• 한국대기환경학회지
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• 제30권4호
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• pp.339-349
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• 2014

$CO_2$ emission has been gradually increased due to rising fossil fuel use. A gliding arc plasma scrubber (GAPS) was proposed to destruct $CO_2$. For optimum design of GAPS, a CFD analysis has been conducted in different configuration for the system. The parameters considered included gas injection velocity at the nozzle and gas flow rate to gap between electrodes. The reactor configuration affected velocity fields which caused changes in the mixture fraction and the retention time. The mixing effect of $CO_2$ and supplied gas ($CH_4$ and steam) was enhanced by installing a orifice baffle. This revealed that the orifice baffle is effective in $CO_2$ conversion by positioning the reactants in the gas into the center of plasma discharge.

• Environmental Analysis Health and Toxicology
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• 제16권3호
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• pp.121-126
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• 2001

Analytical method of benzophenone (BP) in sediment and soil was developed by gas chromatography/mass selective detector/selected ion monitoring (GC/MSD/SIM). The ultrasonic extraction of US EPA (method 3550B) method and liquid-liquid extraction for sediment and soil samples were used for the analysis of BP from sediment and soil. BP was extracted with n-hexane. Organic layer was washed with 5% sodium chloride solution. 1∼2 l of the concentrated solution of organic layer was applied to GC/MSD. The retention time of BP peak was 11.10 min. Recovery (％) of BP by ultrasonication from sediment and soil samples was 96.0∼100.6％ and 40.0∼83.0％, respectively. Recovery of BP by liquid-liquid extraction was 51∼59％ in soil samples. The detection limit of BP in sediment and soil samples were determined to 0.1 ng/g.

• 한국대기환경학회지
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• 제15권5호
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• pp.649-655
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• 1999

Biofiltration of polluted gas streams contained $H_2S$ was studied. The experiments were performed in a laboratory-scale reactor with a porous ceramic media inoculated with sulfur oxidizing bacterium, TAS which was isolated from activiated sludge. The concentration of $H_2S$ in the inlet gas varied from 109 to 3,841 ppm, at the various space velocities(SV) of 50 $h^{-1}$ to 250 $h^{-1}$. Various tests have been conducted to evaluate the effects of such parameters as pH, concentration of sulfate ion and retention time on the pressure drop and maximum elimination capacity. The removal efficiency of $H_2S$ decreased as the $H_2S$ concentration or gas velocity increased in the inlet gas. Pressure drop was insignificant in this system. The maximum elimination capacity could reach up to 16.35g-S/kg-dry packing material/day.

• Nuclear Engineering and Technology
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• 제50권6호
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• pp.849-853
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• 2018

Mechanistic calculations for wet scrubbing of aerosol/vapor from gas bubble rising in liquid pool are essential to safety of sodium-cooled fast reactor. Hence, scrubbing of volatile fission product from mixed gas bubble rising in sodium pool is presented in this study. To understand this phenomenon, a theoretical model has been setup based on classical theories of aerosol/vapor removal from bubble rising through liquid pools. The model simulates pool scrubbing of sodium iodide aerosol and cesium vapor from a rising mixed gas bubble containing xenon as the inert species. The scrubbing of aerosol and vapor are modeled based on deposition mechanisms and Fick's law of diffusion, respectively. Studies were performed to determine the effect of various key parameters on wet scrubbing. It is observed that for higher vapor diffusion coefficient in gas bubble, the scrubbing efficiency is higher. For aerosols, the cut-off size above which the scrubbing efficiency becomes significant was also determined. The study evaluates the retention capability of liquid sodium used in sodium-cooled fast reactor for its safe operation.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2005년도 추계 학술대회논문집
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• pp.21-26
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• 2005

Gas Chromatography (GC) is a wisely technique used for the separation and analysis of liquid and gas sample. Separation of the sample vapors is achieved via their differential migration through a capillary column with an insert carrier gas. The identity and quantity of each vapor in the mixer can be determined from its retention time in the column and a particular property of the gas, such as thermal conductivity, which can be related to the concentration of sample vapor in the carrier gas. Therefore, the flow characteristics in the spiral gas chromatographic column are numerically investigated in this study. Especially, different pressure drop between the front and the rear of GC column with various flow rates is estimated the governing equations are derived from making using of three-dimensional Naver-Stokes equation with incompressible and laminar model due to the nature of low Reynolds number flow. Using a commercial code, FLUENT, the pressure and flow fields in GC column are calculated with various flow rates. The characteristics of thermal cycling which is one of the most important factors affecting the column efficiency and analysis time is also estimated. Furthermore, numerical analyses are also carried out by using commercial code, ANSYS, with various values of power, which is applied to the heating element located at lower GC column.

• 분석과학
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• 제34권5호
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• pp.202-211
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• 2021

Volatile organic compounds (VOCs) in hazardous air pollutants (HAPs) have been regulated by the Air Pollution Control Act (1978) and their atmospheric concentrations have been monitored in 39 monitor sites in Korea. However, measurement standards of volatile organic compounds (VOCs) in HAPs at ambient levels have not been established in Korea. Primary reference gas mixtures (measurement standards) at ambient levels are required for accurately monitoring atmospheric VOCs in HAPs and managing their emissions. In this study, primary reference gas mixtures (PRMs) at 5 nmol/mol were developed in order to establish primary national standards of VOCs in HAPs at ambient levels. Primary reference gas mixtures (PRMs) were prepared in pressurized aluminum cylinders with special internal surface treatment using gravimetric method. Analytical methods using gas chromatography-flame ionization detector (GC-FID) coupled with a cryogenic preconcentrator were also developed to verify the consistency of gravimetrically prepared HAP VOCs PRMs. Three different columns installed in the GC-FID were evaluated and compared for the retention times and separation of eighteen target components in a chromatogram. Results show that the HAP VOCs PRMs at 5 nmol/mol were consistent within a relative expanded uncertainty (k=2) of less than 3 % except acrylonitrile (less than 6 %) and the 18 VOCs were stable for 1 year within their associated uncertainties.

• The Korean Journal of Ecology
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• 제19권4호
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• pp.321-328
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• 1996

The profile and concentration of monoterpene metabolites in the leaf and stem of Artemisia princeps var. orientalis were quantified, and seasonal variation in monoterpenes of Artemisia plant was investigated. Samples were taken from five sites at the campus of Kyungnam University during maturing season. Monoterpenes in leaf and stem were analyzed using gas chromatography-mass spectrometry (GC-MS). The major constituents of A. princeps var. orientalis in both the leaf and stem were 21 monoterpenes.$ {\alpha}-pinene,\;{\beta}-pinene,\;{\beta}-myrcene$, dl-limonene, naphthalene and unknown monoterpenes with 5.49 and 16.27 of retenstion time were present in high concentrations of compounds identified on the leaf and stem of A. princeps var. orientalis. The cmounts of total monoterpenes of leaf were from two to five times higher than stem and rapidly decreased with the time, while that of stem was constnat except early spring. Most of the high percentage of monoterpenes in the leaf were those with later retention time. These results indicated that monoterpenes yields are considered to be more variable than monoterpene composition in responding to the time in both the leaf and stem.

• 한국환경과학회지
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• 제11권6호
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• pp.577-582
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• 2002

Selective catalytic reduction and selective non-catalytic reduction processes are mainly used to treat nitrogen oxidants generated from fossil-fuel combustion. Especially, the selective non-catalytic reduction process can be operated more economical and designed more simply than the selective catalytic reduction. For this reason, many researchers carried out to increase the removal efficiency of nitrogen oxidants in the condition of low oxygen concentration by using the selective non-catalytic reduction process. However, this study was flue gas contained high oxygen concentration of 20(v/v%) with ammonia as a reducing agent. Moreover, it carried out experiment with many factors that are reaction temperature, retention time, initial NO concentration, NSR(normalized stoichiometric ratio). It was determined optimal operating conditions to improve NO removal efficiency with SNCR process. The De-NOx efficiency was increased with NSR, initial NO concentration and retention time increasement. This study has NO removal efficiency over 80% in the high oxygen concentration as well as low oxygen concentration. The injection of reducing agent may be considered for SNCR process and facility operation in 850$\^{C}$ of optimal condition.

• Preventive Nutrition and Food Science
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• 제3권2호
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• pp.111-118
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• 1998

To develop a simple, rapid and simultaneous analytical method of phenolic compounds using gas chromatography (GC) and gas chromatography/mass spectrophometer (GC/Ms), this experiment was carried out to search the retention times of capillary columns and the characteristics of fragment ions in electron impact mass spectra. Most of trimethylsilyl derivatives and underivatized phenolic compounds were separated very well on three kinds of capillary columns(HP-1), Ultra-2 and HP-35). Quantitiative determination of phenolic compounds was achieved by internal standards (p-hydroxybenzoic acid iopropyl ester, p-hydroxybenzoic acid ethyl ester). Calibration plts were linear in the investigated range, and the limits of detection were about 5 ng at split mode method. When analyzed by three columns, theseparation times were fairly constant on two nonpolar columns, but a few compounds showed slightly different separation order by the itnermediate polar HP-35 column. The important characteristic patterns of TMS derivatives of phenolic compounds on the EI/MS spectrra appeared at the base peak of [M-15]+ ion and presented at high abundance in most TMS derivatives of phenoloc compounds. [M]+, [M-CH3-COO]+, [M-Si(CH3)4]+ and [M-Si(CH3)4 -CH3]+ also observed in mass spectra of these compounds . Although several compounds have the same retention times on GC column, it might be possible to identify these compounds by the different patternsof mass frgement ions. The TMS derivatives, thus , provide additional information for identification of phenolic compounds in biological systems.

• 한국환경과학회지
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• 제15권3호
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• pp.211-219
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• 2006

An experimental study on the removal of VOCs gas using a biomembrane reactor were carried out at various inlet gas concentration, specific loading rate, retention time and gas flow rate of volume. The variations of efficiency and various parameters, which are relevant to gas removal, with mixing of soluble gas and without have been discussed. More than 95% of the toluene and methanol present in the feed was successfully removed in each study. The elimination of methanol with mixture of soluble compound of about 300 mg/h corresponds to a portion of 21% if there is a feed stream of 1400 mg/h. On the contrary the maximum efficiency of about 72% of toluene was reached. This is to be rated as a treatment of sorption that the limiting factor of the dismantling speed could be represented by this difficult degradable component. Nevertheless the elimination capacities for this reactor for toluene were on a very high level. For substances which show a very high solubility in silicon rubber an advantage of a bio membrane is clearly shown. Therefore a similarly good result is expected for n-hexane, because of its relatively good permeability which was distinguished during permeation experiments.