• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.57 no.3
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• pp.256-263
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• 2021

In this study, blending oils of diesel oil and butanol were used as fuel oil for diesel engine to measure combustion pressure, fuel consumption, air ratio and exhaust gas emission due to various operating conditions such as engine revolution and torque. Using these data, the results of analyzing the engine performance, combustion characteristics and exhaust emission characteristics such as NOx (nitrogen oxides), CO₂ (carbon dioxide), CO (carbon monoxide) and soot were as follows. The fuel conversion efficiency at each load was highest when driven in the engine revolution determined by a fixed pitch propeller law. Except 30% butanol blending oil, fuel conversion efficiency of the other fuel oils increased as the load increased. Compared to diesel oil, using 10% and 20% butanol blending oil as fuel oil was advantageous in terms of thermal efficiency, but it did not have a significant impact on the reduction of exhaust gas emissions. On the other hand, future research is needed on the results of the 20% butanol blending oil showing lower or similar levels of smoke concentration and carbon monoxide emission rate other than those types of diesel oil.

• Applied Chemistry for Engineering
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• v.35 no.2
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• pp.85-95
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• 2024

Direct air capture (DAC) technology plays a crucial role in mitigating climate change. Reports from the International Energy Agency and climate change emphasize its significance, aiming to limit global warming to 1.5 ℃ despite continuous carbon emissions. Despite initial costs, DAC technology demonstrates potential for cost reductions through research and development, operational learning, and economies of scale. Recent advancements in high-permeance polymer membranes indicate the potential of membrane-based DAC technology. However, effective separation of CO₂ from ambient air requires membranes with high selectivity and permeability to CO₂. Current research is focusing on membrane optimization to enhance CO₂ capture efficiency. This study underscores the importance of direct air capture, evolving cost trends, and the pivotal role of membrane development in climate change mitigation efforts. Additionally, this research delved into the theoretical background, conditions, composition, advantages, and disadvantages of permeance and selectivity in membrane-based DAC.

• Journal of the Korean Electrochemical Society
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• v.25 no.2
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• pp.88-94
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• 2022

The anion exchange membrane used in alkaline membrane fuel cells transports hydroxide ions, and ion conductivity affects fuel cell performance. Thus, the measurement of absolute hydroxide ion conductivity is essential. However, it is challenging to accurately measure hydroxide ion conductivity since hydroxide ions are easily poisoned in the form of bicarbonate by carbon dioxide in the atmosphere. In this study, we applied electrochemical ion exchange treatment to measure the absolute hydroxide ion conductivity of the anion exchange membrane. In addition, we investigated the effect of carbon dioxide poisoning of hydroxide ions on electrochemical performance by measuring bicarbonate conductivity. Commercial anion exchange membranes (FAA-3-50 and Orion TM1) and polyphenylene-based block copolymer (QPP-6F) were used.

• Journal of Korean Society for Atmospheric Environment
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• v.17 no.1
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• pp.57-66
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• 2001

Gas phase photocatalytic oxidation of tetrachloroethylene (PCE) under 370 nm ultra-violet irradiation was investigated with TiO$_2$ catalyst. During the photocatalytic oxidation of PCE vapor several kinds of intermediate were produced, and the reaction pathways were proposed on the basis of the production sequency of the intermediates. The intermediates in the pathways of PCE oxidation were hexachloroethane, pentachlotoethane, 1, 1, 2-trichloroethane, carbon tetrachl-oride, dichloroacetylchloride, chloroform, 1,1-dichloroethane, phosgene, CO, $CO_2$, HCl, Cl$_2$.

• Safety and Health at Work
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• v.9 no.4
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• pp.468-472
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• 2018

Background: Firefighters are required to use self-contained breathing apparatus (SCBA), which impairs ventilatory mechanics. We hypothesized that firefighters have elevated arterial $CO_2$ when using SCBA. Methods: Firefighters and controls performed a maximal exercise test on a cycle ergometer and two graded exercise tests (GXTs) at 25%, 50%, and 70% of their maximal aerobic power, once with a SCBA facemask and once with protective clothing and full SCBA. Results: Respiratory rate increased more in controls than firefighters. Heart rate increased as a function of oxygen consumption ($V_{O_2}$) more in controls than firefighters. End-tidal $CO_2$ ($ETCO_2$) during the GXTs was not affected by work rate in either group for either condition but was higher in firefighters at all work rates in both GXTs. SCBA increased $ETCO_2$ in controls but not firefighters. Conclusions: The present study showed that when compared to controls, firefighters' hypoventilate during a maximal test and GXT. The hypoventilation resulted in increased $ETCO_2$, and presumably increased arterial $CO_2$, during exertion. It is proposed that firefighters have altered $CO_2$ sensitivity due to voluntary hypoventilation during training and work. Confirmation of low $CO_2$ sensitivity and the consequence of this on performance and long-term health remain to be determined.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.45 no.2
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• pp.46-55
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• 2013

Recently, there are growing interests on carbon emissions related in climate change which is worldwide emerging important issue. Some research works are now carrying out in order to reduce the carbon emission in pulp and paper industries by the synthesis of precipitated calcium carbonate using the exhaust carbon dioxide from combustion furnace or incinerator. However, for solving the original problems on carbon emission, we need to consider the analysis of basic methodology on $CO_2$ through the process efficiencies. There are two general tools for carbon emissions; one is the greenhouse gas inventory and the other is $LCCO_2$ method which is applied to particular items of raw materials and utilities in unit process. In this study, the carbon emissions in wood-containing printing paper production line were calculated by using $LCCO_2$ method. The general materials and utilities for paper production, such as fibrous materials, chemical additives, electric power, steam, and industrial water were analyzed. As the results, $Na_2SiO_3$ showed the highest loads in carbon emissions, and the total amount of carbon emissions was the highest in electricity. In the production line of printing paper using de-inked pulp and BTMP, as the mixing ratio of DIP was higher, the carbon emissions were decreased because of high use of electric power in TMP process.

• Korean Chemical Engineering Research
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• v.60 no.4
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• pp.606-612
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• 2022

Relatively high indoor CO₂ concentration (>1,000 ppm) has a negative impact on human health. In this work, indoor CO₂ adsorbent was developed by impregnating KOH or K₂CO₃ on commercial activated carbon, named as KOH/AC and K₂CO₃/AC. Commercial activated carbon (AC) showed relatively high BET surface area (929 m²/g) whereas KOH/AC and K₂CO₃/AC presented lower BET surface area of 13.6 m²/g and 289 m²/g. Two experimental methods of TGA (2,000 ppmCO₂, weight basis) and chamber test (initial concentration: 2,000 ppmCO₂, CO₂ IR analyzer) were used to investigate the adsorption capacity. KOH/AC and K₂CO₃/AC exhibited similar adsorption capacities (145~150 mg_CO2/g), higher than K₂CO₃/Al+Si supports adsorbent (84.1 mg_CO2/g_sample). Similarly, chamber test also showed similar trend. Both KOH/AC and K₂CO₃/AC represented higher adsorption capacities (KOH/AC: 93.5 mg_CO2/g K₂CO₃/AC: 94.5 mg_CO2/g_sample) K₂CO₃/Al+Si supports. This is due to the KOH or K₂CO₃ impregnation increased alkaline active sites (chemical adsorption), which is beneficial for CO₂ adsorption. In addition, the regeneration test results showed both K-based adsorbents pose a good regeneration and reusability. Finally, the current study suggested that both KOH/AC and K₂CO₃/AC have a great potential to be used as CO₂ adsorbent for indoor CO₂ adsorption.

• Korean Journal of Materials Research
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• v.30 no.11
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• pp.581-588
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• 2020

Reducing CO₂ into high value fuels and chemicals is considered a great challenge in the 21st century. Efficiently activating CO₂ will lead to an important way to utilize it as a resource. This article reviews the latest progress of g-C₃N₄ based catalysts for CO₂ reduction. The different synthetic methods of g-C₃N₄ are briefly discussed. Article mainly introduces methods of g-C₃N₄ shape control, element doping, and use of oxide compounds to modify g-C₃N₄. Modified g-C₃N₄ has more reactive sites, which can significantly reduce the probability of photogenerated electron hole recombination and improve the performance of photocatalytic CO₂ reduction. Considering the literature, the hydrothermal method is widely used because of its simple equipment and process and easy control of reaction conditions. It is foreseeable that hydrothermal technology will continue to innovate and usher in a new period of development. Finally, the prospect of a future reduction of CO₂ by g-C₃N₄-based catalysts is predicted.

• KSBB Journal
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• v.19 no.6 s.89
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• pp.427-432
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• 2004

The purpose of this study is to investigate the feasibility of a cosolvent-modified supercritical $CO_2\;(scCO_2)$ extraction technique for the production of licorice extracts with high levels of glabridin. The effects of various parameters such as the type and amount of modifiers, extraction temperature ($40{\sim}80^{\circ}C$) and pressure ($10{\sim}50.0\;MPa$) on the extraction efficiency were examined at a fixed flow rate of 1 mL/min. The organic solvent extraction with pure methanol was also conducted for a quantitative comparison with the $scCO_2$ extraction. The recovery of glabridin from licorice was found to be extremely small for pure $scCO_2$. However, the addition of modifiers such as ethanol and acetone to $scCO_2$ resulted in a significant improvement in the recovery of glabridin. The recovery of glabridin was observed to increase with pressure at a constant temperature. Furthermore, the purity of the glabridin obtained from the $scCO_2$ extraction was higher compared with the organic solvent extraction.

• Journal of Environmental Health Sciences
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• v.36 no.2
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• pp.128-135
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• 2010

The main purpose of this study was to develop the greenhouse gas emission factor for power plant using sub-bituminous coal. In Korea, Fired power plant are a major source of greenhouse gases within the fossil fuel combustion sectors, thus the development of emission factors is necessary to understand the characteristics of the national specific greenhouse gas emission and to develop nation specific emission factors. These emission factors were derived from the $CO_2$ concentrations measurement from stack and fuel analysis of sub-bituminous coal. Caloric value of sub-bituminous coal used in the power plants were 5,264 (as received basis), 5,936 (air-dried basis) and 6,575 kcal/kg (dry basis). The C emission factors by fuel analysis and $CO_2$ concentration measurement was estimated to be 26.7(${\pm}0.9$), 26.3(${\pm}2.8$)tC/MJ, respectively. Our estimates of C emission factors were comparable with IPCC default value.