• Biomolecules & Therapeutics
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• v.15 no.2
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• pp.102-107
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• 2007

Cimetidine, a substrate for P-glycoprotein (P-gp), is a well known drug interacting with a variety of drugs and results in alteration of pharmacokinetic parameters by concomitant administration. The aim of present study was to investigate whether cimetidine affects the transport of various quinolone antibiotics in human colorectal cancer cell line (Caco-2) system which has been typically used to investigate drug transport via P-gp. The apparent permeability coefficients (P$_{app}$) value of 9 quinolone antibiotics in the co-treatment with cimetidine was examined. Apical to basolateral (AP-to-BL) transport of fleroxacin in the co-treatment with cimetidine was increased to 1.5-fold (p<0.01) compared with that of fleroxacin alone, whereas basolateral to apical (BL-to-AP) transport of fleroxacin was decreased to 0.83-fold significantly (p<0.05). Ofloxacin was decreased to 0.8-fold (p<0.01) and 0.72-fold (p<0.01) significantly in AP-to-BL and BL-to-AP direction, respectively by cimetidine cotreatment. The P$_{app}$ values of gatifloxacin, moxifloxacin, ciprofloxacin and rufloxacin also were changed by cimetidine. These results have a potential that cimetidine influences on the pharmacokinetics of quinolone antibiotics. It suggests that careful drug monitoring and dosage adjustment may be necessary during the co-administration of quinolone antibiotics with cimetidine.

• Nuclear Engineering and Technology
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• v.26 no.2
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• pp.285-293
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• 1994

The transport of radionuclides in a compacted bentonite is dominated by diffusion. Through-diffusion tests for iodide were performed to investigate the diffusion characteristics of anionic radionuclides in a domestic bentonite. The bentonite used was sampled from the southeastern area of Korea and the solution was synthetic groundwater spiked with a tracer of I -125(as Na$^{125}$ I). The dry densities of compacted bentonite were 1.2, 1.4, and 1.7 Mg/㎥. The apparent diffusion coefficients and the effective diffusion coefficients of the iodide decrease with increasing dry density. The values were from 3.80 to 7.12$\times$10$^{-11}$ $m^2$/s for the apparent diffusion coefficients and from 1.25 to 7.97$\times$10$^{-12}$ $m^2$/s for the effective diffusion coefficient, respectively. The experimental results also showed that the apparent diffusion coefficients depended on the pore structure of compacted bentonite and the effective diffusion coefficients were attributed to the pore structure and the effective porosity that represents the available pathway for the diffusional transport of iodide. The results obtained will be used as basic data for the safety assessment of a repository.

• The Journal of Asian Finance, Economics and Business
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• v.7 no.7
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• pp.209-217
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• 2020

Taxes are levied in almost every country, primarily to raise revenue for government expenditures. This study explores factors influencing tax compliance of small- and medium-sized enterprises (SMEs) in Vietnam. Data from 376 SMEs, who are business taxpayers, were collected through a researcher-administered questionnaire survey method. The results indicate that six groups of factors have significant impacts on tax compliance among Vietnamese SMEs. These groups include: Business characteristics (BC), Characteristics of accounting practices within organization (AP), Awareness of tax obligations (TO), Tax policy (TP), View on tax compliance (TC), and Probability of tax examination on taxpayer compliance (TE). Multivariate analysis was adopted; Cronbach's alpha coefficients were calculated, then, Exploratory Factor Analysis (EFA) was used. The findings show that, among these six factors, the most influential is Characteristics of accounting practices (AP). Thus, it is recommended that tax agencies should help SMEs improve their accounting skills and increase their knowledge by organizing training workshops and short courses on taxation. SMEs also need to have an adequate accounting system in accordance with principles and standards prescribed by the Tax Law. It is expected that this study can provide important insights and understandings to policy-makers, practitioners, academicians and other regulatory authorities in tax policy formulations.

• Proceedings of the KIEE Conference
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• 1996.07c
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• pp.1932-1934
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• 1996

Electron transport coefficients are calculated in nitrogen over the E/p range $50{\sim}700\;V\;cm^{-1}$ $Torr^{-1}$ by a Monte Carlo method, using a set of electron collision cross sections measured by authors.

• Korean Membrane Journal
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• v.7 no.1
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• pp.67-70
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• 2005

It is well known as the role of ion exchange membrane with functional group in membrane matrix. Recently, we were reported that the charged mosaic membrane within parallel array of negative and positive charge groups. In this study we are reported the properties for the various transport coefficients of metal and heavy metal ions across charged mosaic membrane based on non-equilibrium thermodynamics is not based on equilibrium state.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.05b
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• pp.1398-1402
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• 2005

Riverbank filtration is a natural process using alluvial aquifers to remove contaminants and pathogens in river water for the production of drinking water. In riverbank filtration, the understanding of contaminant transport is an important task for the production of high quality drinking water. This study investigates the transport behavior of hydrophobic organic contaminants when colloids (dissolved organic matter and bacteria) are present in the aquifer. A mathematical model for the transport of contaminants is developed and solved numerically for various situations. Results show that in the riverbank filtration the presence of DOM and bacteria enhances the mobility of contaminant significantly. Sensitivity analysis indicates that the distribution of the total aqueous Phase contaminant is significantly affected by distribution coefficients which account for affinity of solid or colloidal Phase to contaminant.

• Journal of Mechanical Science and Technology
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• v.16 no.9
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• pp.1175-1182
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• 2002

The commercial viability of heat exchanger is mainly dependent on its long-term fouling characteristic because the fouling increases the pressure loss and degrades the thermal performance of a heat exchanger. An experimental study was performed to investigate the characteristics of fluid flow and heat transfer in a fluidized bed heat exchanger with circulating various solid particles. The present work showed that the higher densities of particles had higher drag force coefficients, and the increases in heat transfer were in the order of sand, copper, steel, aluminum, and glass below Reynolds number of 5,000.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 1998.11a
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• pp.27-31
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• 1998

Most models for the simulation of multi-phase flow and multi-species transport employ the capillary approach which uses the Darcy's law for the representation of mass flux of each phase. The capillary approach based on the Darcy's law require many empirical coefficients with complex functional dependencies rather than rigrous mathematical and physical formulation. The shortcoming of the capillary approach cause the numerical errors in the simulations by the multi-phase flow and transport models. This study discuss some of the problems related with the use of models.

• Proceedings of the KIEE Conference
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• 1998.07e
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• pp.1752-1754
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• 1998

Recently the research about electron transport characteristic and energy distribute function in mixture gases within Helium, has been used and developed widely as industrial quality improvement of extinguish characteristic, electrical dielectric strength ability of application of each species high voltage apparatus, gas plasma etching progress of work to use manufacture of semiconductor, thin film molding by CVD, insulation film to use ultra LSI, etc. This paper analyze electron transport characteristic in the range E/N $1{\sim}60$[Td], pressure $0.1{\sim}6.0$[Torr] by MCS. It is necessary to seek electron drift velocity, diffusion coefficient, lonization coefficients, characteristic energy, mean energy and electron energy distribution function as electron transport characteristic.

• Bulletin of the Korean Chemical Society
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• v.34 no.10
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• pp.2931-2936
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• 2013

This paper presents results for the calculation of transport properties of noble gases (He, Ne, Ar, Kr, and Xe) at 273.15 K and 1.00 atm using equilibrium molecular dynamics (EMD) simulations through a Lennard-Jones (LJ) intermolecular potential. We have utilized the revised Green-Kubo formulas for the stress (SAC) and the heat-flux auto-correlation (HFAC) functions to estimate the viscosities (${\eta}$) and thermal conductivities (${\lambda}$) of noble gases. The original Green-Kubo formula was employed for diffusion coefficients (D). The results for transport properties (D, ${\eta}$, and ${\lambda}$) of noble gases at 273.15 and 1.00 atm obtained from our EMD simulations are in a good agreement with the rigorous results of the kinetic theory and the experimental data. The radial distribution functions, mean square displacements, and velocity auto-correlation functions of noble gases are remarkably different from those of liquid argon at 94.4 K and 1.374 $g/cm^3$.