• Journal of Energy Engineering
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• v.27 no.4
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• pp.27-35
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• 2018

The passive containment cooling system (PCCS) has been designed to remove the released decay heat during the accident by means of the condensation heat transfer phenomenon to guarantee the safety of the nuclear power plant. The heat removal performance of the PCCS is mainly governed by the condensation heat transfer of the steam-air mixture. In this study, the heat removal performance of the PCCS was evaluated by using the MARS-KS code with a new empirical correlation for steam condensation in the presence of a noncondensable gas. A new empirical correlation implemented into the MARS-KS code was developed as a function of parameters that affect the condensation heat transfer coefficient, such as the pressure, the wall subcooling, the noncondensable gas mass fraction and the aspect ratio of the condenser tube. The empirical correlation was applied to the MARS-KS code to replace the default Colburn-Hougen model. The various thermal-hydraulic parameters during the operation of the PCCS follonwing a large-break loss-of-coolant-accident were analyzed. The transient pressure behavior inside the containment from the MARS-KS with the empirical correlation was compared with calculated with the Colburn-Hougen model.

• Journal of Soil and Groundwater Environment
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• v.12 no.4
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• pp.25-31
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• 2007

Characterizing the risk posed by a mixture of chemicals is a challenging task due to the chemical interactions of individual components that may affect their physical behavior and hence alter their exposure to receptors. In this study, cell tests that represent subsurface environment were carried out using benz[a]anthracene (BaA) and p-xylene focusing on phasetransforming interaction to verify increased mobility and risk of highly sorbed pollutants in the presence of less sorbed, mobile liquid pollutants. A transport model was also developed to interpret results and to simulate the same process on a field scale. The experimental results showed that BaA had far greater mobility in the presence of p-xylene than in the absence of that. The main transport mechanisms in the vadose zone were by dissolution to p-xylene or water. The transport model utilizing Defined Time Steps (DTS) was developed and tested with the experimental results. The predicted and observed values showed similar tendency, but the more work is needed in the future study for more precise modeling. The field-scale simulation results showed that transport of BaA to groundwater table was significantly faster in the presence of NAPL, and the oral carcinogenic risk of BaA calculated with the concentration in groundwater was 15${\sim}$87 times larger when mixed with NAPL than when solely contaminated. Since transport rate of PAHs is very slow in the subsurface without NAPL and no degradation of PAHs was considered in this simulation during the transport, the increase of risk in the presence of NAPL is expected to be greater for the actual contaminated site.

• Korean Journal of Pharmacognosy
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• v.40 no.3
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• pp.196-204
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• 2009

This study was carried out to investigate the in vivo and in vitro inhibitory effect of a traditional herbal complex (HC) extract prepared from a mixture of four oriental herbs (Dioscorea Rhizoma, Glycine soja Sieb. et Zucc, Bombycis corpus, Fermented Glycine soja) that have been widely used for the treatment and prevention of diabetes mellitus on hyperglycemia. The water extract of HC showed potent inhibitory effect on $\alpha$-glucosidase with $IC_{50}$ value of 1.24 mg/mL. Additionally, the ethanol extract of HC was also found to exhibit significant inhibitory effect against protein tyrosine phosphatase $1{\beta}$ ($PTP1{\beta}$), which is known as a major regulator of both insulin and leptin signaling. In the $PTP1{\beta}$ inhibitory assay, the most active n-hexane fraction obtained from the ethanol extract of HC, was identified as a mixture of fatty acid derivatives by gas chromatography-mass spectrometry (GC-MS). In high-fat diet-low dose streptozotocin (STZ)-induced diabetic rat, the water extract of HC improved the oral glucose intolerance as compared with rosiglitazone. HC also caused a marked decrease of body weight and fasting blood glucose and a significant improvement on glucose tolerance in metabolic syndrome mice model. These findings support that this traditional HC may be useful in the control of blood glucose in diabetes mellitus and metabolic syndrome.

• Journal of Life Science
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• v.33 no.11
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• pp.923-935
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• 2023

Rubus crataegifolius (RC), Ulmus macrocarpa (UM), and Gardenia jasminoides (GJ) are well-known folk medicines in Asia used to treat various gastrointestinal disturbances. The present study evaluated the gastroprotective effect of LS-RUG-com, a mixture of commercially prepared powders of RC, UM, and GJ with a ratio of 3:1:2(w/w/w) against HCl/ethanol-induced gastritis, indomethacin-induced ulcers, and esophageal reflux-induced esophageal mucosal damage and Helicobacter pylori infections. In addition, TNF-α and IL-1β expressions were also determined and measured in esophageal tissue. As to HCl/ethanol-induced gastritis, the LS-RUG-com treatment at a dose of 150 mg/kg showed a remarkable anti-gastritis effect. Regarding indomethacin-induced gastric ulcers, the LS-RUG-com treatment had a significant anti-gastric ulcer effect. Furthermore, in the gastroesophageal reflux disease (GERD) model experiment, the LS-RUG-com treatment resulted in the histological recovery of stomach damage and mucosal injuries. Furthermore, the LS-RUG-com treatment led to an increase in gastric content pH, an increase in mucus protection, and a decrease in gastric pepsin output with a significant decrease in TNF-α and IL-1β. As to the Helicobacter pylori infected animal model, LS-RUG-com had a notable inhibitory effect on Helicobacter growth. The use of RC, UM, or GJ in isolation or the LS-RUG-com treatment as whole had good effects in terms of anti-oxidation, anti-neutralization, gastric acid secretion inhibition, and anti-lipid peroxidation, which supported the use of natural products as systemic gastric protective agents. Our results suggest that the LS-RUG-com might be a significant systemic gastroprotective agent that could be utilized for the treatment and/or protection from gastric disturbances and related damage.

• Journal of Aerospace System Engineering
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• v.14 no.5
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• pp.107-121
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• 2020

The performance analysis of the small satellites launch vehicle using the electric pump cycle as the upper stage engines was performed. The first stage is the launch vehicle that uses the test launch vehicle of the Korea Space Launch Vehicle II and the second stage employs elecpump cycle engine that uses liquid methane and kerosene (RP-1) as fuel. A model for the mass estimation was presented and the analysis was conducted for the range of thrust of 20 to 40 kN and combustion pressure of 3 to 6 MPa with a nozzle expansion ratio of 60 to 100. The mixture ratio with the maximum velocity increment was calculated and the performance of the LEO and SSO payload were calculated from the stage mass estimation. In both the cases, liquid methane, and RP-1 showed maximum payload for 20 kN thrust, 3 MPa combustion pressure, and the nozzle expansion ratio of 100, with a mixture ratio of 3.49 for liquid methane and 2.75 for RP-1. In addition, the ditching points of the first stage and the fairing in the LEO mission were analyzed using ASTOS.

• Korean Chemical Engineering Research
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• v.55 no.5
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• pp.660-667
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• 2017

Equilibrium data of the mixture is essential in the design and operation of separation equipment such as distillation or extraction in chemical processes. These equilibrium data can be obtained through experiments or by calculations using the known binary parameters and the thermodynamic models. Generally, to obtain these parameters, phase equilibrium experimental data such as gas-liquid and liquid-liquid are used. In this study, the excess enthalpy of the mixture was measured using the flow type microcalorimeter which is a simpler method than phase equilibria experiments, and the parameters of various theories were obtained by using this data. In order to investigate the relationship between carbon chain length, enthalpy and binary parameters in the alkane system, excess enthalpies for the n-hexane + alkane (n-pentane, n-heptane, n-octane and n-dodecane) were measured at 298.15 K and the banary interaction parameters of Wilson, NRTL, and UNIQUAC were obtained from the experimental data. In addition, we wanted to obtain basic information on the interaction and association phenomena of the system including electrolyte applicable to various fields by using the excess enthalpy experimental data and the existing theory. First, we investigated the excess enthalpy for the NaOH / Water / Ethanol system as a basic experiment and examined the applicability using the electrolyte-NRTL (eNRTL) theory.

• Journal of the Korean Society of Food Science and Nutrition
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• v.36 no.11
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• pp.1377-1384
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• 2007

A previous study suggested that the phyto-extract mixture (PEM381) containing Camellia sinensis (leaf), Psidium guajava (leaf), and Rosa hybrida (flower) inhibited not only arachidonic acid cascade-related enzymes (5-lipoxygenase and cyclooxygenase) in vitro but also degranulation and histamine release from rat peritoneal mast cells. In this study, the same PEM381 was used to investigate its inhibitory effects on the syntheses of leukotrienes and prostaglandins as well as on serum concentration of histamine and eosinophils infiltration in type I allergic reaction-induced mice. The PEM381 could decrease concentrations of serum cysteinyl leukotrienes from mice activated by anti-DNP IgE and DNP-albumin. The concentration of serum histamine by oral administration of PEM381 (25, 50, and 100 mg/kg of body weight) in type I allergic reaction-induced mice was $395.93{\pm}190.37$ nM, $315.59{\pm}164.23$ nM, and $325.07{\pm}112.02$ nM, respectively, while that of positive control (promethazine hydrochloride 10 mg/kg of body weight) was $270.12{\pm}24.02$ nM. In addition, the PEM381 also showed inhibitory effect on the eosinophils infiltration in the nasal mucosa of mice which were sensitized with ovalbumin. However, the effect of PEM381 on the syntheses of prostaglandins seemed to be insignificant. Consequently, these results suggest that PEM381 may be useful for the prevention and treatment of type I allergy-related diseases.

• Korean Journal of Food Science and Technology
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• v.36 no.4
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• pp.594-597
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• 2004

Effects of various levels and molecular weights (MWs) of chitooligosaccharides and chitosan with pork salt-soluble protein (SSP) on pH, moisture (%), viscosity, and hardness of protein-chitosan mixtures were determined in a model study. Mixtures of 0.15, 0.3, and 0.45% chitosan at various MWs (Low, 1.5 kDa; Medium, 30-50 kDa; High, 200 kDa) were dissolved in 3% SSP solution for measurement of pH and viscosity at $20^{\circ}C$. pH value increased with addition of 0.45% low MW of chitooligosacchearides into SSP (p<0.05), whereas decreased with addition of 0.45% medium MW and 0.3% or higher level of high MW chitosan. Viscosity increased with addition of more than 0.3% either medium or high MW chitosan (p<0.05), as compared to mixture with low MW chitolligosaccharide and control (p<0.05). No differences in gel pH, moisture, and hardness values were observed among treatments (p>0.05). Further study will be performed to evaluate rheological properties actual meat products with various levels and MWs of chitosan.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.33 no.1
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• pp.73-79
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• 2001

Stricter environmental demands have increased the need to replace conventional C/D bleaching sequence by chlorine-free sequence. Permanganate is well known as a powerful oxidant and have been used industrially in variable fields. However, it has considered to be difficult to use permanganate as a bleaching reagent because of its strong oxidative effect decreasing the viscosity of pulps extremely. We have tried to use permanganate as a bleaching reagent for KP under the mild condition and it was clear that pernanganate oxidized lignin remained in pulps selectively and increased pulp brightness decreasing K number of pulps with small degradation of cellulose. We have employed the neutral condition in the permanganate bleaching process in this study. In this case, permanganate was converted to manganese dioxide after bleaching reaction. The manganese dioxide is remained in the treated pulp fibers because of its insolublity in water. So it was required to reduction the manganese oxide to manganese ion by using reductants with acid. In this paper, we proposed to use oxalic acid as a reducing reagent converting manganese oxide to manganese ion after bleaching reaction. Oxalic acid plays the role as a reductant and a acid, so post-treatment after bleaching became to be easy by using oxalic acid. On the study using lignin model compounds, it was clear that permaganate react with phenols firstly, after that oxalic acid reduce the manganese oxide to manganese ion in the mixture of permanganate, phenols and oxalic acid. Several lignin model compounds ($\textit{p}$-hydroxybenzaldehyde, vanillin, syringaldehyde, veratraldehyde) are selected to elucidate the effect of substituents on reaction rate and its mechanism with permanganate including oxalic acid in this study. Except for veratraldehyde, the rate of oxidative degradation of phenolic compounds by permanganate with oxalic acid are higher than neutral condition. Especially, the degradation rate of $\textit{p}$-hydroxybenzaldehyde are strongly dependent on pH of reaction mixture. On the other hand, the degradation rate of veratraldehyde are decreased with decreasing pH and main degradation product is veratric acid. This result indicate that pH of bleaching liquor should be kept over 2 to degrade of non-phenolic lignin in the pulps effectively in permanganate bleaching.

• Analytical Science and Technology
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• v.16 no.2
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• pp.95-101
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• 2003

In this study, water content in the mixture of methanol and ethanol was nondestructively measured by near infrared (NIR) spectroscopy. Two types of NIR instruments, portable NIR system with a photo-diode array and scanning type NIR spectrometer were used and the calibration results were compared. Partial least squares regression (PLSR) was applied for the calibration and validation for the quantitative analysis. The calibration results from both instruments showed good correlation with actual values. The calibration with the use of PLS model predicted water concentration with a standard error of prediction (SEP) of 0.10% and 0.12% for photo diode array and scanning type, respectively. During 6 days, routine analyses for 3%, 5% and 7% water in ethanol solution with 2% methanol were performed to validate the robustness of the developed calibration model. The routine analyses showed good results with coefficient of variation (CV) of within 3% for both types of NIR spectrometers. This study showed that the rapid determination of water in the mixture of methanol and ethanol was successfully performed by NIR spectroscopy and the performance of the portable NIR system with a photo diode array detector was comparable to that of the scanning type NIR spectrometer.