• Bulletin of the Korean Chemical Society
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• v.23 no.2
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• pp.301-308
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• 2002

As part of perfluorocarbon (PFC) tracer release experiment conducted at the western coastal area of Korea in February 2001, the background concentration level of perfluorocarbons (PFCs) in the atmosphere was determined by gas chromatography with electron capture detector. Prior to the PFC tracer release experiment in the field, air samples were collected using active samplers and the background concentrations of PFCs were determined. The concentrations of perfluoromethylcyclohexane ($C_7F_{14}$, PMCH) in the western coastal area of Korea were in the range of 5.8-8.7 fL/L. The mean concentration of the PMCH in the region exhibited no significant spatial and temporal variations. This concentration level is somewhat higher and has larger standard deviation than those of studies previously conducted in USA and Europe on the background concentration levels of PFCs. Because the background concentration of PMCH in Korea is still very low and consistent temporally and spatially, the PMCH tracer can be used suitably for the studies of long-range atmospheric transport.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.193-193
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• 2013

Perfluorocarbons (PFCs) have been suggested as possible replacements for $SF_6$ and the fluorocarbons used in and emitted during technological plasma treatments because PFCs have significantly low greenhouse warming potentials. Of many PFCs, c-$C_4F_8$ and 2-$C_4F_8$ attract special attention because of their high CF2 radicallevels in commercial plasma treatments. Accordingly, several experimental and theoretical studies of these $C_4F_8$ species have been conducted, although only the geometries at their stationary states and their adiabatic electron affinities (EAs) have been determined. However, this information is not sufficient for a deep understanding of all the possible fates and roles of $C_4F_8$ species and their fragments in plasma phases. Although the performance and reliability ofeach DFT functional have been examined carefully by the development team of each functional form with respect to the training and test data sets of well-known molecular systems, no PFC was included in the data sets. So a careful additional assessment of the reliability of DFT functionals for the study of PFC systems is highly required. In order to find a DFT method appropriate to PFCs, the geometry, energy, and chemical reaction properties of $C_4F_8$ were calculated and compared with reference data.

• Textile Coloration and Finishing
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• v.31 no.4
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• pp.258-267
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• 2019

Synthetic suede without PFCs(perfluorinated compounds) are followed by subsequent high temperature treatment. But migration fastness of synthetic suede may be reduced due to sublimation of disperse dyes that results from the high temperature treatment. Therefore, in this study, chitosan treatment was used to improve the migration fastness before polyurethane dipping process. Polyester fiber was treated with sodium hydroxide aqueous solution before chitosan processing. This samples treated with a chitosan concentration upto 0.5% were dyed and coated with PUD(polyurethane dispersion). The migration fastness was most improved at 0.35% application. This is presumably due to the fact that the chitosan may increase the dye-binding capability through intermolecular hydrogen bonding.

• Membrane Journal
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• v.23 no.3
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• pp.189-203
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• 2013

F-gases, gases containing fluorine such as perfluorocarbons (PFCs), sulfurhexafluoride ($SF_6$), nitrogen trifluoride ($NF_3$) are known to have green house effects. Although the net emission rates of gases containing fluorine are much lower than those of $CO_2$, their contribution to global warming cannot be ignored because of their extremely high global warming potential (GWP). F-gases mainly have been used for a variaty of applications in the semiconductor/LCD processes and in the electric power distribution industry of the national key industry. One of practical solutions of controlling the emission rates of F-gases is to reuse by separation and recovery of F-gases of low concentration from the gases mixtures with nitrogen or air. This work investigates some methods for F-gases recovery and separation around the membrane-based process.

• Journal of Korean Society for Atmospheric Environment
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• v.23 no.5
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• pp.547-556
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• 2007

The release, sampling and analytical methods have been developed and tested for perfluorocarbons (PFCs) atmospheric tracers in order to gain insight into the atmospheric transport and dispersion over the urban conditions of Seoul, Korea. Although PFCs tracer experiments provide unique opportunities to test local and urban scale of transport and dispersion, no previous experiment with PFCs has been conducted in Korea. PMCH and PDCH were chosen as targeted tracers in our study due to their extreme low ambient concentrations and great sensitivities among various PFCs. For PFCs release system, a set of micro-metering pump, electronic balance, vaporizing furnace and high speed blower was constructed for precise and accurate release of tracers. The precision of released rate by this system was estimated to be 1%. Samplings of PFCs were carried out by fabricated portable air samplers with micro pumps and rotameters into glass tubes packed with 150 mg of Carboxen-569. The uncertainty of these sampling system was maintained below 14%. PMCH and PDCH were quantified in GC/ECD with preconditioned injection system to eliminate the interference compounds using traps and subsequent catalytic conversion system prior to column separation. Three intensive field test were undertaken during the springtime of 2002 to 2004 in eastern part of Seoul. Daily background samples were collected to characterize the background levels of PMCH and PDCH prior to their release. The observed background concentrations of PMCH ranged from 3.5 to 10.1 fL/L and varied randomly in location and time in this study. Its mean and standard variation of background concentration ($6.8{\pm}1.9\;fL/L$) are higher than those ($3.2{\sim}5.8\;fL/L$) of other historic tracer studies. Identified uncertainty for background PMCH was $1.7{\sim}2.0\;fL/L$ using this analytical system. Combined relative uncertainty in determining the tracer's concentrations was estimated as 17%. However, its background concentrations and uncertainty in concentration determination were found to be low and stable enough for tracer study.

• Journal of Korean Society for Atmospheric Environment
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• v.26 no.6
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• pp.624-632
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• 2010

Perfluorocarbons (PFCs) are widely used in semiconductor industry. These gases need to be removed efficiently because of their strong absorption of infrared radiation and long atmospheric lifetimes which cause the global warming effect. To destruct $CF_4$, a waterjet gliding arc plasma was designed and manufactured. The highest $CF_4$ destruction showed at waterjet plasma case, compared to plasma discharge only or water scrubber only, respectively. In addition, it could be known that the $CF_4$ destruction should be associated with the electron and OH radicals. The operating conditions such as waterjet flow rate, initial $CF_4$ concentration, total gas flow rate, specific energy input were investigated experimentally using a plasma waterjet scrubber. Through the parametric studies, the highest $CF_4$ destruction of 94.5% was achieved at 0.2% $CF_4$, 2.1 kJ/L SEI, 20 L/min total gas flow rate and 18.5 mL/min waterjet flow rate.

• Journal of Animal Environmental Science
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• v.16 no.3
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• pp.175-180
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• 2010

Many greenhouse gases occur naturally, such as water vapor, carbon dioxide, methane, nitrous oxide, and ozone. Others such as hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulfur hexafluoride ($SF_6$) result exclusively from human industrial processes. Current global warming has been linked to anthropogenic greenhouse gas concentration increases. Methods to quantify greenhouse gas emissions during animal agriculture and the possibility to apply those to circumstance in the world were studied. Various chamber methods with trace gas analyzer (TGA) were used to quantify greenhouse gas emissions from stored manure. Methane fluxes from pails storing liquid swine manure were measured. Methane emissions increased a little with time and mean was 393.2 ${\mu}g\;m^{-2}\;s{-1}$ (standard error : 4 ${\mu}g\;m^{-2}\;s{-1}$).