• The Korean Journal of Nuclear Medicine Technology
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• v.16 no.2
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• pp.126-130
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• 2012

Purpose : Methode an effective block was investigated to deal with volatile radioactive gas, short lived radioactive waste generated as a result of the routinely produced radiopharmaceuticals FDG (2-deoxy-2-[$^{18}F$]fluoro-D-glucose) and compound with $^{11}C$. Materials and Methods : All components of the radiation stack monitoring and data management system for continuous radioactive gas detection in the air extract system purchase from fixed noble gas monitor of Berthold company. TEDLAR gas sampling bags purchase from the Dongbanghitech company. TEDLAR gas sampling bags (volume: 10 L) connected via paraflex or PTFE tubing and Teflon 3 way stopcock. When installing TEDLAR gas sampling bags in Hot cell on the inside and not radioactive gas concentrations were compared. According to whether the Hot cell inside a activated carbon filter installed, compare the difference in concentration of the radioactive gas $^{18}F$. Comparison of radiation emission concentration difference of module a FASTlab and TRACElab. Results : Activated carbon filter are installed in the Hot cell, a measure of the concentration of radioactive gas was 8 $Bq/m^3$. Without activated carbone filter in the hot cell was 300 $Bq/m^3$. Tedlar bag prior to installation of the radioactive gases a measure of the concentration was 3,500 $Bq/m^3$, $^{11}C$ synthesis of the measured concentration was 27,000 $Bq/m^3$. After installed a Tedlar bag and a measure concentration of the radioactive gases was 300 $Bq/m^3$ and $^{11}C$ synthesis was 1,000$Bq/m^3$. Conclusion : $^{11}C$ radioactive gas that was ejected out of the Hot cell, with the use of a Tedlar gas sampling bag stored inside. A compound of 11C is not absorbed onto activated carbon filter. But can block the release out by storing in a Tedlar gas sampling bag. We was able to reduce the radiation exposure of the worker by efficient radiation protection.

• Journal of Climate Change Research
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• v.8 no.1
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• pp.31-39
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• 2017

The emission quantity of nitrous oxide is second largest among non-$CO_2$ greenhouse gas in Korea. In this study, we investigated loss rate of nitrous oxide which was filled in PVF and Al-PE bag as time goes on. Concentrations of tested samples were about 25 ppmv, 50 ppmv, 75 ppmv prepared by standard reference gas. In case of all experiments, loss rate of PVF bag was higher than Al-PE bag. After 18 days, loss rate of PVF bag was from 29.7% to 38.6% while Al-PE bag was from 21.7% to 23.7%. Especially the differential growed bigger when initial concentration of $N_2O$ in PVF bag was lower. And we also studied the effect of cock opening/closing procedures on loss rate. Prepared samples in experimental group were analyzed several times for 20 days and samples in control group were analysed only 1 time after 20 days. The experimental results showed that cock opening/closing procedures appeared to have little impact on loss rate.

• Bulletin of the Korean Chemical Society
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• v.23 no.3
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• pp.488-496
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• 2002

SPME techniques have proven to be very useful tools in the analysis of wide VOCs in the air. In this study, we estimated VOCs in ambient and workplace air using a Tedlar ba /SPME/GC/MS system. The calibration curve was set to be linear over the range of 1-30 ppbv. The detection limits ranged from 10 pptv to 0.93 ppbv for all VOCs. Reproducibility of TO-14 target gas mixtures by SPME/GC/MS averaged at 8.8 R.S.D (%). Air toxic VOCs (hazardous air pollutants, HAPs) containing a total of forty halohydrocarbons, aromatics, and haloaro-matic carbons could be analyzed with significant accuracy, detection limit and linearity at low ppbv level. Only reactive VOCs with low molecular weight, such as chloromethane, vinylchloride, ethylchloride and 1,2-dichloro-ethane, yielded relatively poor results using this technique. In ambient air samples, ten VOCs were identified and quantified after external calibration. VOC concentration in ambient and workplace air ranged from 0.04 to 1.85 ppbv. The overall process was successfully applied to identify and quantify VOCs in ambient/workplace air.

• Analytical Science and Technology
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• v.18 no.4
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• pp.338-343
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• 2005

In this work, sample loss of reduced sulfur compounds (RSC) was investigated with respect to bag sampling techniques. For comparison purpose, calibration slopes were obtained by analyzing standards prepared by 'within syringe dilution' (WSD) method against those made either by 'Tedlar bag dilution' (TBD) or by 'polyester aluminum bag dilution' (PBD) method. The results indicated that the recovery rate of TBD showed the mean values of about 87%, while those of PBD about 77%. Despite the fact that sample loss is inevitable, precise sampling of reduced sulfur compounds may still be possible, if one acknowledges and be prepared for such loss rates of bag sampling methods.

• Journal of the Korean earth science society
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• v.25 no.4
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• pp.265-269
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• 2004

본 연구에서는 대기 중 황성분을 채취하는데 가장 널리 활용되는 방법 중의 하나인 테들러 백 방식의 채취와 관련된 오차요인을 여러 가지 관점에서 검정하고자 하였다. 이를 위해, 표준시료를 백과 백간에 이동시켜 주므로서, 백의 벽면을 통해 초래될 수 있는 성분별 손실율을 비교하였다. 상대습도 0 %, 실온 조건에서 실험한 결과, 황화수소와 멀캡턴과 같은 성분들은 백과의 접촉이 일어나면서, 20 %에 가까운 손실율이 확인되었다. 반면, 상대적으로 이들에 비해 반응성이 높지 않은 DMS, DMDS와 같은 성분들도 10 %내외의 손실율이 확인되었다. 이들 성분의 정확한 정량을 위해서는 테들러 백의 흡착손실 등에 대한 특성을 정확하게 파악하는 것이 중요하다. 특히, 습도나 온도와 같은 환경조건의 변화에 대한 고려도 동시에 수반되어야 할 것이란 점을 확인할 수 있었다.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2005.11a
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• pp.193-195
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• 2005

• Analytical Science and Technology
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• v.19 no.6
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• pp.553-558
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• 2006

In this study, an attempt was made to measure uncertainties involved in the VOC analysis for the VOC working standards prepared by a dilution technique using Tedlar bags. For this purpose, VOC standard gases of benzene, toluene, xylene, and styrene were prepared at four different concentrations (4, 8, 20, and 40 ppb). These standard samples were then loaded on to the GC system equipped with air server/thermal desorption (AS/TD) system. Each of these four standard concentrations was analyzed individually to derive their respective calibration results. These calibration data sets were then compared across four different compounds. According to this comparison, differences in calibration patterns were moderately insignificant within the selected concentration range of 4~40 ppb. It was also observed that the loss of styrene standard was fairly high compared to other VOCs investigated simultaneously. The results of our study suggest that the analytical uncertainty associated with the preparation of VOC starndard gas using a dilution technique can be assessed in a fairly reasonable manner for samples with a narrow concentration range.

• Journal of Climate Change Research
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• v.7 no.4
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• pp.477-484
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• 2016

In general, $CH_4$ concentrations generated in combustion facilities are known to be ppm units. In most cases, $CH_4$ samples are collected in Tedlar bags and transported to laboratories for analysis. Considering this fact, in the present study, an attempt was made to find out how long samples can be stored in cases where they are kept in bags and transported as a preliminary study for sampling. According to the results of the experiment using simulated gases (1 ppm, 5 ppm, 10 ppm) in Tedlar bag, $CH_4$ was safe up to 240 hr which is the full time. In the case of simulated gases are containing 4 kind gases ($N_2$, $CO_2$, $CH_4$, and $N_2O$). Field samples (samples of obtained by collecting combustion facilities' exhaust gases) are known to contain highly reactive substances (for example NOx, SOx, and VOCs) and may affect each other. In the present study, one site sample was secured from each of a bituminous coal combustion facility and an LNG combustion facility and whether the concentrations of $CH_4$ gas would change over time (24 hr, 96 hr, 144 hr, 192 hr) was checked. Since site samples could not be analyzed on the day of collection, an experiment was started 24 hr after the time point of sampling to analyze the samples. As with the results of analysis of the simulated gas (240 hr), the results of analysis using the site sample indicated that it could be stored for the full study period 192 hr. Therefore, it was judged that if 192 hr would be taken after sampling before the sample would be analyzed, the concentration value should be reliable.

• Analytical Science and Technology
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• v.26 no.6
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• pp.381-386
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• 2013

The sixty nine chemicals that are closely linked to chemical accident are designated as the substances requiring preparation for accidents and managed for public health under the Toxic Chemicals Control Act. In this study, storage stability of allyl chloride (AC) and carbon disulfide (CD), which are highly inflammable and volatile in tedlar bags, was studied for gaseous chemicals sampling. Storage stability was studied considering storage temperature ($2^{\circ}C$, $25^{\circ}C$), chemical concentration (low conc. ppm, high conc. ppm) and storage time (0, 48, 96, and 144 hr). Also, the stability of bags containing one type of chemical substance and the bags containing a mixture of chemicals was compared against each other. As a result, two chemicals showed decreasing storage stability based on storage time. Also two chemicals presented statistical significance of concentration and mixing type.

• Environmental Analysis Health and Toxicology
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• v.17 no.2
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• pp.117-123
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• 2002

A gas chromatographic method for the determination of airborne formaldehyde was established. In order to be highly detectable with the electron capture detector, formaldehyde was derivatized to its pentafluorobenzyl oxime form by reacting with O- (2,3,4,5,6- pentafluorobenzyl)hydroxylamine hydrochloride (PFBHA) at pH of 4.6 and temperature of 50$^{\circ}C$ for 1 hour. Air samples were collected into a Tedlar$\^$(R)/ bag followed by transferring into water contained in two impingers in series. Collection efficiency in the front trap was higher than 90％. Measurement of selected indoor and outdoor air samples showed higher formaldehyde concentrations in indoor air environments and the importance of ventilation for reducing indoor pollution.