• Transactions of Materials Processing
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• v.7 no.5
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• pp.426-431
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• 1998

This study is concerned with cold repressing of sintered preforms by the rotary forging process. An experiment has been carried out using the rotary powder forging press(500kN) which was designed and constructed in the authors' laboratory. The effect of process variables and aspect ration of sintered preform on the densification behavior during the rotary repressing was studied by several mechanical test such as working force hardness distribution density and microstructures of the specimens. Since a higher densification can be achieved by applying the rotary repressing on presinted preforms it was successively demonstrated that the cold rotary powder forging is an effective operation to improve quality of P/M parts.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.1301-1302
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• 2006

Sintered composites of Al-8wt%Cu-10vol%SiCp were deformed by repressing or equal channel angular pressing(ECAP) at room temperature, $500^{\circ}C$ and $600^{\circ}C$. Repressing produced more densification than ECAP but resulted in much lower transverse rupture strengths. In both cases, deformation at room temperature and $500^{\circ}C$, resulted in much lower strengths than deformation at $600^{\circ}C$, and also caused the fracturing of some SiC particles. The higher bend strengths and less SiC fracturing at $600^{\circ}C$ are attributable to the presence of an Al-Cu liquid phase during deformation. The employment of copper coated SiC instead of bare SiC particles for preparing the composites was found not improving the properties.

• Journal of Powder Materials
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• v.11 no.2
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• pp.171-178
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• 2004

Effects of liquid phase and reinforcing particle morphology on the sintering of Al-6 wt％Cu-10 vol％ $Al_2O_3$ or SiC particles were studied in regards to densification, structure and transverse rupture properties. The Al-Cu liquid phase penetrated the boundaries between the aluminum matrix powders and the interfaces with reinforcing particles as well, indicating a good wettability to the powders. This enhanced the densification during sintering and the resulting strength and ductility. Since most of the copper added, however, was dissolved in the liquid phase and formed a brittle $CuAl_2$ phase upon cooling rather than alloyed with the aluminum matrix, the strengthening effect by the copper was not fully realized. Reinforcing particles of agglomerate type were found less suitable for the liquid phase sintering than solid type particles. $Al_2O_3$ and SiC particles protluced little difference on the sintering behavior but their size had a large effect. Repressing of the sintered composites increased density and bending properties but caused debonding at the matrix-particle interfaces and also fracturing of the particles.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 1993.11a
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• pp.6-6
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• 1993

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1997.03a
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• pp.281-286
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• 1997

Thin study is concerned with the cold repressing of sintered preform by rotary forging process. A experiment has been carried out using the rotary powder forging press(500kN) which was designed and constructed in the authors' laboratory. The effect of process variables and aspect ratios of sintered preform was observed and measured by several mechanical test, such as working force, hardness distribution, density, and microstructures of the specimens. It is found that the highly densified P/M parts can be obtained and this process is very effective for improving quality of the powder products.

• Journal of Ginseng Research
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• v.42 no.3
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• pp.288-297
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• 2018

Background: The incidence of colorectal cancer (CRC) is increasing, with metastasis of newly diagnosed CRC reported in a large proportion of patients. However, the effect of Korean Red Ginseng extracts (KRGE) on epithelial to mesenchymal transition (EMT) in CRC is unknown. Therefore, we examined the mechanisms by which KRGE regulates EMT of CRC in hypoxic conditions. Methods: Human CRC cell lines HT29 and HCT116 were incubated under hypoxic (1% oxygen) and normoxic (21% oxygen) conditions. Western blot analysis and real-time PCR were used to evaluate the expression of EMT markers in the presence of KRGE. Furthermore, we performed scratched wound healing, transwell migration, and invasion assays to monitor whether KRGE affects migratory and invasive abilities of CRC cells under hypoxic conditions. Results: KRGE-treated HT29 and HCT116 cells displayed attenuated vascular endothelial growth factor (VEGF) mRNA levels and hypoxia-inducible $factor-1{\alpha}$ ($HIF-1{\alpha}$) protein expression under hypoxic conditions. KRGE repressed Snail, Slug, and Twist mRNA expression and integrin ${\alpha}V{\beta}6$ protein levels. Furthermore, hypoxia-repressed E-cadherin was restored in KRGE-treated cells; KRGE blocked the invasion and migration of colon cancer cells by repressing $NF-{\kappa}B$ and ERK1/2 pathways in hypoxia. Conclusions: KRGE inhibits hypoxia-induced EMT by repressing $NF-{\kappa}B$ and ERK1/2 pathways in colon cancer cells.

• Journal of Microbiology and Biotechnology
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• v.22 no.6
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• pp.780-787
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• 2012

The maize pathogen Gibberella moniliformis produces fumonisins, a group of mycotoxins associated with several disorders in animals and humans, including cancer. The current focus of our research is to understand the regulatory mechanisms involved in fumonisin biosynthesis. In this study, we employed a proteomics approach to identify novel genes involved in the fumonisin biosynthesis under nitrogen stress. The combination of genome sequence, mutant strains, EST database, microarrays, and proteomics offers an opportunity to advance our understanding of this process. We investigated the response of the G. moniliformis proteome in limited nitrogen (N0, fumonisin-inducing) and excess nitrogen (N+, fumonisin-repressing) conditions by one- and two-dimensional electrophoresis. We selected 11 differentially expressed proteins, six from limited nitrogen conditions and five from excess nitrogen conditions, and determined the sequences by peptide mass fingerprinting and MS/MS spectrophotometry. Subsequently, we identified the EST sequences corresponding to the proteins and studied their expression profiles in different culture conditions. Through the comparative analysis of gene and protein expression data, we identified three candidate genes for functional analysis and our results provided valuable clues regarding the regulatory mechanisms of fumonisin biosynthesis.

• BMB Reports
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• v.30 no.1
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• pp.41-45
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• 1997

The present study was performed to analyze the molecular mechanism which dictates the transcription regulation of the $O^6$-methylguanine-DNA methyltransferase (MGMT) gene in Saccharomyces cerevisiae. Previously we identified one possible upstream repressing sequence (URS) in MGMT promoter by promoter deletion and competition analysis. In this paper we report another regulatory element (UAS: upstream activating sequence. -213 to -136) which affects the transcription activity of MGMT promoter. Gel mobility shift assay and Southwestern blot analysis using UAS probe showed several specific proteins which were able to bind to this sequence.

• Journal of Korean Society of Water and Wastewater
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• v.13 no.3
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• pp.36-41
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• 1999

High quality drinking water can be produced by membrane separation process. A major problem in the current system is a membrane fouling control. In order to investigate membrane fouling due to E.coll removal, lab scale experiment using MF and UF and semi pilot plant experiment using UV radiation or not was performed. AS a result, the possibility of membrane fouling control by repressing of micro-organism on the membrane surface was clearly verified. But it was not clearly verified in this experiment the combined effect with other factors such as Turbidity, organic and inorganic matters.

• Molecules and Cells
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• v.42 no.10
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• pp.687-692
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• 2019

Transfer RNA-derived small RNAs (tsRNAs) play a role in various cellular processes. Accumulating evidence has revealed that tsRNAs are deeply implicated in human diseases, such as various cancers and neurological disorders, suggesting that tsRNAs should be investigated to develop novel therapeutic intervention. tsRNAs provide more complexity to the physiological role of transfer RNAs by repressing or activating protein synthesis with distinct mechanisms. Here, we highlight the detailed mechanism of tsRNA-mediated dual regulation in protein synthesis and discuss the necessity of novel sequencing technology to learn more about tsRNAs.