• Korean Journal of Crystallography
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• v.12 no.3
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• pp.166-170
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• 2001

Dopants implanted in silicon substrate affect the reaction between cobalt and silicon substrate. Phosphorous, unlike boron and arsenic, suppressing the reaction between cobalt and silicon induces CoSi formation during a low temperature thermal treatment instead of CoSi₂formation. The CoSi layer should move to the silicon substrate to fill the vacant volume that is generated in the silicon substrate due to the silicon out-diffusion into the cobalt/CoSi interface. The movement of CoSi at gate sidewall spacer region is suppressed by a cohesion between gate oxide and CoSi layers, resulting in a void formation at the gate sidewall spacer edge.

• Journal of Magnetics
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• v.14 no.4
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• pp.150-154
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• 2009

The effect of Ga and, Nb addition on the kinetics and mechanism of the disproportionation of a Nd-Fe-B alloy were investigated by isothermal thermopiezic analysis (TPA) using $Nd_{12.5}Fe_{(81.1-(x+y))}B_{6.4}Ga_xNb_y$ (x=0 and 0.3, y= 0 and 0.2) alloys. The addition of Ga and Nb retarded the disproportionation kinetics of the Nd-Fe-B alloy significantly, and increased the activation energy of the disproportionation reaction. The disproportionation kinetics of the $Nd_{12.5}Fe_{(81.1-(x+y))}B_{6.4}Ga_xNb_y$ alloys measured under an initial hydrogen pressure of 0.02 MPa were fitted to a parabolic rate law. This suggested that during the disproportionation of $Nd_{12.5}Fe_{(81.1-(x+y))}B_{6.4}Ga_xNb_y$ alloys with an initial hydrogen pressure of 0.02 MPa, a continuous disproportionation product is formed and the overall reaction rate is limited by the diffusion of hydrogen atoms (or ions).

• Nuclear Engineering and Technology
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• v.44 no.1
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• pp.79-88
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• 2012

Migration tests were performed with conservative tracers in a fractured zone that had a single fracture of about 2.5 m distance at the KURT. To interpret the migration of the tracers in the fractured rock, a solute transport model was developed. A two dimensional variable aperture channel model was adopted to describe the fractured path and hydrology, and a particle tracking method was used for solute transport. The simulation tried not only to develop a migration model of solutes for open flow environments but also to produce ideas for a better understanding of solute behaviours in indefinable fracture zones by comparing them to experimental results. The results of our simulations and experiments are described as elution and breakthrough curves, and are quantified by momentum analysis. The main retardation mechanism of nonsorbing tracers, including matrixdiffusion, was investigated.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1665-1668
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• 2008

Arrhythmia causes sudden cardiac death. In the past, there were medical limitations in finding the cause of arrhythmia. As an alternative solution for research of arrhythmia, there have been studies to find the causes of arrhythmia by producing a virtual heart model. Medically, arrhythmia has two main causes: abnormal occurrence of action potential and abnormal conduction of action potential. Based on these, the tachycardia, which is one of the arrhythmia, was manifested and the phenomenon of ventricular fibrillation was numerically analyzed in this study. For this purpose, an electrophysiological model of ventricular cells was implemented, which was subsequently applied to the reaction-diffusion partial differential equation to interpret the macroscopic conduction phenomenon in two-dimensional tissues. The ventricular fibrillation refers to a condition where several irregular waves occur in cardiac tissue, whose generation mechanism is pathologically related to the cardiac tissue.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1758-1760
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• 2008

Under typical operating conditions, flows in microfluidic devices are laminar and molecular diffusion across the channels is slow, which makes an efficient mixing in microfluidic devices difficult to achieve. The mechanism to achieve effective mixing in laminar flows is that of repetitive stretching and folding. Essential is to generate spatially periodic flows with crossing cross sectional streamlines. A mapping method is employed to analyze mixing in micromixers, enabling us to investigate the progress of mixing both qualitatively and quantitatively. The progress of mixing is characterized by a measure of mixing, called the discrete intensity of segregation. The mapping method is applied to mixing in such micromixers as the staggered herringbone mixer, the barrier embedded micromixer, and the three-dimensional serpentine channel to demonstrate the capability of the numerical scheme to tackle general mixing problems in microfluidic devices.

• Journal of Korean Neurosurgical Society
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• v.54 no.2
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• pp.139-141
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• 2013

Presented here is a 36-year-old male with arterial hypertension who developed brainstem edema and intracranial hemorrhage. Magnetic resonance scan revealed diffuse brainstem hyperintensity in T2-weighted and fluid-attenuated inversion-recovery images, with an increase in apparent diffusion coefficient values. After a reduction in blood pressure, rapid resolution of the brainstem edema was observed on follow-up. The patient's condition was thus interpreted as hypertensive brainstem encephalopathy. While many consider this a vasogenic phenomenon, induced by sudden, severe hypertension, the precise mechanism remains unclear. Prompt recognition and aggressive antihypertensive treatment in such patients are essential to prevent permanent or life-threatening neurologic injury.

• KSBB Journal
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• v.6 no.1
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• pp.79-83
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• 1991

Using PHB biopolymer as polymer matrix, the release mechanism of a model drug, silver sulfadiazine was studied. The release behavior actually conformed to the Higuchi's diffusion controlled model. The release rate was delayed with an increasing proportion of PHB, whereas decreased as glycerine concentration incresed. The release rate was increased as the polymer matrix thickness increased.

• Journal of Surface Science and Engineering
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• v.29 no.6
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• pp.720-723
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• 1996

The behavior of electrodeposition of amorphous nickel-phosphorus has been studied from the point of deposition mechanism, kinetic parameters, morphology and formation of alloy films. The electorode reaction and electrode kinetics of deposition of nickel were significantly influenced by the content of phosphorus. The cathodic deposition of nickel-phosphorus alloy might be governed by the diffusion process of phosphorous acid. The direction of growth layer of the nickel-phosphorus alloy was different with substrate material. The formation of nickel-phosphorus alloy films was affected considerably by the solution compositions, electrolytic conditions and properties of the material as an underlayer.

• Textile Coloration and Finishing
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• v.14 no.2
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• pp.85-85
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• 2002

The interaction between berberine and tannin in aqueous solution was investigated spectrophotometerically. The dyeing mechanism of silk fabrics (control and tannin treated silk fabrics) with berberine was based on thermodynamic parameters obtained from equilibrium adsorption experiments. In adsorption spectra of aqueous solution of berberine and tannin mixture two isosbestic points (328nm, 357nm) were found and the mole fraction of reaction of components was 1:1. Initial dyeing rates were increased and the diffusion of dye was more effective by tannin treatment. Without regard to tannin treatment the adsorption isotherm of berberine was the langmuir type except high temperature, 80℃. By tannin treatment the saturation dye uptake was increased, the increase of dye uptake appeared to be a result of entropy change rather than enthalpy change. All these results can be interpreted by the hydrophobic interaction between berberine and silk treated with tannin and it is reasonable to conclude that not only the ionic force, but also the hydrophobic interaction contributes to the binding of berberine and tannin treated silk treated with tannin.

• Textile Coloration and Finishing
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• v.14 no.2
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• pp.9-17
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• 2002

The interaction between berberine and tannin in aqueous solution was investigated spectrophotometerically. The dyeing mechanism of silk fabrics (control and tannin treated silk fabrics) with berberine was based on thermodynamic parameters obtained from equilibrium adsorption experiments. In adsorption spectra of aqueous solution of berberine and tannin mixture two isosbestic points (328nm, 357nm) were found and the mole fraction of reaction of components was 1:1. Initial dyeing rates were increased and the diffusion of dye was more effective by tannin treatment. Without regard to tannin treatment the adsorption isotherm of berberine was the langmuir type except high temperature, $80^\circ{C}$. By tannin treatment the saturation dye uptake was increased, the increase of dye uptake appeared to be a result of entropy change rather than enthalpy change. All these results can be interpreted by the hydrophobic interaction between berberine and silk treated with tannin and it is reasonable to conclude that not only the ionic force, but also the hydrophobic interaction contributes to the binding of berberine and tannin treated silk treated with tannin.