• Particle and aerosol research
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• v.9 no.3
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• pp.149-161
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• 2013

Experiments on photochemical reactions of purified air alone in an indoor smog chamber were carried out after flushing Teflon bags with purified air for many hours in order to check the level of contamination on the chamber wall. Ozone concentrations were linearly increased from <4 ppb up to about 8 ppb with irradiation time for four hours. Outgassing of NOx from the chamber wall was found to be less than 1 ppb. New ultrafine particles were formed and grown up to about 70 nm during the photochemical reactions, and then total number and mass concentrations of particles were increased from <10 particles/$cm^3$ up to about 4,000 particles/$cm^3$ and $1.3{\mu}g/m^3$, respectively. The wall conditions of these Teflon bags flushed with purified air might not severly affect the chamber experimental results for photochemical reactions of polluted urban ambient air. The difference of gaseous species between two chambers was 2.4 ppb of ozone at most, indicating that the wall cleaning performance of two chambers was nearly similar.

• Particle and aerosol research
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• v.12 no.1
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• pp.1-9
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• 2016

In this work, we evaluated the characteristics of flow field and uniformity of the nose-only exposure chambers for the inhalation toxicity test. Computational fluid dynamics (CFD) modeling was carried out to demonstrate uniformity of the nose-only exposure chambers. Because it is very important in the inhalation toxicity experiments that test materials are distributed uniformly to each holder of the chamber. The test was done with these 3 types of chamber with different form to develop inhalation toxicity evaluation system, easy-to-operate system among exposure chamber used for evaluating inhalation toxicity of environmental chemical mixtures. Through CFD interpretation, nose-only exposure chamber was made with the selection of the optimal conditions. For its evaluation, one type of fragrance was selected and measured particle size distribution of each port. The gene becoming luminous to green fluorescence was combined with GPT-SPE, a type of tGFP vector, to be inhaled to the mouse. Based on this, luminous intensity was checked. As a result, total particle number concentration of each port had average value of $3.17{\times}10^6{\sharp}/cm^3$ and range of the highest and lowest concentration value was approximately ${\pm}4.8%$. Autopsy of lung tissues of mouse showed that it had clearly better delivery of gene compared to the control group.

• Nuclear Engineering and Technology
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• v.49 no.7
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• pp.1489-1494
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• 2017

The use of a room-temperature gamma spectrometer is an issue in environmental radiation monitoring. To monitor radionuclides released around a nuclear power plant, suitable instruments giving fast and reliable information are required. High-pressure xenon (HPXe) chambers have range of resolution and efficiency equivalent to those of other medium resolution detectors such as those using NaI(Tl), CdZnTe, and $LaBr_3:Ce$. An HPXe chamber could be a cost-effective alternative, assuming temperature stability and reliability. The CEA LIST actively studied and developed HPXe-based technology applied for environmental monitoring. Xenon purification and conditioning was performed. The design of a 4-L HPXe detector was performed to minimize the detector capacitance and the required power supply. Simulations were done with the MCNPX2.7 particle transport code to estimate the intrinsic efficiency of the HPXe detector. A behavioral study dealing with ballistic deficits and electronic noise will be utilized to provide perspective for further analysis.

• Journal of Korean Society for Atmospheric Environment
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• v.23 no.3
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• pp.353-363
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• 2007

To differentiate temperature effect from the light intensity effect on the formation of secondary products during the photooxidation of toluene-$NO_x$-air mixtures, steady-state air temperature was changed from $20^{\circ}C\;to\;33^{\circ}C$ at the same light intensity of $0.39min^{-1}$ in an indoor smog chamber. Smog chamber consisted of 64 blacklights and a $5.8m^3$ reaction bag made of Teflon film. Air temperature was controlled by an air-conditioning system. The starting time for rapid conversion of NO to $NO_2$ was slightly delayed with decreasing air temperature. In contrast to light intensity effect, the ozone formation time and the ozone production rate were insensitive to air temperature. Although the formation time for secondary organic aerosols was not changed, the particle number concentration increased with temperature. However, the newly formed secondary organic aerosol mass at lower temperature was higher than that at higher temperature. Since light intensity significantly affected the starting time and quantity of ozone and aerosol formation, it is considered that the temperature could contribute partly the quantity of aerosol formation during the photooxidation of toluene-$NO_x$-air mixtures.

• Journal of Microbiology and Biotechnology
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• v.22 no.9
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• pp.1288-1295
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• 2012

Exposure to bioaerosols causes various adverse health effects including infectious and respiratory diseases, and hypersensitivity. Controlling exposure to bioaerosols is important for disease control and prevention. In this study, we evaluated the efficacies of various functional filters coated with antimicrobial chemicals in deactivating representative microorganisms on filters or as bioaerosols. Tested functional filters were coated with different chemicals that included (i) Ginkgo and sumac, (ii) Ag-apatite and guanidine phosphate, (iii) $SiO_2$, ZnO, and $Al_2O_3$, and (iv) zeolite. To evaluate the filters, we used a model ventilation system (1) to evaluate the removal efficiency of bacteria (Escherichia coli and Legionella pneumophila), bacterial spores (Bacillus subtilis spore), and viruses (MS2 bacteriophage) on various functional filters, and (2) to characterize the removal efficiency of these bioaerosols. All experiments were performed at a constant temperature of $25^{\circ}C$ and humidity of 50%. Most bacteria (excluding B. subtilis) rapidly decreased on the functional filter. Therefore, we confirmed that functional filters have antimicrobial effects. Additionally, we evaluated the removal efficiency of various bioaerosols by these filters. We used a six-jet collision nebulizer to generate microbial aerosols and introduced it into the environmental chamber. We then measured the removal efficiency of functional filters with and without a medium-efficiency filter. Most bioaerosol concentrations did not significantly decrease by the functional filter only but decreased by a combination of functional and medium-efficiency filter. In conclusion, functional filters could facilitate biological removal of various bioaerosols, but physical removal of these by functional was minimal. Proper use of chemical-coated filter materials could reduce exposure to these agents.

• Korean Journal of Agricultural and Forest Meteorology
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• v.5 no.2
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• pp.94-100
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• 2003

Soil $CO_2$ emission is one of the primary components in carbon balance of terrestrial ecosystems. To accurately assess their net ecosystem exchange of $CO_2$ and net primary production, measurement of soil $CO_2$ efflux is required along with that of canopy $CO_2$ flux. In this paper, soil $CO_2$ flux measurement technique using closed dynamic chamber systems is briefly reviewed. Preliminary results on soil $CO_2$ exchange and inter-comparison of different measurement systems currently used in Korean regional network of tower flux measurement sites (KoFlux) are also reported.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.12 no.4
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• pp.404-413
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• 2000

Environmental chamber (EC) is an experimental facility used to analyze the characteristics of thermal response of testing objects by the artificial control of weather conditions. The EC in KIER can simulate the weather conditions by the control of temperature, humidity, and solar radiation. A two-storied testing building is located inside of EC. For the exact thermal response analysis of testing building, monthly or yearly scheduled operations are necessary. Although this long term operation gives the exact experimental data, it requires a high operational cost, long duration, and lots of manpower. Therefore it is necessary to perform the shortened experiments without sacrificing the validity of the obtained results. Since the characteristics of thermal response from the shortened experiments are different from the full time results, the analytical method to analyze the thermal response from the shortened experiments to estimate a full times results is developed in this study. The thermal response of testing building is performed using commercial software TRNSYS.

• International Journal of Air-Conditioning and Refrigeration
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• v.9 no.3
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• pp.18-26
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• 2001

Environmental chamber (EC) is an experimental facility used to analyze the characteristics of thermal response of testing objects by the artificial control of weather conditions. The EC in KIFR can simulate the weather conditions by the control of temperature, humidity, and solar radiation. A two-storied testing building is located inside EC. For the exact thermal response analysis of testing building, monthly or yearly scheduled operations are necessary. Although this long term operation gives the exact experimental data, it requires a high operational cost, long duration, and lots of manpower. Therefore it is necessary to perform the shortened experiments without sacrificing the validity of the obtained results. Since the characteristics of thermal response from the shortened experiments are different from the full time results, the analytical method to analyze the thermal response from the shortened experiments to estimate a full times results is developed in this study The thermal response of testing building is performed using commercial software TRNSYS.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2004.05a
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• pp.234-236
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• 2004

• Bulletin of the Korean Chemical Society
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• v.29 no.8
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• pp.1525-1532
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• 2008

An instrument was developed for the simultaneous determination of gas- and aerosol-phase nitrous acid (HONO). Gaseous HONO (HONO(g)) was sampled by a diffusion scrubber and particulate nitrite ($NO_2\;^-$(p)) was collected by a particle growth chamber. The collected samples were analyzed in time-sharing manner, based on the peroxynitrite-induced luminol chemiluminescence. The automated system was found to be sensitive with 13 pptv of detection limit, fast with 4 min. of sampling frequency, and simple and affordable to construct and operate. The system was optimized by adjusting the experimental parameters. The system was applied to the field measurement of gas- and particle-phase HONO during the springtime of 2004 in Gwangju, South Korea. HONO(g) concentrations varied diurnally from 200 pptv around 3 P.M. to 800 pptv at 5 A.M. The variation of $NO_2\;^-$(p) was not significant with the maximum of 240 pptv at 11 P.M. and the minimum of 170 pptv at 4 P.M., not displaying distinct characteristics.