• Journal of ILASS-Korea
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• v.16 no.2
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• pp.82-89
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• 2011

When pipe components made of carbon steel in nuclear, fossil, and industry plants are exposed to flowing fluid, wall thinning caused by FAC(flow accelerated corrosion) can be generated and eventually ruptured at the position of pressure boundary. The aim of this study is to identify the locations at which local wall thinning occurs and to determine the turbulence coefficient related to local wall thinning. Experiment and numerical analyses for the tee sections of down scaled piping components were performed and the results were compared. In particular, flow visualization experiment which was used alkali metallic salt was performed to find actual location of local wall thinning inside tee components. In order to determine the relationship between turbulence coefficients and local wall thinning, numerical analyses were performed for tee components in the main feedwater systems. The turbulence coefficients based on the numerical analyses were compared with the local wall thinning based on the measured data. From the comparison of the results, the vertical flow velocity component(Vr) flowing to the wall after separating in the wall due to the geometrical configuration and colliding with the wall directly at an angle of some degree was analogous to the configuration of local wall thinning.

• Biomolecules & Therapeutics
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• v.8 no.2
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• pp.119-124
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• 2000

We hypothesized that the extent of hypoxic injury would be involved in reduction of oxygen delivery to the tissue. Livers isolated from 18 hr-fasted rats were subjected to $N_2$-induced hypoxia or low flow hypoxia. Livers were perfused with nitrogen/carbon dioxide gas for 45min or perfused with normoxic Krebs-Henseleit bicarbonate buffer (KHBB) at low flow rates around 1 ml/g liver/min far 45min, which caused cells to become hypoxic because of insufficient delivery of oxygen. When normal flow rates(4 ml/g liver/min) of KHBB (pH 7.4, 37$^{\circ}C$, oxygen/carbon dioxide gas) were restored for 30min reoxygenation injury occurred. Lactate dehydrogenase release gradually increased in $N_2$-induced hypoxia, whereas it rapidly increased in low flow hypoxia. Total glutathione in liver tissue was not changed but oxidized glutathione markedly increased after hypoxia and reoxygenation, expecially in $N_2$-induced hypoxia. Similarly, lipid peroxidation in liver tissue significantly increased after hypoxia and reoxygenation in low flow hypoxia. Hepatic drug metabolizing functions (phase I, II) were suppressed during hypoxia, especially in $N_2$-induced hypoxia but improved by reoxygenation in both models. Our findings suggest that hypoxia results in abnormalities in drug metabolizing function caused by oxidative stress and that this injury is dependent on hypoxic conditions.

• Corrosion Science and Technology
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• v.16 no.1
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• pp.23-30
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• 2017

The inhibition effect of thioureido imidazoline inhibitor (TAI) for flow accelerated corrosion (FAC) at different locations for an X65 carbon steel elbow was studied by array electrode and computational fluid dynamics (CFD) simulations. The distribution of the inhibition efficiency measured by electrochemical impedance spectroscopy (EIS) is in good accordance with the distribution of the hydrodynamic parameters at the elbow. The inhibition efficiencies at the outer wall are higher than those at the inner wall meaning that the lower inhibition efficiency is associated with a higher flow velocity, shear stress, and turbulent kinetic energy at the inner wall of the elbow, as well as secondary flow at the elbow rather than the mass transport of inhibitor molecules. Compared to the static condition, the inhibition efficiency of TAI for FAC was relatively low. It is also due to a drastic turbulence flow and high wall shear stress during the FAC test, which prevents the adsorption of inhibitor and/or damages the adsorbed inhibitor film.

• Environmental Engineering Research
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• v.21 no.4
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• pp.355-364
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• 2016

Beijing, as a cradle of modern industry and the third largest metropolitan area in China, faces more responsibilities to adjust industrial structure and mitigate carbon emissions. The purpose of this study is aimed at predicting and comparing industrial carbon emissions of Beijing in ten scenarios under different policy focus, and then providing emission-cutting recommendations. In views of various scenarios issues, system dynamics has been applied to predict and simulate. To begin with, the model has been established following the step of causal loop diagram and stock flow diagram. This paper decomposes scenarios factors into energy structure, high energy consumption enterprises and growth rate of industrial output. The prediction and scenario simulation results shows that energy structure, carbon intensity and heavy energy consumption enterprises are key factors, and multiple factors has more significant impact on industrial carbon emissions. Hence, some recommendations about low-carbon mode of Beijing industrial carbon emission have been proposed according to simulation results.

• Journal of Chest Surgery
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• v.37 no.2
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• pp.131-138
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• 2004

High-flow gas insufflation to get a bloodless field during off-pump coronary artery bypass may have adverse effects on the coronary endothelium. This study was designed (1) to elucidate the effect of carbon dioxide gas insufflations on the coronary endothelium at different flow rates and (2) to assess the protective effect of humidifcation against the coronary endothelial damage. Material and Method: In nine pigs, the left anterior descending coronary artery (LAD) was exposed after a median sternotomy. The LAD was divided into 4 segments and a coronary arteriotomy was made in each LAD segment in the beating heart. The far distal arteriotomy was exposed to room air for 10 minutes and was harvested as a control. Non-humidified carbon dioxide gas at a continuous flow rate of 5 L/min (Group I), humidified carbon dioxide gas at a continuous flow rate of 5 L/min (Group II), and humidified carbon dioxide gas at a continuous flow rate of 10 L/min (Group III) were insufflated for 10 minutes on each coronary arteriotomy site, respectively. After harvesting the coronary segments, hematoxylin-eosin staining, elastic fiber staining, and immunostaining with a CD34 monoclonal antibody were performed to evaluate the depth of endothelial damage and to count the residual endothelial cells, Result: In all three groups (Group I, II, and III), internal elastic laminae were preserved, however, the endothelial layers were significantly damaged by carbon dioxide gas insufflation. The mean percentages of remaining endothelial cells were 20,9$\pm$16.7%, 39.3$\pm$19.6%, and 6.8$\pm$5.3%, in groups I, II, and III, respectively. The percentages of remaining cells were significantly higher in group II than in groups I and III (p=0.008). The percentages of remaining cells were significantly higher in group I than in group III (p=0.008). Conclusions: The harmful effect of carbon dioxide gas insufflation on the coronary endothelium was dependent on the flow rate. The addition of humidification did not protect the coronary endothelium from denudation injury caused by high flow carbon dioxide gas insufflations.

• Journal of Energy Engineering
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• v.24 no.3
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• pp.89-95
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• 2015

Carbon felts manufactured by (Co)CNF were subjected to heat treatment under different temperatures to use for the electrode of a redox-flow battery. BET and weight loss were tested to investigate the physical properties of the carbon felt according to the heat treatment conditions. SEM and XPS were also analyzed to characterize their surface area. In addition, electrical resistance, CV (cyclic voltammetry) and RFB charge on the electrode properties were examined in accordance with the heat treatment conditions with the discharge performance. The changes of physical properties on the carbon felt surface was confirmed via SEM and BET analysis, The most addition of oxygen functional groups on the carbon felt surface was obtained when one hour heat treatment at $550^{\circ}C$ and it was confirmed by XPS analysis. After resulting the CV tests, the active area of the electrode was the largest at $550^{\circ}C$ heat treatment. The heat treatment experiment of vanadium redox flow battery using the carbon felts were tested at $400^{\circ}C$, $500^{\circ}C$ and $550^{\circ}C$. As a result, the charge-discharge energy efficiency of the heat treatment electrode was 72.9% and 79.8%, at $400^{\circ}C$ and $500^{\circ}C$, respectively. The efficiency of the heat treatment electrode at $550^{\circ}C$ was the best as 79.8% at $550^{\circ}C$.

• Journal of the Korean Vacuum Society
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• v.18 no.1
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• pp.49-53
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• 2009

The chemical properties of SiOC film was studied for inter-layer insulator. SiOC film was formed with non polarity due to the appropriate union by the alkyl and hydroxyl group. An amorphous structure of non polarity can induce the low dielectric constant materials. The chemical properties of thin film can define the bonding structure owing to the ionic variation, and the analysis of chemical properties was researched by the carbon content using the FTIR spectra, and induced the film with non polarity. The electrical properties is the electron flow, and is always not the same as the chemical properties. The electrical properties of SiOC film with various flow rate ratios was analyzed and researched the correlation between the chemical properties. SiOC film showed the increasing of the leakage current after annealing process, and abruptly increased the carbon content at some samples. But the sample with increasing the carbon content decreased the leakage current. It means that the chemical properties is not the same as the electrical properties, and the carbon is related with the variation of the bonding structure, and does not contribute the current flow.

• Carbon letters
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• v.13 no.2
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• pp.109-114
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• 2012

A nuclear, biological, chemical (NBC) canister was indigenously developed using active carbon impregnated with ammoniacal salts of copper (II), chromium (VI) and silver (I), and high efficiency particulate aerosol filter media. The NBC canister was evaluated against carbon tetra chloride ($CCl_4$) vapours, which were used as a simulant for persistent chemical warfare agents under dynamic conditions for testing breakthrough times of canisters of gas masks in the National Approval Test of Respirators. The effects of $CCl_4$ concentration, test flow rate, temperature, and relative humidity (RH) on the breakthrough time of the NBC canister against $CCl_4$ vapour were also studied. The impregnated carbon that filled the NBC canister was characterized for surface area and pore volume by $N_2$ adsorption-desorption isotherm at liquid nitrogen temperature. The study clearly indicated that the NBC canister provides adequate protection against $CCl_4$ vapours. The breakthrough time decreased with the increase of the $CCl_4$ concentration and flow rate. The variation in temperature and RH did not significantly affect the breakthrough behaviour of the NBC canister at high vapour concentration of $CCl_4$, whereas the breakthrough time of the NBC canister was reduced by an increase of RH at low $CCl_4$ vapour concentration.

• Carbon letters
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• v.25
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• pp.68-77
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• 2018

Soybean straw (SS)-based activated carbon was employed as a precursor to prepare carbon molecular sieves (CMSs) via chemical vapor deposition (CVD) technique using methane as carbon source. Prior to the CVD process, SS was activated by 0.5 wt% $ZnCl_2$, followed by a carbonization at $500^{\circ}C$ for 1 h in $N_2$ atmosphere. $N_2$ (77 K) adsorption-desorption and $CO_2$ (273 K) adsorption tests were carried out to analyze the pore structure of the prepared CMSs. The results show that increasing the deposition temperature, time or methane flow rate leads the decrease in $N_2$ adsorption capacity, micropore volume and average pore diameter of CMSs. The adsorption selectivity coefficient of $CO_2/CH_4$ achieves as high as 20.8 over CMSs obtained under the methane flow rate of $30mL\;min^{-1}$ at $800^{\circ}C$ for 70 min. The study demonstrates the prepared CMSs are a candidate adsorbent for $CO_2/CH_4$ separation.

• 한국연소학회:학술대회논문집
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• 2006.10a
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• pp.299-303
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• 2006

From the analysis of fly ash, which contains unburned carbon, collected from the coal-fired Yong Hung power station, most particles are turned out to be hollow cenosphere and agglomerated soot particles. The sooting potential from six coals used in the plant were investigated with CPD model. The results show that the higher potential presented to Peabody, Arthur, Shenhua coals rather than other coals. It is necessary to measure the coal flow rates at each coal feeding pipe for four burner levels since they affect the extent of mixing of soot with oxidant, in turn, the oxidation rate of soot particles. The unbalance in coal flow rate was found in several coal pipes. We successfully reduced unburned carbon in ash by increasing the excess air and changing the SOFA yaw angle.