• Journal of Korean Society of Water and Wastewater
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• v.33 no.3
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• pp.225-234
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• 2019

This study is focused on effects of factors that affect the formation of THMs during chlorination in drinking water treatment. During the chlorination, chlorine consumption is increased by increasing the initial chlorine dose, the pH and the total dissolved solid (TDS) concentration. Also THMs formation is increased up to $58.82{\mu}g/L$ and $55.54{\mu}g/L$ by increasing initial chlorine concentration and increasing pH. However, concentration of chloroform is decreased by increasing TDS concentration. This is caused the cation($Na^+$) of the total dissolved solids preferentially reacts with the functional groups of the organic material which influence the trihalomethane formation. But total trihalomethane formation is increased up to $127.46{\mu}g/L$ by $Br^-$ contained in the total dissolved solids. DOC reduction was not influenced by any of the factors.

• Journal of Microbiology and Biotechnology
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• v.8 no.3
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• pp.237-244
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• 1998

A study was carried out to elucidate the relation between the production of flavonol glycosides and the change of phenylalanine ammonia-lyase activity in cell suspension cultures of Ginkgo biloba by the unassisted and synergistic effects of various factors. The quercetin production showed a mixed-growth-associated pattern in cell suspension cultures. Fluorescent light and UV radiation increased phenylalanine ammonia-lyase (PAL) activity, and resulted in the increase of the production of quercetin and kaempferol ten- and four-fold, respectively, as compared to that obtained in the normal culture condition. The cell growth of Ginkgo biloba was enhanced .at higher temperatures whereas the quercetin production was at its maximum at low temperatures. Moreover, the quercetin production was increased by temperature change during the culture period. In particular, the quercetin production was at the highest level when the culture temperature was elevated from $10^{\circ}C\;to\;30^{\circ}C$. The addition of phenylalanine as a precursor in the culture medium stimulated an 8-fold increase in the production of quercetin; the addition of naringenin caused a l0-fold increase. The quercetin production was also greatly increased by feeding enzyme cofactors such as 2-ketoglutarate and ascorbic acid in the culture medium, but specific PAL activity was not increased except with phenylalanine feeding. The synergistic effect of UV radiation and naringenin feeding was observed, resulting in the increase of flavonol glycoside production at a rate higher than in any other case investigated.

• Korean Chemical Engineering Research
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• v.47 no.1
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• pp.127-132
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• 2009

This report examines the economic feasibility of a commercial 50,000 barrel per day direct coal liquefaction(DCL) facility to produce commercial-grade diesel and naphtha liquids from medium-sulfur bituminous coal. The scope of the study includes capital and operating cost estimates, sensitivity analysis and a comparative financial analysis. Based on plant capacity of 50,000BPD, employing Illinois #6 bituminous coal as feed coal the total capital cost appeared $3,994,858,000. Also, the internal rate of return of DCL appeared 6.60% on the base condition. In this case, coal price and sale price of products were the most influence factors. And DCL's payback period demanded a long time(12.3 years), because of high coal price at the present time. According to sensitivity analyses, the important factors on DCL processes were product sale price, feed coal price and the capital cost in order.

• Journal of Korean Society on Water Environment
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• v.23 no.1
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• pp.111-121
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• 2007

The experimental design and response surface methodologies haven been applied to the investigation of the chemical coagulation of livestock wastewater. The chemical coagulation reactions were mathematically described as a function of parameters raping mixing (rpm) of chemical coagulation ($X_1$), slow mixing (rpm) of chemical coagulation ($X_2$), $FeCl_3 $ concentration (mg/L) ($X_3$) and pH ($X_4$) being modeled by use of the central composite design. Empirical models were developed to describe relationship between the experimental variables and response. Statistical analysis indicates that three factors ($X_1$: raping mixing (rpm), $X_2$: slow mixing (rpm), $X_3$: $FeCl_3 $ concentration (mg/L) on the linear term (main effect), slow mixing (rpm) (${X_2}^2$) on the non-linear term (quadratic), and two factors ($X_1-X_3$, $X_2-X_3$) on the non-linear term (cross-product) had significant effects, respectively. The estimated ridge of maximum responses and optimal conditions for CODcr using canonical analysis was 87.44% ($X_1$: 229 rpm, $X_2$: 51 rpm, $X_3$: 877 mg/L, $X_4$: 4.3). To confirm this optimum condition, three additional experiments were performed and the mean CODcr removal (%) and concentration (mg/L) with a standard deviation of $87{\pm}1.2%$ ($576{\pm}34ppm$) were obtained.

• Journal of the Korean Institute of Gas
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• v.18 no.4
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• pp.68-75
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• 2014

It is necessary to control and evaluate human factors to reduce economic loss by major accident in toxic gas facilities. Conventional works to evaluate hazards have been focused on mechanical and systematic failure, while only a little works have been studied on managing human errors. In this work, a classification system of performance shaping factor (PSF) was suggested to consist human error in managing accident in the toxic gas facilities. Four types of PSFs (human, system, task characteristics, and task environment) were collected, reviewed, and analyzed to be categorized selected according their characteristics of situational, task, and environmental parameters. The PSFs were further modified to set up PSF systems adequate to evaluate human error, and the proposed system to consist PSFs to evaluate human error was further studied through accident analysis in toxic gas facilities.

• Toxicological Research
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• v.28 no.4
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• pp.269-277
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• 2012

The purpose of this study was to understand the mechanism of cardiovascular disease (CVD) caused by exposure to hazardous chemicals. We investigated changes in the symptoms of metabolic syndrome, which is strongly related to CVD, and in levels of other CVD risk factors, with a special emphasis on the roles of catecholamines and oxidative stress. The results revealed that neither body mass index (BMI) nor waist and hip circumferences were associated with exposure to hazardous chemicals. Among metabolic syndrome criteria, only HDL-cholesterol level increased on exposure to hazardous chemicals. Levels of epinephrine (EP) and norepinephrine (NEP) were not influenced by exposure to hazardous chemicals; however, the total antioxidative capacity (TAC) reduced because of increased oxidative stress. Both hazardous chemical exposure level and metabolite excretion were related to EP, NEP, and the oxidative stress index (OSI). Logistic regression analysis with these factors as independent variables and metabolic syndrome criteria as dependent variables revealed that EP was associated with blood pressure, and NEP with metabolic syndrome in the chemical-exposed group. In conclusion, the results suggest that reactive oxygen species generated and oxidative stress due to exposure to hazardous chemicals act as mediators and cause changes in the physiological levels of EP and NEP to increase blood pressure. This ultimately leads to the development of CVD through increase in cholesterol, triglyceride, and blood glucose levels by lipid peroxidation.

• Applied Chemistry for Engineering
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• v.9 no.5
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• pp.768-773
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• 1998

A mathematical model of discharge mechanism of metal-hydride (MH) electrode was presented. A computer simulation program was developed in order to predict the variation of electrode potential and the distribution of hydrogen concentration within MH particles during discharge. By investigating the effects of the discharge current density, the size of MH particle, the diffusivity of hydrogen in MH particle, and the porosity of the electrode, it was found that these factors exerted a collective effect on the discharge characteristic of the electrode and the utilization of hydrogen in the MH particle. It was confirmed that and optimization of design factors of an MH electrode is necessary in order to execute a high-rate discharge and to improve the utilization of hydrogen in MH particle.

• Journal of radiological science and technology
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• v.44 no.4
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• pp.335-342
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• 2021

Studies on the side effects of contrast agents are being discussed based on various cases, but studies analyzing the chemical structure of the underlying contrast agents are difficult to understand as the manufacturers have not disclosed them. Therefore, in this study, the chemical structure of the contrast medium was analyzed using ¹H-NMR spectrometer for Omnipaque contrast medium prepared from Iohexol, which is a nonionic iodide contrast medium, Xenetix contrast medium from Iobitridol, and Iomeron contrast medium from Iomeprol. As a result, it was found that the Omnipaque contrast medium of Iohexol had 6 carboxyl groups, 3 carbonyl groups, 4 amine groups, 1 methyl group, and 2 cyano groups. It was found that the Xenetix contrast medium of the iobitridol formulation had 6 carboxyl groups, 3 carbonyl groups, 2 amine groups, and 4 cyano groups. It was found that the Iomeron contrast agent of the Iomeprol formulation had 5 carboxyl groups, 3 carbonyl groups, 4 amine groups, 1 methyl group, and 2 cyano groups. As shown in this study, the chemical structure of the non-ionic monomer contrast agent increases its affinity with water by binding a number of hydroxyl groups (OH) to the carboxyl group. It is necessary to accurately identify each of these factors and analyze the physical and chemical changes of the contrast medium according to various environmental factors.

• Bulletin of the Korean Chemical Society
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• v.33 no.8
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• pp.2651-2656
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• 2012

Sulfonated cellulose tris(3,5-dimethylphenylcarbamate) (SCDMPC)-coated zirconia monolith (ZM) was used as the chiral stationary phase in capillary electrochromatography for separation of enantiomers of ten chiral compounds in acetonitrile (ACN)-phosphate buffer mixtures as the eluent. Influences of the ACN content, buffer concentration and pH on chiral separation have been investigated. Separation data on SCDMPC-ZM have been compared with those on CDMPC-ZM. Resolution factors were better on SCDMPC-ZM than CDMPC-ZM while retention factors were in general shorter on the former than the latter. Best chiral resolutions on SCDMPC-ZM were obtained with the eluent of 50% ACN containing 50 mM phosphate at pH around 4.

• Elastomers and Composites
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• v.52 no.4
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• pp.272-279
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• 2017

The heterocoagulation of latex is a simple and useful method to fabricate various polymer nanocomposites in which a precise control of the colloid stability is essential. In this work, a multi-layered graphenes (MLGs)/poly(styrene-co-butyl acrylate) (P(S-co-BA)) nanocomposite having an excellent dispersion of MLGs was prepared via the sudden heating heterocoagulation process. The P(S-co-BA) component was obtained by emulsion polymerization. This process can effectively shorten the process and particles growth steps. The colloid stability of these dispersions was controlled by factors such as ionic charge, temperature, and reaction times. The influence of these factors on heterocoagulation was evaluated and the properties of the nanocomposites were investigated. The conductivity of the MLGs/P(S-co-BA) nanocomposites increased from -11.53 to -5.70 S/cm for an increase in MLG content from 0.01 to 5 wt%. Moreover, percolation threshold was observed in the case of 0.01 wt% MLGs.