• Bulletin of Food Technology
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• v.9 no.1
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• pp.61-76
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• 1996

• Journal of the Korea Concrete Institute
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• v.27 no.2
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• pp.177-184
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• 2015

In order to use the high-volume slag cement as a construction materials, a proper activator which can improve the latent hydraulic reactivity is required. The dissolved aluminum silicon ions from ground granulated blast furnace slag (GGBFS) react with sulfate ions to form ettringite. The proper formation of ettringite can increase the early-age strength of high-volume GGBFS (80%) cement. The aim of this study is to investigate the hydration properties with sulfate activators (sodium sulfate, anhydrite). In this paper, the effects of $Na_2SO_4$ and $CaSO_4$ on setting, compressive strength, hydration, micro-structure were investigated in high-volume GGBFS cement and compared with those of without activator. Test results indicate that equivalent $SO_3$ content of 3~5% improve the early-age hydration properties such as compressive strength, heat evolution rate, micro-pore structure in high-volume GGBFS cement.

• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.5
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• pp.104-111
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• 2015

This study shows the mechanical properties of alkali-activated slag cement (AASC) synthesized using sulfate with NaOH solution. The used sulfates were calcium sulfate ($CaSO_4$, denoted CS) and sodium sulfate ($Na_2SO_4$, denoted SS). The replacement ratio of sulfates was 2.5, 5.0, 7.5 and 10.0% by weight of slag. NaOH solution of 2M and 4M concentration was used. A sample was activated with sulfate and activated with blended activator (blending NaOH solution with sulfate) respectively. 24 mix ratios were used and the water-binder weight ratio for the test was set 0.5. This research carried out the compressive strength, flexural strength, ultrasonic pulse velocity (UPV), absorption and X-ray diffraction (XRD). In the case of samples with CS, sample with 7.5% CS, sample with 2M NaOH+5.0% CS and sample with 4M NaOH+5.0% CS showed the good performance in the strength development. In the case of samples with SS, sample with 10.0% SS, sample with 2M NaOH+7.5% SS and sample with 4M NaOH+2.5% SS obtained good performance in strength. The results of UPV and water absorption showed a similar tendency to the strength properties. The XRD analysis of samples indicated that the hydration products formed in samples were ettringite, CSH and silicate phases. In this study, it is indicated that when compared to the use of sulfate only, the use of both sulfate and NaOH solution makes mechanical properties of AASC better.

• Economic and Environmental Geology
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• v.56 no.5
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• pp.619-628
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• 2023

In this study, we investigated the feasibility of calcium sulfate fertilizer as a stabilizing agent for As and Hg contaminated farmland soil and its stabilization characteristics in 3 different physical forms (particulate, powder, and solution) through a pot experiment including 34 days of lettuce growth. As and Hg contents of the lettuce grown in the stabilized soils were decreased by at least 70%. However the lettuce yield of the soil stabilized with the solution agent was decreased by 46% due to the overabundance of the nutrients from the solution agent. Thus, if a solution-type agent is planned for agricultural farmland soil stabilization, additional tests for optimal dosage are needed to preserve vegetation growth. In Hg fractionation, a lower concentration of elemental fractions and a higher concentration of residual/sulfide fractions were identified in the soils stabilized with the solution, powder, and pariculate agents in descending order while there were no significant changes in As fractionation. Overall results suggest that calcium sulfate fertilizer can be used as a stabilizing agent, and a solution-type agent could be used when the operation of heavy machinery for the soil stabilization process is impossible.

• Proceedings of the Korean Society of Food and Cookery Science Conference
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• 2003.05a
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• pp.105-105
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• 2003

본 연구는 쇠고기 분쇄육에 천연항산화제인 pycnogenol, catechin 및 $\alpha$-tocopherol과 합성항산화제인 BHT를 처리한 후 3, 5, 7, 10일 동안 냉장저장하면서 색도 및 pH, TBA 값 및 지방산 조성의 변화와 항산화효소인 SOD 및 catalase 활성의 변화를 검토하였다. 명도는 catechin 처리군이 저장에 따른 색의 변화가 가장 작았으며, pH는 처리 당일 5.83~5.87의 비슷한 수준이었으나 저장함에 따라 저하되어 5일째에는 대조군이 약 0.45 수준으로 크게 감소한 것에 비하여 항산화제처리군은 약 0.2 수준의 감소로 대조군과 큰 차이를 나타냈다. (중략)

• Journal of Food Hygiene and Safety
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• v.3 no.2
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• pp.83-88
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• 1988

Propyl gallate used as an antioxidant was examined for its effects on murine Immune system and metbemoglobin content treated with anillne. As immunotoxicology assay parameters, we adopted circulating leukocytes and immunoorgan weights for pathtoxicology, IgM plaque forming cells and Artbus reaction for humoral immunity. Propyl gallate's effects were observed as follows; 1. Propyl gallate decreased circulating leukocyte counts, dose dependently. 2. Relative immunoorgan weigbts were not affected. 3. Propyl gallate diminisbed IgM PFCs/spleen cell and IgM PFCs/spleen. 4. Propyl gallate decreased Arthus reaction. 5. Propyl gallate did not affect metbemogiobin content treated wltb aniIIne.

• Applied Chemistry for Engineering
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• v.2 no.4
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• pp.372-384
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• 1991

The sulfation of the domestic titaniferous magnetite ore with ammonium sulfate was investigated to find a cyclic process for the production of synthetic rutile and high purity iron oxide and to test the feasibility of ammonium sulfate being an alternative sulfation agent. The proper sulfation conditions were determined to be a temperature of $425^{\circ}C$, 2.5 hours of reaction time, the weight ratio of ammonium sulfate to titaniferous magnetite : 11, and particle size or titaniferous magnetite : -250 mesh. 90.4 % of $TiO_2$ and 85.3 % of iron were extracted from the titaniferous magnetite sulfated under these conditions by the water leaching. From the leachate $TiO_2$ of 93.8 % purity as a mixture of rutile and anatase and ${\alpha}-Fe_2O_3$ of 97.6 % purity were obtained.

• Journal of the Korea Concrete Institute
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• v.27 no.4
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• pp.443-450
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• 2015

This paper presents an investigation of the mechanical and microstructural properties of Class F fly ash based geopolymer containing sodium sulfate as an additive. Sodium sulfate was used as an chemical additive at the dosage levels of 0, 2, 4, and 6wt% of fly ash. Sodium hydroxide and sodium silicate solutions were used to activate fly ash. The compressive strengths of geopolymer pastes were measured at the age of 28 days. The microstructures of the geopolymer pastes were examined using XRD, MIP and SEM tests. The additions of 2wt% and 4wt% sodium sulfate produced geopolymers with high strength, while increasing the dosage of levels to 6% resulted in almost no changes in strength, comparing with the control geopolymer. The optimum increase in strength was obtained with the addition of 4wt% sodium sulfate. As the amount of sodium sulfate is increased, no additional crystalline phase was detected and no change of amorphous phase indicated despite the change in the strength development. The increase in the strength was due to the change of pore size distribution in samples. As addition of sodium sulfate altered the morphologies of reactive productions and Si/Al ratios of the reaction products, the strengths were thus affected. It was found that the strengths of geopolymer were larger for lower Si/Al ratios of reaction products formed in samples. The optimal amount of sodium sulfate in the fly ash based geopolymer helps to improve mechanical properties of the geopolymer, on the other hand, the high percentage of sodium sulfate could exist as an impurity in the geopolymer and hinder the geopolymer reaction.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.545-548
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• 2008

In this study aluminium sulfate, Ca(OH)$_2$, K-R Slag and $Na_2SO_4$ were used as active admixtures and their concentration 1, 3, 5, 7 weight percent in cement. The physical properties of active admixtures cement mortar were investigated by flow test and compressive strength. It was found that the resulting active admixtures exhibited the higher compressive strength than OPC mortar up. From the test results, cement mortars added active admixture have a good fundamental property.

• Journal of Food Hygiene and Safety
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• v.5 no.1
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• pp.41-48
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• 1990

Propyl gallate used as an antioxidant was examined for its effects on murine immune system. As immunotoxicology assay parameters, we adopted circulating leukocytes and immunoorgan weights for pathotoxicology, delayed hypersensitivity and colloidal carbon clearance for cell mediated immuntity. Propyl gallate's effects were observed as follows; 1) Propyl gallate decreased circulating leukocyte counts, dose dependently. 2) Propyl gallate decreased delayed hypersensitivity reaction. 3) Phagocytic index were similar in the test and control groups.