• Journal of the Korea Concrete Institute
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• v.11 no.4
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• pp.13-20
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• 1999

Recently, the study for practical construction application no recycled aggregate concrete is actively being proceeded, on the purpose of technical development for recycling on the construction waste concrete occurred at the time of destruction of building construction by the rapid increase of building wastes and exhaustion of natural aggregates. But, the durability of investigation with all sorts of fluidity and engineering property for application recycled aggregate concrete to practical construction must be done at the same time. Especially, because of the real condition for chemical attack of concrete construction by the acid rain, acidification of soil, deepening of air pollution and dirty water etc. being come to the fore a serious problem, the study on the chemical soundness of concrete durability must be accompanied. This study is composed as: I series: Analysis for chemical soundness of aggregates. II series: Analysis for chemical soundness of natural and recycled aggregate concrete against $Na_2$$SO_4$ solution in drying and wet curing condition ($at20~80^{\circ}C$).

• Applied Chemistry for Engineering
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• v.24 no.4
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• pp.350-356
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• 2013

Dissolution of ferronickel slag depending on aging condition was studied. Ferronickel slag typically contains 54.05% $SiO_2$, 34.33% MgO, and 5.51% $Fe_2O_3$. The main structure composite was similar to Enstatite [(Mg, $Fe^{2+}$ )$SiO_3$]. Ferronickel slag aging was made in 3 months under various experimental conditions, in water, bubbling water and wetting air. The most effective aging condition was the wetting air treatment. In this condition, the dissolving concentration of Mg and Fe was 80.0% and 75.1% respectively. The XRD and SEM data revealed that the wetting air condition also showed the biggest structural damage.

• Journal of Korean Society of Water and Wastewater
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• v.25 no.3
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• pp.285-291
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• 2011

Membrane fouling is an unavoidable phenomenon and major obstacle in the economic and efficient operation under sea water reverse osmosis (SWRO). When fouling occurs on the membrane surface, the permeate quantity and quality decrease, the trans-membrane pressure (TMP) and operation costs increase, and the membrane may be damaged. Therefore, chemical cleaning process is important to prevent permeate flow from decreasing in RO membrane filtration process. This study focused on proper chemical cleaning condition for Shuaibah RO plant in Saudi Arabia. Several chemical agents were used for chemical cleaning at different contact time and concentrations of chemicals. Also autopsy analysis was performed using LOI, FT-IR, FEEM, SEM and EDX for assessment of fouling. Specially, FEEM analysis method was thought as analyzing and evaluating tool available for selection of the first applied chemical cleaning dose to predict potential organic fouling. Also, cleaning time should be considered by the condition of RO membrane process since the cleaning time depends on the membrane fouling rate. If the fouling exceeds chemical cleaning guideline, to perfectly remove the fouling, certainly, the chemical cleaning is increased with membrane fouling rate influenced by raw water properties, pre-treatment condition and the point of the chemical cleaning operation time. Also choice of cleaning chemicals applied firstly is important.

• Korean Chemical Engineering Research
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• v.44 no.6
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• pp.555-562
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• 2006

Recently, liquid chromatography (LC) has been used more frequently to separate drugs and natural substances. Especially, to selection of the solutes from the products, the operation condition of analytical chromatography should be necessarily determined. So accurate computer modeling and simulation of chromatographic performances has become a necessary part of the development and design of processes. High-Purity Separation Lab. Inha University developed the resulting HCI software for the purpose of the optimization of chromatographic performances. The HCI program was utilized to find the optimum operating condition more accurately and rapidly, reducing the number of many possible experiments. The elution profiles were calculated by the plate theory based on the three retention mechanism of capacity factor.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.31 no.2
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• pp.50-57
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• 1999

This study was carried out to compare a conventional alkaline flotation deinking conditions with neutral deinking conditions with and without enzyme addition with respect to the ink removal efficiency and theflotation deinking filtrate quality such as chemical oxygen demand, cationic demand, suspended solids. Based on ink removal rate the neutral deinking condition without enzyme was better than the alkaline deinking condition, and the neutral deinking with enzyme addition turned out to be the best. The brightness of the deinked pulp was found to be the same trend as the ink removal rate. Flotation reject rate for the neutral deinking condition without enzyme was higher than that of the alkaline deinking condition, but that of the neutral deinking condition with enzyme was lower than that of the alkaline and the neutral deinking condition without enzyme. On the freeness of the deinked pulp, the neutral deinking condition with enzyme had the highest value and the alkaline deinking condition had the lowest value among the conditions tested. On the filtrate of the flotation stage, the cationic polymer demand of the neutral deinking condition with enzyme was much lower than the other conditions. Suspended solids and chemical exygen demand for the neutral flotation deinking filtrate was lower than those of the alkaline flotation deinking filtrate.

• Korean Journal of Weed Science
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• v.30 no.4
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• pp.429-436
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• 2010

Herbicidal activity and characteristics of chrysophanic acid were investigated in semi-field condition. At early and middle post-emergence, Trifolium repens appeared to be very susceptible to chrysophanic acid of $2,000{\mu}g\;mL^{-1}$. However, herbicidal activity of chrysophanic acid of $2,000{\mu}g\;mL^{-1}$ estimated by visual injury to Artemisia princeps was not caused considerable phytotoxicity. Also by foliar application, the concentration of crysophanic acid for effectively control to Polygonum aviculare was much higher than $2,000{\mu}g\;mL^{-1}$. Herbicidal activity of chrysophanic acid to Echinochloa crus-galli, Cypres difformis, Setaria viridis, Digitaria sangguinalis, Bidens tripartita by foliar application was more effective at concentration ranges from 4,000 to $6,000{\mu}g\;mL^{-1}$. These results suggest that chrysophanic acid demanded for higher than $2,000{\mu}g\;mL^{-1}$ to successful weed control in the field condition.

• Bulletin of the Korean Chemical Society
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• v.22 no.10
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• pp.1153-1155
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• 2001

• Bulletin of the Korean Chemical Society
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• v.21 no.7
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• pp.669-670
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• 2000

• Journal of the Korean Society for Precision Engineering
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• v.15 no.6
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• pp.79-89
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• 1998

In determining optimal cutting condition for face milling operation, tool wear is an important factor. For the purpose of establishing the relationship between various machining factors and tool wear, cutting tests have been performed. As a result, hardness and chemical composition of workpiece material, chemical composition and grain size of cutting tool and cutting speed have been selected as machining factors. In addition, relationship between feed rate and workpiece hardness has been observed. Prior to utilizing cutting conditions recommended by ‘Machining Data Handbook(MDH)’ as a knowledge base, an analysis for the validity of the MDH has been provided. Based on this analysis, tool life criteria applied by MDH has been modified. Finally, using MDH recommended data for neural network trainning, the results from the trained neural network for optimal cutting condition for some given workpiece and cutting tool can be used as reference cutting conditions.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.501-504
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• 1999

In the shallow trench isolation(STI) chemical mechanical polishing(CMP) process, the key issues are the optimized thickness control within- wafer-non-uniformity, and the possible defects such as nitride residue and pad oxide damage. These defects after STI CMP process were discussed to accomplish its optimum process condition. To understand its optimum process condition, overall STI related processes including reverse moat etch, trench etch, STI filling and STI CMP were discussed. It is represented that the nitride residue can be occurred in the condition of high post CMP thickness and low trench depth. In addition there are remaining oxide on the moat surface after reverse moat etch. It means that reverse moat etching process can be the main source of nitride residue. Pad oxide damage can be caused by over-polishing and high trench depth.