• Korean Journal of Optics and Photonics
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• v.3 no.3
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• pp.178-182
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• 1992

An air-cooled discharge-heated copper-vapor laser system with its inter-electrode distance of 45 cm has been developed by utilizing an alumina ceramic plasma tube of 1.6 cm in diameter and 50 cm in lengih. For operating the laser, a dc high voltage power supply with output rating of 6 kV and 500 mA, a resonant charging circuitry consisting partly of an 1.8 H inductor assembly and a 5 nF storage capacitor, and a thyratron driver operating up to 7 kHz have also been developed. The present laser system starts lasing at the tube temperature of about $1350^{\circ}C$ and an maximum average output power of 0.7 W has been obtained at 12 kV, 4.5 kHz. 50 mbar of Ne buffer gas pressure, and at the tube temperature of $1460^{\circ}C$.

• Journal of the Korean Institute of Gas
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• v.23 no.5
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• pp.24-34
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• 2019

In this study, the experimental studies were conducted to analyzing characteristics of combustion and flame stabilizing according to with and without water tube in boiler. The burner has consisted of SiC foam where has the location of submerged flame between a ceramic board acting as flash-back arrestor. Porous burner is also insulated to minimize heat loss in the radial direction. In the condition of fixed equivalence ratio, the flame mode was divided into three stability zones by the flow rate. The main factor for blow-off and flash-back depends on mixture flow rate. Consequently, the case of burner with water-tube has higher NOx emissions than without case. This result explains that the presence of water-tube makes the heat loss resistant to ambient temperature with increasing of NOx. This tendency was proved by predicting the relationship between O₂ emission and NO production rate, and by analysing temperature profiles.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.10a
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• pp.273-276
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• 2003

High-temperature superconduction materials(Bi2223) possess electrical/electronic and magnetic properties. Because high-temperature superconduction materials is a ceramic powder, that can not be produced singlehandedly. So Ag sheathed Bi-2223 wire was produced by drawing process using powder-in-tube(PIT) method. This superconductor has many difficulties to produce. The main difficulty is that the mechanical properties of the ceramic powder are very different from those of the Ag sheath. Bi2223 high-temperature superconductivity have a single filament drawing process, and multi-filament drawing process. This study analysed multi-filament drawing process by FEM, a defects during multi-filament drawing was studied by FEM.

• Journal of the Korean Society of Industry Convergence
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• v.1 no.2
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• pp.49-54
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• 1998

In the catalytic combustor, combustion characteristic and deterioration of catalysts were affected by non-uniformity of pre-mixed gas, Therefore, formation of uniform pre-mixed gas is one of important subjects. In this study, the effect of uniformity and non-uniformity of pre-mixed gas supplied to the catalyst was examined to clarify reaction acceleration and combustion characteristic of the catalytic combustion. It was clarified that static mixer or vaporizer tube length of about 150mm and weak swirl to a combustion air were effictive expedient to make uniform pre-mixed gas. And catalystic inlet temperature needs more than $600^{\circ}C$ with rich pre-mixed gas to active reaction.

• Journal of the Korean Ceramic Society
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• v.19 no.3
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• pp.199-204
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• 1982

Bowl 형태의 일본산 Nagano 점토에 대한 분류 및 특성화 연구를 하였다. 결정입자 크기를 1$\mu$ 이하로 침강분리 시킨후 전자현미경으로 결정형태를 관찰하였다. 아울러 결정형태, 구조적 결함 및 intercalation 반응성의 상호관계를 검토하기 위하여 tube 형태의 한국산 halloysite 및 plate 형태의 kaolinite를 비교 조사하였다. 특이한 Bowl 형 Nagano 점토는 tube형 halloysite와 화학 반응성에서 동일하여 극성 내지는 hydrogen bridge 결합을 하는 guest 분자와 반응하여 층간삽입 화합물을 형성 하였다. 화학반응성에 따른 점토분류방법에 의해 Nagano 점토가 halloysite임을 밝혔으며 아울러 결정의 형태는 반응성에 영향을 미치지 않음을 알 수 있었다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11b
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• pp.152-155
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• 2005

Diesel particulate filter (DPF) is comprised of a number of capillary tubes enclosed by porous ceramic wails, shaped like a plugged duct. Hot gas flows through the DPF along with the exhaust noise from Diesel engine. Based on previous works on the sound propagation through DPF, in this study, losses at entrance, exit, and ceramic walls are considered and the gradients in temperature and flow velocity are considered. Transfer matrix at entrance, monolith, and exit parts are obtained by employing the segmental approach in analyzing the sound propagation through DPF. The predicted transmission loss agrees very well with the empirical one, which is measured by the improved method with correction terms.

• Transactions of Materials Processing
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• v.13 no.1
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• pp.78-83
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• 2004

High-temperature superconduction materials(Bi2223) possess electrical/electronic and magnetic properties. Because high-temperature superconduction materials is a ceramic powder, that cannot be produced singlehandedly. So Ag sheathed Bi-2223 wire was produced by drawing process using powder-in-tube(PIT) method. This superconductor has many difficulties to produce. The main difficulty is that the mechanical properties of the ceramic powder are very different from those of the Ag sheath. And by these properties, Bi2223 high-temperature superconductor, which has a single filament drawing process and multi-filament drawing process, has a defect like sausaging and bursting at a center. This study analyzed multi-filament drawing process by FEM, and a defect generated during multi-filament drawing was studied by FEH. Specially, in order to prevent a bursting at a center, this study presented a method that inserts a pure Ag at a center of multi-filament wire

• Journal of the Korean Ceramic Society
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• v.35 no.2
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• pp.201-207
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• 1998

A tube-type filter dam(or baffle with holes) for ferrous melt refining is applied to the tundish operation for molten steel having low carbon and ultra-low carbon. The changes in the total oxygen content insoluble aluminum content and the distribution of inclusion size in molten steel during tundish operation were in-vestigated at the pouring part strand and mold of tundish. Removal mechanism of inclusions is considered to be caused by buoyancy action of the filter dam better than filtration action and the size range of in-clusions filtrated by the filter dam was for 30-50$\mu\textrm{m}$. Decrease in deviation of inclusion content in molten steel was confirmed for appling the filter dam in comparison with using conventional dam and weir. Also the filter dam had the advantage of baffle with holes at lower part in the efficiency of inclusions removal.

• Journal of the Korean Ceramic Society
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• v.25 no.2
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• pp.95-100
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• 1988

Single crystals of sapphire were grown from solution by slow cooling method using B2O3 and PbO as flux agents. The morphology of grown crystals was tube, rhombohedral, or hexagonal-plate. It was found that the morphology and the size of grown crystal were highly dependent on the amount of fluxes in the solution, the ratio of B2O3 vs. PbO, and cooling rate.

• Journal of the Korean Ceramic Society
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• v.37 no.4
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• pp.332-337
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• 2000

Forming mechanism of fibrous TiC during self-propagating high temperature synthetic reaction was analyzed and suggested. It was revealed that critical temperature for the stable fiber formation was not the melting point of TiC, but the eutectic reaction temperature of TiC and C. Minimum amount of TiC diluent addition required to form fibers was calculated to be 25.6%, which was consistent with the experimental result. Synthesized fibers were found hollow tube-like. The morphology was explained by the diffusion rates of C and Ti in TiC, and by the molar volume chnage of C during the reaction. Expanding shell model was suggested for the hollow fiber formation mechanism.