• Membrane and Water Treatment
• /
• v.2 no.3
• /
• pp.159-173
• /
• 2011

The air gap membrane distillation (AGMD) process was applied for water desalination. The main objective of the present work was to study the heat and mass transfer mechanism of the process. The experiments were performed on a flat sheet module using aqueous NaCl solutions as a feed. The membrane employed was hydrophobic PTFE of pore size 0.22 ${\mu}m$. A mathematical model is proposed to evaluate the membrane mass transfer coefficient, thermal boundary layers' heat transfer coefficients, membrane / liquid interface temperatures and the temperature polarization coefficients. The mass transfer model was validated by the experimentally and fitted well with the combined Knudsen and molecular diffusion mechanism. The mass transfer coefficient increased with an increase in feed bulk temperature. The experimental parameters such as, feed temperature, 313 to 333 K, feed velocity, 0.8 to 1.8 m/s (turbulent flow region) were analyzed. The permeation fluxes increased with feed temperature and velocity. The effect of feed bulk temperature on the boundary layers' heat transfer coefficients was shown and fairly discussed. The temperature polarization coefficient increased with feed velocity and decreased with temperature. The values obtained were 0.56 to 0.82, indicating the effective heat transfer of the system. The fouling was observed during the 90 h experimental run in the application of natural ground water and seawater. The time dependent fouling resistance can be added in the total transport resistance.

• THE INTERNATIONAL COMMERCE & LAW REVIEW
• /
• v.60
• /
• pp.213-234
• /
• 2013

e-Trade 3.0 era which means the expansion of seamless e-Trade process into global business has been come. e-Trade is in the evolution stage with the reflection of time changes and IT development. Furthermore e-Trade marketing method of SMEs has been generalized. However, SMEs have not utilized e-Trade marketing very actively even if it has much benefits in exploring overseas marketing. In this regard this paper has cautiously suggested the strategic using plan of e-Marketplace and SNS along with policy improvement in order to promote extensive diffusion of e-Trade marketing. First of all, a comprehensive evaluation system has to be developed for the assessment of overseas marketing program and provide organized guideline including SMEs support system. Also e-Marketplace operation company is necessary to invent management system for supervising and detecting risk factors of participating firms and business model to share information which each e-Marketplace possesses through mutual connection. Finally, the effective supports such as short-term education and acting operation of initial account to use SNS strategically are needed and continuous contents development to adopt SNS is absolute.

• Journal of The Korean Society of Integrative Medicine
• /
• v.6 no.3
• /
• pp.131-139
• /
• 2018

Purpose : The study objective was to assess the antibacterial activity of essential oil of basil against S. mutans and P. gingivalis and to explore its potential to prevent dental caries and peridontal disease. Method : Essential oil of basil, extracted using steam distillation, was diluted with triple distilled water and Tween 20 to generate samples at various concentration, that is 30%, 50%, and 70% (v/v). Strains of S. mutans and P. gingivalis were incubated in the medium under anaerobic condition. Broth microdilution susceptibility testing and plate incubation diffusion were utilized to determine the minimum inhibitory concentration (MIC) and to measure antibacterial activity, respectively. Result : An upsurge in antibacterial activity was seen to correlate with and increase in the concentration used for both bacterial strains, but was more significant with S. mutans. A statistically significant growth inhibition effect and reduction in the number of colonies was also observed with both strains dependent on the concentration used following 24 hours of incubation. Conclusion : Thus, the current study finding was that essential oil of basil was effective against dental caries and periodontal disease and could be used in dentifrice to help prevent oral disease.

• Journal of The Korean Astronomical Society
• /
• v.35 no.1
• /
• pp.41-57
• /
• 2002

We have written a code called QDM_sca, which numerically solves the problem of radiative transfer in an anisotropically scattering, spherical atmosphere. First we formulate the problem as a second order differential equation of a quasi-diffusion type. We then apply a three-point finite differencing to the resulting differential equation and transform it to a tri-diagonal system of simultaneous linear equations. After boundary conditions are implemented in the tri-diagonal system, the QDM_sca radiative code fixes the field of specific intensity at every point in the atmosphere. As an application example, we used the code to calculate the brightness of atmospheric diffuse light(ADL) as a function of zenith distance, which plays a pivotal role in reducing the zodiacal light brightness from night sky observations. On the basis of this ADL calculation, frequent uses of effective extinction optical depth have been fully justified in correcting the atmospheric extinction for such extended sources as zodiacal light, integrated starlight and diffuse galactic light. The code will be available on request.

• Journal of Powder Materials
• /
• v.16 no.5
• /
• pp.305-309
• /
• 2009

The effect of light scattering layers (400 nm, TiO$_2$ particle) of 4 $\mu$m thickness on the dye-sensitized solar cell has been investigated with a 12 $\mu$m thickness of photo-anode (20 nm, TiO$_2$ particle). Two different structures of scattering layers (separated and back) were applied to investigate the light transmitting behaviors and solar cell properties. The light transmittance and cell efficiency significantly improved with inserting scattering layers. The back scattering layer structure had more effective transmitting behavior, but separated scattering layer (center: 2 $\mu$m, back: 2 $\mu$m) structure (9.83% of efficiency) showing higher efficiency (0.6%), short circuit current density (0.26 mA/cm$^2$) and fill factor (0.02). The inserting separating two scattering layers improved the light harvesting, and relatively thin back scattering layer (2 $\mu$m of thickness) minimized interruption of ion diffusion in liquid electrolyte.

• Journal of Ocean Engineering and Technology
• /
• v.21 no.4
• /
• pp.8-14
• /
• 2007

A particle method recognized as one of gridless methods has been developed to investigate incompressible viscous flaw. The method is more feasible and effective than conventional grid methods for solving the flaw field with complicated boundary shapes or multiple bodies. The method is consists of particle interaction models representing pressure gradient, diffusion, incompressibility and the boundary conditions. In the present study, the models in case of various simulation condition were checked with the analytic solution, and applied to the two-dimensional Poiseuille flow in order to validate the developed method.

• Biotechnology and Bioprocess Engineering:BBE
• /
• v.10 no.5
• /
• pp.432-443
• /
• 2005

Microarray technology has contributed Significantly to the understanding of bacterial genetics and transcriptional regulation. One neglected aspect of this technology has been optimization of microarray-generated signals and quality of generated information. Full genome microarrays were developed for Clostridium acetobutylicum through spotting of PCR products that were designed with minimal homology with all other genes within the genome. Using statistical analyses it is demonstrated that Signal quality is significantly improved by increasing the hybridization volume. possibly increasing the effective number of transcripts available to bind to a given spot, while changes in labeled probe amounts were found to be less sensitive to improving signal quality. In addition to Q-RT-PCR, array validation was tested by examining the transcriptional program of a mutant (M5) strain lacking the pSOL1 178-gene megaplasmid relative to the wildtype (WT) strain. Under optimal conditions, it is demonstrated that the fraction of false positive genes is 1% when considering differentially expressed genes and 7% when considering all genes with signal above background. To enhance genomic-scale understanding of organismal physiology, using data from these microarrays we estimated that $40{\sim}55%$ of the C. acetobutylicum genome is expressed at any time during batch culture, similar to estimates made for Bacillus subtilis.

• Journal of Photoscience
• /
• v.10 no.2
• /
• pp.199-202
• /
• 2003

The relationship between the morphology of nanostructured TiO$_2$ films and the photo-injected electron transport has been investigated using intensity-modulated photocurrent spectroscopy (IMPS). For this purpose, three different TiO$_2$ films with 5 ${\mu}{\textrm}{m}$ thickness are prepared: The rutile TiO$_2$ film with 500 nm-sized cluster-like spherical bundles composed of the individual needles (Tl), the rutile TiO$_2$ film made up of non-oriented, homogeneously distributed rod-shaped particles having a dimension of approximately 20${\times}$80 nm (T2), and the anatase TiO$_2$ film with 20 nm-sized spherically shaped particles (T3). Cross sectional scanning electron micrographs show that all of the TiO$_2$films have a quite different particle packing density: poorly packed Tl film, loosely packed T2 film and densely packed T3 film. The electron transport is found to be significantly influenced by film morphology. The effective electron diffusion coefficient D$_{eff}$ derived from the IMPS time constant is an order of magnitude lower for T2 than for T3, but the D$_{eff}$ for the Tl sample is much lower than T2. These differences in the rate of electron transport are ascribed to differences in the extent of interparticle connectivity associated with the particle packing density.ity.

• Journal of the Korean Society of Tobacco Science
• /
• v.10 no.1
• /
• pp.75-82
• /
• 1988

Cigarettes were made using a triple filter with several porous materials in its cavity. The removal effect of the adsorbents on carbon monoxide and hydrogen cyanide in cigarette smoke was investigated with the variation of their surface area and pore volume distributions. Several attempts were made to activated coconut shell based char under the fixed steam purging rate. 1. The specific surface area increased in number of micropore. It was found for transitional pore to have a little effect on the total surface area. 2. A Small amount of the particulate matter adsorbed on the adsorbents with transitional pores, Zeolite showed a little effect on the carbon monoxide adsorption though its small pore volume, but there was no significant difference in the adsorption capacity zeolite and the others. 3. In the adsorption for hydrogen cyanide as a vapor phase in cigarette smoke, the adsorption effect of the adsorbents increased remarkably with increasing their surface area and number of micropore. It was considered that the adsorbents with small pore volume like molecular seive 4A, in which the capillary diffusion of adsorbates could not be able, would not be effective for the adsorption of hydrogen cyanide.

• Journal of Pharmaceutical Investigation
• /
• v.33 no.1
• /
• pp.29-36
• /
• 2003

Clenbuterol, a selective ${\beta}_2-adrenergic$ receptor stimulant, has been introduced as a potent bronchodilator for patients with bronchial asthma, chronic obstructive bronchial disease, chronic bronchitis and pulmonary emphysema. The percutaneous permeation of clenbuterol was investigated in hairless mouse skin after application of 50/50 buffer(pH 10)/propylene glycol solvent mixture. The enhancing effects of various penetration enhancers such as terpenes, non-ionic surfactants, pyrrolidones, fatty acids and some other enhancers on the permeation of clenbuterol were evaluated using Franz diffusion cell. Among terpenes studied, 1,8-cineole was the most effective enhancer, which increased the permeability of clenbuterol approximately 39.33-fold compared with the control without penetration enhancer, followed by menthone with enhancement ratio of 23.57. Nonionic surfactants did not have significant enhancing effects. N-Lauryl-2-pyrrolidone increased the permeability of clenbuterol approximately 4.51-fold compared with the control. Lauric acid increased the permeability of clenbuterol approximately 35.57-fold with decreasing the lag time from 2.64 to 0.52 hr. Oleic acid, linoleic acid, linolenic acid and capric acid showed enhancement ratio of 22.62, 19.60, 17.45 and 16.51, respectively. $Labrafil^{\circledR}$ enhanced the permeability of clenbuterol 9.24-fold compared with that without enhancer.