• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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• pp.2094-2097
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• 2007

본 연구에서는 사석경사제의 전면부에 불투과성 수중방파제를 설치하여, 불규칙파의 반사에 대한 수치모의와 수리모형실험을 수행하였다. 수치해석 모형에는 Reynolds Averaged Navier-stokes (RANS) 방정식을 지배방정식으로 사용하였고, 난류해석을 위하여 $\kappa-\varepsilon$ 방정식을 사용하였다. 자유수면변위의 정확한 예측을 위하여 VOF 기법을 적용하였다. 수리모형실험은 한양대학교 수리실험실의 조파수로에서 수행되었다. 본 연구에서는 입사파랑으로 불규칙파를 조파하였으며, Bretsch neider-Mistuyasu 스펙트럼을 목표스펙트럼으로 하여 재현하였다. 반사율의 산정에서 입사파와 반사파를 분리하기 위하여 수치모형실험에서는 3점법을 사용하였고, 수리모형실험에서는 2점법을 사용하였다. 수치모의를 통하여 예측된 반사율과 수리모형실험에서 관측한 결과는 서로 잘 일치하였다.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.04a
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• pp.261-266
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• 1998

The purpose of this study is to present the reference data on the development of undispersed underwater mortar for augered pile under various replacement ratio of fly-ash. According to the experimental results, when 10% of fly-ash is mixed under mix proportion of 1:1.5(c:s), as strength and shrinkage decrease slightly, whereas fluidity increase, high quality mortar for augered pile can be achieve in case above condition is applied.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.04a
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• pp.267-270
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• 1998

Recently, underwater concrete constructions are increasing. Therefore it is considered important to control the quality of underwater concrete. In this paper, we have an intention of evaluating fundamental properties of underwater concrete using the anti-washout admixtures. Thus, it has been investigated that the setting slump flow of the concrete, pH value and suspended solids in solution, compressive strength on both of specimens made above and under water. Also the percentage of fine aggregate has been found to alter the compressive strength in underwater concrete.

• Magazine of the Korea Concrete Institute
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• v.14 no.4
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• pp.33-39
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• 2002

레미콘의 품질성능을 좌우하는 것은 콘크리트 사용재료 및 배합뿐만 아니라 레미콘을 제조하는 믹서 및 이를 현장까지 운반하는 트럭 에지테이터의 품질성능에 크게 좌우된다. 그러나, 레미콘 공장의 혼합 설비인 믹서 및 트럭 에지테이터에 관한 국내 자료는 거의 전무한 실정이며 이에 관한 연구도 상대적으로 매우 부족하다. 특히, 최근에는 고강도 콘크리트, 고유동 콘크리트, 고강도 경량 콘크리트, 수중불분리 콘크리트, 섬유보강 콘크리트 등 고성능 콘크리트 성능에 대한 요구가 날로 증가하는 추세이며 이에 따라 레미콘 공장에서도 혼합설비 및 운반설비가 고성능화 되어 가는 추세이다.(중략)

• Proceedings of the Korea Concrete Institute Conference
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• 1996.10a
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• pp.387-393
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• 1996

The purpose of this study is analyze the properties of undispersed concrete according to replacement of the ratio of fly-ash. The test results show that as the ratio of flyash replacement which increasing fluidity but the amounts of air content, suspended solid and pH values dicreased and setting time is delayed. The ten persent replacment of fly-ash has less water pollution and high compressive strength value than other ratio of fly-ash replacement.

• Proceedings of the Korea Concrete Institute Conference
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• 1996.10a
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• pp.373-378
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• 1996

This paper presents the characteristics of various strengths of underwater non-segregation concrete. Three types of cements including low-heat cements has been used to make the test specimens for compressive strength, modulus of rupture and bond strength. The test specimens have been made both in ambient and underwater conditions to take into account the variation according to the environmental condition.

• Magazine of the Korea Concrete Institute
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• v.11 no.2
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• pp.231-239
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• 1999

When the concrete is cast at the sea, there are lots of restrictions in the working process being different from in land, and the concrete is suffered from the physical and chemical action in terms of marine environment. The compressive strength was measured after antiwash out underwater concrete mixed with fly ash had been cast and cured in order to produce the endurable high performance concrete, and then its characteristic was discussed by comparing one cured in air with in fresh water, and the effect of fly ash usage under the properly controled sea water temperature of $15{\pm}3^{\circ}C$ was also covered. The present work showed that the proper usage of fly ash was obtained at the condition of around 10% of substituted binder weight under the structure required the early age strength, and at the condition of over 40% if considering its durability and economy.

• Journal of Ocean Engineering and Technology
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• v.25 no.3
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• pp.40-46
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• 2011

This paper describes the effects of fly ash replacement on the sulfate resistance of antiwashout underwater concrete which was replaced cement by fly ash from 0% to 50%. and the experimental works were performed on sulfate acceleration test of 5%$Na_2SO_4$ solution to find out the variance of length and weight of specimens. The experimental result shows that the length of specimens of antiwashout underwater concrete age at 180day was highly increased compare with normal concrete by acceleration test. but the mixture which was replaced 50% of fly ash shows reduction of the expansion, weight various, compare with normal concrete specimen. accordingly by using fly ash as admixture in antiwashout underwater concrete in sea environment, it will makes more durable for the attacks of sulfate by sea water.

• Journal of Ocean Engineering and Technology
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• v.22 no.4
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• pp.40-45
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• 2008

This paper describes the effects of fly ash replacement on the water tightness of antiwashout underwater concrete, which replaced the cement with fly ash from 0% to 30%. The experimental work was performed to find out the depth of permeation of concrete specimens cast in air and cured in 23 $^{\circ}C$ tap water using an open center pressure type of water permeation tester. The results showed that the permeation depth values of antiwashout underwater concrete were deeper than normal concrete, but that an admixture using fly ash during antiwashout underwater concrete casting in air made it more watertight than normal concrete according to the water permeation testing. SEM observations of the specimens of fly ash antiwashout underwater concrete showed that it wasmore packed with structures because of the pozzolan reaction of the fly ash and cement.

• Journal of Ocean Engineering and Technology
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• v.19 no.6 s.67
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• pp.29-34
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• 2005

This paper describes the effect of fly ash replacement on seawater resistance of anti-washout underwater concrete, which was replaced cement by fly ash from $0\%$ to $50\%$. The experimental work was performed to find out the variations of length and weight of specimens, using a chloride acceleration test in $40\^{\circ}$C The results shaw that the admixture using fly ash on an anti-washcout underwater concrete in the sea environment makes it more durable for the attacks of chloride by seawater. Also, the length of specimens of anti-washout underwater concrete, at age 180 days, increased substantially, compared with normal concrete; however, the mixture in which cement was replaced $50\%$ of fly ash shows $93\%$ reduction of the expansion, compared with the normal anti "washout underwater concrete specimen.