• Journal of the Korean Ceramic Society
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• v.46 no.6
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• pp.548-553
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• 2009

This study is on the application of ceramic body and art glaze by using coal ash according to each wt%. Body color was turned red and dark as increasing coal ash contents in the body and art glaze because of the effect of noncombustible carbon in $Fe_2O_3$ and coal ash. Not only pore and black core were generated but also absorptance and shrinkage were increased as increasing coal ash contents. The glaze of coal ash 20 wt% showed blue absorption band, turned red band as increasing coal ash contents, $Al_2O_3\;to\;SiO_2$ ratio got lower and became mat because glaze is estranged from $Al_2O_3\;to\;SiO_2$ mol ratio 1:10 of transparent glaze as increasing coal ash contents. Glaze showed unstable dissolving condition in the more coal ash contents.

• Journal of Environmental Health Sciences
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• v.22 no.3
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• pp.17-27
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• 1996

The purpose of this study was to evaluate the decreasing effects of Korean garlic against the accumulation of mercury levels in maternal and fetal organs in pregnant Fischer 344 rats, based on the theory and information that neutral amino acids have protective effects against mercury poisoning and garlic contains a large of neutral amino acids. The results obtained are as follows: 1. On the 20th day of gestation, the maternal body weight in 20 mg/wt$\cdot$kg methyl mercuric chloride groups was 76.1% of those in control group, but those recovered to be 81.2% and 93.6% by treating with garlic (0.5 g/wt$\cdot$kg and 1.0 g/wt$\cdot$kg). 2. The mercury levels in maternal organs were reduced 6.2% and 47.2% (p<0.05) in kidney, 8.2% and 42.1% (p<0.05) in spleen, 9.7% and 40.9% (p<0.05) in blood, 35.6% (p<0.05) and 67.2% (p<0.05) in liver, 38.0% (p<0.05) and 57.6% (p<0.05) in brain, by treating with garlic (0.5 g/wt$\cdot$kg and 1.0 g/wt$\cdot$kg). 3. The mercury levels were reduced 22.4% and 44.3% (p<0.05) in placenta, and 34.7% (p<0.05) and 54.9% (p<0.05) in fetal body, by treating with garlic (0.5 g/wt$\cdot$kg and 1.0 g/wt$\cdot$kg). 4. The mercury levels in fetal organs were reduced 17.5% and 46.7% (p<0.05) in kidney, 15.1% and 37.0% (p<0.05) in brain, 30.2% (p<0.05) and 46.7% (p<0.05) in liver, by treating with garlic (0.5 g/wt$\cdot$kg and 1.0 g/wt$\cdot$kg). 5. Mercury levels in maternal kidney were 6.73~7.71 times higher than those in fetal kidney, but those in fetal liver and brain were 1.67~2.25 times and 1.98~2.93 times higher than those in maternal liver and brain, respectively. In conclusion, Korean garlic decrease the accumulation of mercury levels in maternal and fetal organs in pregnant Fischer 344 rats as increasing the dose.

• Korean Journal of Materials Research
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• v.25 no.5
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• pp.258-263
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• 2015

To fabricate porous SiC-Si composites for heating element applications, both SiC powders and Si powders were mixed and sintered together. The properties of the sintered SiC-Si body were investigated as a function of SiC particle size and/or Si particle contents from 10 wt% to 40 wt%, respectively. Porous SiC-Si composites were fabricated by Si bonded reaction at a sintering temperature of $1650^{\circ}C$ for 80 min. The microstructure and phase analysis of SiC-Si composites that depend on Si particle contents were characterized using scanning electron microscope and X-ray diffraction. The electrical resistivity of SiC-Si composites was also evaluated using a 4-point probe resistivity method. The electrical resistivity of the sintered SiC-Si body sharply decreased as the amount of Si addition increased. We found that the electrical resistivity of porous SiC-Si composites is closely related to the amount of Si added and at least 20 wt% Si are needed in order to apply the SiCSi composites to the heating element.

• Journal of Technologic Dentistry
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• v.40 no.3
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• pp.125-131
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• 2018

Purpose: Automatic dental prosthesis manufacturing process was accelerated by the spread of dental CAD / CAM system. The CAD / CAM system with milling alloys were needed supplement. So, sintered alloy blocks were introduced. In this study, we want to study sintered alloy block. And to evaluate the alloy block manufacture and alloy properties. Methods: The alloy powders were prepared by high pressure water dispersion method. The sintered alloy blocks were prepared by low temperature pressing method. Their components observation were EDX, and the alloy structure was observed by XRD. Results: Co-Cr alloy powders were observed to have a circle shape with an average diameter of about $100{\mu}m$ and a Ni-Cr alloy powder had a circle shape with an average diameter of about $50{\mu}m$. The Co-Cr alloy block is composed of Co (34.62 wt%), Cr (17.33 wt%), Mo (2.98 wt%), Si (0.36 wt%) and C (44.17 wt%). The Ni-Cr alloy powder was composed of Ni (40.29 wt%), Cr (19.37 wt%), Mo (3.53 wt%), Si (0.52 wt%) and C (33.18 wt%). The peak of the Co and CoCr peaks were observed in the CoCr alloy body by the means of XRD study. Cr2Ni3 of the peak was observed in the Ni-Cr alloy material. Conclusion : As a result, the following conclusions were obtained. 1. Prepared by high-pressure water-law Co-Cr alloy powder has an average diameter $100{\mu}m$, Ni-Cr alloy powder was found to have the form of sphere having an average diameter $50{\mu}m$. 2. Co-Cr alloy and Ni-Cr alloy block produced by low-temperature processing showed a certain ratio. 3. In the XRD study, Co phase appeared in Co-Cr alloy block after sintering. and Cr2Ni3 phase appeared in Ni-Cr alloy block after sintering.

• Journal of the Korean Ceramic Society
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• v.26 no.1
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• pp.67-72
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• 1989

In order to define the composition range of bone china body with use of calcium phosphate, kaolin, quartz and feldspar as raw materials, we varied calcium phosphate from 40 to 55wt/o and selected basic composition by the change of raw materials in ternary system. After these bodies were fired at 120$0^{\circ}C$, 123$0^{\circ}C$, 125$0^{\circ}C$ and 128$0^{\circ}C$ their properties were closely tested to determine the compositions and firing conditions of bone china body.

• Journal of the Korean Ceramic Society
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• v.37 no.5
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• pp.511-515
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• 2000

The effect of Ba2+ ion dissolution with different pH and amount of PAA on microstructural changes of green and sintered bodies and its electrical properties was studied in aqueous nano-size BaTiO3 slurry system. The dissolution of Ba2+ was least at strong base, pH 10.8 and by addition of amount of 0.15 wt% PAA. The green body with the lowest of dissolution of Ba2+ at pH 10.8 and 0.15 wt% PAA had minimum values of average pore size, 40nm and shown high increase of sintered density. The compact sintered at 125$0^{\circ}C$ for 2 hr with highest Ba2+ dissolution had low density and dielectric constant due to abnormal grian growth. However, the sintered body with the lowest Ba2+ dissolution had high sintered density and then shown high dielectric constant.

• Journal of Environmental Health Sciences
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• v.23 no.2
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• pp.83-88
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• 1997

To evaluate the effect of bromobenzene pretreatment on the bromobenzene metabolism, the animal group was induced the stage of slight liver damage with 7 times bromobenzene injection every two days (400 mg/kg body wt. i.p.). In the present experimental animal model, the single dose of bromobenzene(400 mg/kg body wt. i.p.) was injected to the bromobenzene-pretreated rats and the hepatic aniline hydroxylase(AH) activity, glutathione(GSH) content and glutathione S-transferase (GST) activity were determined at the intervals of 2, 4, 8, 24 hours throughout 24 hr. The activities of hepatic AH and GST were generally higher in bromobenzene-pretreated rats than those in normal group throughout the whole course of experiment. Furthermore, the decreasing rate of hepatic GSH content was also higher in bromobenzene pretreated rats than in normal rats. Moreover, the value of V$_{max}$ in hepatic GST was higher in bromobenzene pretreated rats than that in the normal rats. In conclusion, these results indicate that the pretreatment of bromobenzene may rather enhance the bromobenzene metabolism.

• Journal of the Korean Ceramic Society
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• v.32 no.4
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• pp.413-418
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• 1995

The (B.Si)C composite was prepared form the mixture of metal boron, silicon, and carbon powders in Ar atmosphere by Self-propagating High-temperature Synthesis Chemical Furnace. The characterization of synthesized power and sintered body were investigated. The microstructure of sintered body suggested that SiC boundary was made between B4C grains. The most excellent mechanical properties, the relative density of 95% oftheoretical value, 3 point flexural strength of 360MPa, and fracture toughness of 3.6MN/m3/2 could be obtained in 80wt% B4C-20 wt% SiC composite were obtained.

• Asian-Australasian Journal of Animal Sciences
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• v.17 no.1
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• pp.13-17
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• 2004

The aim of this study was to investigate genetic development and genotype${\times}$environment interactions (GEI) in postweaning body weight of fattening bulls at the end of test period (WT-T) under various beef fattening environments. Data on a total of 24,247 fattening bulls obtained from the industrial farm, breeding farms and testing stations were used. Heritability estimates for WT-T in all environments were nearly similar. Significant genetic developments of sire, dam and progenies for WT-T were observed in all environments. However, many differences in annual genetic developments between the environments were significant. The genetic correlations for WT-T between industrial farm and breeding farms, industrial farm and testing stations and breeding farms and testing stations were respectively 0.004, 0.004 and 0.013. These low estimates of genetic correlations and significant differences in genetic developments among environments clearly show the existence of GEI for WT-T among various fattening environments. Results of this study indicate the need for environment-specific genetic evaluation and selection of beef bulls for commercial beef production.

• Journal of the Korean Society for Heat Treatment
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• v.8 no.2
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• pp.149-154
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• 1995

The alloying of 6.5wt % Silicon in iron decreases the magnetization and the anisotropy and minimizes the iron loss noticeably. But it is very difficult to make thin sheets because of its poor ductility which is due to an ordering reaction (body centered cubic to CsCI type crystal structure). However the ordering reaction can be suppressed by rapid solidification method. The cooling rate of rapidly solidified Fe-6.5wt % Si alloy is about $10^3K/s$ and rapidly solidified structure are fine structure, cellular structure, dendrite and equiaxed grain from surface. The precipitates of $DO_3$ Phase emerges on $B_2$ matrix and the coercive force was 0.51 Oe (50cycle, 15KGauss) in Fe-6.5wt% Si alloy which was processed by heat treatment of $1150^{\circ}C$ for 1hr in high vacuum.