• 한국고분자학회:학술대회논문집
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• 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
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• pp.219-219
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• 2006

This study focuses on the effects of dispersion method of a nanoparticle in a polymer matrix such as melt mixing, solution blending, and in-situ polymerization on the physical properties of the nanocomposites. Introduction of a nanoparticle to a polymer resulted in some unusual physical properties. In some cases the nanoparticle played a role of a nucleating agent, leading to decreasing induction time to crystallization. In addition, the dispersion state of the nanoparticle in the polymer matrix also had a significant influence on the physical properties of the nanocomposites. Hence the method of introducing the nanoparticle to the polymer made contribution to the rheological properties of the nanocomposite systems.

• 대한수학회지
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• 제44권3호
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• pp.627-645
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• 2007

We investigate the eigenvalues of the semi-circulant preconditioned matrix for the finite difference scheme corresponding to the second-order elliptic operator with the variable coefficients given by $L_vu\;:=-{\Delta}u+a(x,\;y)u_x+b(x,\;y)u_y+d(x,\;y)u$, where a and b are continuously differentiable functions and d is a positive bounded function. The semi-circulant preconditioning operator $L_cu$ is constructed by using the leading term of $L_vu$ plus the constant reaction term such that $L_cu\;:=-{\Delta}u+d_cu$. Using the field of values arguments, we show that the eigenvalues of the preconditioned matrix are clustered at some number. Some numerical evidences are also provided.

• Biomolecules & Therapeutics
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• 제23권5호
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• pp.428-433
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• 2015

Acetylshikonin, a natural naphthoquinone derivative compound, has been used for treatment of inflammation and cancer. In the present study, we have investigated whether acetylshikonin could regulate the NF-${\kappa}B$ signaling pathway, thereby leading to suppression of tumorigenesis. We observed that acetylshikonin significantly reduced proliferation of several cancer cell lines, including human pancreatic PANC-1 cancer cells. In addition, acetylshikonin inhibited phorbol 12-myristate 13-acetate (PMA) or tumor necrosis-${\alpha}$ (TNF-${\alpha}$)-induced NF-${\kappa}B$ reporter activity. Proteome cytokine array and real-time RT-PCR results illustrated that acetylshikonin inhibition of PMA-induced production of cytokines was mediated at the transcriptional level and it was associated with suppression of NF-${\kappa}B$ activity and matrix metalloprotenases. Finally, we observed that an exposure of acetylshikonin significantly inhibited the anchorage-independent growth of PANC-1 cells. Together, our results indicate that acetylshikonin could serve as a promising therapeutic agent for future treatment of pancreatic cancer.

• Food Science and Biotechnology
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• 제18권2호
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• pp.475-480
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• 2009

Ultraviolet B (UVB) radiation provokes the generation of reactive oxygen species (ROS) in the cells and skin, which induce oxidative stress in the exposed cells, leading to photoaging and cancer. Using the human keratinocytes HaCaT cell line, we investigated the photoprotective effects of aucubin isolated from Eucommia ulmoides. Pretreatment with aucubin markedly suppressed UVB-induced oxidative stress, which manifests as a decrease in intracellular lipid peroxidation, elevation of catalase activity, and reduced glutathione content. In addition, aucubin significantly reduced expression of matrix metalloproteinase-1 (MMP-1) protein (54%) and mRNA. Taken together, these results suggest that aucubin may offer protection against UVB-induced oxidative stress and may be used as a potential agent in prevention of UVB-induced photoaging.

• Applied Science and Convergence Technology
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• 제27권5호
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• pp.86-89
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• 2018

Observations of neutrino oscillations are very strong evidence for the existence of neutrino masses and mixing. From recent experimental results on neutrino oscillation, we find that neutrino mixing angles are quite consistent with the so-called tri-bi-maximal mixing pattern, but the deviation from observational results is non-negligible. However, the tri-bi-maximal mixing pattern is still useful as a leading order approximation and provides a good guideline to search for the flavor symmetry in the neutrino sector. We introduce the $S_4$ permutation symmetry as a flavor symmetry to the standard model of particle physics with additional particle contents of heavy right-handed neutrinos and scalar fields. Finally, we obtain the tri-bi-maximal mixing pattern as a mixing matrix in the lepton sector within the suggested model. To derive the required unitary mixing matrix for the neutrino sector, the double seesaw mechanism is utilized.

• 한국해양바이오학회지
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• 제10권2호
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• pp.83-90
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• 2018

Ultraviolet (UV) radiation causes inflammation and matrix metalloproteinase (MMP) over-expression and extra cellular matrix depletion, leading to skin photo-aging such as wrinkle formation, dryness, and sagging. In this study, we demonstrated that pretreatment with the hexane extract of microalgae protects UVB mediated cell damages. The results of clinical study showed that Microalgal Oil treated group reduced wrinkle and improve elasticity. All these results suggest Microalgal Oil may be useful as new photo-aging cosmetics for protection against UV induced activity.

• 대한약학회:학술대회논문집
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• 대한약학회 2002년도 Proceedings of the Convention of the Pharmaceutical Society of Korea Vol.2
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• pp.304.2-304.2
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• 2002

In central nervous system. matrix metalloproteinases (MMPs) are produced by neuron as well as glia and implicated in physiological events such as neurite outgrowth and myelination etc. In addition. MMPs also contribute to the pathogenesis of several CNS diseases such as multiple sclerosis, Alzheimer's disease and malignant glioma. In spite of their functional importance, little is known about the signal transduction pathways leading to the induction of MMPs in CNS. Here. we investigated whether the activation of Erk(1/2) is involved in the induction of MMP-9 in LPS-stimulated primary astrocytes. (omitted)

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2020년도 봄 학술논문 발표대회
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• pp.79-80
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• 2020

The class-C fly ash (FA) and ground granulated blast-furnace slag (GGBS) based geopolymer activated in NaOH (4M) was studied regarding compressive strength, porosity, microstructure and formation of crystalline phases. The class-C FA and GGBS blends resulted in reduced strength and increased porosity of the matrix with the increase in FA content. The unreactivity of calcium in blends was observed with increasing FA content leading to strength loss. it is evident from XRD patterns that calcium in FA did not contribute in forming CSH bond, but formation of crystalline calcite was observed. Furthermore, XRD analyses revealed that reduction in FA leads to the reduction in crystallinity and SEM micrographs showed the unreactive FA particles which hinder the formation of denser matrix.

• 한국생물물리학회:학술대회논문집
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• 한국생물물리학회 2001년도 학술 발표회 진행표 및 논문초록
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• pp.25-25
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• 2001

Diabetes is the leading cause of end-stage renal disease worldwide. In Korea, diabetic kidney disease accounted for 39％ of all new dialysis patients in 1998. Diabetic nephropathy is characterized by glomerular hyperfiltration, albuminuria, and expansion of glomerular mesangium. Since glomerular mesangial cells regulate glomerular filtration rates and are capable of producing extracellular matrix (ECM) proteins, the functional abnormalities of mesangial cells under diabetic milieu play an important role in the development and progression of diabetic nephropathy.(omitted)

• International Journal of Concrete Structures and Materials
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• 제18권2E호
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• pp.97-102
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• 2006

In this study, the effect of supplementary materials(GGBS, PFA, SF) on sulfuric acid corrosion resistance was assessed by measuring the compressive strength, corroded depth and weight change at 7, 28, 56, 91, 180 and 250 days of immersion in sulfuric acid solution with the pH of 0.5, 1.0, 2.0 and 3.0. Then, it was found that an increase in the duration of immersion and a decrease in the pH, as expected, resulted in a more severe corrosion irrespective of binders: increased corroded depth and weight change, and lowered the compressive strength. 60% GGBS mortar specimen was the most resistant to acid corrosion in terms of the corroded depth, weight change and compressive strength, due to the latent hydraulic characteristics and lower portion of calcium hydroxide. The order of resistance to acid was 60% GGBS>20% PFA>10% SF>OPC. In a microscopic examination, it was found that acid corrosion of cement matrix produced gypsum, as a result of decomposition of hydration products, which may loose the structure of cement matrix, thereby leading to a remarkable decrease of concrete properties.