• Journal of Chest Surgery
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• v.49 no.6
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• pp.456-460
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• 2016

Background: Surgical correction needs to be considered when diaphragm eventration leads to impaired ventilation and respiratory muscle fatigue. Plication to sufficiently tense the diaphragm by VATS is not as easy to achieve as plication by open surgery. We used pneumatic compression with carbon dioxide ($CO_2$) gas in thoracoscopic diaphragmatic plication and evaluated feasibility and efficacy. Methods: Eleven patients underwent thoracoscopic diaphragmatic plication between January 2008 and December 2013 in Pusan National University Hospital. Medical records were retrospectively reviewed, and compared between the group using $CO_2$ gas and group without using $CO_2$ gas, for operative time, plication technique, duration of hospital stay, postoperative chest tube drainage, pulmonary spirometry, dyspnea score pre- and postoperation, and postoperative recurrence. Results: The improvement of forced expiratory volume at 1 second in the group using $CO_2$ gas and the group not using $CO_2$ gas was $22.46{\pm}11.27$ and $21.08{\pm}5.39$ (p=0.84). The improvement of forced vital capacity 3 months after surgery was $16.74{\pm}10.18$ (with $CO_2$) and $15.6{\pm}0.89$ (without $CO_2$) (p=0.03). During follow-up ($17{\pm}17$ months), there was no dehiscence in plication site and relapse. No complications or hospital mortalities occurred. Conclusion: Thoracoscopic plication under single lung ventilation using $CO_2$ insufflation could be an effective, safe option to flatten the diaphragm.

• Geophysics and Geophysical Exploration
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• v.19 no.1
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• pp.37-44
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• 2016

$CO_2$-EOR (Carbon Dioxide-Enhanced Oil Recovery), one of the enhanced oil recovery methods, helps to not only enhance the production of oil, but also store carbon dioxide in underground. However, if micro fractures occur when during the injection of $CO_2$, it is difficult to make permanent storage of $CO_2$ in reservoir and can cause contamination of groundwater and soil. Therefore, in this study, we performed microseismic monitoring to investigate the occurrence of fractures during the $CO_2$ injection at the Meruap oil reservoir, Indonesia. To pick the first arrivals of microseismic events, Improved MER (Modified Energy Ratio) method was used. After picking the first arrivals, hodogram analysis was carried out by using the data recorded at three component geophones to calculate the back azimuth of events. Finally, locations of microseismic events were decided by using the results of first arrival picking and hodogram analysis. Estimated locations showed that all microseismic events were occurred at surface and any fracture did not occur around the reservoir. Moreover, by analyzing noise characteristic, we confirmed that almost of picked first arrivals were due to the repetitive mechanical noise.

• Journal of Marine Bioscience and Biotechnology
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• v.2 no.1
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• pp.55-59
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• 2007

The oil and concentrated protein powder from squid viscera was extracted and recovered by a semi-batch supercritical carbon dioxide ($SCO_2$) extraction system and the degree of oxidation in the extracted oil was measured in order to compare with extracted oils using organic solvents. The degree of storage in treated squid viscera by $SCO_2$ extraction was measured in order to compare with untreated squid viscera. As results obtained, it was found that the auto-oxidation of the oils using $SCO_2$ extraction occurred very slowly compared to the oils by organic solvent extraction. And the treated squid viscera by $SCO_2$ extraction was reached the point of initial rottenness slowly than untreated squid viscera.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.1
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• pp.55-62
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• 2012

The present paper investigates the performance of the KOH aqueous solution as an absorbent to capture carbon dioxide ($CO_2$). The chemical absorption was carried out according to consecutive reactions that are generated in the order of $K_2CO_3$ and $KHCO_3$. The overall absorption was completed with following the physical absorption. When the absorption was conducted with the KOH as the limiting reactants in batch a reactor, $K_2CO_3$ production rate was the 1st order reaction for $OH^-$. However, $KHCO_3$ generation reaction was independent of the $CO_3^{2-}$ concentration and the rate was calculated to be $0.18gCO_2/min$ for all KOH absorbents, which is the same value of the reaction rate using $K_2CO_3$ aqueous solution as the absorbents. The overall $CO_2$ capture ratio of the 5% KOH absorbent was estimated to be 19% and the individual value in section 1 and 2 was 57 and 12%, respectively. The amount of $CO_2$ absorbed in the solution was very slightly less than the theoretical value, which was ascribed to the side reaction that produces $K_2CO_3{\cdot}KHCO_3{\cdot}1.5H_2O$ during the reaction and the consequent diminish in $CO_2$ absorption in the KOH solution.

• Journal of Environmental Science International
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• v.8 no.1
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• pp.33-43
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• 1999

This paper aims to describe the characteristics of air pollution using air pollutants concentration and meteorological data observed at Kimhae from December 1996 to November, 1997. The results are as follows : The concentration distribution of sulfur dioxide($SO_2$), carbon monoxide(CO), particulate matter(PM-10), and nitrogen dioxide($NO_2$) is high during the late fall and winter and low during the summer, but ozone concentration is low during the winter season and high during summer season except Jangma period and these distributions appear to be closely connected with insolation and the number of clear day. Diurnal variation of concentrations for sulfur dioxide, particulate matter, and carbon monoxide are high during the rush hours and nighttime and low during the daytime and these variations are distinct toward the winter season. And diurnal variation of nitrogen dioxide concentration has also same pattern and these patterns are closely related to the increasing traffic volume at rush hours. Diurnal variation of ozone concentration is generally increase for daytime and decrease for the late afternoon and are closely related to the insolation and photochemical reaction. The 24 hour average concentrations of air pollutant observed at Kimhae represented a positive correlation and a negative correlation for $O_3$ and also a negative correlation for the meteorological elements such as wind speed and cloud cover.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.5
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• pp.342-351
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• 2014

The present paper investigates the performance of direct wet mineral carbonation technology to fix carbon dioxide ($CO_2$) from relatively high $CO_2$ concentration feeding gas using wollastonite ($CaSiO_3$)-water (and 0.46 M acetic acid) suspension solution. To minimize the energy consumed on the process, the carbonation in this work is carried out at atmospheric pressure and slightly higher room temperature. As a result, carbon fixation is confirmed on the surface of $CaSiO_3$ after carbonation with wollastonite-water suspension solution and its amount is increased according to the $CO_2$ composition in the feeding gas. The leaching and carbonation ratio of wollastonite-water suspension system obtained from the carbonation with 50% of $CO_2$ composition feeding gas is 13.2% and 10.4%, respectively. On the other hand, the performance of wollastonite-acetic acid in the same condition is 63% for leaching and 1.39% for carbonation.

• Applied Chemistry for Engineering
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• v.10 no.1
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• pp.129-134
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• 1999

This study is related to the investigation of the direct incorporation of $CO_2$ to polymer using quaternary ammonium salt catalysts. Quaternary ammonium salts showed good catalytic activity of $CO_2$ fixation in the synthesis of poly[(1,3-dioxolane-2-oxo-4-yl)methyl methacrylate] [poly(DOMA)] by the direct incorporation of $CO_2$ to poly(glycidyl methacrylate)[poly(GMA)]. Among the salts tested, the ones with higher alkyl chain length and with more nucleophilic counter anion showed higher catalytic activity. The yield of carbon dioxide addition increased with the reaction temperature. Kinetic study was carried out by measuring the variation of $CO_2$, pressure in a high pressure batch reactor. The reaction rate was first order to the concentration of poly(GMA) and $CO_2$, respectively. The rate constant was $0.69L/mol{\cdot}h$ and Henry's constant of $CO_2$ in DMSO at $80^{\circ}C$ was $6.8{\times}10^{-4}mol/L{\cdot}KPa$.

• Transactions of the Korean hydrogen and new energy society
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• v.29 no.5
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• pp.530-537
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• 2018

The effect of temperature and absorption capacity on heat of reaction, which is one of the characteristic studies of $CO_2$ absorption, were investigated in a differential reaction calorimeter (DRC) by using piperazine (PZ) and 2-methylpiperazine (2-MPZ). For all absorbents, $CO_2$ loading capacity decreased with increasing the temperature, while the heat of reaction increased, it figured out that these had a linear correlation between $CO_2$ loading capacity and/or heat of reaction and the temperature. The heat of reaction of all absorbents increased with increasing $CO_2$ loading capacity, especially 2-MPZ rapidly increased at $70^{\circ}C$. The reason for increase in the heat of reaction was occurred the regeneration of $CO_2$, which is a reverse-reaction, simultaneously with the absorption.

• Korean Journal of Chemical Engineering
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• v.35 no.11
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• pp.2150-2156
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• 2018

We suggest a systematic method for obtaining the optimal compression ratio in the multi-stage closed-loop compression process of carbon dioxide. Instead of adopting the compression ratio of 3 to 4 by convention, we propose a novel approach based on mathematical analysis and simulation. The mathematical analysis prescribes that the geometric mean is a better initial value than the existing empirical value in identifying the optimal compression ratio. In addition, the optimization problem considers the initial installation cost as well as the energy required for the operation. We find that it is best to use the fifth stage in the general closed-loop type carbon dioxide multi-stage compression process.

• Applied Chemistry for Engineering
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• v.29 no.4
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• pp.382-387
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• 2018

In this study, the reaction characteristics of combined steam and carbon dioxide reforming of methane (CSCRM) reaction using Pd-Ni-YSZ catalyst were investigated according to types of catalysts and gas compositions. Catalysts were prepared in the form of powder and porous disk. The injected gases were supplied at different ratios of $CH_4/CO_2/H_2O$. As a result, the conversion of $CH_4$ and $CO_2$ was improved as a result of using the porous disc type catalyst as compared with that of the powder type catalyst. When the $CH_4/CO_2/H_2O$ ratio of the feed gas was 1 : 0.5 : 0.5, the $H_2/CO$ ratio was adjusted close to 2. However, after 6 hours of the reaction, $CH_4$ conversion was partially reduced by the carbon deposition and the pressure drop increased from 0.1 to 0.8. This issue was then solved by optimizing the water content. As a result, it was confirmed that the durability was secured by preventing the carbon deposition when the gas was supplied at a $CH_4/CO_2/H_2O$ ratio of 1 : 0.5 : 1, and the conversion rate was maintained at a relatively high level.