• Journal of the Korean Institute of Gas
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• v.20 no.4
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• pp.65-77
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• 2016

Modeling for complex reacting flow in Fischer-Tropsch reactor is one of the challenges in the field of Computational Fluid Dynamics (CFD). It is hard to derive each and every reaction rate for all chemical species because Fisher-Tropsch reaction produces many kinds of hydrocarbons which include lots of isomers. To overcome this problem, after analyzing the existing methodologies for reaction rate modeling, non-Anderson-Schulz-Flory methodology is selected to model the detailed reaction rates. In addition, the inside flow has feature of multi-phase flow, and the methodologies for modeling multi-phase flow depend on the interference between the phases, distribution of the dispersed phase, flow pattern, etc. However, existing studies have used a variety of inside flow modeling methodologies with no basis or rationale for the feasibility. Modeling inside flow based on the experimental observation of the flow would be the best way, however, with limited resources we infer the probable regime of inside flow based on conventional fluid dynamics theory; select the appropriate methodology of Mixture model; and perform systematic CFD modeling. The model presented in this study is validated through comparisons between experimental data and simulation results for 10 experimental conditions.

• Membrane Journal
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• v.23 no.5
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• pp.352-359
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• 2013

In the present study, $CO_2$ permeation through a hydrophilic NaY zeolite membrane was studied under permeate evacuation mode for $CO_2$ single gas, $CO_2-N_2$ and $CO_2-O_2$ binary mixtures, and $CO_2-N_2-O_2$ ternary mixture. It was reconfirmed that the $CO_2$ permeation was governed by surface diffusion and the $CO_2$ selectivity was induced from blocking effect of adsorbed $CO_2$ molecules. The $CO_2$ permeance measured in permeate evacuation mode was much lower than that done in He sweeping mode, but was comparable to that obtained under feed pressurization mode. The NaY zeolite membrane showed a considerable $CO_2$ separation for $14%CO_2-80%N_2-6%O_2$ mixture : $CO_2$ permeance was about $1{\times}10^{-7}mol/m^2secPa$ and $CO_2$ selectivity was more than 10. Therefore, it was concluded that NaY zeolite membrane was one of promising membranes for post-combustion CCS process.

• The Journal of Internal Korean Medicine
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• v.42 no.1
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• pp.11-24
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• 2021

Objective: Chronic reflux esophagitis (CRE), characterized by esophageal mucosa ulcer, is caused by continuous backflow of gastric acid and consequent inflammation due to unstable gastroesophageal sphincter. The aim of the present study was to clarify the effect of an Arecae Semen and Coptidis Rhizoma mixture (AC-mix) on CRE. Methods: CRE was surgically induced in SD rats with three experimental groups used: normal; CRE control; and CRE treatment (200 mg/kg AC-mix). Blood and esophageal tissue were collected after two weeks of drug administration. The anti-oxidant activity of the AC-mix was measured by total polyphenol and total flavonoid contents as well as by radical scavenging activity with protein levels evaluated using western blotting. Results: CRE damage to the esophageal mucosa was significantly reduced in the AC-mix group as compared with the controls, and administration of the AC-mix was seen to inhibit NF-κBp65 activity. Consequently, the inactivation of NF-κBp65 significantly inhibited inflammatory mediators such as COX-2 and iNOS. Moreover, the anti-oxidant enzyme HO-1 significantly increased through activation of the Nrf2-Keap1 pathway. Matrix metalloproteinase-2 (MMP-2), which can break down collagen from the basement membrane and extracellular matrix, was decreased following AC-mix treatment, and elevated levels of MMP-2 were regulated by its tissue inhibitor. Conclusions: These results show that AC-mix can alleviate esophageal mucosa ulcer though inhibition of the NF-κBp65 inflammatory pathway and enhancement of the anti-oxidant Nrf2-Keap1 pathway.

• Food Engineering Progress
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• v.15 no.1
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• pp.75-79
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• 2011

Analytical methods for food antioxidants including ascorbic acid, erythorbic acid, ascorbyl palmitate (AP), and ascorbyl stearate (AS), were validated using high performance liquid chromatography. Validation parameters such as linearity, limit of detection (LOD), limit of quantification (LOQ), and recovery were tested using lard and cider as food model systems. Linearity of ascorbic acid and erythorbic acid were both higher than ($R^2$> 0.99), LOD of these compounds were 0.46 and 0.48 ${\mu}g/mL$, respectively and LOQ were 1.39 and 1.45 ${\mu}g/mL$, respectively. The recovery rates of these compounds were 86.35-94.78% and 84.76-95.02%, respectively. However, the concentration of AP and AS decreased in methanol stock solution. Four other solvents including ethanol, acetonitrile, mixture of methanol and acetonitrile, and mixture of ethanol and acetonitrile were tested to increase the stability of AP and AS under room temperature and refrigerated temperature. Ethanol provided better stability of AP and AS under both room and refrigerated temperature. This study can help to accurately analyze the content of ascorbic acid and its derivatives in processed foods.

• The Korea Journal of Herbology
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• v.36 no.1
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• pp.59-66
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• 2021

Objectives : Forsythiae Fructus has been reported to have anti-inflammatory effects in many diseases, and Corydalis Tuber has been used as a pain suppressor in Eastern Asia. However, the protective effects of individual water extract of Forsythiae Fructus (FF) and Corydalis Tuber (CT) and the mixture of FF and CT (FC) on chronic pancreatitis (CP) were not well-investigated. Therefore, we investigated the protective effects of FF, CT, and FC on CP in mice. Methods : To induce CP, cerulein was injected 6 times a day, 4 times a week for 3 weeks. 1 h before the every cerulein injection, 200 mg/kg of FF, CT, or FC was intraperitoneally injected to mice. Histological analysis of pancreas was examined by hematoxylin and eosin stain and collagen deposition was examined by Masson's trichrome stain. Fibrogenic parameters such as α-smooth muscle actin (α-SMA), extracellular matrix (ECM) deposition, and fibrotic cytokines such as transforming growth factor (TGF)-β1 and platelet-derived growth factor (PDGF) were also analyzed by immunofluorescence stain and real-time PCR. Results : Histological damages in pancreas were inhibited by pre-treatment of FF or FC but not CT. α-SMA and ECM in pancreas were inhibited by pre-treatment of CT or FC but not FF. Moreover, the expression of TGF-β1 and PDGF in pancreas were inhibited by FF, CT or FC. Conclusions : Our results suggest that FC have protective effect on CP in mice through inhibition of α-SMA, ECM, TGF-β1 and PDGF in pancreas, and these findings could suggest new clinical strategy for CP.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.5
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• pp.95-102
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• 2020

For the purpose of developing a PE fiber-reinforced highly ductile cementitious composite having high tensile strain capacity more than 2% under the condition of containing aggregates with large particle size, this study investigated the tensile behavior of composites according to the particle size and distribution of aggregates in the composite. Compared with the mixture containing silica sand of which particle size is less than 0.6 mm, mixtures containing river sand and/or gravel with the maximum particle size of 2.36 mm, 4.75 mm, 5.6 mm, 6.7 mm were considered in the experimental design. The particle size distributions of aggregates were adjusted for the optimized distribution curves obtained from modified A&A model by blending different sizes of aggregates. All the mixtures presented clear strain-hardening behavior in the direct tensile tests. The mixtures with the blended aggregates to meet the optimum curves of aggregate size distributions showed higher tensile strain capacity than the mixture with silica sand. It was also found that the tensile strain capacity was improved as the maximum size of aggregate increased which resulted in wider particle size distribution. The mixtures with the maximum size of 5.6 mm and 6.7 mm presented very high tensile strain capacities of 4.83% and 5.89%, respectively. This study demonstrated that it was possible to use coarse aggregates in manufacturing highly ductile fiber-reinforced cementitous composite by adjusting the particle size distribution.

• The Korea Journal of Herbology
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• v.32 no.5
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• pp.27-38
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• 2017

Objective : In the present study, we examined whether Canavalia gladiata D.C. (CG) and Arctium lappa L., Redix (AL) mixture (CGAL), their components, lupeol and chicoric acid, regulate immune system and suppress the tumor in vitro and in vivo. Methods : LPS-induced reactive oxygen species (ROS) and nitric oxide (NO) were measured after treatment with CG extract (CGE), CGAL, lupeol, chicoric acid and lupeol and chicoric acid mixture (lupeol+CA) in Raw264.7 cell. To determine the effect of CGE on immune responses, immune cell population and IgG production were assessed in mice. To investigate the effect of CGAL and their component on anti-tumor activity, tumor volume and weight were measured, cell cycles and immune cell population were analyzed in MC38 injected tumor bearing mice. Also, NK cell activity was determined in splenocyte isolated from tumor bearing mice. Results : CGE, CGAL, lupeol, chicoric acid and lupeol+CA decreased the LPS-induced ROS and NO production without cell toxicity in RAW264.7 cells. CGE increased the immune cell populations of $CD4^+T$, $CD8^+T$ and macrophages in various immune organ of mice. In tumor bearing mice, CGAL, lupeol, chicoric acid and lupeol+CA suppressed tumor volume and weight. In cell cycle analysis, they decreased the percentages of S phase. In addition, CGAL, lupeol, chicoric acid and lupeol+CA immune cell populations of $CD4^+T$, $CD8^+Tcell$, NK cell and macrophage in tumor as well as NK cell activity. Conclusion : CGAL and its compounds may enhance immune responses and suppress tumor growth, and may be capable of developing health functional foods.

• Composites Research
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• v.36 no.3
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• pp.199-204
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• 2023

A combination of a metallic mesh and an adhesive layer of metallic particle/epoxy composite was introduced as an intermediate layer to enhance the adhesion between cold-sprayed particles and fiber-reinforced composites (FRCs). Aluminum was considered for both the metallic particles in the adhesive and the metallic mesh. To predict the mechanical characteristics of the intermediate bond layer under a high strain rate, the properties of the adhesive layer needed to be calculated or measured. Therefore, in this study, the Al particle/epoxy adhesive was homogenized by using a rule of mixture. To verify the homogenization, the penetration depth, and the thickness decrease after the cold spray deposition from the undeformed surface, was monitored with FE analysis and compared with experimental observation. The comparison displayed that the penetration depth was comparable to the diameters of one cold spray particle, and thus the homogenization approach can be reasonable for the prediction of the stress level of particulate polymer composite interlayer under a high strain rate for cold spray processing.

• Food Science and Preservation
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• v.30 no.3
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• pp.514-525
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• 2023

New types of vinegar drinks are being processed and developed using various raw materials. In this study, a beverage containing a mixture of 0.25% red ginseng extract and 5% Prunus mume fruit vinegar (RPV) was evaluated for its anti-fatigue effect on high-intensity exercised rats. RPV administration markedly enhanced running endurance and significantly decreased fatigue-related serum biomarkers, such as inorganic phosphate, ammonia, and L-lactate, compared to the other groups. In addition, RPV administration increased glycogen contents in the liver and muscles and decreased creatine kinase activity in the serum and muscles. RPV administration also remarkedly increased the activity of lactate in the muscles. Furthermore, HPLC analysis revealed that main organic acids in RPV were acetic acid, malic acid, and citric acids. Overall, the results indicate that RPV improved fatigue recovery in exhausted rats, thus proving a promising material of functional food to attenuate fatigue.

• Journal of Food Hygiene and Safety
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• v.28 no.3
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• pp.217-221
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• 2013

This study developed predictive models for the kinetic behavior of Staphylococcus aureus on processed cheeses. Mozzarella slice cheese and cheddar slice cheese were inoculated with 0.1 ml of a S. aureus strain mixture (ATCC13565, ATCC14458, ATCC23235, ATCC27664, and NCCP10826). The inoculated samples were then stored at $4^{\circ}C$ (1440 h), $15^{\circ}C$ (288 h), $25^{\circ}C$ (72 h), and $30^{\circ}C$ (48 h), and the growth of all bacteria and of S. aureus were enumerated on tryptic soy agar and mannitol salt agar, respectively. The Baranyi model was fitted to the growth data of S. aureus to calculate growth rate (${\mu}_{max}$; ${\log}CFU{\cdot}g^{-1}{\cdot}h^{-1}$), lag phase duration (LPD; h), lower asymptote (log CFU/g), and upper asymptote (log CFU/g). The growth parameters were further analyzed using the square root model as a function of temperature. The model performance was validated with observed data, and the root mean square error (RMSE) was calculated. At $4^{\circ}C$, S. aureus cell growth was not observed on either processed cheese, but S. aureus growth on the mozzarella and cheddar cheeses was observed at $15^{\circ}C$, $25^{\circ}C$, and $30^{\circ}C$. The ${\mu}_{max}$ values increased, but LPD values decreased as storage temperature increased. In addition, the developed models showed acceptable performance (RMSE = 0.3500-0.5344). This result indicates that the developed kinetic model should be useful in describing the growth pattern of S. aureus in processed cheeses.