• Bulletin of the Korean Chemical Society
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• v.34 no.4
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• pp.1145-1152
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• 2013

The rate constant of alkaline fading of methyl green ($ME^{2+}$) was measured in the presence of non ionic (TX-100), cationic (DTAB) and anionic (SDS) surfactants. $ME^{2+}$ hydrolyses and fades in neutral water and in this work we search the effects of surfactants on its fading rate. The rate of reaction showed remarkable dependence on the electrical charge of the used surfactants. It was observed that the reaction rate constant decreased in the presence of DTAB and SDS and increased in the presence of TX-100. Binding constants of $ME^{2+}$ to TX-100, DTAB and SDS and the related thermodynamic parameters were obtained by classical (or stoichiometric) model. The results show that binding of $ME^{2+}$ to TX-100 and DTAB are two-region and that of SDS is three-region. Also, the binding constants of $ME^{2+}$ to surfactant molecules in DTAB/TX-100 and SDS/TX-100 mixed solutions and their stoichiometric ratios were obtained.

• Nuclear Engineering and Technology
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• v.56 no.2
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• pp.636-643
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• 2024

The coolability of the debris bed with a simulant of solidified corium is experimentally studied, focusing on the effects of the structure of the axial stratified debris bed on the dryout heat flux (DHF). DHF was obtained for the four structures with different particle sizes for the axial stratified debris bed under top flooding. The experimental results show that the dryout position of the axial stratified debris bed is formed at the stratified interface indicated by the temperature rise, and the DHF of the axial stratified bed is much lower than that of the homogeneous bed packed with the upper small particles. To predict the dryout heat flux of the stratified debris beds, by considering the properties of the mixed area, a one-dimensional dryout heat flux model of the porous medium is derived from a water and vapor momentum equation for porous medium, two-phase permeability modifications, interfacial drag, and the correlation between capillary pressure and liquid saturation and verified with the experimental data. The modified model can give reasonable results under different structures.

• Environmental Analysis Health and Toxicology
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• v.21 no.2 s.53
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• pp.127-138
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• 2006

In urban areas, diesel exhaust particles (DEP) are probably a major component of particulate matters, especially in Korea where drive many diesel vehicles. The aim of this study was to investigate genotoxic effects of DEP using single ceil gel electrophoresis. In order to evaluate the mechanisms of DEP genotoxicity, the rat microsome mediated and DNA repair enzyme treated comet assays together with conventional comet assay were performed. Total diesel particles (DEPT) was collected without site fractionation from diesel engine bus and dichloromethane extract was obtained. The organic extract of DEPT revealed DNA damage itself in NIH/3T3 cells. The level of DNA breaks plus oxidative DNA lesions and microsome mediated DNA damage was assessed by modified single cell gel eletrophoresis. DEPT was able to induce oxidative DNA damage as well as microsome mediated DNA damage. Vitamin C as an model antioxidant reduced DNA damage in endonuclase III treated comet assay. One of flavonoid, galangin as a CYP1A1 inhibitor. reduced DNA damage in the presence of S-9 mixture. $DEP_T$ is the sources of oxidative stress, but antioxidants can significantly reduce oxidative DNA dmage. And $DEP_T$ may contain indirect mutagens which can be inhibited by CYP1A1 inhibitors. The ethanol extracts of the mixed vegetables (BV) or the mixed fruits (BF) were evaluated for their in vitro antigenotoxic effects. BV and BF showed potent Inhibitory effects against DEPT induced DNA damage with oxidative DNA lesions and in the prescence of S-9 mixture. These results indicate that BV and BF could prevent cellular DNA damage by inhibiting oxidative stress and suppressing cytochrome P4501A1 in cell culture.

• The Journal of Korean Association of Computer Education
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• v.4 no.2
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• pp.31-39
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• 2001

In this paper, we investigate the effects of group composition according to the personality type of learner on the content of discussion in web-based synchronous online discussion. The experiment for this study was conducted with high school students. First, we conducted the MBTI(Myers Briggs Type Indicator) test and based upon the result, we classified learners into 3 groups; introverts group, extroverts group, and introverts/extroverts mixed group. After the online discussion, the content of discussion were analyzed by the units of meaning, based on the four dimensions which were proposed in the 'content analysis model' by Henri(l992). Among four dimensions, 'social' and 'interactive' dimension belonged to category of inter-dependence, and 'cognitive' and 'metacognitive' dimension belonged to category of subject-relevance. The introverts/extroverts mixed group, which was heterogeneously composed, had the most positive effects on the total numbers of the units of meaning, the inter-dependence, and the subject-relevance of the contents of discussion.

• The Journal of Korean Medicine
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• v.39 no.4
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• pp.86-113
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• 2018

Objectives: We examined the effects of a mixed formula consisting of dried pomegranate concentrate powder (PCP) and the aqueous extracts of Eucommiae cortex (EC) and Achyranthis radix (AR) in rats with surgically induced osteoarthritis (OA). Methods: Two weeks after OA-inducing surgery, a PCP:EC:AR 5:4:1 (g/g) combination or single formula was orally administered. Changes in body weight, knee thickness, maximum knee extension angle, bone mineral density of the knee joints, femoral and tibial articular surfaces, and compressive strength of the femoral and tibial articular cartilage (AC) were assessed, along with the prostaglandin E2 level, 5-lipoxygenase, matrix metalloproteinase (MMP)-2 and MMP-9 activity, and chondrogenic gene mRNA expression in the femoral and tibial AC with the synovial membrane (SM). In addition, the number of cleaved poly(ADP-ribose) polymerase, cyclooxygenase and tumor necrosis factor-${\alpha}$-immunoreactive cells in the femoral and tibial AC with SM were monitored, and the rate of cell proliferation was determined with a 5-bromo-2'-deoxyuridine uptake assay. Results : The signs of surgically induced OA in rats were significantly inhibited by both PCP, EC and AR combined and single formulas. In particular, the combination formula-treated OA model rats showed dose-dependent, significantly increased inhibitory activity against all tested criteria compared with single formula-treated rats. Conclusions: Taken together, our results suggest that the combination formula synergistically increased the anti-OA effects of its components through anti-inflammatory and chondrogenic activity in rats with surgically induced OA. In addition, 200, 100 and 50 mg/kg combination formula treatments showed dose-dependent inhibitory activity against all of the tested criteria.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.28 no.5
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• pp.599-606
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• 1995

The feasibility of foam separation to remove protein produced from fish culture water was investigated, By assuming foam separation column as a single well-mixed pool, a simplified model for foam separator conditions was alse studied under the batch operation. The model indicated that the protein removal could be described as a first-order reaction whose rate increases with both superficial air velocity and protein concentration in the bulk solution. from ,the results of an experimental study on the effects of superficial air velocity, the protein concentration, temperature, and pH on protein removal, the superficial air velocity and initial protein concentration in bulk solution were found to be important operational factors. Other experimental results important that foam separator operated under batch conditions would be considered as a completely mixed reactor. The protein removal rate by foam separation process was increased proportionally with the superficial air velocity, and the adsorptive removal rate of protein was found to obey Langmuir adsorption formula. The preposed simplified model was verified with the experimental data obtained from this study. Under the experimental range used, both temperature and pH did not affect the protein removal.

• Korean Journal of Veterinary Research
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• v.56 no.3
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• pp.155-160
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• 2016

This study was conducted to evaluate three different mixed formulations of sodium hyaluronate (SH) and carboxymethyl cellulose (CMC) using a low-humidity air flow-induced rat dry eye model and determine the most suitable mixture. The total thickness of the cornea, corneal epithelial thickness, corneal stroma thickness, damaged corneal epithelium percentage region, thickness of the bulbar conjunctiva epithelium, number of goblet cells, goblet cell occupation percentage region, and damaged bulbar conjunctiva epithelium percentage region were measured by histomorphological evaluation. After 5 h exposure to drying airflow, the thickness of the cornea and conjunctiva was decreased with desquamation of the corneal and conjunctiva epithelium. However, these dry eye symptoms were markedly inhibited by treatment with the reference and test formulations. More favorable effects on decreased thickness were detected in response to the CMC than the SH. However, SH had a greater protective effect against corneal and conjunctiva epithelial damage. The application of a mixture of 0.1% SH and 0.2% CMC showed more favorable effects on the corneal and conjunctival damage and the stabilization of the ocular surface than SH or CMC alone.

• Korean Journal of Food Science and Technology
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• v.28 no.1
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• pp.197-202
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• 1996

The effects of erythrosine on the oxidative stability of cholesterol in an aqueous model system were studied by depleted headspace oxygen and cholesterol oxidation products (COP). As the oncentration of erythrosine was increased, headspace oxygen depletion, 7-COP and total COP increased during storage at $25^{\circ}C$ for 50 hours under the fluorescent light. As the intensity of fluorescent light was increased, amounts of headspace oxygen depleted and COP formed in an aqueous cholesterol dispersion containing erythrosine also increased. Addition of ${\alpha}-,\;{\delta}-$, mixed-tocopherol and ${\beta}-carotene$ resulted in the enhanced oxidative stability of an aqueous cholesterol dispersion containing erythrosine during the fluorescent light storage.

• Journal of the Korea Computer Graphics Society
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• v.28 no.4
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• pp.31-40
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• 2022

This study assumed two key parameters that describe smoothness. Previously, the number of studies that defined smoothness with the concept of curvature has been limited. The parameters were the two physical characteristics of curvature: the number of waves and the amplitude of them. The purpose of the study was to observe which of the two parameters influences the perception of smoothness and to examine the relationship between the sense of aesthetic beauty and smoothness. The visual stimuli used in the study were transformed three-dimensional spheres, based on the combination of the three levels of the two parameters of nine distinct conditions. We analyzed the three responses that measured the preference of each visual stimuli, the familiarity score, and the smoothness evaluation score, each with the linear mixed model whose fixed effects were the two parameters and random effects were the participants' individual differences. Nearly the eighty percent of the variance of the smoothness evaluation score was explained by the linear model with the two key parameters and their interaction. The physical characteristics of a viewed object were far more significant than individual differences such as personality factors and the manner of art appreciation. In conclusion, the study examined the perception of smoothness based on the change of the physical characteristics of a shape. The study further recognized the relationship between smoothness and the aesthetic preference. No significant influence of the participants' individual difference such as gender, the degree in fine arts, personality factors, and the manner of art appreciation was observed. The amplitude of waves, rather than the number of them, was far more significant to the perception of smoothness.

• Journal of Korean society of Dental Hygiene
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• v.12 no.2
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• pp.335-343
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• 2012

Objectives : The aim of this investigation was to evaluate the remineralization effect of Bamboo salt and NaF+Bamboo salt solutions on bovine enamel formed incipient artificial enamel caries by microcomputed tomography (micro CT). Methods : Experimental solutions were distilled water(negative control), 2% sodium fluoride solution (2% NaF group), 3% bamboo salt solution (3% BS group) and the solution mixed 2% sodium fluoride solution and 3% bamboo salt solution (2% NaF+3% BS group). Specimens were prepared from extracted bovine teeth and divided into 4 groups of 10 specimens each by randomized blocks according to density. Then the specimens surface were divided equally into three parts to observe sound enamel area, incipient enamel carious area and remineralized enamel area. Only one-third of specimen surface was coated with nail varnish and these were exposed to a lactate carbopol buffer system for 72 hours. Then one-half of the demineralized enamel area was coated with nail varnish. The specimens were carried out under pH cycling model for 14 days as follows; samples were immersed in each experimental solution for 2 mins 3 times per day, demineralized for 4 hours and in mixed saliva for the remaining hours. After pH cycling, density was measured using micro CT. Results : All experimental groups showed remineralization effects except for negative control group(p<0.05). The differences of density after experimental solution treatment were statistically significant difference among 4 groups (p<0.01). The density difference values of groups were $0.04{\pm}0.01$ in negative control group, $0.19{\pm}0.01$ in 2% NaF group, $0.14{\pm}0.01$ in 3% BS group, and $0.21{\pm}0.01$ in 2% NaF+3% BS group. Conclusions : The bamboo salt solution showed remineralization effects on incipient artificial enamel caries and the solution mixed sodium fluoride solution and bamboo salt solution showed more remineralization effects than the bamboo salt solution. Thus, it is suggested that bamboo salt can be used as remineralization agent in incipient enamel caries lesion.