• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 봄 학술발표회 논문집
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• pp.683-688
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• 2001

In case of constructing the concrete structures under seawater environment, the concrete suffers from deterioration due to penetration of various ions such as chloride, sulfate and magnesium in seawater. Tn the present study, Immersion tests with artificial seawater were carried out to investigate the resistance to seawater attack of antiwashout underwater concrete. From the results of compressive strength, it was found that blended cement concrete due to mineral admixtures such as fly ash(FA) and ground granulated blast-furnace slag(SGC), were superior to ordinary portland cement concrete with respect to the resistance to seawater attack. Moreover, XRD analysis indicated that the formed reactants of ordinary portland cement paste by sulfate and magnesium ions led to the deterioration of concrete. As expected, however, the blended cements with FA or SGC have a good resistance to seawater attack. This paper would discuss the mechanism of seawater deterioration and benefical effects of antiwashout underwater concretes with mineral admixtures.

• 한국건축시공학회지
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• 제18권2호
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• pp.185-193
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• 2018

In this study, using Granulated Blast Furnace Slag (GBFS), an industrial byproduct, and Phosphogypsum (PG), and Waste Lime (WL) as activator, non-sintering binder (NSB) which does not require a sintering process was produced, and the chemical penetration resistance was evaluated through a seawater resistance experiment. The result of the experiment showed that the inside of NSB mortar saw almost no influence from the ions in seawater due to its dense structure. Also, as it appears that only the surface reacts with ions in seawater while spreading inward is suppressed, the high seawater resistance of NSB could be confirmed.

• Advances in concrete construction
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• 제14권3호
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• pp.205-214
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• 2022

Due to seawater's physical and chemical deterioration effects on concrete structures, it is crucial to investigate the durability of these structures in marine environments. In some conditions, concrete structures are exposed to seawater from the first days of construction or because of the lack of potable water, part of the concrete curing stage is done with seawater. In this research, the effects of exposure to seawater after 7 days of curing in standard conditions were evaluated. To improve the durability of concrete, fly ash has been used as a substitute for a part of the cement in the mixing design. For this purpose, 5, 15, and 30% of the mixing design cement were replaced with type F fly ash, and the samples were examined after curing in seawater. The resistance of concrete against chloride ion penetration based on the rapid chloride penetration test (RCPT), water permeability based on the depth of water penetration under pressure, and water absorption test was done. The changes in the compressive strength of concrete in different curing conditions were also investigated. The results show that the curing in seawater has slightly reduced concrete resistance to chloride ion permeation. In the long-term, samples containing FA cured in seawater had up to 10% less resistance to chloride ion penetration. The amount of reduction in chloride ion penetration resistance was more for samples without FA. Whiles, for both curing conditions in the long-term up to 15%, FA improved the chloride ion penetration resistance up to 40%. Curing in seawater slightly increased the penetration depth of water under pressure in samples containing FA, while this increase was up to 12% for samples without FA. In the long-term the compressive strength of samples cured in seawater is not much different from the compressive strength of samples cured in plain water, while at the age of 28 days, due to seawater salts' accelerating effects the difference is more noticeable.

• 콘크리트학회지
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• 제9권3호
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• pp.189-197
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• 1997

본 연구에서는 보통의 일반콘크리트와 플라이애쉬를 혼입한 강섬유보강 콘크리트의 해수에 대한 저항성을 고찰하기 위하여 수행되었다. 콘크리트 배합 인자를 물.시멘트비, 강섬유혼입률, 플라이애쉬 혼입률별로 각각 제조하였으며, 표준수(수도물)와 인공으로 제조한 해수에 장기간 침지한 경우와 건조와 습윤의 반복작용에 의한 촉진시험으로 시험을 수행하여 콘크리트의 성능저하에 미치는 영향을 비교.고찰하였다. 시험방법은 소정의 재령에 각각의 배합조건별로 압축강도와 재령 1일을 기준으로 길이변화와 동탄성계수를 측정하여 성능저하정도를 비교분석하였다. 그 결과 강섬유와 플라이애쉬의 적정량의 혼입은 콘크리트의 내해수성을 현저히 개선시키는 효과를 나타내었다.

• 한국구조물진단유지관리공학회 논문집
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• 제15권1호
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• pp.129-137
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• 2011

본 연구는 석회석미분말을 4단계(0, 10, 20 및 30%)로 대체한 모르타르 및 콘크리트의 내해수성을 평가하기 위하여 수행되었다. 내해수성 평가를 위하여 모르타르의 해수침식 저항성 및 콘크리트의 염소이온 침투저항성 실험을 각각 실시하였다. 실험결과에 의하면, 시멘트 경화체의 내해수성은 석회석미분말의 대체율에 의존적으로 나타났다. 다시 말해서, 석회석미분말을 10% 대체한 모르타르 및 콘크리트는 대체적으로 OPC와 유사한 내해수성을 나타낸 반면, 석회석미분말의 대체율이 큰 모르타르 및 콘크리트의 내해수성은 OPC와 비교하여 현저하게 떨어지는 것으로 조사되었다.

• Journal of Advanced Marine Engineering and Technology
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• 제39권5호
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• pp.536-541
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• 2015

Copper has been used extensively as an electric wire or as a base material in various types of machineries owing to its good electrical and thermal conductivity and good fabricating property, as well as its good corrosion resistance compared to iron. Furthermore, the copper-nickel alloy has significant corrosion resistance in severely corrosive environments. Although, cupro-nickel alloy shows better corrosion resistance than the brass and bronze series, this alloy also corroded in severely corrosive environments, including aggressive chloride ions, dissolved oxygen, and condition of fast flowing seawater. In this study, and annealing treatment at various annealing temperatures was carried out on the cupro-nickel (Cu-10%Ni) alloy, and the effects of annealing were investigated using electrochemical methods, such as measuring the polarization and impedance behaviors under flowing seawater conditions. The corrosion resistance increased by annealing compared to non heat treatment in the absence of flowing seawater. In particular, the sample annealed at $200^{\circ}C$ exhibited the best corrosion resistance. The impedance in the presence of flowing seawater showed higher values than in the absence of flowing seawater. Furthermore, the highest impedances was observed in the sample annealed at $800^{\circ}C$, irrespective of the present of flowing seawater. Consequently, the corrosion resistance of cupro-nickel (Cu-10%Ni) alloy in a severely corrosive environment can be improved somewhat by annealing.

• Journal of Microbiology
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• 제45권1호
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• pp.64-68
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• 2007

In this study we examined the multi-drug resistance profiles of the tetracycline (TC) resistant genus Vibrio to determine its susceptibility to two ${\beta}-lactams$, ampicillin (ABPC), and mecillinam (MPC), as well as to macrolide, erythromycin (EM). The results showed various patterns of resistance among strains that were isolated from very close geographical areas during the same year, suggesting diverse patterns of drug resistance in environmental bacteria from this area. In addition, the cross-resistance patterns suggested that the resistance determinants among Vibrio spp. are acquired differently within the sediment and seawater environments.

• Environmental Engineering Research
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• 제15권1호
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• pp.15-21
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• 2010

This study was conducted to evaluated seawater bacteria and their seasonal characteristics in the arsenic contaminated coastal seawater of Yeosu Bay, the Republic of Korea. Arsenite-oxidizing bacteria play an important role in the seawater of the arsenic contaminated bay, with a variety of arsenic resistance system (ars) genotypes being present during summer. Specifically, Bacillus sp. strain SeaH-As22w (FJ607342), isolated from the bay, were found to contain the arsB, arrA and aoxR type operons, which are involved in arsenic resistance. The isolated bacteria showed relatively high tolerance to sodium arsenite (III; $NaAsO_2$) at concentrations as high as 50 mM. Additionally, batch seawater experiments showed that Bacillus sp. strain SeaH-As22w completely oxidized 1 mM of As (III) to As (V) within 10 days. Ecologically, the arsenic-oxidizing potential plays an important role in arsenic toxicity and mobility in As-contaminated coastal seawater of Yeosu Bay during all seasons because it facilitates the activity of Bacillus sp. groups.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 가을 학술발표회 논문집
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• pp.527-530
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• 2002

In the present study, immersion test using artificial seawater was performed to evaluate the resistance of mortar specimens with or without ground granulated blast-furnace slag (SG) and fly ash (FA). Another variable was the fineness levels of SG (4,450, 6,000 and 8,000 ㎠/g). From the results of the immersion test for 270 days of exposure, the excellent resistance to seawater attack for SG mortar mixtures, especially in a high fineness levels, was confirmed. However, the reductions in compressive strength of FA mortar specimens was similar to those of OPC mortar specimens irrespective of replacement of FA.. In order to understand the deterioration mechanism due to seawater attack, X-ray diffraction (XRD) analysis were also carried out. Some reactants such as ettringite, gypsum, brucite and Friedel's salt were possibly detected through XRD technique.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1997년도 봄 학술발표회 논문집
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• pp.315-322
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• 1997

This paper describes an experimental study on the seawater resistance of steel fiber reinforced concrete. The test method adopted for this study may be devided into long-term immersion test and accelerated test by wetting and drying. Test were carried out to evaluate the procedure in which reduction in dynamic modulus, length change and compressive strength to nine months were measured. Resistance indicators are the water - cement ratio, the content of steel fiber, the immersion water(artificial seawater or freshwater). The conditions of intervals of immersing in artificial seawater and drying, low water-cement ratio, and non-steel fiber became most deteriorated.