• 열처리공학회지
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• 제37권1호
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• pp.16-22
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• 2024

The conventional degreasing process involves removing oil and contaminants at temperatures above 80℃, resulting in excessive energy consumption, increased process costs, and environmental issues. In this study, we aimed to find the optimal degreasing conditions for the pre-treatment process of electro-galvanizing cold-rolled steel sheets, conducted efficiently at room temperature without the need for a separate heating device. To achieve this, we developed a room temperature degreasing solution and a brush-type degreasing tool, aiming to reduce energy consumption and normalize the decrease in degreasing efficiency caused by temperature reduction. Alkaline degreasing solution were prepared using KOH, SiO₂, NaOH, Na₂CO₃, and Sodium Lauryl Sulfate, with KOH and NaOH as the main components. To enhance the degreasing performance at room temperature, we manufactured additives including sodium oleate, sodium stearate, sodium palmitate, sodium lauryl sulfate, ammonium lauryl sulfate, silicone emulsion, and EDTA-Na. Room temperature additives were added to the alkaline degreasing solution in quantities ranging from 0.1 to 20 wt.%, and the uniformity of degreasing and the adhesion of the galvanized layer were evaluated through Dyne Test, T-bending Test, OM, SEM, and EDS analyses. The results indicated that the optimal degreasing solution composition consisted of NaOH (30 g/L), Na₂CO₃ (30 g/L), SLS (6 g/L), and room temperature additives (≤1 wt%).

• Membrane and Water Treatment
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• 제6권2호
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• pp.141-160
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• 2015

This study aims to investigate the impacts of chemical cleaning on the performance of a reverse osmosis membrane. Chemicals used for simulating membrane cleaning include a surfactant (sodium dodecyl sulfate, SDS), a chelating agent (ethylenediaminetetraacetic acid, EDTA), and two proprietary cleaning formulations namely MC3 and MC11. The impact of sequential exposure to multiple membrane cleaning solutions was also examined. Water permeability and the rejection of boron and sodium were investigated under various water fluxes, temperatures and feedwater pH. Changes in the membrane performance were systematically explained based on the changes in the charge density, hydrophobicity and chemical structure of the membrane surface. The experimental results show that membrane cleaning can significantly alter the hydrophobicity and water permeability of the membrane; however, its impacts on the rejections of boron and sodium are marginal. Although the presence of surfactant or chelating agent may cause decreases in the rejection, solution pH is the key factor responsible for the loss of membrane separation and changes in the surface properties. The impact of solution pH on the water permeability can be reversed by applying a subsequent cleaning with the opposite pH condition. Nevertheless, the impacts of solution pH on boron and sodium rejections are irreversible in most cases.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 가을 학술발표회 논문집
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• pp.27-32
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• 2002

In this research influences of type and concentration of alkali activator and curing condition on the hydration, and properties of alkali activated blast furnace slag(AAS) concrete were investigated. Sodium carbonate and sulfate were used as alkali activators and their concentration were 4~10 weight percent with Na$_2$O equivalent to binder. The curing conditions were standard curing using 23$^{\circ}C$ water and activated curing chamber at $65^{\circ}C$. Results show that in case of sodium carbonate addition high early strengths were gained by activation of early hydration, but later strength gained was slight. On the other side sodium sulfate strengths were continuously increased with adding amount and ages. Steam curing activated early hydration so that early strengths were improved but later strengths were similar to standard curing. The strength reduction of AAS mortar with sodium sulfate was less than OPC mortar in 5% sulfuric acid solution so that AAS concrete can be useful for acid-resistance concrete.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 춘계 학술발표회 논문집(II)
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• pp.277-280
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• 2006

This paper presents the findings on the sulfate resistance of mortar specimens with or without alkali-free accelerator exposed to sodium sulfate solution for 270 days. Test results confirms a negative effect of alkali-free accelerator on the sulfate deterioration. Additionally, the influences of exposure concentration and temperature of sulfate solution on expansion were investigated. Especially, at a high concentration of solution a significant expansion of mortar specimens with alkali-free accelerator was observed. Further, low temperature also promoted the deterioration of the cement system due to sulfate attack.

• Journal of Chest Surgery
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• 제41권5호
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• pp.550-562
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• 2008

배경: 조직공학분야에서 이종조직의 세포성분에 대한 면역반응을 없애기 위한 기본적인 과정으로 조직의 탈세포화에 대한 연구가 있어왔다. 본 연구는 기존에 탈세포화에 효과적이었다고 보고되었던 방법들을 변형 혹은 재현해 보고, 이를 통해 치적의 탈세포화를 얻을 수 있는 조건을 찾고자 하였다. 대상 및 방법: 돼지의 대동맥 및 폐동맥판막, 대동맥 및 폐동맥벽, 심낭을 탈세포화 세정제(detergents)에 대한 농도 및 배양시간, 온도조건, 용질에 대한 삼투압 등을 달리하고, 여러 탈세포화용액 및 그 조합을 통해 단일단계 및 여러 단계의 방법으로 배양하여 탈세포화를 시행하였다. 이렇게 탈세포화 실험을 마친 조직은 hematoxylin-eosin (H&E) 염색을 통해 탈세포화의 정도와 세포 외 기질의 보존 정도를 평가하였고, 일부탈세포화된 조직에서는 이종항원면역제거 정도를 파악하는 alpha-Gal 염색과 DAPI 염색을 동시 시행하여 관찰하였다. 결과: Polyethylene glycol이나 peracetic acid를 이용한 방법에서는 탈세포화가 되지 않았다. 단일단계방법으로는 sodium deoxycholate (DOA), sodium dodesyl sulfate (SDS), Triton X-100, SDS와 Triton X-100을 섞은 용액에서, 다단계방법으로는 저장성 완충용액 ${\rightarrow}$ X-100 ${\rightarrow}$ SDS, DOA ${\rightarrow}$ 저장성 완충용액 ${\rightarrow}$ SDS, 저장성 완충용액 ${\rightarrow}$ SDS에서 탈세포화가 이루어 졌다. DOA는 다른 탈세포화 방법에 비해 세포 외 기질의 파괴가 심하였고, 특히 실험온도가 높아질 수록 세포 외 기질의 파괴가 더욱 현저함을 알 수 있었다. 사용되는 화학물질의 종류, 양, 처리시간 및 세포 외 기질의 파괴 정도를 고려하여 지속적으로 재현 가능한 탈세포화에 비교적 적합한 조합 및 조건은 단일단계방법으로 $4^{\circ}C$에서 SDS와 Triton X-100를 섞은 저장성용액에서 24시간 배양하는 방법과, 다단계방법으로 저장성 완충용액과 SDS를 연속적으로 사용하는 방법으로, $4^{\circ}C$에서 $6{\sim}8$시간 이상 저장성 완충용액에 처리한 후, 0.25% SDS가 섞인 저장성 완충용액에 16시간 배양 후 등장성 완충용액에 처리하는 방법이었다. 결론: $4^{\circ}C$에서 SDS 과 Triton X-100을 섞은 저장성 완충용액에서 24시간 배양하는 단일단계방법이나, 저장성완충용과 SDS를 연속적으로 사용하는 다단계 방법을 통해 세포 외 조직을 비교적 잘 보존하면서 적은 수의 탈세포화 용액을 사용하여 효과적인 탈세포화를 얻을 수 있었다.

• 한국환경보건학회지
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• 제35권1호
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• pp.58-63
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• 2009

This study investigated improvement to sludge dewaterability and coagulation for sewage treatment plant sludge by using sodium hypochlorite solution (NaOCl), ferric sulfate [$Fe_2(SO_4)_3$] and zeolite. The specific resistance to filtration(SRF), chloride, pH and turbidity were used to evaluate the sludge dewatering behaviors. The results of study were as follows: By varying the amount of NaOCl added the optimum result in terms of enhancement for pretreatment occurred when 34 mg/l of NaOCl was injected. When the total solids concentration of the sludge was 10,000 mg/l, the optimum ferric sulfate dosage for the sludge dewaterability was 150 mg/l and the corresponding SRF was $1.7{\times}10^7sec^2/g$. It was observed that injecting zeolite into sludge was effective in improving the dewaterability of sludge.

• 대한토목학회논문집
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• 제28권5A호
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• pp.757-764
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• 2008

본 연구는 농도조건을 달리한 시험용액에 침지한 모르타르의 내구성을 평가하기 위하여 수행되었다. 3종류 시멘트 모르타르를 제조한 후, ${SO_4}^{2-}$ 이온의 농도가 4225, 8450, 16900 및 33800 ppm인 4종류 황산나트륨 용액에 540일간 침지하였으며, 침지재령별 압축강도 및 선형팽창을 측정하므로써 모르타르의 황산염침식 저항성을 실험적으로 평가하였다. 실험결과에 의하면, 고농도 황산나트륨 용액에 침지한 모르타르 공시체가 가장 심한 성능저하 현상을 나타내었다. 특히, 고농도 환경에서 모르타르의 팽창 특성은 사용된 시멘트의 $C_3A$량과 직접적인 관련이 있었으며, GGBS를 대체한 SGC 모르타르는 조직구조의 투수성이 상대적으로 낮은 탓으로 인하여 시험용액의 농도조건에 관계없이 우수한 황산염침식 저항성을 나타내었다.

• Computers and Concrete
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• 제19권2호
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• pp.143-152
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• 2017

This paper has numerically investigated the changes of loading-induced stress in concrete with the corrosion time in the sulfate-containing environment. Firstly, based on Fick's law and reaction kinetics, a diffusion-reaction equation of sulfate ion in concrete is proposed, and it is numerically solved to obtain the spatial and temporal distribution of sulfate ion concentration in concrete by the finite difference method. Secondly, by fitting the existed experimental data of concrete in sodium sulfate solutions, the chemical damage of concrete associated with sulfate ion concentration and corrosion time is quantitatively presented. Thirdly, depending on the plastic-damage mechanics, while considering the influence of sulfate attack on concrete properties, a simplified chemo-mechanical damage model, with stress-based plasticity and strain-driven damage, for concrete under axial loading and sulfate attack is determined by introducing the chemical damage degree. Finally, an axially compressed concrete prism immersed into the sodium sulfate solution is regarded as an object to investigate the time-varying stress in concrete subjected to the couplings of axial loading and sulfate attack.

• Bulletin of the Korean Chemical Society
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• 제11권6호
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• pp.505-508
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• 1990

The electrochemical reduction and electrogenerated chemiluminescence (ECL) of $Ru(bpy)_3^{2+}-S_2O_8^{2-}\;in\;CH_3CN-H_2O$ solution were studied in the presence of sodium dodecyl sulfate (SDS) as an anionic surfactant. SDS enhanced the ECL and the fluorescence intensities and lengthened the duration of ECL due to the solubilization of reactants and possibly to the stabilization of ECL intermediates in the SDS micellar environment.

• 분석과학
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• 제8권4호
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• pp.643-648
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• 1995

Cyclic voltammetric method is used to survey microscopic environments which take place at the surfactant-modified carbon electrode when the hydrophobic and hydrophilic environments of $Ru(ph){_3}^{2+}$(tris 1,10-phenanthroline ruthenium(II) chloride) is created by the addition of anionic surfactant, sodium dodecyl sulfate(SDS). Critical micelle concentration(CMC) of SDS in $Ru(ph){_3}^{2+}$ measured by cyclic voltammetry(CV) is in aggrement with that by surface tensiometry. Influence of the concentration of supporting electrolyte at surfactant-modified carbon electrode is investigated.