• Journal of the Korea Concrete Institute
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• v.16 no.2 s.80
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• pp.277-282
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• 2004

In a hardened concrete, diffusion of oxygen, carbon dioxide, aggressive ions, and moisture from the environment to the concrete takes place through the pore network. It is well known that making dense cement matrix enhances the durability of concrete as well as all the characteristics including strength of concrete. In this paper,9 mix concretes with water to cementitious material ratio (40,45, and $50\%$) and replacement ratio of GGBFS (40 and $60\%$ of cement by weight) were studied on the micro-pore structure by mercury intrusion porosimetry and the accelerated chloride diffusion test by potential difference. From the results the average pore diameter and accelerated chloride diffusivity of concrete were ordered NPC > G4C > G6C. It is concluded that there is a good correlation between the average pore diameter and the chloride diffusivity, and the mineral admixtures has a filling effect, which increases the tortuosity of pore and makes large pores finer, on the pore structure of cement matrix due to the latent hydraulic reaction with hydrates of cement.

• Korean journal of food and cookery science
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• v.26 no.2
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• pp.206-213
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• 2010

In this study, the antibacterial activities of essential oil from Zanthoxylum schinifolium against four Gram-positive bacteria and six Gram-negative bacteria were investigated. The antibacterial activity of the oils was determined using the agar-well diffusion assay, MIC (minimum inhibitory concentration) and MBC (minimum bactericidal concentration). In particular, essential oil from Z. schinifolium showed higher antibacterial activity against Gram-positive bacteria than against Gram-negative bacteria. Essential oil from Z. schinifolium displayed large inhibition zones especially against Bacillus cereus (31 mm). At concentrations between 0 and $20\;{\mu}g/mL$ the oils showed an antibacterial effect against both Gram-negative and Gram-positive bacteria. The minimum inhibitory concentration (MIC) values against nine bacteria ranged from 1.25 to $5\;{\mu}g/mL$. The minimum bactericidal concentration (MBC) values against eight bacterial ranged from 2.5 to $20\;{\mu}g/mL$, except Shigella sonnei. Furthermore, our finding on the antibacterial activities of essential oils from Zanthoxylum schinifolium validated the use of this plant for medical purposes.

• Investigative Magnetic Resonance Imaging
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• v.22 no.2
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• pp.131-134
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• 2018

Susceptibility-weighted imaging (SWI) is well known for detecting the presence of hemorrhagic transformation, microbleeds and the susceptibility of vessel signs in acute ischemic stroke. But in some cases, it can provide the tissue perfusion state as well. We describe a case of a patient with hyperacute ischemic infarction that had a slightly hypodense, patchy lesion at the left thalamus on the initial SWI, with a left proximal posterior cerebral artery occlusion on a magnetic resonance (MR) angiography and delayed time-to-peak on an MR perfusion performed two hours after symptom onset. No obvious abnormal signals at any intensity were found on the initial diffusion-weighted imaging (DWI). On a follow-up MR image (MRI), an acute ischemic infarction was seen on DWI, which is the same location as the lesion on SWI. The hypointensity on the initial SWI reflects the susceptibility artifact caused by an increased deoxyhemoglobin in the affected tissue and vessels, which reflects the hypoperfusion state due to decreasing arterial flow. It precedes the signal change on DWI that reflects a cytotoxic edema. This case highlights that, in some hyperacute stages of ischemic stroke, hypointensity on an SWI may be a finding before the hyperintensity is seen on a DWI.

• Mycobiology
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• v.37 no.2
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• pp.141-146
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• 2009

Novel copper(II) complexes have been synthesized from the macrocyclic Schiff bases derived from Knoevenagel condensed ${\beta}$-ketoanilides (obtained by the condensation of acetoacetanilide and substituted benzaldehydes), 4-aminoantipyrine and ophenylene diamine. The structural features have been determined from their analytical and spectral data. All the Cu(II) complexes exhibit square planar geometry. Their high molar conductance values support their 1 : 2 electrolytic nature. The magnetic moment data provide evidence for the monomeric nature of the complexes. The X-band ESR spectra of the |$CuL^1$|$(OAc)_2$ in DMSO solution at 300 and 77 K were recorded and their salient features are reported. The in vitro biological screening effects of the investigated compounds were tested against the bacterial species Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, Proteus vulgaris and Pseudomonas aeruginosa and fungal species Aspergillus niger, Rhizopus stolonifer, Aspergillus flavus, Rhizoctonia bataicola and Candida albicans by well diffusion method. A comparative study of inhibition values of the Schiff bases and their complexes indicate that complexes exhibit higher antimicrobial activity than the Schiff bases. Copper ions proved to be essential for the growth-inhibitor effect. The extent of inhibition appeared to be strongly dependent on the initial cell density and on the growth medium.

• Nuclear Engineering and Technology
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• v.34 no.3
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• pp.218-231
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• 2002

Using a three-dimensional numerical code, B3R developed for nuclide transport of an arbitrary length of decay chain in the buffer between the canister and adjacent rock in a high- level radioactive waste repository by adopting a finite difference method utilizing the control- volume scheme, some illustrative calculations have been done. A linear sorption isotherm, nuclide transport due to diffusion in the buffer and the rock matrix, and advection and dispersion along thin rigid parallel fractures existing in a saturated porous rock matrix as well as diffusion through the fracture wall into the matrix is assumed. In such kind of repository, buffer and rock matrix are known to be important physico-chemical harriers in nuclide retardation. To show effects of buffer and rock matrix on nuclide transport in HLW repository and also to demonstrate usefulness of B3R, several cases of breakthrough curves as well as three- dimensional plots of concentration isopleths associated with these two barriers are introduced for a typical case of decay chain of $^{234}$ Ulongrightarrow$^{230}$ Thlongrightarrow$^{226}$ Ra, which is the most important chain as far as the human environment is concerned.

• Biomedical Science Letters
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• v.29 no.3
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• pp.130-136
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• 2023

In this study, the anti-bacterial activity of three medicinal herbs such as Dioscorea batatas, Morus alba, and Tagetes erecta, have been applied in oriental medicine against Escherichia coli and Staphylococcus aureus. The antibacterial activity of Dioscorea batatas ethanol extract (DBEE), Morus alba ethanol extract (MAEE), and Tagetes erecta ethanol extract (TEEE) was analyzed by disk diffusion, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC) assays. As a result, three medicinal herbs exhibited antibacterial activity in a dose-dependent manner as well as MAEE and TEEE showed the most potent antibacterial activity followed by disk diffusion assay against E. coli and S. aureus, respectively. MIC against E. coli and S. aureus was 1.6 mg/mL of MAEE and TEEE as well as 0.2 mg/mL of TEEE. MBC against both strains was 5 mg/mL of DBEE and 2.5 mg/mL of TEEE. Consequently, three medicinal herbs in this study showed potent antibacterial activity through the inhibited growth of E. coli and S. aureus, which is considered as a potential candidate for cosmeceutic agents to attenuate the pruritus. In addition, antibacterial and antihistamine effects followed by the extraction solvents should be analyzed in future studies.

• Journal of Photoscience
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• v.11 no.1
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• pp.11-17
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• 2004

Fluorescence quenching of l,4-bis [2-(2-methylphenyl) ethenyl]-benzene (Bis-MSB) by carbon tetrachloride in five different solvents namely hexane, cyclohexane, toluene, benzene and dioxane has been carried out at room temperature with a view to understand the quenching mechanisms. The Stern-Volmer plot has been found to be non-linear with a positive deviation for all the solvents studied. In order to interpret these results we have invoked the Ground state complex and Sphere of action static quenching models. Using these models various rate parameters have been determined. The magnitudes of these parameters imply that sphere of action static quenching model agrees well with the experimental results. Hence the positive deviation in the Stem-Volmer plots is attributed to the static and dynamic quenching. Further, with the use of Finite Sink approximation model, it was possible to check whether these bimolecular reactions as diffusion limited and to estimate independently distance parameter R' and mutual diffusion coefficient D. Finally an effort has been made to correlate the values of R'and D with the values of the encounter distance R and the mutual diffusion coefficient D determined using the Edwardis empirical relation and Stokes-Einstein relation.

• 한국연소학회:학술대회논문집
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• 2003.05a
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• pp.93-101
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• 2003

The extinction of unsteady diffusion flame was experimentally studied in an opposing jet counterflow burner using diluted methane. The stabilized flame was perturbed by linearly varying velocity change that was generated by pistons installed on both sides of the air and fuel stream. As the results, the extinction of unsteady flame is dependent not only on the history of unsteadiness, but also on the initial condition. We found that there are several unsteady effects on the flame extinction. First, the extinction strain rates of unsteady cases are extended well beyond steady state extinction limits. Second, as the slope of the strain rate change increases, the unsteady extinction strain rate becomes larger. Third, the extension of unsteady extinction strain rate becomes smaller as the initial strain rate increases. We also found that the extension of the extinction limit mainly results from the unsteady response of the reaction zone because there is no retardation effect of a mixing layer for our experimental condition.

• The Journal of the Korea Contents Association
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• v.14 no.4
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• pp.227-236
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• 2014

This study was conducted to explore the mediation effects of irrational belief on the relationship between game addiction and anger behavior. For this study, 431 middle school boys in Chungcheong areas were included in the analysis. The results showed that game addiction was positively correlated with direct anger-out, rumination, diffusion as well as irrational belief. The boys at high risk of game addiction showed higher mean scores on irrational belief, direct anger-out, rumination: and diffusion than other students. Irrational belief (mediator) partially mediated the influence of the boys' game addiction (independent variable) on direct anger-out, rumination, and diffusion (dependent variable). Finally, limitations of this study and suggestions for future study were discussed.

• Knowledge Management Research
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• v.12 no.1
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• pp.53-76
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• 2011

This study aims to examine the effects of on premium convergence products buying behavior. This paper analyzed the positive attitude formation using the basic and extended TAM and also revealed how the positive premium convergence product attitude relate to relationship purchasing intention and word of mouth intention. The samples of 562 consumer indicate that the antecedents are consist of four dimension(perceived usefulness, perceived ease of use, social value) and attitude is developed into buying intention and word of mouth intention. We have reached the following conclusion about the antecedents and outcomes factors of customer attitude for the launch of premium convergence product. First, perceived usefulness, perceived delight, and social value had a positive effect on customer attitude but perceived ease of use did not. Second, we found that customer attitude had a positive effect on purchase intention and word-of mouth intention. Finally, interaction effect of perceived usefulness/perceived delight and social value had a positive effect on customer attitude. Our findings suggested that adoptian and diffusion of premium convergence product is influenced by several behavior factors. Managerially, our result emphasize that premium convergence products must satisfy not only the perceived usefulness/delight but also social value that consumers are seeking in order to be successful in the market. The theoretical and practical implications of these findings are discussed as well.