• Toxicological Research
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• v.20 no.3
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• pp.195-203
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• 2004

4-Tert-Octylphenol (OP) is a surfactant additive widely used in the manufacture of a variety of detergents and plastic products. OP can disrupt endocrine function in humans and animals. This study was carried out to obtain toxicokinetic parameters of OP in male Sprague-Dawley (SD) rats. Male rats were administered with OP by single oral application of 200 mg/kg body weight. Blood, urine and tissues samples were taken at several time intervals after administration. Analysis of samples for OP was performed by column-switching high performance liquid chromatography (HPLC). In addition, we exam-ined tissue distribution and accumulation of OP after single oral application of 50, 100, and 200 mg/kg, single intravenous injection of 1, 5 and 10 mg/kg or daily application of 50 mg/kg for 14 consecutive days. After single oral administration of 200 mg/kg, Cmax of 213 $\pm$ 123 ng/ml was reached within the first 1.3 hr (Tmax) in the plasma. AUC was calculated for 1,333$\pm$484 ngㆍhr/ml. The final elimination half-life of plasma was longer than that of urine, but urinary clearance was lower than oral. A very small fraction of OP (Fe < 0.0017%) was excreted in urine within 24 hr. These results indicated that the major excretion route of OP was not urine. The mean maximal tissue distribution of OP was obserbed at 6 hr after treatment and slowly decreased time-dependently. High OP concentrations were detected in fat at 24 hr. The OP in fat was slowly released with longer elimination half-life and lower clearance than that of other tissues. OP was not accumulated in the liver following single oral application but 14-day oral treatments resulted in two-fold accumulation. It was probably due to the saturation of detoxification pathways. On the other hand, the mRNA expression of cytochrome P450 isoforms except CYP2C11 was not affected by OP at any dose. The expression of CYP2C11 mRNA decreased in a dose-dependent manner. This result suggests that OP changes expression of the male-specific cytochrome P450 isoforms in rat liver, and these changes are closely related to the toxic and estrogenic effect of OP.

• Toxicological Research
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• v.19 no.1
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• pp.21-27
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• 2003

A teratogenic study of dimethyl dimethoxy biphenylate derivative (DDB-S) was carried out on Sprague-Dawley rats. DDB-S dissolved in saline was administered to male and female rats by intravenously injection at daily doses of 50 mg/kg, 75 mg/kg, and 100 mg/kg. A half of dams were sacrificed at 20th day of gestation to scrutinize the pregnant performances and fetal development. And the remaining dams were allowed to deliver. The growth, reflex, behaviour and reproductive function of F1 offsprings were examined. There was no treatment-related difference in body weight, food consumption and necropsy findings of dams. No gross, skeletal and visceral abnormalities was observed in F1 fetuses from dams treated with DDB-S. F1 offsprings did not show any treatment-related difference in growth, reflex, behaviour and reproductive performance. At caesarean section of F1 dams, no growth retardation and gross abnormality was observed in F2 fetuses. In conclusion, DDB-S did not show any potential teratogenic effect in rats.

• 한국지구물리탐사학회:학술대회논문집
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• 2006.06a
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• pp.117-122
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• 2006

In the geophysical monitoring to understand the change of subsurface material properties with time, the time-invariant static subsurface model is commonly adopted to reconstruct a time-lapse image. This assumption of static model, however, can be invalid particularly when fluid migrates very quickly in highly permeable medium in the brine injection experiment. In such case, the resultant subsurface images may be severely distorted. In order to alleviate this problem, we develop a new least-squares inversion algorithm under the assumption that the subsurface model will change continuously in time. Instead of sampling a time-space model into numerous space models with a regular time interval, a few reference models in space domain at different times pre-selected are used to describe the subsurface structure continuously changing in time; the material property at a certain space coordinate are assumed to change linearly in time. Consequently, finding a space-time model can be simplified into obtaining several reference space models. In order to stabilize iterative inversion and to calculate meaningful subsurface images varying with time, the regularization along time axis is introduced assuming that the subsurface model will not change significantly during the data acquisition. The performance of the proposed algorithm is demonstrated by the numerical experiments using the synthetic data of crosshole dc resistivity tomography.

• Tunnel and Underground Space
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• v.30 no.5
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• pp.446-461
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• 2020

Numerical simulations of CIEMAT column test in Spain are performed to investigate the coupled thermo-hydro-mechanical (THM) behavior of MX80 bentonite pellets using TOUGH2-FLAC3D. The heater power and injection pressure of water in the numerical simulations are identical to those in the laboratory test. To investigate the applicability of the thermo-hydraulic (TH) model used in TOUGH2 code to prediction of the coupled TH behavior, the simulation results are compared with the observations of temperature and relative humidity with time. The tendencies of the coupled behavior observed in the test are well represented by the numerical models and the simulator in terms of temperature and relative humidity evolutions. Moreover, the performance of the models for the reproduction and prediction of the coupled TH behavior is globally satisfactory compared with the observations. However, the calculated stress change is relatively small and slow due to the limitations of the simple elastic and swelling pressure model used in numerical simulations. It seems that the two models are insufficient to realistically reproduce the complex coupled THM behavior in the bentonite pellets.

• Journal of the Korean Society of Food Science and Nutrition
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• v.39 no.8
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• pp.1231-1235
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• 2010

The method for residue analysis of four sulfonylurea pesticides, rimsulfuron, ethametsulfuron-methyl, tribenuron-methyl and chlorimuron-ethyl was examined and analyzed by HPLC with ODS column ($250\;mm{\times}4.6\;mm$, $5\;{\mu}m$ diameter particle size) which was maintained at $35^{\circ}C$. Mobile phase consisted of solvent A (20 mM $KH_2PO_4$, pH 2.5) and solvent B (acetonitrile). Isocratic elution of the column with 45% solvent A and 55% solvent B at a flow rate of 1 mL/min resulted in retention times of 5.92, 6.54, 9.28, and 14.35 min for rimsulfuron, ethametsulfuron-methyl, tribenuron-methyl, and chlorimuron-ethyl, respectively. All injection volumes were $20\;{\mu}L$. The limit of quantitation was 0.02, 0.01, 0.001, and 0.004 mg/kg for rimsulfuron, ethametsulfuron-methyl, tribenuron-methyl, and chlorimuron-ethyl, respectively. Recovery rate test was performed with three farm products, rice, apple and soybean. Four sulfonylurea pesticides were spiked at concentrations of 0.05, 0.1 and 0.5 mg/kg. The recovery rates were ranged from 86.12% to 116.26% and the standard deviations of all experiments were within 10%.

• Journal of the Korean Society of Food Science and Nutrition
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• v.43 no.6
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• pp.799-806
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• 2014

The present study was conducted to evaluate the effects of extract from Eriobotrya japonica leaves (EJE) on cognitive impairment induced by scopolamine, a muscarinic antagonist, in rats. Scopolamine injection (1 mg/kg, i.p.) impaired performance in rats in the passive avoidance test as well as in water maze test and severely reduced cholinergic system reactivity, as indicated by reduced acetylcholine levels and increased acetylcholinesterase activity. Daily administration of EJE significantly increased step-through latency in the passive avoidance test, reduced escape latency, and increased time spent in the platform quadrant in the Morris water maze test. EJE protected against scopolamine-induced cholinergic system deficit, including reduced acetylcholine levels and increased acetylcholinesterase activity in whole brain homogenates. These results suggest that EJE provides a significant anti-amnesic effect against scopolamine-induced cholinergic system deficits and cognitive impairment.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.40 no.3
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• pp.127-138
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• 2016

Diesel vehicles should be equipped with urea-selective catalytic reduction(SCR) system as a high-performance catalyst, in order to reduce harmful nitrogen oxide emissions. In this study, a three-dimensional Eulerian-Lagrangian CFD analysis was used to numerically predict the multiphase flow characteristics of the urea-SCR system, coupled with the chemical reactions of the system's transport phenomena. Then, the numerical spray structure was modified by comparing the results with the measured values from spray visualization, such as the injection velocity, penentration length, spray radius, and sauter mean diameter. In addition, the analysis results were verified by comparison with the removal efficiency of the nitrogen oxide emissions during engine and chassis tests, resulting in accuracy of the relative error of less than 5%. Finally, a verified CFD analysis was used to calculate the interanl flow of the urea-SCR system, thereby analyzing the characteristics of pressure drop and velocity increase, and predicting the uniformity index and overdistribution positions of ammonia.

• Journal of IKEEE
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• v.24 no.3
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• pp.913-916
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• 2020

In this paper, we propose the development of nitrogen cooling equipment for personalized local area. The proposed equipment consists of a cold air supply module, a body, and nitrogen injection with the following characteristics. First, it automatically controls the amount and time of cold air supply by utilizing information measuring skin temperature with volumetric temperature sensors, so it can have a competitive edge in function by ensuring complete safety. Second, if the distance measuring sensor is applied to the skin for more than a certain distance, it can block the cold air or control the discharge of nitrogen in conjunction with the control GUI to improve the efficiency of higher cooling therapy while providing safe management. Third, by installing a control module that can control the supply of nitrogen, the cost of maintenance can be minimized by minimizing the loss of nitrogen. Experiments at an external testing agency to evaluate the performance of the proposed equipment showed that the accuracy of the temperature sensor was measured in the range of ±3.8%, which is lower than the world's highest level(±5%), with a range of 110℃ to -160℃ similar to the world's highest level. Distance accuracy was measured in the range of ±3.0%, lower than the world's highest level(±5%), and weight accuracy in the range of ±0.1%, lower than the world's highest level(±5%). In addition, emission control was measured in four stages, higher than the world's highest level(stage 1) and nitrogen use was measured at 0.8L/min below the world's highest(6L/min). Therefore, the effectiveness of the methods proposed in this paper was demonstrated because they produced the same results as the world's highest levels.

• Analytical Science and Technology
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• v.8 no.2
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• pp.215-220
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• 1995

A simple, efficient and sensitive method was described for the simultaneous determination of catecholamine, indoleamine and related metabolites from the homogenates of the rat brain striatum by HPLC-ECD. The optimum mobile phase on a reverse phase $C_{18}$ column was 35mM sodium acetate buffer(included 10mM citric acid, 0.13mM $Na_4EDTA$, 0.58mM SOS, pH3-4):MeOH=85:15. The column temperature was $30^{\circ}C$. Dopamine(DA), 3, 4-dihydroxyphenyl acetic acid(DOPAC), homovanilic acid(HVA), 5-hydroxyindole acetic acid(5-HIAA), serotonin(5-HT) and noradrenaline(NA) could be separated and analysed to very small amount. The detection limits of this method were 2~10pg per injection for all components. The effects of age and sex of rat on the contents of the catecholamines and their metabolites in rat brain striatum were studied. The levels of DA and 5-HT contents of the 7 week old female rats were higher than those of the 7 week old male rats. As the age of rat increases, the contents of DOPAC increased significantly.

• The Korean Journal of Nuclear Medicine
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• v.31 no.1
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• pp.50-56
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• 1997

Gated SPECT can evaluate the regional wall motion of the heart. We evaluated the regional wall motion of the perfusion abnormality in conventional perfusion SPECT with gated SPECT. In case of suspicious perfusion abnormalities, we tried to differentiate the artifact from true abnormality in coronary vascular disease using gated SPECT. We thought that artifacts would have normal wall motion, whereas fixed defects with decreased wall motion would probably represent coronary artery disease. A total of 275 patients who were performed coronary angiography and T1-201 rest/Tc-99m MIBI dipyridamole stress gated SPECT within 2 months were enrolled. In coronary angiography, stenosis more than 50% was considered as coronary artery disease. After injection of 111MBq T1-201 rest image was obtained on triple head SPECT system. 370MBg Tc-99m MIBI was used for the stress image. Eight-frame per-cardiac-cycle gated Tc-99m SPECT studies were done. All the images were analyzed visually. Using perfusion SPECT, the overall sensitivity and specificity were 87% and 55% respectively. Regarding artery territory, sensitivity and specificity were 68% and 73% for left anterior descending artery(LAD), 62% and 78% for right coronary artery(RCA), 42% and 90% for left ciramflex artery(LCX). Using gated SPECT, the overall sensitivity and specificity were 87% and 66% respectively. Sensitivity and specificity were 68% and 78% for LAD, 62% and 79% for RCA, 42% and 90% for LCX. Among 21 false positive cases in perfusion SPECT, 5 cases were interpreted as true negative with gated SPECT. We conclude that gated SPECT provides a valuable adjunct to perfusion SPECT in characterizing perfusion abnormalities and to improve specificity.