• 한국건축시공학회지
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• 제8권1호
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• pp.91-96
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• 2008

This study is to investigate the influence of the over-added chemical agents, such as water reducing agent(WRA) and AE water reducing agent(AEWRA), on the physical properties of concrete to estimate the degree of damage due to over-added chemical agents. For the fresh concrete, slump and slump flow increased with the increase of WRA and AEWRA as expected. Material segregation phenomenon was observed with the over dosage of lignin based AEWRA about 4 times larger than recommended dosage. The over dosage of AE water reducing agent about 4 times larger than recommended dosage resulted in an increase of air contents remarkably. The set retardation occurred greatly with the increase of AEWRA and WRA. For the properties of the hardened concrete corresponding to the over dosage of AEWRA, it is found that compressive strength of over added AEWRA and WRA concrete are much smaller than those of base and recommended dosage concrete proportionally due to associated increasing air content.

• 환경영향평가
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• 제16권1호
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• pp.27-33
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• 2007

Hexavalent chromium-contaminated soils are encounted at many unregulated discharge and improper handling of wastes from electroplating, leather tanning, steelmaking, corrosion control, and wood preservation industries. Contamination of hexavalent chromium in the soil is a major concern because of its toxicity and threat to human life and environment. Current technologies for hexavalent chromium-contaminated soil remediation are usually costly and/or cannot permanently prohibit the toxic element from entering into the biosphere. Thus, as an alternative technique, immobilization is seen as a cost-effective and promising remediation technology that may reduce the leachable potential of hexavalent chromium. The purpose of this paper is to develope an immobilization technique for the formation of the geochemically stabilized hexavalent chromium-contaminated soil from the reactions of labile soil hexavalent chromium forms with the added soluble phosphate and chromium reducing agent. From the liquid phase experiment, reaction order of chromium reducing agent, soluble phosphate, alkali solution shows the best removal efficiency of 95%. In addition, actual soil phase experiment demonstrates up to 97.9% removal efficiency with 1:1 molar ratio of chromium reducing agent and soluble phosphate. These results provide evidence for the potential use of soluble phosphate and chromium reducing agent for the hexavalent chromium-contaminated soil remediation.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1998년도 봄 학술발표회 논문집(I)
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• pp.63-68
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• 1998

The fluidity of high flowing concrete can be affected by numerous parameters which characterize either the cement of the admixture. The reactivity of a cement as determined by its chemical composition(especially its $C_3$A content), its fineness and its content in sulfates and alkalies obviously plays a key role in rheology of high flowing concrete in fresh state. Specific properties of high range water reducing AE agent used to enhance the workability of high flowing concrete also exert important influence. The purpose of this experimental study is to investigate and analyze the effect of cement and high range water reducing AE agent in fluidity, setting, compressive strength of high flowing concrete. As a result, we found that fluidity of high flowing concrete is affected greatly by kind of cement and high range water reducing AE agent, also, there is harmonic character between high belite cement and polycarbonic acid high range water reducing AE agent.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1999년도 봄 학술발표회 논문집(I)
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• pp.631-637
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• 1999

Effect of excessive addition of water reducing agent was examined by concrete tests. Water reducing agents of lignin or naphtalene base were used in the experiment. Setting of concrete was retarded according to the increase of dosage of water reducing agent and was extremely delayed at the 3 times or more use of lignin base agent and near 5 times or more use of naphtalene base agent respectively. When water reducing agent was used more than 6 times of standard dosage, early strength of concrete was very low and the strength reduction was very severe at all test ages in the concrete using lignin base agent.

• 한국건축시공학회지
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• 제17권3호
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• pp.245-252
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• 2017

최근 소비패턴의 변화에 따라 대형마트, 아울렛 및 물류창고 등과 같은 구조물들이 증가하고 있다. 이와 같은 구조물들은 초평탄 바닥부재를 포함하고 있기 때문에 소성 및 건조수축에 의한 슬래브 부재의 균열 억제 관리를 철저하게 실시한다. 슬래브 부재의 균열을 억제하기 위한 방안으로 화학적 균열저감 방법을 사용하고 있으며, 특히 수축저감제에 대한 사용검토가 증가하고 있다. 그러나 이에 대한 국내 연구결과는 부족한 상황이다. 본 연구에서는 수축저감제를 사용한 콘크리트의 수축특성과 배합요인 변동에 따른 건조수축 특성을 검토하였다. 국내 수축저감제는 해외 고급형 수축저감제와 성능이 유사한 것으로 나타났으며, 수축저감제 사용량이 증가할수록 건조수축 억제 효과는 높아지는 것으로 나타났다. 수축저감제 1.5%를 사용한 시험체는 재령 100일에서 수축저감제를 사용하지 않은 시험체에 비해 건조수축량이 약 절반으로 나타났다. 또한, 혼화재료 사용에 대해 특별한 성능변화는 없는 것으로 확인되었다.

• 한국표면공학회지
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• 제55권2호
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• pp.120-132
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• 2022

In the non-cyanide-based electroless Au plating solution using thiomalic acid as a complexing agent and aminoethanethiol as a reducing agent, analysis of each component constituting the plating solution is essential for the analysis of the reaction mechanism. And component analysis in the plating solution is important for monitoring component changes in the plating process and optimizing the management method. Capillary Electrophoresis (CE) method is rapid, sensitive and quantitative and could be readily applied to analysis of Auⁿ⁺ ion, complexing agent and reducing agent in electroless Au plating solution. In this study, the capillary electrophoresis method was used to analyze each component in the electroless Au plating solution in order to elucidate the complex bonding form and the plating mechanism of the non-cyanide-based electroless Au plating bath. The purpose of this study was to establish data for optimizing the monitoring and management method of plating solution components to improve the uniformity of precipitation and stability. As a result, it was confirmed that the analysis of thiomalic acid as a complexing agent and Auⁿ⁺ ions and the analysis of aminoethanethiol as a reducing agent were possible by capillary electrophoresis. In the newly developed non-cyanide-based electroless Au plating solution, it was confirmed that Auⁿ⁺ ions exist in the form of Au⁺ having a charge of +1, and that thiomalic acid and Au⁺ are combined in a molar ratio of 2 : 1. In addition, it was confirmed that aminoethanethiol can form a complex by combining with Au⁺ ions depending on conditions as well as acting as a reducing agent.

• 콘크리트학회논문집
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• 제28권5호
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• pp.519-525
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• 2016

본 논문에서는 혼화제에 따른 3성분계 그라우트에 대하여 자유수축 및 구속수축에 대하여 평가하였다. 본 연구에서 3성분계 그라우트는 플라이애쉬, 지르코늄 실리카퓸을 사용하였고, 팽창재(a, b)와 수축저감제 혼화제를 병용 사용하였다. 또한 유럽규정 EN 445에 따라 그라우트의 기본재료특성 실험을 수행하여 블리딩, 체적변화량, 유동성, 압축강도 실험을 수행하여 기본재료특성 거동도 분석하였다. 실험결과, 팽창재와 수축저감제 혼입률에 따라 유동성은 다소 영향은 없었으나, 우수한 블리딩 및 침하 저감성능과 압축강도를 나타났다. 자유수축 거동에서는 팽창재와 수축저감제를 혼입한 변수들은 0.0E-0.0R 변수보다 최소 29%의 수축저감성능을 보여 주었다. 특히 팽창재 a와 수축저감제를 병용 사용한 변수에서는 수축 저감의 효과가 더욱 우수한 것으로 나타났으며, 혼화제의 혼입률이 증가할수록 텐던 구속에 의한 수축균열은 뒤늦게 발생함을 알 수 있었다. 그러나 유독 팽창재 a 2.0%, 수축저감제 0.50%를 혼입한 변수에서는 우수한 수축저감성능으로 수축균열이 발생하지 않았다. 종합하여 볼 때, 본 연구의 실험 조건에서는 팽창재 a 2.0%, 수축저감제 0.50%인 조합이 PSC 교량용 고품질 3성분계 그라우트의 최적의 혼입률인 것으로 분석된다.

• 콘크리트학회논문집
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• 제16권5호
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• pp.605-612
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• 2004

본 연구에서는 W/B $30\%$의 고성능 콘크리트에서 팽창재와 수축저감제 병용 사용에 따른 콘크리트의 기초적 특성 및 수축특성에 대하여 분석하였다. 실험결과, 고성능 콘크리트의 유동성은 팽창재와 수축저감제를 단독사용보다 병용사용일 때 더 크게 저하하여 고성능 감수제의 사용량이 증가되었고, 공기량은 증가하여 AE제의 사용량이 감소되었다. 또한, 압축강도는 팽창재량의 혼입률 $5.0\%$를 사용한 경우가 최대가 되고, 수축저감제는 사용량 증가에 따라 저하되는 것으로 나타났다. 고성능콘크리트의 건조수축 및 자기수축을 저감시키기 위해서는 팽창재와 수축저감제를 혼합하여 사용할 때 가장 양호한 결과가 나타났다. 따라서 유동성, 강도 및 수축특성을 종합적으로 고려한 결과, 본 연구실험 조건에서는 팽창재 $5.0\%$, 수축저감제 $1.0\%$의 조합이 최적배합으로 분석되었다.

• 소성∙가공
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• 제15권8호
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• pp.615-620
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• 2006

The reduction behavior of $TiO_{2}$ in Al and Al/CaSi containing self-reducing $TiO_{2}$ briquettes(SRTB) was investigated. The maximum yield of Ti was expected with the slag composition of 45-55%CaO in the $CaO-Al_{2}O_{3}$ system. When $CaCO_{3}$ was used as a flux, the oxidation loss of reducing agent by $CO_{2}$ should be compensated, and therefore it leads to excessive requirement of the reducing agent. By using Al and CaSi mixture as a reducing agent of $TiO_{2}$, the reaction products both oxide and metal could be liquefied, and separated effectively with each other. As a result, the yield of Ti increases remarkably. The optimum mixing ratio of CaSi to Al is 78%CaSi-22%Al.

• Nuclear Engineering and Technology
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• 제3권3호
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• pp.141-147
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• 1971

Tetrachloro-p-tetraiodo-R-Fluorescein 및 sodium orthoiodohippurate등 요오드화 합물과 요오드화합물이 아닌 human serum Albumin을 요오드 표지함에 있어서 표지속도와 수율등을 비교 검토하였다. 위의 각각의 화합물들을 여러가지 다른 조건하에 있는 $Na^{131}$ I, 즉, 환원제를 함유한것, 환원제를 함유하지 않으며 거의 순수하게 131 I$^{-}$형으로 있는것, 및 환원제를 함유하지 않으며 상당량이 131 IO$_3$$^{-}$형으로 있는것 등을 써서 표지 반응시켰다. 환원제인 $Na_2$S$_2$O$_3$를 함유한 $Na^{131}$ I를 쓰는 경우는 위의 세가지 화합물들의 표지수율이 10% 내외로 매우 저조하였으며 환원제는 없지만 상당량이 $Na^{131}$ I$^{-}$로 존재하는 $Na^{131}$ I를 쓰는 경우도 50~60%의 낮은 수율이었다. 환원제가 없으며 대부분 $Na^{131}$ I$^{-}$로 존재하는 $Na^{131}$ I를 쓰는 경우에만 70~90%의 높은 표지수율을 보였다. 이들 반응에 관여하는 중간체에 대해서도 토의하였다.