• Journal of Korean Society for Atmospheric Environment
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• v.27 no.5
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• pp.580-602
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• 2011

Volatile organic compound (VOC) emissions in the 2007 CAPSS (Clean Air Protection Supporting System) emissions inventory are chemically speciated for the SAPRC99 (Statewide Air Pollution Research Center 99) mechanism, following the Source Classification Code (SCC) matching method to borrow the U.S.EPA's chemical speciation profiles. CMAQ simulations with High-order Direct Decoupled Method (HDDM) are in turn applied to evaluate uncertainty in the method by comparing the simulated model VOC species to the observations in the Seoul Metropolitan Area (SMA) for a 2007 June episode. Simulations under-predicted ALK1 to ALK4 in SAPRC99 by a factor of 2 to 5 and over-predicted ALK5 by a factor of 7.5 while ARO1, ARO2, OLE1, and ethylene (ETH) are comparable to the observations, showing relative difference by 10 to 30%. OLE2 emissions are roughly 4 times overestimated. Emission rates for individual VOC model species are revised referring to the ratio of simulated to observed concentrations. Impact of the VOC emission changes on the overall ozone prediction was insignificant for the days of which 1-hr maximum ozone are lower than 100 ppb. However, simulations showed ozone difference by 5 to 10 ppb when high ozone above 120 ppb was observed in the vicinity of Seoul. This result suggests that evaluations on individual model VOC emissions be necessary to lead ozone control plans to the right direction. Moreover, the simulated ratios of ARO1 and ARO2 to $NO_x$ are roughly 50% lower than the observed ones, which imply that adjustment in $NO_x$ and VOC emission rates may be required to mimic the real VOC/$NO_x$ condition over the area.

• Journal of Korean Society for Atmospheric Environment
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• v.27 no.5
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• pp.614-622
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• 2011

In this study, a new tunnel ventilation method with a high velocity air curtain flow has been investigated for improving the ventilation exhaust efficiency and removing air pollutants in subway tunnels. At upper or lower position right downstream of a main duct connected with a ventilation opening, air curtain flows were suppled into the main duct where the air flow velocity was in the range of 2~6 m/s. Exhaust efficiency was monitored for both cases with and without air curtain flow for different air velocities, locations and injection angles of the air curtain. Particulate matter concentrations (PM10, PM2.5 and PM1.0) were also checked at both the main duct and ventilation opening before and after supplying air curtain flows. Lower air velocity of the main duct flow, higher air velocity of the air curtain led to higher exhaust efficiency and the air curtain condition of 30..inclined injection toward the main flow showed the maximum exhaust efficiency. The exhaust efficiency of about 24% without the air curtain could be improved to about 34% after using the air curtain flow. PM concentration decreased at the main duct and increased at the ventilation opening after using the air curtain flow. Therefore, the suggested method to use air curtain flows in tunnels will be probably one of the promising tools to reduce air pollutants in subway tunnels.

• Journal of Korean Society for Atmospheric Environment
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• v.27 no.3
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• pp.281-290
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• 2011

In this study, a series of experiments were carried out to measure temporal stability of reduced sulfur compounds (RSCs) in Tedlar bag samples as a function of elapsed storage time. To this end, temporal variability of 4 RSC standard gases ($H_2S$, $CH_3SH$, DMS, DMDS) was measured up to 29 days. For the purpose of comparison, RSC samples were stored in both individual and mixed state. In the case of mixed standard, samples were also examined to allow comparison between light and dark condition. Then results of $CH_3SH$ data were the most stable with the least change in its concentrations through the end of exps (29 days). When compared with previous studies, the extent of stability appeared to be influenced by the initial concentration levels of samples. When the patterns were compared between individual and mixture samples, differences were not significant in the case of $H_2S$ and DMS. The effects of light conditions on temporal stability were seen to be fairly sensitive on most RSC other than $H_2S$. The results of our study confirm that the stability of RSC storage is affected by their involvement in photochemical reactions.

• Journal of Korean Society for Atmospheric Environment
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• v.23 no.2
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• pp.250-260
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• 2007

It was investigated that the emission characteristics of volatile organic compounds (VOCs) from small and medium companies located on industrial complexes in Metropolitan area. The emission characteristics are intermittent sources in which VOCs emissions are highly depends on the working condition. Optimized ventilation system to improve air quality in working area for the three typical companies were installed. Adsorption characteristics of major VOCs such as MEK, IPA, and toluene emitted front the companies were investigated for design of the activated carbon vessel as a VOCs control facility in each company. Concentration of total hydrocarbon and gas amounts needed to ventilation were also used as a design parameter. Mixed adsorbent to improve adsorption characteristics of problematic solvents like IPA and the design guideline of the activated carbon vessel have been suggested.

• Asian Journal of Atmospheric Environment
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• v.9 no.4
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• pp.259-271
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• 2015

This study conducted analyses on biogenic volatile organic compounds (BVOC) emission sources contributing to urban ozone ($O_3$) concentration in Osaka Prefecture, Japan in summer 2010 by using the Weather Research and Forecasting model (WRF) version 3.5.1 and the Community Multiscale Air Quality model (CMAQ) version 5.0.1. This prefecture is characterized by highly urbanized area with small forest area. The contributions of source regions surrounding Osaka were estimated by comparing the baseline case and zero-out cases for BVOC emissions from each source region. The zero-out emission runs showed that the BVOC emissions substantially contributed to urban $O_3$ concentration in Osaka (10.3 ppb: 15.9% of mean daily maximum 1-h $O_3$ concentration) with day-by-day variations of contributing source regions, which were qualitatively explained by backward trajectory analyses. Although $O_3$ concentrations were especially high on 23 July and 2 August 2010, the contribution of BVOC on 23 July (35.4 ppb: 25.6% of daily maximum $O_3$) was much larger than that on 2 August (20.9 ppb: 14.2% of daily maximum $O_3$). To investigate this difference, additional zero-out cases for anthropogenic VOC (AVOC) emissions from Osaka and for VOC emissions on the target days were performed. On 23 July, the urban $O_3$ concentration in Osaka was dominantly increased by the transport from the northwestern region outside Osaka with large contribution of $O_3$ that was produced through BVOC reactions by the day before and was retained over the nocturnal boundary layer. On 2 August, the concentration was dominantly increased by the local photochemical production inside Osaka under weak wind condition with the particularly large contribution of AVOC emitted from Osaka on the day.

• Journal of Korean Society for Atmospheric Environment
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• v.24 no.4
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• pp.415-422
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• 2008

This study was carried out to investigate the effect of operating and design conditions of gas dispersion type of absorber on $SO_2$ removal efficiency. pH difference between upper and lower part of gas dispersing plate of absorber was 0.2, which was relatively low. This was supposed that recirculation capacity of absorbing liquid between froth zone and reaction zone of absorber be increased by oxidation air injection through liquid riser which acted as liquid pump. Test results showed that $SO_2$ removal efficiency was more sensitive than absorber ${\Delta}P$. High $SO_2$ removal even at lower pH resulted from very low concentration of $HSO_3^-$ ion in absorbing liquid because of direct supply of dissolved oxygen into froth zone. 96% of $SO_2$ removal efficiency was obtained under the condition of absorber pH 5.2, flue gas flow rate of $1,530\;Nm^3/hr$, inlet $SO_2$ concentration of 800 ppm, absorber ${\Delta}P$ of 250mmAq. The following equation by a multiple linear regression was obtained to describe the relationship between $SO_2$ removal and operating variables. $$f=1-{\exp}(-1.3939+1.060pH+0.0139{\Delta}P-0.00267G-0.000064SO_2Conc.),\;R^2=0.9719$$

• Journal of Korean Society for Atmospheric Environment
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• v.26 no.1
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• pp.1-9
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• 2010

In this study, the selective catalytic reduction of $NO_x$ with ammonia was carried out in a filter bag support reactor. The experiments were performed by powder type $MnO_x$ and $V_2O_5$/$TiO_2$ catalyst at low temperature between 130 and $250^{\circ}C$. Also, the effect of $SO_2$ and $H_2O$ on the NO conversion was investigated under our test conditions. The powder type catalysts were analyzed by X-ray photoelectron spectrum (XPS), X-ray diffraction(XRD), scanning electron microscopy (SEM) and thermal gravimetric analysis (TGA). It was observed that NO removal efficiency of the powder type $V_2O_5$/$TiO_2$ catalyst was 85% at low temperature($200^{\circ}C$) under presence of oxygen and that of $MnO_x$ was 50% at the same condition. The powder type $V_2O_5$/$TiO_2$ catalyst, in conclusion, was found to be available for SCR reaction in a filter bag support system.

• Journal of Environmental Science International
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• v.16 no.12
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• pp.1401-1409
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• 2007

The formation mechanism of the snow cells of the Yellow Sea associated with snowfall over the southwestern part of Korea on 4 February, 2004 has been investigated using special upper-air sounding and radar data obtained for the KEOP(Korea Enhanced Observing Period) Intensive Observing Period(IOP). Results show that the types of snow cells for the selected period are classified into L(Longitudinal)-mode, Low-level convergence, and T(Transverse)-mode with their evolution from L-mode to T-mode. In particular, the existence of low-level warm and humid layer associated with temporally southwesterly inflow for about 4 hours provides a favorable condition in forming the T-mode snow cells. The vertical depth of the T-mode snow cells is deeper than that of L-mode ones due to the southeastward penetration of cold and dry air into relatively warm and humid air. In addition, it is found that wind shear vector between 1000 hPa and 600 hPa is one of the factors which control the orientation of snow cells in formation embedded into the snowbands for the both modes.

• Transactions of the Korean hydrogen and new energy society
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• v.7 no.2
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• pp.147-155
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• 1996

The aim of this study is the development of technologies of methanol production from carbon dioxide by catalytic hydrogenation. Experiments about carbon dioxide hydrogenation by catalyst mixed with CuO, ZnO, $Cr_2O_3$ and $Al_2O_3$ were conducted to find optimum catalyst and reaction condition. Reactions were carried out at atmospheric and high pressures between 200 to $350^{\circ}C$. High yield of methanol was obtained with $Cu/ZnO/Cr_2O/Cr_2O_3/Al_2O_3$ catalyst at $250^{\circ}C$ and above 30 atmospheric pressure. There was not any increament of hydrogenation reactivity for the catalysts which was made by the addition of Pd to $Cu/ZnO/Cr_2O/Cr_2O_3/Al_2O_3$.

• The Plant Pathology Journal
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• v.34 no.3
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• pp.208-217
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• 2018

In this study, samples were collected from the leaves and stems of healthy wild Pistachio trees (Pistacia atlantica L.) from various locations of Baneh and Marivan regions, Iran. In total, 61 endophytic bacteria were isolated and grouped according to phenotypic properties. Ten selected isolates from each group were further identified by partial sequencing of the 16S rRNA gene. Based on the results, isolates were identified as bacteria belonging to Pseudomonas, Stenotrophomonas, Bacillus, Pantoea and Serratia genus. The ability of these isolates was evaluated to phytohormone production such as auxin and gibberellin, siderophore production, phosphate solubilization, atmospheric nitrogen fixation, protease and hydrogen cyanide production. All strains were able to produce the plant growth hormone auxin and gibberellin in different amounts. The majority of strains were able to solubilize phosphate. The results of atmospheric nitrogen fixation ability, protease and siderophore production were varied among strains. Only Ba66 could produce a low amount of hydrogen cyanide. The results of biocontrol assay showed that Pb78 and Sp15 strains had the highest and lowest inhibition effects on bacterial plant pathogens, Pseudomonas syringae pv. syringae Pss20 and Pseudomonas tolaasii Pt18 under in vitro condition. Pb3, Pb24 and Pb71 strains significantly promote root formation on carrot slices. To our knowledge this is the first report of the isolation of endophytic bacterial strains belonging to Pantoea, Bacillus, Pseudomonas, Serratia and Stenotrophomonas genus from wild pistachio trees with plant growth promoting potential and biocontrol activity.