• Journal of Powder Materials
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• v.10 no.2
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• pp.108-117
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• 2003

WC and dense WC-10 vol%Co materials with grain size of~1${\mu}m$ were synthesized by high-frequency induction heated combustion synthesis (HFIHCS) method in one step from elemental powders of W, C and Co within several minutes. Simultaneous combustion synthesis and densification were accomplished under the combined effects of an induced current and mechanical pressure. In the absence of cobalt additive, WC can be formed, but its relative density was low (about 73%) under simultaneous application of a 60 MPa pressure and the induced current. However, in the presence of 10 vol.%Co, the relative density increased to 99% under the same experimental condition. The percentages of the total shrinkage occurring before and during the synthesis reaction of WC-10 vol.%Co were 5% and 51%, respectively. The fracture toughness and hardness values of WC-10 vol.%Co were 10 MPa . m$^{1/2}$ and 1840 kg/$mm^2$, respectively.

• Journal of the Korean Ceramic Society
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• v.33 no.11
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• pp.1285-1291
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• 1996

Using Cr2O3 Al and graphite powders as starting materials Cr3C2 was synthesized by combustion synthesis process according to the following reaction : 3Cr3C2 +4C+6Allongrightarrow2Cr3C2 +3Al2O3. The synthesis was conducted at 2 atm in an argon atmosphere. in this study main-product was monolithic phase of Cr3C2 /Cr7C3 mixture and sub-product was slag state of $\alpha$-Al2O3. Single phase of Cr3C2 was obtained when crushed main-product was heat-treated at 120$0^{\circ}C$ for 3h in vacuum state with addition of 2.5wt% C. The obtained Cr3C2 powder can be used as plasma-arc deposit material because the flowability index of powder with the size of 9-50${\mu}{\textrm}{m}$ was 66.

• Archives of Plastic Surgery
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• v.32 no.3
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• pp.363-368
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• 2005

It was assumed that the effect of estrogen on wound healing would be variable according to patient's gender and age since estrogen is a sex steroid. This study was designed to determine the variability of the effect of estrogen on proliferation of human dermal fibroblasts and collagen synthesis which are most important in wound healing considering patient's gender and age. Fibroblasts were isolated from the dermis of female patients in premenstrual, menstrual, or postmenopausal age group and that of male patients. The isolated fibroblasts were cultivated in the presence of estrogen($1.0{\mu}g/ml$). The cells were seeded at $5.0{\times}10^3cell/well$ in Dulbecco's Modified Eagle's Medium/Ham's F-12 nutrient including 5% fetal bovine serum in 96-well plates. The cells were incubated for 3 days. For fibroblast proliferation MTT assay method was used. To measure the production of collagen, the collagen type I carboxy- terminal propeptide enzyme immunoassay was carried out. Estrogen stimulated the proliferation of fibroblasts in female patients, but not in male patients. The greatest cell proliferation and collagen synthesis was seen at women in menstrual and postmenopausal age. These results demonstrated that effects of estrogen on dermal fibroblast proliferation and collagen synthesis were variable with gender and age.

• Bulletin of the Korean Chemical Society
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• v.35 no.8
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• pp.2326-2330
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• 2014

A carbazole-based Schiff base CB2 was synthesized and applied as a highly selective and sensitive fluorescent probe for $Cu^{2+}$ in $H_2O$-DMSO (8/2, v/v, pH = 7.4) solution. CB2 exhibits an excellent selectivity to $Cu^{2+}$ over other examined metal ions with a prominent fluorescence "turn-on" at 475 nm. CB2 and $Cu^{2+}$ forms a 1:2 binding ratio complex with detection limit of $9.5{\mu}M$. In addition, the $Cu^{2+}$ recognition process is hardly interfered by other examined metal ions.

• Journal of the Korean Chemical Society
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• v.44 no.2
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• pp.166-169
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• 2000

• Journal of the Korean Chemical Society
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• v.42 no.4
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• pp.13-482
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• 1998

• Journal of the Korean Ceramic Society
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• v.30 no.11
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• pp.979-985
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• 1993

Diamond films were synthesized using CH4-H2-Ar mixture gases by MWCVD, and cutting ability was tested after brazing them onto WC tools. Growth rates were in the range of 0.5~10${\mu}{\textrm}{m}$/hr depending on the deposition conditions, and diamond films with thickness of 100~300${\mu}{\textrm}{m}$ were obtained. Diamond tools brazed by RF induction method showed an enhanced cutting ability in the cutting test of Si single crystal rod.

• THE JOURNAL OF KOREAN ORIENTAL ONCOLOGY
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• v.7 no.1
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• pp.61-75
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• 2001

The purpose of this study is to prove the angiogenesis effects of WhaYoungJiTongTang (hereinafter referred to as the 'WYJTT'). For the study, by utilizing liver cancer cell line; SK-HEP-1, lung cancer cell line: A549, stomach cancer cell line: AGS and bovine capillary endothelial cell: BCE, the effects of the WYJTT on toxicity and proliferation ability of cells and the effects on anti-angiogenesis of bovine capillary endothelial cell and of mice's aorta were studied. 1. Cell viability assay In comparison with the control group, when $100{\mu}g/ml$ of WYJTT was injected, the viability was reduced in SK-Hep-1, $400{\mu}g/ml$ in A549 and $200{\mu}g/ml$ in AGS. 2. Cell proliferation assay In comparison with the control group, when $600{\mu}g/ml$ of WYITT was injected, DNA synthesis was reduced to 35.1% in the SK-Hep-1, 56.0% in A549, and 25.8% in BCE (bovine capillary endothelial cell); and when $400{\mu}g/ml$ was injected, DNA synthesis was reduced to 12.1 in AGS. 3. Tube formation assay In the event that BCE is injected with WYJTT in each of its content gradient, the anti-angiogenesis was effective in amounts of $400{\mu}g/ml$ with 6 hours of the treatment. 4. Aortic ring assay In comparison with the control group, the angiogenesis was restricted to the remarkable degree in amount of $200{\mu}g/ml$: 10% in $400{\mu}g/ml$; and fully inhibited in each of $800{\mu}g/ml$ and $1600{\mu}g/ml$. As a result of the experiments mentioned above, WYJTT showed its anti-angiogenesis effects against cancer cell line.

• Molecules and Cells
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• v.24 no.1
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• pp.69-75
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• 2007

Alzheimer's disease is a neurodegenerative disorder associated with progressive loss of cognitive function and memory. Amyloid beta peptide ($A{\beta}$) is the major component of senile plaques and is known to exert its cytotoxic effect mainly by producing $H_2O_2$. Vascular endothelial growth factor (VEGF) is elevated in the cerebrospinal fluid (CSF) and brain of AD patients, and $H_2O_2$ is one of the factors that induce VEGF. Therefore, we tested whether $A{\beta}$ might be responsible for the increased VEGF synthesis. We found that $A{\beta}$ induced the production of $H_2O_2$ in vitro. Comparison of the amount of $H_2O_2$ required to induce VEGF synthesis in HN33 cells and the amount of $H_2O_2$ produced by $10{\mu}M\;A{\beta}_{1-42}$ in vitro suggested that a toxic concentration of $A{\beta}$ might induce VEGF synthesis in these cells. However, toxic concentrations of $A{\beta}$ failed to induce VEGF synthesis in several cell systems. They also had no effect on antioxidant enzymes such as glutathione peroxidase, catalase, and peroxiredoxin in HN33 cells. $Cu^{2+}$, $Zn^{2+}$ and $Fe^{3+}$ are known to accumulate in the brains of AD patients and promote aggregation of $A{\beta}$, and $Cu^{2+}$ by itself induces synthesis of VEGF. However, there was no synergistic effect between $Cu^{2+}$ and $A{\beta}_{1-42}$ in the induction of VEGF synthesis and $Zn^{2+}$ and $Fe^{3+}$ also had no effect on the synthesis of VEGF, alone or in combination with $A{\beta}$.

• Journal of the Korean Ceramic Society
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• v.44 no.3 s.298
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• pp.152-156
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• 2007

Tungsten carbide powder was synthesized by SHS (self-propagating high-temperature synthesis). Except $WO_{3}$, each concentration of raw material ($WO_{3},\;Mg,\;NaCl,\;Na_{2}CO_{3},\;C$) was investigated. Final product was characterized by XRD and SEM. X-ray data demonstrated that the $NaCl+Na_{2}CO_{3}$ combined mixture has superiority in the WC formation process. Single phase and submicrometer WC powder was synthesized at the temperature below $1600^{\circ}C$. The role of sodium salts in combustion process was discussed, and chemical mechanism of WC formation was proposed. WC powder prepared by salt-assisted combustion synthesis has a size $0.2{\sim}3\;{\mu}m$ and low agglomeration degree.