• Journal of the Korean Ceramic Society
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• v.42 no.12 s.283
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• pp.854-859
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• 2005

Performance of micro scale intermediate temperature solid oxide fuel cell system has been successfully evaluated by computer simulation based on macro modeling. Two systems were studied in this work. The one is designed that the ceria-based electrolyte placed between composite electrodes and the other is designed that electrodes alternately placed on the electrolyte. The injected gas was composed of hydrogen and air. The polarization curve was obtained through a series of calculations for ohmic loss, activation loss and concentration loss. The calculation of each loss was based on the solving of mathematical model of multi physical-phenomena such as ion conduction, fluid dynamics and diffusion and convection by Finite Element Method (FEM). The performance characteristics of SOFC were quantitatively investigated for various structural parameters such as distance between electrodes and thickness of electrolyte.

• Geomechanics and Engineering
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• v.34 no.3
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• pp.221-231
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• 2023

Biopolymer stabilization is a sustainable alternative to traditional techniques that cause a lesser negative impact on the environment during production and application. The study aims to minimize the biopolymer dosages by sizing the bio-additives to the nanoscale. This study combines the advantages of bio and nanomaterials in geotechnical engineering applications and attempts to investigate the behaviour of a low viscous biopolymer, nano sodium carboxymethyl cellulose (nCMC), to treat organic soil. Soil is treated with 0.25%, 0.50%, 0.75% and 1.00% of nano-bio additive, and its effect on the plastic behaviour, compaction characteristics, strength, hydraulic conductivity (HC) and compressible nature are investigated. The strength increased by 1.68 times after 90 days of curing at a dosage of 0.5% nCMC through the formation of gel threads connecting the soil particles that stiffened the matrix. The viscosity of 1% nCMC increased exponentially, deterring fluid flow through the voids and reduced the HC by 0.85 times after curing for 90 days. Also, beyond the optimum dosage of 0.50%, the nCMC forms a film around the soil particles that inhibits the inter-particle cohesion causing a reduction in strength. Experimental results show that nCMC can effectively substitute conventional additives to stabilize the soil.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.308-308
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• 2006

We have demonstrated that the cylindrical micelles self-assembled from coil-rod-coil molecules can be interconnected by addition of a small amount of rod-coil-rod molecule as a bridging agent. Subsequently, these dynamic interconnections lead to stiff bundles composed of cylindrical micelles that are responsible for the formation of a reversible nematic gel. The results described here represent a significant example that dynamic bridging of supramolecular cylinders in aqueous solution can provide a useful strategy to construct one-dimensional nematic structure with three dimensional elastic properties.

• Journal of the Korean Ceramic Society
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• v.55 no.2
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• pp.145-152
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• 2018

Although many bone graft materials have been developed, powder graft materials are somewhat difficult to use in surgery. To solve this problem, a bone graft material in the form of a viscous paste was prepared. Hydroxyapatite was used as a bone graft material, and methyl cellulose was used to impart viscosity. Three cases of samples were prepared, and freeze-dried block type and sintered specimens were made from the paste. The recrystallization of the graft material in a simulated body fluid and the degree of graft adhesion with a tooth were observed by scanning electron microscopy (SEM). The test for cytotoxicity was carried out and the sample was grafted into the back of a mouse to confirm the presence or absence of side effects in the animal's body. Based on these investigations, composites of this type are expected to be applicable for bone grafts.

• 한국전산유체공학회:학술대회논문집
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• 2008.03a
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• pp.14-17
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• 2008

Recently, several advanced flow visualization techniques such as Particle Image Velocimetry (PIV) including stereo PIV, holographic PIV, and dynamic PIV have been developed. These advanced techniques have strong potential as the experimental technology which can be used for verifying numerical simulation. In addition, there would be indispensable in solving complicated thermo-fluid flow problems not only in the industrial fields such as automotive, space, electronics, aero- and hydro-dynamics, steel, and information engineering, but also in the basic research fields of medical science, bio-medical engineering, environmental and energy engineering etc. Especially, NT Nano Technology) and BT (Bio Technology) strongly demand these advanced measurement techniques, because it is difficult for conventional methods to observe most complicated nano- and bio-fluidic phenomena. In this paper, the basic principle of these advanced visualization techniques and their practical applications which cannot be resolved by conventional methods, such as flow in automotive HVAC system, ship and propeller wake, three-dimensional flow measurement in micro-conduits, and flow around a circulating cylinder will be introduced.

• 한국전산유체공학회:학술대회논문집
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• 2008.10a
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• pp.14-17
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• 2008

Recently, several advanced flow visualization techniques such as Particle Image Velocimetry (PIV) including stereo PIV, holographic PIV, and dynamic PIV have been developed. These advanced techniques have strong potential as the experimental technology which can be used for verifying numerical simulation. In addition, there would be indispensable in solving complicated thermo-fluid flow problems not only in the industrial fields such as automotive, space, electronics, aero- and hydro-dynamics, steel, and information engineering, but also in the basic research fields of medical science, bio-medical engineering, environmental and energy engineering etc. Especially, NT (Nano Technology) and BT (Bio Technology) strongly demand these advanced measurement techniques, because it is difficult for conventional methods to observe most complicated nano- and bio-fluidic phenomena. In this paper, the basic principle of these advanced visualization techniques and their practical applications which cannot be resolved by conventional methods, such as flow in automotive HVAC system, ship and propeller wake, three-dimensional flow measurement in micro-conduits, and flow around a circulating cylinder will be introduced.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.228-232
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• 2003

It has recently been shown that the instability of thin film of a nanoscale can be used in the processes of building nano-size structures, which have potential practical importance in nanotechnology. Molecular dynamics simulation is conducted to probe the thin fluid film of a nano-size and its dynamic behavior during destabilization and structure formation. Non-continuum characteristics are shown in the properties like pressure tensor, viscosity, and thermal conductivity. The thermocapillary force induces a slow growth of long waves in the scale considered. A long-range interaction with the solid wall induces vertical structures, whose formation time and space between neighbors are proportional to the strength of the interaction.

• Advances in nano research
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• v.10 no.4
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• pp.349-357
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• 2021

In present study, the numerical investigations are carried out for effects of suction and blowing on boundary layer slip flow of casson nano fluid along permeable stretching cylinder in an exponential manner. The modeled PDEs are changed into nonlinear ODEs through appropriate nonlinear transformations. Change in physical quantities like friction coefficient, Nusselt and Sherwood numbers with variation of the aforementioned parameters are also examined and their numerical values are listed in the form of tables. Effects of Reynold number, suction parameter, Prandtl number, Lewis number, Brownian motion parameter and thermophoresis parameter are seen graphically with temperature profile.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.3
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• pp.997-1002
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• 2013

The article is aiming to investigate the thermal-fluidic characteristics of magnetic fluid in a cavity using GSMAC (generalized-simplified marker and cell method). The transport equations of the magnetic fluid are including the continuity equation, momentum equation and energy equation for natural convection and Maxwell equation and magnetization equation of magnetite nano-sized particles motion. In addition, the heat transfer characteristics such as temperatures and Nusselt numbers and flow characteristics such as streamlines and isotherms of the magnetic fluid were analyzed with the intensity and direction of the magnetic fields. As a result, the thermal-fluidic characteristics of the magnetic fluid in a cavity were could be controlled by the intensity and direction of the magnetic fields.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.37 no.1
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• pp.43-53
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• 2011

The conditions in fluid-bed processor for nanoencapsulation of azelaic acid-milk nano powder for acne nanocosmetics were optimized by response surface methodology (RSM). The maximum value of yield was 70.97 %. The yield was appreciably influenced by inlet air temperature, atomizing pressure, and feeding speed. The particle size increased with an increase in the feeding speed and a decrease in the atomizing pressure. The elution rate in saline solutions was appreciably influenced by inlet air temperature and atomizing pressure. The moisture content increased with higher atomizing pressure, which was demonstrated to be similar to the nanoencapsulation characteristics related to water activity. The Hunter's L and b values increased with an increase in the inlet air temperature. The optimum conditions estimated by RSM for the maximized values of yield, moisture content, particle size and elution rate in skin suitability were $67{\sim}73^{\circ}C$ of inlet air temperature, 0.6 ~ 0.8 mL/min feeding speed and 1.8 ~ 2.0 kg/$cm^2$ of atomizing pressure, respectively. These estimated values were in agreement with those measured by real experiments.