• 전기화학회지
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• 제16권3호
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• pp.99-110
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• 2013

레독스 플로우 전지(RFB)는 대형에너지 장치로서 신재생 에너지와 같은 전력발생이 일정하지 못한 상황이나 전력수요가 급증감하여 효율적인 에너지의 운용이 요구될 때 효과적으로 사용할 수 있는 전지모델이다. 일부 상용화된 종류도 있지만 다양한 레독스 쌍과 소재가 연구됨에 따라 개선의 여지가 많은 전지이다. 본 총설에서는 전지의 레독스 쌍(redox pair)의 종류들에 대한 설명을 통하여 레독스 플로우 전지의 전반적인 이해를 돕고자 한다. 레독스 쌍의 혼합오염, crossover, 이온 선택성, 용해도 등의 개선을 통해서 새로운 레독스 플로우 전지의 탄생을 기대할 수 있다. 용량의 개선을 위해서 다양한 수계 및 비수계 레독스 쌍의 연구가 되고 있는데 crossover에 의해 다소의 용량손실이 있다고 하더라도 혼합오염이 없는 전지라면 레독스 플로우 전지의 내구성의 장점을 살릴 수 있을 것이라 기대한다. 혼합오염이 없는 레독스 플로우 전지 중에는 멤브레인이 필요 없는 전지도 새로운 연구방향으로 모색되고 있다.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.487-488
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• 2006

Novel bisphenol-based wholly aromatic poly(ether sulfone-ketone) copolymer containing pendant sulfonate groups were prepared by direct aromatic nucleophilic substitution polycondensation of 4,4-difluorobenzophenone, 2,2'-disodiumsulfonyl-4,4'-fluorophenylsulfone (40mole% of bisphenol A) and bisphenol A. Polymerization proceeded quantitatively to high molecular weight in N-methyl-2-pyrrolidinone at $180^{\circ}C$. Organic-inorganic composite membranes were obtained by mixing organic polymers with hydrophilic $SiO_2$ (ca. 20nm) obtained by sol-gel process. The polymer and a series of composite membranes were studied by FT-IR, $^1HNMR$, differential scanning calorimetry (DSC) and thermal stability. The proton conductivity as a function of temperature decreased as $SiO_2$ content increased, but methanol permeability decreased. The nano composite membranes were found to posse all requisite properties; Ion exchange capacity (1.2meq./g), glass transition temperatures $(164-183\;^{\circ}C)$, and low affinity towards methanol $(4.63-1.08{\times}10^{-7}\;cm^2/S)$.

• Journal of Microbiology and Biotechnology
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• 제13권2호
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• pp.276-281
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• 2003

The adhesion of probiotic bacteria to the intestinal mucosa is one of the desirable properties for their colonization in the intestinal tract, where these bacteria constantly compete with other bacteria. The adhesion of different strains of bifidobacteria to Caco-2 cells was compared. Among the strains examined, BGN-4 showed the highest adhesion level and the greatest cell surface hydrophobicity (CSH). No close relationship was found between the adhesion and CSH of the strains. Upon protease and heat treatment, the adhesion of the BGN-4 to the Caco-2 cells decreased significantly. The cells grown at $42^{\circ}C$ showed a lower CSH and self-aggregation levels than cells grown at $37^{\circ}C$. The treatment of EGTA did not have any effect on the adhesion. The degree of adhesion did not differ among the experimental groups in which galactose, mannose, or fucose were added in the adhesion assay mixture. The results suggest that the adhesion of the Bifidobacterium to the epithelial cells may be affected by the composition and structure of the cell membrane and interacting surfaces.

• International Journal of Aeronautical and Space Sciences
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• 제18권3호
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• pp.450-466
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• 2017

This paper defines the modified effective membrane stiffness, bending stiffness considering the directionally dependent mechanical properties and mode shape function of a composite lattice rectangular plate, which is assumed to be a Kirchhoff-Love plate. It subsequently presents an approximate method of conducting a buckling analysis of the composite lattice rectangular plate with various boundary conditions under uniform compression using the Ritz method. This method considers the coupled buckling mode as well as the global and local buckling modes. The validity of the present method is verified by comparing the results of the finite element analysis. In addition, this paper performs a parametric analysis to investigate the effects of the design parameters on the critical load and buckling mode shape of the composite lattice rectangular plate based on the present method. The results allow a database to be obtained on the buckling characteristics of composite lattice rectangular plates. Consequently, it is concluded that the present method which facilitates the calculation of the critical load and buckling mode shape according to the design parameters as well as the parametric analysis are very useful not only because of their structural design but also because of the buckling analysis of composite lattice structures.

• 한국농공학회지
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• 제27권2호
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• pp.38-46
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• 1985

The reinforced concrete farm silos on the elastic foundatin are widely used in agricultural engineering because of their superior structural performance, economy and attractive appearance. Various methods for the analysis and design of farm silo, such as the analytical method, the finite difference method, and the finite element methods, can be used. But the analytical procedure can not be applied for the intricate conditions in practice. Therefore lately the finite element method has been become in the structural mechanics. In this paper, a method of finite element analysis for the cylindrical farm silo on ffness matrix for the elastic foundation governed by winkler's assumption. A complete computer programs have been developed in this paper can be applicable not only to the shell structures on elastic foundation but also to the arbitrary three dimensional structures. Assuming the small deflection theory, the membrane and plate bending behaviours of flat plate element can be assumed mutually uncoupled. In this case, the element has 5 degrees of freedom per node when defined in the local coordinate system. However, when the element properties are transformed to the global coordinates for assembly, the 6th degree of freedom should be considered. A problem arises in this procedure the resultant stiffness in the 6th degree of freedom at this node will be zero. But this singularity of the stiffness matrix can be eliminated easily by merely replacing the zero diagonal by dummy stiffness.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 하계학술대회 논문집 Vol.6
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• pp.340-341
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• 2005

Three different composition 130um thickness PZT were fabricated by extrusion method and burned out at $550^{\circ}C$ and sintered at $1260^{\circ}C$/2.5hrs. Actuator was fabricated using glass and Si(100) wafer by MEMS process. From XRD data, in case of DECH, perovskite phase peak strength is higher than others. We were able to obtain the information of grain growth and porosity by SEM images. Also DECH PZT on glass membrane(100um thickness) have larger displacement than others.

• Biomolecules & Therapeutics
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• 제7권1호
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• pp.66-78
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• 1999

In order to investigate the pharmacological properties of New Wonbang Woohwangchungsimwon Liquid (NSCL), effects of Wonbang Woohwangchungsimwon Liquid (SCL) and NSCL were compared. In isolated rat aorta, NSCL and SCL showed the relaxation of blood vessels in maximum contractile response to phenylephrine (10$^{-6}$ M) regardless to intact endothelium or denuded rings of the rat aorta. Furthermore, the presences of the inhibitor of NO synthase and guanylate cyclase did not affect the relaxing effect of NSCL and SCL. NSCL and SCL inhibited the vascular contractions induced by acetylcholine, prostaglandin endoperoxide or peroxide in a dose-dependent manner. In conscious spontaneously hypertensive rats (SHRs), NSCL and SCL significantly decreased heart rate. NSCL and SCL, at high doses, had a negative inotropic effect that was a decrease of left ventricular developed pressure and (-dp/dt)/(+dp/dt) in the isolated perfused rat hearts, and also decreased the contractile force and heart rate in the isolated rat right atria. In excised guinea-pig papillary muscle, NSCL and SCL had no effects on parameters of action potential such as resting membrane potential, action potential amplitude, APD$_{90}$ and V$_{max}$ at low doses, whereas inhibited the cardiac contractility at high doses. These results suggested that NSCL and SCL have weak cardiovascular effects with relaxation of blood vessels and decrease of heart rate, and that this effect is no significant differences between cardiovascular effects of two preparations.s.

• Biomolecules & Therapeutics
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• 제23권4호
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• pp.301-312
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• 2015

Metastasis is one of hallmarks of cancer and a major cause of cancer death. Combatting metastasis is highly challenging. To overcome these difficulties, researchers have focused on physical properties of metastatic cancer cells. Metastatic cancer cells from patients are softer than benign cancer or normal cells. Changes of viscoelasticity of cancer cells are related to the keratin network. Unexpectedly, keratin network is dynamic and regulation of keratin network is important to the metastasis of cancer. Keratin is composed of heteropolymer of type I and II. Keratin connects from the plasma membrane to nucleus. Several proteins including kinases, and protein phosphatases bind to keratin intermediate filaments. Several endogenous compounds or toxic compounds induce phosphorylation and reorganization of keratin network in cancer cells, leading to increased migration. Continuous phosphorylation of keratin results in loss of keratin, which is one of the features of epithelial mesenchymal transition (EMT). Therefore, several proteins involved in phosphorylation and reorganization of keratin also have a role in EMT. It is likely that compounds controlling phosphorylation and reorganization of keratin are potential candidates for combating EMT and metastasis.

• 한국표면공학회지
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• 제46권5호
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• pp.192-196
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• 2013

Stainless steels (AISI 316L) are carburized by Inductively coupled plasma using $CH_4$ and Ar gas. The ${\gamma}_c$ phase(S-phase) is formed on the surface of stainless steel after carburizing process. The XRD peak of carburized samples is shifted to lower diffracting angle due to lattice expansion. Overall, the thickness of ${\gamma}_c$ phase showed a linear dependence with respect to increasing temperature due to the faster rate of diffusion of carbon. However, at temperatures above 500, the thickness data deviated from the linear trend. It is expected that the deviation was caused from atomic diffusion as well as other reactions that occurred at high temperatures. The interfacial contact resistance (ICR) and corrosion resistance are measured in a simulated proton exchange membrane fuel cell (PEMFC) environment. The ICR value of the carburized samples decreased from 130 $m{\Omega}cm^2$ (AISI 316L) to about 20 $m{\Omega}cm^2$. The sample carburized at 200 showed the best corrosion current density (6 ${\mu}Acm^{-2}$).

• Bulletin of the Korean Chemical Society
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• 제15권8호
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• pp.650-654
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• 1994

Stable polyion-complexed polymeric monolayers were prepared by spreading perfluoroalkyl monomaleate copolymers, $C_2F_8MA-VE_2$ and $C_2F_8MA-VE_3$, on a aqueous poly(allylamine) subphase. The monolayer properties have been studied by the surface pressure-area (${\pi}$-A) isotherms. The $C_2F_8MA-VE_3$ containing longer oligoethyleneglycol pendant showed more expanded monolayer phase than the $C_2F_8MA-VE_2$. The polyion-complexed monolayers were transferable on various substrates, and the resulting Langmuir-Blodgett (LB) films were characterized by FT-IR spectroscopy and scanning electron microscopy (SEM). Two-dimensional crosslinking to form a polymer network was achieved by amide formation through heat treatment under vacuum with concurrent removal of perfluoroalkyl tails. SEM observation of this film on a porous membrane filter showed that the four layer film was sufficiently stable to cover the filter pore size of 0.1 ${\mu}$m. The $C_2F_8MA-VE_3$ revealed better covering capability than the $C_2F_8MA-VE_2$. Immersion of this film in water or in benzene did not cause any change in its appearance and in Fl-IR spectra.