concrete, a thermal property value of concrete obtained by conducting a simple adiabatic temperature test, and a normal thermal property value of material used in concrete, using a simple equation. Moreover, it analyzes and investigates the hydration heat property of high flowing self-compacting concrete and the thermal stress caused by hydration heat by conducting a 3D temperature stress analysis for the hydration heat and the adiabatic temperature obtained by temperature analysis, using MIDAS CIVIL 06 program.

• Transactions of the Korean hydrogen and new energy society
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• v.19 no.2
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• pp.156-162
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• 2008

The condensation pressure drop for R-22 and R-410A flowing in a small diameter tube was investigated. The test section is a counterflow heat exchanger with refrigerant flowing in the inner tube and coolant flowing in the annulus. The test section consists of 1220 mm length with horizontal copper tube of 3.38 mm outer diameter and 1.77 mm inner diameter. The refrigerant mass fluxes ranged from 450 to $1050\;kg/m^2{\cdot}s$ and the average inlet and outlet qualities were 0.05 and 0.95, respectively. The main experimental results were summarized as follows : In the case of two-phase flow, the pressure drop increases with increasing mass flux and decreasing quality. The pressure drop of R-22 is slightly higher than that of R-410A for the same mass flux. Most of correlations proposed in the large diameter tube showed enormous deviations with experimental data.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.10a
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• pp.567-572
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• 2002

This research investigates experimentally an effect on the quality performances of the high flowing concrete according to binder types. The purpose of this study is to determine the optimum mix proportion of the high flowing concrete having good flowability, viscosity and no-segregation. For this purpose, two types using belite cement＋lime stone powder(LSP) and furnace slag cement+lime stone powder are selected and tested by design factors including water cement ratio, fine and coarse aggregate volume ratio. As test results of this study, the optimum mix proportion for binder types is as followings. 1) One type based belite cement ; water cement ratio $51^{\circ}C$, fine aggregate volume ratio $43^{\circ}C$ and coarse aggregate volume ratio $53^{\circ}C$, replacement ratio of LSP $42.7^{\circ}C$. 2) Another type based slag cement : water cement ratio $41^{\circ}C$, fine aggregate volume ratio $47^{\circ}C$ and coarse aggregate volume ratio $53^{\circ}C$, replacement ratio of LSP $13.5^{\circ}C$.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.10a
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• pp.258-261
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• 1998

Aggregate is cheaper than cement and confers considerable technical advantages on concrete, which has a higher volume stability and better durability than hydrated cement paste alone. and coarse aggregate is the largest particle size out of concrete and is much affect on the fruidity, compaction and non-segregation ability of high flowing concrete. As the compaction, fillingability and shrinkage of high flowing concrete, the volume ratio of coarse aggregate is prescribed by Japanese Architectural Standard Specificateon (JASS 5) : from 0.500 to 0.500㎥/㎥. It is the aim of this study to compare and analysis the fruidity, fillingability and non-segregation of high flosing concrete according to the volume ratio of coarse aggregate of concrete(G/Glim).

• Proceedings of the Korea Concrete Institute Conference
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• 2001.05a
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• pp.339-344
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• 2001

This study is to investigate properties of high strength.high flowing concrete using blast-furnace slag in temperature conditions of 5, 10, 15 and $20^{\circ}C$. The result of this study can be summarized as follows. 1) The use of blast-furnace slag leads to decrease of air content and increase of fluidity in the fresh concrete. 2) The early compressive strength of high strength.high flowing concrete containing blast-furnace slag is lower than the case with portland cement only. 3) The compressive strength development of incorporating in the concrete is poor at low temperature below about $15^{\circ}C$.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2005.05a
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• pp.215-218
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• 2005

This paper intended to evaluate the applicability of drying shrinkage reducing superplasticizer (DSRA) by investigating physical properties of concrete using DSRA, The application of flowing concrete method exhibited a less loss of slump and air content with time than those of conventional concrete and had small bleeding. Flowing concrete had larger compressive strength than base and conventional concrete by as much as $3\~5\%$. It also had less drying shrinkage by as much as $20\%$ compared with conventional concrete. This is due to the coupled effect of reduced water content and aqueous type expansive admixture. On the other hand, neutralization depth of flowing concrete showed greater than conventional concrete.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.293-296
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• 2001

This paper presents the results of field application test on the manufacturing of high fluidity concrete by applying flowing methods with segregation reducing type superplasticizer. Base concrete is made with 20% of fly ash, which is flowed during the transportation. According to test results, fluidity, placeability and segregation reducing performance meet the range of high fluidity concrete after flowing, while air loss occurs due to fly ash. There are no noticeable differences in compressive strengths between non-compacting and compacting methods. According to non-destructive tests with rebound and core strength test, we cannot detect any differences in strength according to the height in the structures.

• Proceedings of the KIEE Conference
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• 1992.07b
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• pp.915-917
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• 1992

This paper shows the discharge characteristics in flowing air with variation of tempearature(T) under the needle-needle gap. Flowing air duct of this investigation is circular tube. The flow at the experimental position's section is described as fully developed laminar flow. The important results obtained from this study are as follows. The ratio sparkover voltages to the Reynolds number(Re) increases with decreasing the Re. The velocity profiles can be visualized by this experimental method. The breakdown voltage ($V_{s1}$) for variation of T at 1[m/s] can be expressed by $V_{s1}$ = $K_1$(23.98$\rho$d + 6.98$\sqrt{\rho{d}}$) [kV].