• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 C
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• pp.1727-1729
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• 2004

Chemical mechanical polishing (CMP) process has been widely used to planarize dielectric layers, which can be applied to the integrated circuits for sub-micron technology. Despite the increased use of CMP precess, it is difficult to accomplish the global planarization of in the defect-free inter-level dielectrics (ILD). we investigated the performance of $WO_3$ CMP used silica slurry, ceria slurry, tungsten slurry. In this paper, the effects of addition oxidizer on the $WO_3$ CMP characteristics were investigated to obtain the higher removal rate and lower non-uniformity.

• 한국세라믹학회지
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• 제21권4호
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• pp.327-332
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• 1984

Proper amount of $Al_2O_3$ must be added to increase the yield of mullite which is formed from free silica decomposed from kaolin. The previous study has suggested that Al powder may be a good $Al_2O_3$ supply source at 1400~150$0^{\circ}C$. In this study the application of Al powder is discussed about its mullitization behavior in the higher temperature range of 1500~175$0^{\circ}C$ the results of which compared with those obtained from the reactive $Al_2O_3$ and activated $Al_2O_3$. The oxdation and reaction stages of Al powder were analyzed by DTA crystal growth andmorphology of the mullite were observed by SEM and the yields of the mullite were compared according to their solubilities in HF solution.

• 동의생리병리학회지
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• 제22권4호
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• pp.903-906
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• 2008

Woodfordia fruticosa Kurz (Lythraceae) is used in the treatment of various ailments in traditional medicines. DPPH activity guided fractionation and purification process was used to identify the free radical-scavenging components from the flowers of this plant. The methanolic extract of the plant was first fractionated into four extracts; namely, n-hexane, chloroform, ethyl acetate and water fractions. Among them, the ethyl acetate fraction was found to be the most effective and was further subjected to activity guided-fractionation and isolation procedures. After successive column chromatography on silica gel and Sephadex LH-20, gallic acid, which is responsible for the radical scavenging activity, was isolated and its structure was elucidated by spectral methods ($^1H$ NMR, $^{13}C$ NMR) and by comparison with literature.

• Natural Product Sciences
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• 제14권3호
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• pp.202-205
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• 2008

The antioxidant activity of Paeonia suffruticosa (Paeoniaceae) was determined by measuring the radical scavenging effect on DPPH (1,1-diphenyl-2-picrylhydrazyl). The methanolic extract of P. suffruticosa showed the strong antioxidant activity. The antioxidant activity of ethyl acetate soluble fraction was stronger than that of the others ($IC_{50}$, $1.2\;{\mu}g/mL$), and the fraction was subjected to purification by repeated silica gel and Sephadex LH-20 column chromatography. Suffruticosol A, suffruticosol B, methyl gallate, and gallic acid, were isolated from the ethyl acetate soluble fraction. Their structures were elucidated by physico-chemical and spectroscopic studies.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 가을 학술발표회 논문집
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• pp.787-792
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• 2001

The chloride ion penetrating into concrete is classified as the fixed chloride ion being bound in reacting to cement hydrate and the free chloride ion having a direct effect on rebar corrosion because being in solution inside porosity of concrete. Therefore, in order to study the diffusion properties of chloride ion, it is needed to evaluate binding chloride ion in concrete. In this study, we tried to give a fundamental information on diffusion of chloride ion in concrete with mineral admixtures through analysis of micro-structure transformations in concrete and effects on binding of chloride ion in cement paste when mixed with fly-ash, blast furnace slag, silica fume etc. which are used to improve durability and permeability of concrete

• 한국미생물·생명공학회지
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• 제27권5호
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• pp.391-398
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• 1999

A methylotrophic actinomycetes strain MO-16, which produce the antimicrobial compound, was isolated from soil and supposed as Amycolatopsis sp. based on taxonomic studies. The cell-free extract of methanol-grown strain MO-16 showed dehydrogenase activity for methanol and formaldehyde when various electron acceptors were added for oxidation. On the other hand, methanol did not affect the production of antimicrobial compounds, and organic nitrogen sources such as corn steep liquor and peptone were better than inorganic nitrogen sources. These compounds showed broad antimicrobial spectrum to the tested strains such as bacteria and yeast. The antimicrobial comounds were very stable under heat(121$^{\circ}C$), acid(pH2.0), alkali(pH11.0) treatments. These compounds were isolated by ethylacetate extract, silica gel column chromatography and reverse phase HPLC. Two compounds(peak 1 and 2) were detected as antimicrobial compounds through the HPLC analysis. The peak 2 was purified as a single compound and revealed a 98% purity.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 춘계 학술발표회 논문집(II)
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• pp.41-44
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• 2006

Recently, single shell lining method of construction is studied by economical method of construction to make use of high-performance shotcrete of permanent shotcrete lining concept in the UStA, Europe, Japan etc. High-performance shotcrete use is essential as permanent support that single shell lining method of construction has two functions of lining and support to shotcrete. In this research, optimum accelerator amount was decided after setting time test using alkai-free and cement mineral accelerator. Also replacement ratio of silica fume and fly-ash was determined.

• 한국세라믹학회지
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• 제29권6호
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• pp.496-504
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• 1992

Alumina tubes suitable for the support of gas separation membranes have been prepared by the slipcasting technique. These supports have the average pore size of 0.1 ${\mu}{\textrm}{m}$ within the narrow distribution. The sol-gel dipcoating process of nanoparticulate sols is very sensitive to microstructure of the support, and the coating on the inside surface of the tube is found to be more successful than on the outside surface. Nanoparticulate silica sols (0.82 mol/ι) have been synthesized by an interfacial hydrolysis reaction between TEOS and high alkaline water. When coating an alumina tube with these sols, the minimum limits of the particle size and the aging time required for forming the coated gel layer at the given pH are provided. It is optimum to coat the support with less concentrated sols stabilized through aging for the appropriate time (more than 22 days) at the lower pH (pH 2.0) for producing a reproducible crack free thin film coating in composite membranes.

• 세라미스트
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• 제22권3호
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• pp.256-268
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• 2019

Ceramic nano pigments have attracted much interest owing to recent demand for nontoxic, heavy metal-free pigments. In general, ceramic pigments must possess thermal stability at high temperature, however nanosized powder easily undergoes aggregation at high temperature, and its color turns. serveral groups have focused on to minimize agglomeration and oxidation, a core-shell structure with a silica coating is suggested. In this review, we introduce the reported the trend of nano-ceramic powders and we summarized method improve color and physical properties throuth morphology control and ceramic coating technology.

• Computers and Concrete
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• 제14권3호
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• pp.263-277
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• 2014

This study investigated four electric field configurations of two-dimensional accelerate lithium migration technique (ALMT), including line-to-line, plane-to-line, contour-to-line and plane-to-plane, and analyzed the ion migration behavior and efficiency. It was found that the free ion distribution diagram and voltage distribution diagram were similar, and ions migrated in the power line direction. The electrode modules were used for the mortar specimen with w/c ratio of 0.5. The effectively processed areas accounted for 14.1%, 39.0%, 49.4% and 51.4% of total area respectively on Day 28. Larger electrode area was more advantageous to ion migration. In addition, it was proved that the two-dimensional electric field could be divided into different equifield line active regions, and regarded as affected by one-dimensional electric field, and the ion migration results in various equifield line active regions were predicted by using the duration analysis method based on the theoretical model of ion migration obtained from one-dimensional test.