• Journal of the Korea Safety Management & Science
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• 제6권1호
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• pp.301-309
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• 2004

An inorganic filling agent, ATH (alumina trihydrate) was used to induce inorganic-organic coupling by mixing with stearic acid, acryl silane, vinyl silane as surface treatment agents in order to apply as a high voltage insulating material. Volumetric resistivity was shown to vary with surface treatment agents, and the highest value was obtained in case of the mixture with vinyl silane. The dielectric breakdown intensity was shown to decrease gradually and saturate to a stable value, possibly due to the increase of cross link density in the vinyl radicals introduced to silica surface, resulting in stable dielectric breakdown intensity in the final stages. Tracking and flame retardant properties were also shown to be the best among the samples investigated in this study.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 한국전기전자재료학회 2003년도 제5회 학술대회 논문집 일렉트렛트 및 응용기술연구회
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• pp.105-108
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• 2003

CMP(chemical mechanical polishing) process has been attracted as an essential technology of multi-level interconnection. However, the COO(cost of ownership) is very high, because of high consumable cost. Especially, among the consumables, slurry dominates more than 40 %. So, we focused how to reduce the consumption of raw slurry. In this paper, We have studied the CMP (chemical mechanical polishing) characteristics of slurry by adding of raw alumina abrasive and annealed alumina abrasive. As a experimental results, we obtained the comparable slurry characteristics compared with original silica slurry in the view point of high removal rate and low non-uniformity. Therefore, we can reduce the cost of consumables(COC) of CMP process for ULSI applications.

• Journal of Korean Society for Atmospheric Environment
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• 제14권1호
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• pp.63-72
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• 1998

Simultaneous CO and $C_3H_6$ oxidation was carried out over noble metal supported monolith catalysts in a flow thorugh type reactor at the temperature ranging from room temperature to $500^\circ$C. Pt and Pd were selected as major active species, 10wt% of Ce was impregnated as an additive and alumina and silica were used as supports. The reactant gases were simulated and the reaction products were analyzed by on-line G.C.. EDX, SEM, TGA, XRD and optical microscope were used to analyze the characteristics of the prepared catalysts. Under the given conditions in this study, the catalysts supported on alumina showed better activity for CO oxidation, while Pd catalysts showed better activity for $C_3H_6$ oxidation. The improvement of conversion due to increase in thermal stability possibily by Ce addition was observed only for Pt catalysts.

• Journal of the Korean Ceramic Society
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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.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 한국마이크로전자및패키징학회 2003년도 기술심포지움 논문집
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• pp.256-259
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• 2003

To develop cleaning process various particles should be deposited on wafer surfaces to measure particle removal efficiencies. The purpose of the article in to evaluate, removal efficient)r of silica and alumina particles from wafer surfaces when they are deposited by dry and wet method. Dry deposition in air and wet spray deposition using solutions are used. van der Waals are considered to calculate the adhesion force of particles on surfaces. Higher adhesion force is measured on alumina particles on silicon when particles are deposited in air.

• Bulletin of the Korean Chemical Society
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• 제19권6호
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• pp.617-618
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• 1998

A simple and reproducible pretreatment method was developed for the determination of dioxins in milk sample. Liquid-liquid extraction (LLE) was used for the initial extraction of the analyte from milk. For the elimination of interferences coextracted from milk, acid treatment followed by multilayer silica gel, and then alumina column clean-up were performed. The clean extract could be obtained without carbon column or high performance liquid chromatographic (HPLC) clean-up procedure. Polychlorinated biphenyles (PCBs) and dioxins were separated on neutral alumina activated at 180 ℃ for 12 hours. The final extract was analyzed by HPLC and high resolution gas chromatography/high resolution mass spectrometry (HRGC/HRMS). The recovery of dioxins spiked in milk at 75-300 ppt level was 83.3-98.9% and their relative standard deviation was 4.1-14%.

• Bulletin of the Korean Chemical Society
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• 제19권6호
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• pp.619-624
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• 1998

A simple and reproducible pretreatment method was developed for the determination of dioxins in milk sample. Liquid-liquid extraction (LLE) was used for the initial extraction of the analyte from milk. For the elimination of interferences coextracted from milk, acid treatment followed by multilayer silica gel, and then alumina column clean-up were performed. The clean extract could be obtained without carbon column or high performance liquid chromatographic (HPLC) clean-up procedure. Polychlorinated biphenyles (PCBS) and dioxins were separated on neutral alumina activated at 180 ℃ for 12 hours. The final extract was analyzed by HPLC and high resolution gas chromatography/high resolution mass spectrometry (HRGC/HRMS). The recovery of dioxins spiked in milk at 75-300 ppt level was 83.3-98.9% and their relative standard deviation was 4.1-14%.

• Applied Chemistry for Engineering
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• 제23권3호
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• pp.320-325
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• 2012

The catalytic cracking of waste lubricant oil was carried out on silica-alumina (SA), hydrogen-type mordenite (HM), and dealuminated mordenite (DM) with the silica/alumina ratio of 10.5, 10, and 12.5, respectively. Activity in the catalytic cracking was found to be in the order of SA > DM > HM. Carbon number distribution of the oil obtained over SA was similar to that of gasoline while that of the oil obtained over DM was similar to that of diesel. Carbon number distribution of the oil obtained over HM was similar to that between gasoline and diesel. Acid amounts of three kinds of catalysts were found to be in the order of $SA\;{\approx}\;HM$ > DM. Unlike HM and DM with pores of an uniform diameter below 10 A, SA had a pore size distribution within the range of 10 to 50 A. These results indicate that the acid amount and pore size of the catalysts may be related to the carbon number distribution of the cracked oil. The decrement of surface area by the accumulation of carbon and impurities on the surface of the catalyst was found to be in the order of SA > DM > HM.

• The Journal of Natural Sciences
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• 제8권2호
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• pp.119-127
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• 1996

The effect of sodium hydroxide treatment on some physicochemical properties of zeolite mordenite mineral was studied with chemical analyses, powder X-ray diffraction, thermal analyses, infrared analysis, measurement of carbon dioxide adsorption and gas chromatography. Mordenite mineral from tuffaceous rocks in Yeongil and Wolsung area was used as a starting material and treated with 0.1-5N NaOH aqueous solution at about $95^{\circ}C$ in the water bath for three hours.At the concentration of sodium hydroxide below 0.5N, all chemical compositions in the tuff were virtually insoluble and the mordenite structure did not change. At the concentration above 1N, the chemical compositions such as silica, alumina, etc., were dissolved. The dissolution ratio of silica was lager than that of alumina, and the ratio of silica to alumina in the tuff decreased sharply in the concentration range of 2 to 3N. Intensity of X-ray diffraction peak of mordenite (202) plane and the adsorbed amount of carbon dioxide also decreased with the increasing concentration of sodium hydroxide above 1N. These decreases corresponded to the degree of mordenite structure collapsed.The separation of gas chromatography of nitrogen, oxygen and carbon monoxide was not affected by the sodium hydroxide treatment, but elution peaks of methane and krypton tended to be broadened and their retention time was shortened. The elution peaks of both methane and krypton tended to be overlapped with those of nitrogen and oxygen.

• Journal of the Korean Ceramic Society
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• 제17권4호
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• pp.188-196
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• 1980

To investigate the corrosion behavior of the clay-bonded kaolin chamotte by molten aluminum, the mixture of 20 wt% fire clay and 80 wt% kaolin chamotte was prepared and fired in the temperature range 900~120$0^{\circ}C$. The specimens fired at each temperature were reacted with molten aluminum at 90$0^{\circ}C$. The results obtained in this experiment are as followed. 1) It was confirmed through X-ray diffraction analysis that the clay-bonded kaolin chamotte exposed to molten aluminum suffered penetration by the reaction of aluminum with silica forming alumina and metallic silicon. 2) Penetration was independent whether the silica existed as free or one component of mullite. 3) Penetration of the specimen fired at 90$0^{\circ}C$ was negligible while the others fired above 100$0^{\circ}C$ showed remarkable penetration. 4) Penetration rate at 90$0^{\circ}C$ was parabolically increased with the holding time as in the case of metal oxidation.