• Proceedings of the Korea Concrete Institute Conference
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• 1999.04a
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• pp.605-608
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• 1999

In this paper, the application of limestone grain, which produced by being gathered electrically in the process of manufacturing of cement, to high fluidity concrete are investigated. High fluidity mortar is used for this experiment. According to the experimental results, especially, high viscosity and the loss of air content are accomplished by applying limestone grain as the partial substitution of fine aggregates. In case of hardened mortar, high strength development at early age can be achieved by using limestone grain. But excessive dosage of limestone grain can cause high drying shrinkage.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.5A
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• pp.511-518
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• 2009

This study was intended to compare and evaluate the adhesion of High flowing Self-compacting Concrete (HSCC), Conventional Concrete (CC) and deformed bar based on concrete strength 3 (30, 50 and 70 MPa), among the factors affecting the bond strength between concrete and rebar, after fabricating the specimen by modifying the rebar position at Horizontal reinforcement at bottom position (HB), horizontal reinforcement at top position (HT) and vertical reinforcement type (V). As a result of measuring bond strength of HB/HT rebar to evaluate the factor of the rebar at top position, the bond strength of HB/HT rebar at 50 and 70 MPa was 1.3 or less and at 30 MPa, HSCC and CC appeared to be 1.2 and 2,1, respectively. Thus, when designing the anchorage length according to the concrete structure design standard (2007) at HSCC 30, 50 and 70 MPa, it would be desirable to reduce the correction factor of anchorage length of the horizontal reinforcement at top position, which is suggested for the reinforcement at top position, to less than 1.3 of CC.

• Journal of Korean Society on Water Environment
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• v.21 no.1
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• pp.79-83
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• 2005

Foraging behaviour of false dace, Pseudorasbora parva, was investigated in water flowing at various velocities with the existence of a cavity for rest. The pursuit comprised three succeeding processes such as, approaching, chasing and attacking. Angles between the fish body and the water flow direction and swimming speeds increased in the latter stages of approaching, chasing and attacking. All pursuit angles, swimming speeds and distances increased with flow velocity and peaked at the flow velocity of 7 cm/sec. At higher velocities, however, the fish avoided the use of much energy against the large drag force. The probability of capture and the feeding rate steadily decreased with increasing flow velocity. Under the fast flow, the fish adjusted their swimming speed to get the optimum velocity relative to the flowing water for the energetic budget. Fish spent more time in the cavity as flow velocity increased to avoid the energy expenditure necessitated by the high velocity.

• Journal of Surface Science and Engineering
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• v.42 no.6
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• pp.280-286
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• 2009

In this study, the corrosion property of copper alloy tubes in seawater has been investigated. Three copper alloys of nominal composition Cu-20Zn-2Al(Al-Brass), Cu-30Ni(CN70/30) and Cu-10Ni(CN90/10) were considered. The samples were immersed in 3%NaCl flowing solution at $90^{\circ}C$ for 30, 50 and 80 days. Corrosion rate of copper alloy tubes in 3%NaCl flowing solution was investigated by weight-loss measurements and electrochemical test. The CN70/30 showed lowest corrosion rate among three copper alloy tubes. Because of passive films formation, corrosion rates of three types of copper tubes were decrease with time. Surface characteristics of copper alloy tubes were analyzed by optical micrograph(OM), scanning electronic microscopy (SEM), energy dispersive X-ray analysis(EDAX) and X-ray diffraction patterns(XRD). CN70/30 showed partly pitting problem on the surface owing to high Fe content, even though having high resistant against corrosion. Cracks appeared on the surface of CN90/10 and CN70/30 after more than 50 days immersion, which could be derived from high nickel contents.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.10a
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• pp.267-270
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• 1999

In this paper, the application of limestone powder, which produced by being gathered electrically in the process of manufacturing of cement, to high fluidity concrete are investigated. According to the experimental results, especially, high viscosity and the loss of air content are accomplished by applying limestone powder as the partial substitution of fine aggregates. In case of hardened concrete, high compressive strength can be achieved by using limestone powder.

• Proceedings of the Korea Concrete Institute Conference
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• 1995.10a
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• pp.50-55
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• 1995

Recently, high-workable concrete has been developed and began to be used to a great extent in foreign countries, but it isn't familiar with and fully introduced in Korea yet. The aim of this paper is to suggest a reference data for the development of High-workable concrete according to the comparative analysis the effect of mix proportion (unit water sand/aggregate ratio) on the flowing characteristics. And also this paper aims to examine the compactability of High-workable concrete in a model wall-form.

• Proceedings of the Korea Concrete Institute Conference
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• 1997.04a
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• pp.357-364
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• 1997

In this experiment high-strength concrete of good workability is made by means of either replacing unit cement quantity to fly-ash by 20% or using low heat cement to reduce the internal hydration heat suggested as the fault of concrete. Concrete is poured through ready mixed concrete to test the ability of applying to the substantial works and is carried out the test of flowing and core strength and record of temperature of imitating specimens. It is capable to apply high-strength concrete replaced to fly-adh 20% to the substantial works through the experiment

• Proceedings of the Korea Concrete Institute Conference
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• 1997.10a
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• pp.61-64
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• 1997

As construction technology advances, most of concrete structures are becoming larger and taller. Therefore, high strength and quality concrete is necessary for them. So, the proposal of using belite cement is investigated to satisfy high flowing, low heat, and high strength. In this study, the compressive strength, tensile strength, and modulous of elasticity of concrete using belite cement was considered according to the mix proposition condition as a water-cement ratio, unit cement content, and sand percentage.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.04a
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• pp.463-468
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• 1999

The slurry wall of Inchon LNG receiving terminal tank will be planned the super flowing concrete having properties of high strength (required strength 520kg/$\textrm{cm}^2$), no-vibrating and massive structure in the underground. For the performance of this concrete, we investigate and select all materials, the optimum mix design and sensibility test in the laboratory. As test results, we choose portland blast-furnace slag cement and lime stone powder(L.S.P) as cementitious materials, W/C 41%(W/B 35.4%), S/a 50.8% and unit volume of coasre aggregate 0.30 as optimum mix design. Also test result of the fresh and hardened concrete are satisfied with specifications of slurry wall.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2011.11a
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• pp.235-236
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• 2011

This study analyzed flowing and strength properties of mortar depending to fine aggregate types and replacement ratio by using blast furnace slag, red mud, and silica fume that are industrial by products. The findings showed that higher replacement level of fine aggregate increased air content while decreased table flow. In addition, compressive strength showed that the higher replacement level was regardless of fine aggregate types, the lower strength became. Mortar substituted by the dredged sand showed high strength.