• Journal of the Korean Ceramic Society
• /
• v.50 no.5
• /
• pp.319-325
• /
• 2013

In this study, petroleum cokes ash and $C_{12}A_7$-based slag were used for the shrinkage reduction and strength enhancement of mortar. The hydration properties of shrinkage reduction agents were analysed. The flow, change of length and compressive strength were experimented with mortar-added shrinkage reduction agents. As a result of this study, petroleum cokes ash : $C_{12}A_7$-based slag = 60~80% : 20~40% showed excellent results. In the case of mortar with 20% $C_{12}A_7$-based slag, the setting time and change of length were similar to Ref. mortar. The flow and compressive strength were superior to Ref. mortar. In the case of mortar with a 40% $C_{12}A_7$-based slag, the setting time was longer than Ref. mortar. The compressive strength of 3 days and 7 days were superior to Ref. mortar.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2005.05b
• /
• pp.497-500
• /
• 2005

This study was performed to evaluate the characteristics which are slump, air content and time of set in fresh concrete and compressive strength of hardened concrete containing slag powder and fly-ash. Replacement rate of FA is fixed on 10$\%$ and replacement rate of slag powder are 0$\%$, 20$\%$ and 30$\%$. Also AE water-reducing agents(standard type, accelerating type) are used. The results were as follows. (1)Slump flow of concrete using AE water-reducing agents is similar. Flowability is incresed when replacement rate of slag powder is increased due to slag powder's ball bearing reaction.(2)Time of set of concrete using accelerating type agent is more faster than that of concrete using standard type agent because of ettringite generation that promote setting.(3)Early strength of three-component concrete using accelerating type agent is higher than that using standard type agent. Therefore cumulative pore is reduced due to ettringite

• 한국연소학회:학술대회논문집
• /
• 2005.10a
• /
• pp.93-96
• /
• 2005

High temperature furnace such as Steam power plant and incinerator contribute considerable part of NOx generation and face urgent demand of De-NOx system. Reducing agents are necessary to use De-NOx system. In this study mixing caused by direct injection of reducing agent solution spray into flue gas duct was measured. Carbonated water was used as tracer and simulated agent because ammonia as a reducing agent is not proper to experiment. Mixing and evaporation must occur simultaneously and quickly enough to achieve desirable efficiency. To achieve that, the angle of attack of static mixer and the location is simulated and $CO_2$ concentration is measured.

• Resources Recycling
• /
• v.2 no.4
• /
• pp.10-16
• /
• 1993

Reduction behavior of stainless steelmaking dust by microwave heating process was investigated using coke and charcoal as reducing agents. Pellet dust and stanless steelmaking dust pelletized with reducing agent were reduced by the heating upto $1000^{\circ}C$ in microwave oven. The results showed that charcoal and coke seemed effective in the reduction of metals from stainless steelmaking dust by microwave heating and charocal was found to be better than coke. Degree of reduction seemed similar with the power of 500W and 700W in microwave oven. Dusts were rapidly reduced within 20 minutes. Reducing degree decreased in the order of Fe>Ni>Cr.

• KSBB Journal
• /
• v.27 no.3
• /
• pp.157-160
• /
• 2012

When iron oxide magnetic nanoparticles were synthesized by co-precipitation method using aqueous ammonia as reducing agent, the synthesized particles were aggregated and thus precipitation occurred. Using Magnolia kobus leaf extract as reducing agent, spherical nanoparticles of 50~200 nm were synthesized with low yield. By using both Magnolia kobus leaf extract and aqueous ammonia as reducing and stabilizing agents, smaller nanoparticles of 40~120 nm could be synthesized with various shapes. The synthesized magnetic nanoparticles were characterized with field emission transmission electron microscopy (FE-TEM) and scanning electron microscopy (SEM). TEM and SEM images showed that the magnetic nanoparticles are a mixture of triangles, tetragons, rods and spherical structures.

• Bulletin of the Korean Chemical Society
• /
• v.19 no.2
• /
• pp.243-249
• /
• 1998

The reaction of alcohol with a solution of thexylborane (ThxBH2) in tetrahydrofuran (THF) provides a new class of mild and selective reducing agents, thexylalkoxyboranes (ThxBHOR: R=Et, i-Pr, i-Bu, s-Bu, t-Bu, Ph). In order to elucidate the effect of the alkoxy group in reduction reactions, the reducing power of ThxBHOR toward selected organic compounds containing representative functional groups under practical conditions (THF, 25°, the quantitative amount of reagent to compound) has been investigated. Generally, the reactivity of ThxBHOR is largely dependent upon the alkoxy substituent. ThxBHOR can be synthesized from a variety of alcohols, thus allowing control of the steric and electronic environment of these reagents.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2017.05a
• /
• pp.156-157
• /
• 2017

It is possible in the case of the chemical admixtures for concrete currently being used in actual work sites to omit quality evaluation and replace it with the scores of the admixture manufactures; this can create a problem of decline in reliability in quality on the work site. Therefore this study sought to analyze the degree of influence changes in the solid content rate of lignin- and naphthalene-based water-reducing agents have on the fundamental characteristics of cement mortar. The results showed that in fresh mortar, the flow and amount of air decreases with decrease in the solid content ratio. In hardened mortar, the condensation strength had hardly any effect on the use of lignin-based water-reducing agent, but naphthalene-based water-reducing agent increased with the decrease in the solid content ratio.

• The Korean Journal of Food And Nutrition
• /
• v.30 no.1
• /
• pp.139-147
• /
• 2017

The objective of this study was to develop anti-browning agents for commercial ready-to-eat pear products, which are preferred not only to maintain the flavor, color and texture of pears, but also to increase consumers' preference. The sliced 'Shin-go (Niitaka)' pears were immersed in 5% and 10% oxidized starch, 1% citric acid, and 5% and 10% oxidized starch with addition of 0.1% sucralose for 3 minutes, and then they were packaged in vacuum sealed bags at $1^{\circ}C$ for 9 days. In order to evaluate the quality of packaged sliced pears, the quality index was determined in terms of color, firmness, soluble solids, and sensory quality. With the passage of storage time, no specific variation in firmness and soluble solids was observed. However, the ${\Delta}E$ value of the sliced pears treated with 5% oxidized starch solution was significantly lower than that of the other pears. Also, the Hunter L and b values of the sliced pears treated with 5% oxidized starch solution remained nearly constant from the beginning of storage. This observation shows that 5% oxidized starch solution was effective in reducing surface browning of sliced pears. Moreover, sliced pears treated with oxidized starch solution with addition of 0.1% sucralose were given an overall liking score which was slightly higher than that given to the other pears because of the sweetness of sucralose. In conclusion, 5% oxidized starch solution with addition of 0.1% sucralose was effective in reducing browning of sliced pears and in improving the taste of sliced pears.

• Food Science and Preservation
• /
• v.12 no.3
• /
• pp.267-274
• /
• 2005

Oxidant stress is a well-known pivotal parameter for the degenerative immune diseases including asthma, atopic dermatitis, and rhinitis. In order to screen for anti-asthma agents effectively, we first established the infrastructure of high throughput screening(HTS) for anti-oxidant agents from agricultural products and/or oriental medicine library extracted with water, methanol, dimethyl sulfoxide, ethyl acetate and juice, Using the screening system, we found that Chaenomelis langenariae, Rhus javanica L., Camellia sinensis, Helianthus annuus and Angelica utilis Makino had strong anti-oxidant activity. Moreover, Helianthus annuus, Rehmannia glutinosa Libo and Angelica utilis Makino have protection activities by treatment of an oxidant hydrogen peroxide. Together, these results suggest that screened agents could be potential agents against asthma, although the in vivo studies should be clearly tested.

• Journal of Periodontal and Implant Science
• /
• v.35 no.4
• /
• pp.991-1002
• /
• 2005

The purpose of this study was to compare the effect of desensitizing agents applied on hypersensitive root surface following periodontal treatment. This study included 21 subjects(168 vital teeth). To evaluate dentin sensitivity, three clinical tests(tactile, air stream, cold water) were tried and three different densensitizing agents(MS coat, Elmex gel. Superseal) were individually applied. After application, reassessment was done at 1 minute, 1 week, 1 month and 3 months. The results were as follows : 1. The degree of dentin sensitivity was measured highly in the sequence of cold water, air stream and tactile and significantly decreased in all four groups with lapse of time(p<0.05). 2. There was no significant difference between all four groups in the tactile test with lapse of time. 3. There was no significant difference between three experimental groups in the air stream test with lapse of time. however, one minute later, it was measured highly in the sequence of Superseal, MS coat and Elmex 4. There was no significant difference between three experimental groups in the cold water test with lapse of time. As a result of this study, all of three agents were significantly effective in reducing dentin hypersensitivity and these agents could be positively employed to patients complaining of dentin hypersensitivity following periodontal treatment.