• Journal of the Korean Society of Safety
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• v.19 no.2
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• pp.6-10
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• 2004

The magnetic polishing is the useful method to finish using magnetic power of magnet. This method is one of precision polishing techniques and has an aim of the clean technology using for the pure of gas and inside of the clean pipe for transportation. The magnetic abrasive polishing method is not so common for machine that it tis not spreaded widely. There are rarely researcher in this field because of non-effectiveness of magnetic abrasive. Therefore, in ths paper deals with development of the magnetic abrasive using sludge. In this development, abrasive grain WA and GC used to resin bond fabricated low temperature. And magnetic material was fabricated from the sludge which were crused into 200 mesh and average diameter ${\o}$1.2mm ball type. The XRD analysis result show that only WA and GC abrasive and sludge crystal peaks detected which explains resin bond was not any more chemical reaction. From SEM analysis it tis found that WA and GC abrasive and sludge were stron bonding with each other by bond.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.11
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• pp.1538-1544
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• 2014

In recent years, The electronic and energy industries demand low power consumption and high efficiency, so under their demands, the white goods industries which are represented for refrigerator and air conditioner system be implemented energy-saving power suppling structure with inverter control system. As inverter control system is different from step control type, when switching system is optimizing temperature control during short period, the inrush plus current can be flown in the circuit. In despite of these characteristics, there is no fuse which can be applied to this type until now. For this reason, we suggest the method of manufacturing protector in the high efficient inverter control system using the alumina-based ceramic radiated heat characteristics and metal films laminated plating. And through the evaluating electrical characteristics, we make a possible to utilize the method when designing overall fuses.

• Proceedings of the Korea Association of Crystal Growth Conference
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• 1998.09a
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• pp.97-102
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• 1998

Transition metal Cr3+ and Fe3+ ion was diffused in white sapphire {0001}, {1010} crystal plane which were grown by the Verneuil method. It enhanced and changed the physical, electrical and optical properties of sapphires. After mixing the metallic oxide and metal powder, it were used for diffusion. Metallic oxide was synthesized by precipitation method and it's composition was mainly alumina which doped with chromium or ferric oxide. In case using metallic oxide, the dopping was slowly progressed and it needed the longer duration time and higher temperature, relatively. Metallic powder was vapoured under 1x10-4 torr of vacuum pressure at 1900(iron metal) and 2050(chromium)℃, first step. Diffusion condition were kept by 6atm of N2 accelerating pressure at 2050∼2150℃. Each surface density of sapphire crystal are 0.225(c) and 0.1199atom/Å2(a). The color of the Cr-doped sapphires was changed to red. Dopping reaction was come out more deep in th plane of {1010} than {0001}. It was speculated that the planar density was one of the factors to determine diffusion effect.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.529-529
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• 2007

Ruthenium (Ru) is a white metal and belongs to platinum group which is very stable chemically and has a high work function. It has been widely studied to apply Ru as an electrode material in memory devices and a Cu diffusion barrier metal for Cu interconnection due to good electrical conductivity and adhesion property to Cu layer. To planarize deposited Ru layer, chemical mechanical planarization(CMP) was suggested. However, abrasive particle can induce particle contamination on the Ru layer surface during CMP process. In this study, zeta potentials of Ru and interaction force of alumina particles with Ru substrate were measured as a function of pH. The etch rate and oxidation behavior were measured as a function of chemical concentration of several organic acids and other acidic and alkaline chemicals. PRE (particle removal efficiency) was also evaluated in cleaning chemical.

• Conservation Science in Museum
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• v.25
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• pp.63-84
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• 2021

In order to investigate the diverse physicochemical changes that occurred in traditional Korean pottery during its production, including before and after firing, this study produced six replicas of a celadon maebyeong inlaid with cloud-and-crane designs, respectively corresponding to the process of shaping, carving, inlaying designs, first firing, glazing and second firing, respectively. It then conducted a scientific study of these six replicas and analyzed their images through high-resolution three-dimensional transmission imaging. The materials used for the replicas show different mineral phases and even colors depending on the components of each material. For example, black inlay with a high content of iron oxide (Fe₂O₃) shows dark colors and white inlay with a high alumina (Al₂O₃) content appears white. Physicochemical properties such as chromaticity and magnetic susceptibility and major components of the replicas were confirmed by the differences in the density in the computed tomography (CT) images. The characteristics of fired products such as fine structure, absorption ratio, apparent porosity, and other characteristics of the major mineral components were identified by the presence of pores and the formation of cracks inside the replicas in the image analysis.

• Journal of the Korean Ceramic Society
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• v.19 no.3
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• pp.179-186
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• 1982

This research is to aim at the study of sintering mechanism through the observation of microstructure by scanning electron microscopy, after the mixture of 30wt% $Al_2O_3$ (White Alundum) powder is fired in air at the temperature range of 1350~150$0^{\circ}C$ in order to sinter $Al_2O_3$-Al through the oxidation of Al powder. The results obtained in this experiment are as follows: 1. While the compressive strength of $Al_2O_3$(WA) body fired at $1450^{\circ}C$ for 5hrs in air is 150kg/$\textrm{cm}^2$, that of Al-$Al_2O_3$ body fired at 135$0^{\circ}C$, $1400^{\circ}C$ for 5hrs in air is 1100kg/$\textrm{cm}^2$, 1600kg/$\textrm{cm}^2$ respectively, and the higher the firing temperature, the more the compressive strength increases. These results from the sintering effect between $Al_2O_3$(WA) grains and surrounding Al-oxidation layer. 2. While the compressive strength of Al2O3(WA) body fired at 150$0^{\circ}C$ for 5hrs in air is 250kg/$\textrm{cm}^2$, the compressive strength of Al-$Al_2O_3$body fired under the same condition is 2050kg/$\textrm{cm}^2$ and water absorption 9.0%, porosity 23.3%, bulk density 2.60gr/$cm^3$. It is assumed that these results come from not only the grain growth of oxidized Al grains but also the increase of bonding strength between $Al_2O_3$(WA) grains.

• The Journal of Engineering Research
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• v.4 no.1
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• pp.69-85
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• 2002

The chemical composition of bottle glass is consisted of Na2O-CaO-SiO2. However the cullet is mornally used in order to decrease the melting tsmperature. This induce the productivity of bottle and decreases the cost. The addition of plate glass decreases the Al2O3 content and in fluence the stone phenomenon and devitification in botle glass. Tus the Feldspar is added in order to increase the Al2O3 content when plate cullet was added in melting. The Tridymite crystal was observed over 7.5% Al2O3 contents, which shown as white crystal in appearance. It is Supposed that the Wollastonite Would be occurred in more over 7.5% Al2O3. This fad id well consised With the Litertctures.