• Journal of the Korean Ceramic Society
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• v.40 no.11
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• pp.1120-1126
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• 2003

Yttrium Aluminum Garnet (YAG) powders were prepared by precipitation of Y hydroxides during milling of alumina powders. The powder calcined at 1200$^{\circ}C$ for 4 h contained a small amount of Yttrium Aluminum Monoclinic (YAM) in addition to YAG. However, phase-pure YAG was obtained in the compact of the milled powder with an average particle size of 0.57 ${\mu}$m at 1300$^{\circ}C$, which is much lower than those (l500∼1600$^{\circ}C$) for a mixed oxide method. The powder was found to exhibit an excellent sinterability regardless of the addition of a sintering aid, SiO$_2$(350 ppm Si). The undoped sample were sintered to a relative density of 98% at l600$^{\circ}C$. In contrast, the addition of SiO$_2$ caused a considerable densification to occur at 1500$^{\circ}C$ and the relative density reached 97.7%. But the sintering aid had little effect on the densification at 1600$^{\circ}C$, showing a similar relative density to the undoped sample.

• Journal of the Korean Ceramic Society
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• v.39 no.4
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• pp.420-426
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• 2002

$ZrO_2$, $Y_2O_3$-doped $ZrO_2$ and CaO-doped $ZrO_2$ powders were prepared by hydrothermal crystallizing spherical $ZrO_2$ gel which had been synthesized by thermal hydrolysis reaction. After the hydrothermal crystallization process, the formed crystallized powders sustained its original spherical shape and had the mean particle size of $0.4{\mu}m$. The particles were composed of about 10nm sized primary particles. The agglomeration strength between the primary particles appears very weak considering that the spherical particles were broken into the primary particles during the pressing process. The particle shape, size, phase fraction and dopant content were analyzed and crystallization mechanism of spherical gel was discussed.

• Journal of the Korean Ceramic Society
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• v.49 no.6
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• pp.608-613
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• 2012

We investigated the property changes of MgO powders sintered at temperatures ranging from $700^{\circ}C$ to $1900^{\circ}C$ for 5minutes at a pressure of 2.7 GPa for a high-pressure high-temperature(HPHT) diamond synthesis process. The physical properties of the sintered MgO powders were characterized by optical microscopy, field emission scanning electron microscopy (FE-SEM), Vickers hardness tests, and by the apparent density, and X-ray diffractometry. An optical micro-analysis showed that white MgO powders became black after sintering due to carbon contamination from the graphite heat source. FE-SEM revealed the growth in the grain size of the MgO powders from $0.3{\mu}m$ to $50{\mu}m$ after sintering at $1700^{\circ}C$. The hardness and apparent density increased to $1800^{\circ}C$ while the samples were dedensified at $1900^{\circ}C$ due to the growth of isolated pores. According to the XRD analysis, no phase transformation occurred in the MgO powders. These results suggest that HPHT-sintered MgO powders can show an accelerated sintering process characterized by grain neck growth, pore connections, isolated pore growth and dedensification in 5 minutes, while these processes with the conventional sintering process take at least 5 hours.

• The Korean Journal of Mycology
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• v.38 no.2
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• pp.167-171
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• 2010

The present study aims to evaluate Cordyceps militaris water extract (CMWE) with a view to develop melanogenesis inhibitors. Inhibitory activities of CMWE against tyrosinase, L-DOPA(L-3,4-dihydroxyphenylalanine) oxidation, and melanin biosynthesis in B16 mouse melanoma cells were investigated. CMWE, at $5000\;{\mu}g/ml$, inhibited tyrosinase activity of 71% and DOPA oxidation of 40% as reacting with L-DOPA. Furthermore, B16 mouse melanoma cell survived over 50% from low to high dose on MTT assay, and CMWE markedly inhibited (> 50%) melanin synthesis at $5000\;{\mu}g/ml$. The inhibitory effect of CMWE on melanogenesis was attributed to enhancement of tyrosinase degradation. Key enzyme of melanin biosynthesis is tyrosinase which catalyses a beginning step from tyrosine to DOPA quinine and melanin formation step, respectively. These results indicated that CMWE may be a potential source of novel whitening agents for cosmetic or therapeutic application.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.101-101
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• 2010

ZnO shows a direct band gap of 3.37eV, large exciton binding energy (~60 meV), high oxidation ability, high sensitivity to many gases, and low cost, and it has been used in various applications such as transparent electrodes, light emitting diodes (LEDs), gas sensors and photocatalysts. Among these applications ZnO as photocatalyst has considerably attracted attention over the past few years because of its high activities in removing organic contaminants generated from industrial activities. In this research, ZnO nanoparticles were synthesized by spray-pyrolysis method using the zinc acetate dihydrate as starting material at synthesis temperature of $900^{\circ}C$ with concentration varied from 0.01 to 1.0M. The physical and chemical properties of the synthesized ZnO nanoparticles were examined by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Fourier Transformation Infrared (FT-IR), and UV-vis spectroscopy. The Miller indices of XRD patterns indicate that the synthesized ZnO nanoparticles showed a hexagonal wurtzite structure. With increased precursor concentration, a primary, secondary particle sizes of ZnO nanoparticles increased by 0.8 to $1.5{\mu}m$ and 15 to 35nm, and their crystallinity was improved. Methyleneblue (MB) solution ($1{\mu}M$) as a test comtaminant was prepared for evaluating the photocatalytic activities of ZnO nanoparticles synthesized in different precursor concentration. The results show that the photocatalytic efficiency of ZnO nanoparticles was gradually enhanced by increased precursor concentration.

• Korean Journal of Acupuncture
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• v.22 no.1
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• pp.85-93
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• 2005

목적 : 본 연구는 봉독 약침액이 BV2 microglial cell에서 LPS로 유발된 염증반응에 대한 억제효과를 관찰하고자 하였다. 방법 : 봉독 약침액의 항염증작용을 관찰하기 위하여 BV2 microglial cell에 봉독약침액을 1시간전에 농도별$(0.1,\;1,\;100\;{\mu}g/ml)$로 전처치한 후 LPS $(5\;{\mu}g/ml)$로 24시간 동안 처리하여 RT-PCR, western blot, $PGE_2$, assay, NO synthesis assay등의 방법으로 관찰하였다. 결과 : LPS 염증유발에 의해서 BV2 microglial cell에서 COX-2 및 NOS 발현이 증가하였고, 이 러한 증가는 prostaglandin E2 및 NO 합성을 증가시켰다. 이에 반하여 봉독약침액으로 전처치한 군에서는 COX-2 및 NOS 발현을 억제시켜 결과적으로 prostaglandin 합성 및 NO 합성을 억제시킴을 확인할 수 있었다. 또한 LPS 염증유발에 의해서 활성화된 NF-kB의 발현을 억제 시켰다. 결론 : 봉독약침 액은 LPS 염증유발에 의해서 증가된 prostaglandin E2 및 NO 합성을 억제시킴으로써 여러 가지 염종질환의 치료에 유효한 효과가 있을 것으로 사려 된다.

• Applied Chemistry for Engineering
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• v.9 no.5
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• pp.615-618
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• 1998

The zeolite crystals were synthesized by hydrogel process into the pore of activated carbon. The effect of activated carbon in the course of the crystallization of zeolite was investigated. The phenomena of impregnation of zeolite crystals into the pore of the activated carbon were also examined. The results show that in case of the addition of 5% of activated carbon to the aluminosilicate gel including the mole composition of zeolite A, zeolite A was purely synthesized without the existence of other type of zeolite. However, in case of the addition of 20% of activated carbon, zeolite X was purely synthesized. In the pore mouth and internal of activated carbon, zeolite crystals having the size under $1{\mu}m$ was observed. From the results of the pore size and particle size distributions, it was confirmed that the synthetic sample was the composite material impregnated by the zeolite crystals into the pore of activated carbon, not the simple mixture of zeolite and activated carbon.

• The Journal of Korean Obstetrics and Gynecology
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• v.25 no.1
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• pp.1-10
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• 2012

Purpose: This study was conducted to evaluate the inhibitory effect of Achyranthis Radix extract(ARE) loaded hydrogel on osteoclast differentiation. Methods: MTT-assay was performed to estimate cytotoxicity of ARE, Achyranthis Radix-alginate hydrogel disk(ARHD) in bone marrow macrophages stimulated(BMMs) with human receptor activator of nuclear factor-${\kappa}B$ ligand(RANKL), human macrophage-colony stimulating factor(M-CSF). Tartrate resistant acid phosphatase staining and RT-PCR were performed to know the inhibitory effect on osteoclast differentiation. Reactive oxygen species and actin ring formation were analysed to observe the effect of ARHD. Results: ARE has no cytotoxicity at the concentration of 0.1 $mg/m{\ell}$ or lower. ARE decreased the number of TRAP positive cells in RANKL, M-CSF stimulated BMMs and the gene expression. ARHD has no cytotoxicity at the concentration of 10 ${\mu}g/m{\ell}$ (24, 48hours), 50 ${\mu}g/m{\ell}$ (24 hours). ARHD restrained the synthesis of reactive oxygen species and the formation of actin ring. Conclusions: Achyranthis Radix has the inhibitory effect of osteoclast differentiation and bone resorption. Further studies are needed to treat osteoporosis by Achyranthis Radix.

• The Korea Journal of Herbology
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• v.29 no.1
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• pp.7-12
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• 2014

Objectives : Polygoni Multiflori Radix (PMR), the roots of Polygonum multiflorum Thunberg, is used to nourish the blood and yin and used for preventing premature greying of the hair. There are some articles on its preventing effects on the melanogenesis. However, there is no report about its effects on the collagen and elastin. The present study was designed to investigate its effects on collagen metabolism and elastase activity. Methods : The effects of PMR on type I procollagen production and collagenase activity in human normal fibroblasts Hs68 after UVB (312 nm) irradiation were measured by ELISA method. Cells were pretreated with the PMR for 24 hours prior to UVB irradiation. After UVB irradiation, cells were retreated with the sample and incubated for additional 24 hours. The amount of collagen type I was measured with a procollagen type I C-peptide assay kit. The activity of collagenase was measured with a MMP-1 human biotrak ELISA system. The elastase activities after treatment of PMR were measured as well. Results : In the present study, the collagen production was not increased. However, the increased collagenase activity after UVB damage was significantly recovered to $50.2{\pm}14.5%$, $8.2{\pm}3.1%$, and $10.0{\pm}3.3%$ (10, 30, and $100{\mu}g/ml$). The elastase activities (10, 100, and $1000{\mu}g/ml$) significantly reduced to $75.2{\pm}5.2%$, $40.3{\pm}1.2%$, and $27.0{\pm}1.9%$, respectively. Conclusion : PMR showed the inhibitory effects on collagenase and elastase activity. These results suggest that PMR may have potential as an anti-aging ingredient in cosmetic herbal treatment.

• The Korean Journal of Physiology
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• v.8 no.2
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• pp.75-78
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• 1974

It was planned to investigate, by observing incorporation of $[^3H]$ thymidine into liver cells, the influence of Panax Ginseng upon hepatic DNA synthesis in mice that received ACTH. Thirty male mice $(body\;weight:\;18{\sim}20\;g)$ were divided equally into the ginseng-ACTH and the saline-ACTH groups. Each animal of the ginseng-ACTH and the saline-ACTH groups received every day (subcutaneously) 0.05 m1/10 g body weight of ginseng extract (4 mg of ginseng alcohol extract in 1 ml of saline) and the same amount of saline, respectively, for 5 days. On the 5th experimental day, all animals received 0.01 unit of ACTH intraperitoneally one hour. after the last medication, and $1{\mu}Ci/g$ body weight of $[^3H]$ thymidine after one more hour. Five animals, at a time, of each group were sacrificed 1, 10, and 24 hours after thymidine administration, and their hepatic radioactivity was measured autoradiographically in terms of the % number of radioactive cells in 1,000 cell counts (Radioactive Index, R.1.). Following results were obtained: 1. The hepatic radioactive indices obtained from the saline-ACTH group 1, 10, and 24 hr after $[^3H]$ thymidine administration were $1.50{\pm}0.32,\;2.16{\pm}0.33\;and\;2.79{\pm}0.31\;(mean{\pm}S.D.)$, respectively. 2. The corresponding values obtained from the ginseng-ACTH group $(2.71{\pm}0.22,\;3.85{\pm}0.29,\;and\;5.06{\pm}0.31)$ were significantly higher than the values of the saline-ACTH group. It is inferred from the above results that the ginseng tends to prevent reduction in hepatic DNA synthesis caused by ACTH administration.