• Journal of Sensor Science and Technology
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• v.18 no.6
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• pp.441-448
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• 2009

Magnesia partially stabilized zirconia(Mg-PSZ) solid electrolytes for an improvement of thermal shock resistance, which is suitable for the measurement of oxygen activity in a molten steel, were prepared by post-thermal aging treatment. The steelmaking oxygen sensor elements were formed by an injection molding method, sintered at $1650^{\circ}C$, and then thermal aged ranged from 1250 to $1400^{\circ}C$. Sintered density and porosity were decreased as increasing the magnesia content in a zirconia-magnesia solid solution. Fractions of cubic phase to the synthesized Mg-PSZ solid electrolytes were ranged from 13.13 to 79.54.% after post-thermal aging treatment. Very dense microstructure without voids in the grains was obtained by the post-thermal aging process. Fine tetragonal phase crystallites precipitated on the cubic surface during post-thermal aging up to $1300^{\circ}C$ improve a thermal shock resistance and reappearance of electro motive force(EMF) curve.

• Journal of Korea Foundry Society
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• v.37 no.1
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• pp.14-20
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• 2017

The microstructure, electrical conductivity and hardness variation of an AZ91-5wt%Sn Mg alloy sample during a solid-solution and aging heat treatment were instigated by optical microscopy, scanning electron microscopy, X-ray diffraction and by Rockwell hardness techniques in this study. The XRD result shows that the main phases in the as-casted alloy are ${\alpha}$-Mg, $Mg_{17}Al_{12}$ and $Mg_2Sn$. From the SEM images of the AZ91-5wt%Sn Mg alloy after the solution treatment, the $Mg_{17}Al_{12}$ phases in the alloy were found to have dissolved into the matrix with an increase in the holding time during the solution treatment, but $Mg_2Sn$ phases were clearly observable. The highest peak hardness of the AZ91-5wt%Sn Mg alloy is 82HRE at an aging temperature of $200^{\circ}C$.

• Korean Journal of Materials Research
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• v.30 no.8
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• pp.435-440
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• 2020

The relationship between the precipitation of secondary phase and the thermal properties of Al-4.5%Cu alloy (in wt.%) after various heat treatments has been studied. Solid solution treatment of alloy was performed at 808 K for 6 hours, followed by warm water quenching; then, the samples were aged in air at 473 K for different times. The thermal diffusivity of the Al-4.5%Cu alloy changed with the heat treatment conditions of the alloy at temperatures below 523 K. The as-quenched specimen had the lowest thermal diffusivity, and as the artificial aging time increased, the thermal diffusivity of the specimen increased in the temperature range between 298 and 523 K. For the specimen aged for five hours, the thermal conductivity was 12% higher than that of the as-quenched specimens at 298 K. It is confirmed that the thermal diffusivity and thermal conductivity of the Al-4.5%Cu alloy significantly depend on their thermal history at temperatures below 523 K. The precipitation and dissolution of the Al₂Cu phase were confirmed via DSC for the alloys, and the formation of coefficient of thermal expansion peaks in TMA was caused by precipitation. The precipitation of supersaturated solid solution of Al-4.5%Cu alloys had an additional linear expansion of ≈ 0.05 % at 643 K during thermal expansion measurement.

• Journal of the Korean Ceramic Society
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• v.29 no.5
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• pp.396-402
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• 1992

Carbon solid was prepared from dormant mesophase pitch (DMPP) without using a binder and its properties were characterized. DMPP powder was stabilized with air or nitric acid in pretreatment stage so that it might not soften in later heat ttreatment stage. Optimum sintering properties were obtained from carbon powder with 2.36∼2.38 of C/H atomic ratio and 1.27∼1.40 of C/O atomic ration in air stabilization. In nitric acid stabilization, optimum sintering properties were obtained when 20∼40 vol.% of nitric acid solution was used. Compressive strength increased up to 1200$^{\circ}C$ of heat treatment temperature, and the highest compressive strength and bulk density of carbon solid from DMPP were 3000 kgf/㎤, respectively. The optical properties of carbon solid obtained was fine mosaic structure. Carbon solid after graphitization showed the properties of hard carbon due to stabilization and its shore hardness was 120.

• Preventive Nutrition and Food Science
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• v.8 no.3
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• pp.278-283
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• 2003

Textural properties of tofu manufactured with micronized full-fat soyflour (MFS) were enhanced by the addition of soy protein isolate, whey protein concentrate, chitosan oligosaccharide and mushroom powder. The MFS solution (14.2% solid content) was converted to semi-solid tofu by a two-stage heat treatment with the addition of 4% coagulant mix. The MFS tofu was evaluated by a compression test as well as sensory evaluation. To produce the semi-solid gel (MFS tofu) with reasonably high strength and toughness, the MFS solution with 14.2% solid content and 7.0% protein had to be heat treated at 121$^{\circ}C$ for 3min. The relative toughness of MFS tofu was increased by the addition of SPI, showing a 144% increase. The toughness of MFS tofu prepared with the MFS/SPI mixture was greatly increased by the addition of WPC at the level of 0.7% and the water separation from MFS tofu was greatly reduced. Furthermore, the toughness and strength of MFS/SPI tofu was enhanced by the addition of 0.1% chitosan oligosaccharide and 0.2% mushroom powder. The sensory evaluation of the tofu fortified with SPI, chitosan oligosaccharide and mushroom powder was superior to that of MFS tofu, with a higher score for overall preference.

• Clean Technology
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• v.16 no.1
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• pp.39-45
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• 2010

In this paper, 4 bundle modules of PVDF hollow fiber membrane from Woori Tech company (Korea) were manufactured in a treatment capacity of 10 ton/day. A membrane bioreactor (MBR) pilot plant was installed at Sooyoung Wastewater Treatment Plant in Busan. An alternating aeration process was selected to avoid the concentration profile of suspended solid (SS) in the MBR. For stable operation, raw wastewater with mixed liquor suspended solid (MLSS) of about 1,000 ppm, which was in-flowed from the aeration tank of the wastewater treatment plant, was fed and filtered through the pilot plant. Subsequently the pilot plant were washed three times with washing water: once with ethanol solution, once with a solution of 5% NaOCl, and finally with washing water. After the chemical washing, the remaining water in the MBR was fed into the pilot plant. As a result, the SS removal efficiency was found to be more than 99.9%. The amount of filtrate with the aeration tank influent decreased by 16%, compared with that from the initial conditions, giving rise to 30% increase in the suction pressure. These results were used to set up continuous operation conditions. The results from the continuous operation with influent MLSS of 1,900 mg/L showed that the SS removal efficiency was about 99.99% and that the amount of filtrate and the suction pressure were $42{\sim}52L/m^2$ and 16~20 cmHg, respectively, indicating stable operation of the pilot plant. However, for the reuse of wastewater, methods need to be sought to avoid growth of algae which affects the SS removal efficiency at inlet and outlet of the permeate tank.

• Proceedings of the KWS Conference
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• 2005.11a
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• pp.174-176
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• 2005

• Journal of Industrial Technology
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• v.21 no.B
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• pp.45-49
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• 2001

Many cities and provinces are rapidly depleting landfill spaces. As the result, some municities have adopted to incinerate their municipal solid waste(MSW). The motive behind the choice is that incineration significantly reduces the volume of solid waste in need of disposal, destroys the harmful organic compounds that are present in MSW, and provides an attractive source of alternative energy. Conclusively, the generation of MSW ash is expected to increse in the furture. However, disposing the MSW ash in landfills may not always be an environmentally or an economically feasible solution. This paper addresses the various issues associated with MSW ash and its possible use in construction applications.

• Textile Coloration and Finishing
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• v.29 no.3
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• pp.122-130
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• 2017

In the direct digital textile printing process, the pre-treatment process is an essential condition for products by forming a clear pattern by sticking and penetration of DTP dye without spreading on the fabric. Recently, pre-treatment agent is changing from high viscosity to low viscosity in order to reduce defects of fabric during pre-treatment process. In this study, pre-treatment agent of acrylic polymer with low viscosity(less than 50cps) was prepared according to the solid content of the polymer, pre-treated on the cotton fabric, and direct DTP printing was performed to compare the color and sharpness. As a result, it showed high color at a viscosity of 50cps or less. When the solid content of the polyacrylic acid having a high molecular weight(A1) was 2.5wt%, when the solid content of the polyacrylic acid having a low molecular weight(A2) was 1 - 1.5wt%, the color was the best. And when the solid content of A1 and A2 was 1.5wt%, the degree of spreading was small and A1 was superior to A2 at the sharpness.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.422-425
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• 1999

Ultrafine NiO/YSZ (Yttria-Stabilized Zirconic) composite powders were prepared by using a glycine nitrate process (GNP) for anode material of solid oxide fuel cells. The specific surface areas of synthesized NiO/YSZ composite powders were examined with controlling pH of a precursor solution and the content of glycine. The binding of glycine with metal ions occurring in the precursor solution was analyzed by using FTIR. The characteristics of synthesized composite powders were examined with X-ray diffractometer, a BET method with $N_2$ absorption, scanning and transmission electron microscopies. Strongly acid precursor solution increased the specific surface area of the synthesized composite powders. This is suggested to be caused by the increased binding of metal ions and glycine under a strong acid solution of pH=0.5 that lets glycine consist of mainly the amine group of NH$_3$$^{+}$ After sintering and reducing treatment of NiO/YSZ composite powders synthesized by GNP, the Ni/YSZ pellet showed ideal microstructure very fine Ni Particles of 3-5${\mu}{\textrm}{m}$ were distributed uniformly and fine pores around Ni metal particles were formed, thus, leading to an increase of the triple phase boundary among gas, Ni and YSZ.Z.