• Journal of Korean Society for Atmospheric Environment
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• v.29 no.3
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• pp.307-316
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• 2013

The sensitivity of ozone to $NO_x$ and volatile organic compounds (VOCs) emission rates under different ventilation rates and $NO_2-to-NO_x$ emission ratios in a street canyon is investigated using a chemistry box model. The carbon bond mechanism IV (CBM-IV) with 36 gaseous species and 93 chemical reactions is incorporated. $NO_x$ and VOCs emission rates considered range from 0.01 to $0.30ppb\;s^{-1}$ with intervals of $0.01ppb\;s^{-1}$. Three different ventilation rates and three different $NO_2-to-NO_x$ emission ratios are considered. The simulation results show that the ozone concentration decreases with increasing $NO_x$ emission rate but increases with increasing VOCs emission rate. When the emission ratio of VOCs to $NO_x$ is smaller than about 4, the ozone concentration is lower in the street canyon than in the background. On average, the magnitude of the sensitivity of ozone to $NO_x$ emission rate is significantly larger than that to VOCs emission rate. As the $NO_x$ emission rate increases, the magnitude of the sensitivity of ozone to $NO_x$ and VOCs emission rates decreases. Because the ozone concentration is lower in the street canyon than in the background, the increased ventilation rate enhances ozone inflow from the background. Therefore, the increase in ventilation rate results in the increase in ozone concentration and the decrease in the magnitude of the sensitivity of ozone to $NO_x$ and VOCs emission rates when the emission ratio of VOCs to $NO_x$ is smaller than about 4. On the other hand, the increase in $NO_2-to-NO_x$ emission ratio results in the increase in ozone concentration because the chemical ozone production due to the $NO_2$ photolysis is enhanced. In the present experimental setup, the contribution of the change in $NO_2-to-NO_x$ emission ratio to the change in the sensitivity of ozone to $NO_x$ emission rate is larger than that of the change in ventilation rate.

• Journal of Korean Society for Atmospheric Environment
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• v.15 no.E
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• pp.45-54
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• 1999

The effectiveness of NOx emission reductions from power plants to alleviate persistent ozone nonattainment in the esterm Unites States was investigated with a focus on the Northeast Corridor, centered on New York City. The 1995 ozone episode along with the 2007 base case emission scenario was used with the Variable-Grid Urban Airshed Model(UAM-V) to determine ozone concentrations. Several scenarios based on EPA's proposal issued on October 10, 1997 were examined. Although it is widely recognized that the eastern United States includes a large Nox-sensitive region(e.g., Sillman, 1999), the study revealed that reducing NOx emissions from power plants beyond 500 miles (800km) was not effective for reducing ozone exceedances in the region. It was also found that NOx emissions from power plants play an important role in local ozone exceedances.

• Asian Journal of Atmospheric Environment
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• v.9 no.1
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• pp.39-47
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• 2015

The emissions of ozone precursors, NOx and VOCs from a biogenic source and port-related sources (ship, shipping container truck, and cargo handling equipment) were estimated in Busan during 2013. Total biogenic isoprene emission in Busan during 2013 was estimated to be $4,434ton\;yr^{-1}$ with the highest emission (e.g., $28ton\;day^{-1}$) in summer using a BEIS method. Seasonal ozone production rates by isoprene ranged from 0.15 (winter) to 2.08 (summer) $ppb\;hr^{-1}$, contributing the predominant portion to ambient ozone levels. Total emissions of NOx and VOCs from ship traversing Busan ports were estimated to be 29,537 and $814ton\;yr^{-1}$, respectively, showing the significant contribution to total NOx emission in Busan. The emissions of ozone precursors were significantly different depending on ship tonnage and port location. Compared to the ship emission, the emissions of NOx and VOCs from the shipping container trucks in Busan were insignificant (2.9% for NOx and 3.9% for VOCs). Total NOx and VOCs emissions from the cargo handling equipment were estimated to be 1,440 and $133ton\;yr^{-1}$, respectively with the predominance of yard tractors.

• Asian Journal of Atmospheric Environment
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• v.6 no.2
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• pp.111-117
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• 2012

To establish area specific control strategy for ambient ozone in the Seoul Metropolitan Area (SMA), the maximum ozone concentration in each local government district in the SMA were estimated by using the OZone Isopleth Plotting Package for Research (OZIPR) model. The modeling period was June 2000 and the emission inventory data used were from National Institute of Environmental Research (NIER). Except the islands of Incheon, whole Seoul and Incheon areas were volatile organic compounds (VOCs) limited, i.e., decreasing the oxides of nitrogen ($NO_X$) emission alone may increase the maximum ozone concentration upto certain point. In Gyeonggi, 12 areas were VOCs limited while 12 areas were in between VOCs limited and $NO_X$ limited, i.e., decreasing both $NO_X$ and VOCs emission may decrease the maximum ozone concentration. Majority of the estimated ozone values were lower than the measured values. The reason could be inaccuracy in emission inventories and/or transport from other areas. The same calculation was carried out for June 2004 and it was found that Seoul was still in the VOCs limited condition.

• Asian Journal of Atmospheric Environment
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• v.9 no.2
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• pp.146-157
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• 2015

Emissions of ozone precursors ($NO_x$ and VOCs) and photochemical ozone creation potentials (POCPs) of VOC emission sources were investigated in the largest port city (i.e., Busan), Korea during the year 2011. This analysis was performed using the Clean Air Policy Support System (CAPSS) national emission inventory provided by the National Institute of Environmental Research (NIER), Korea. For $NO_x$, the emissions from off-road mobile sources in Busan were the most dominant (e.g., $31,202ton\;yr^{-1}$), accounting for about 60% of the total $NO_x$ emissions. The emission from shipping of off-road mobile sources (e.g., $24,922ton\;yr^{-1}$) was a major contributor to their total emissions, amounting to 47% of the total $NO_x$ emissions due to the port-related activities in Busan. For VOCs, the emission source category of solvent usage was predominant (e.g., $36,062ton\;yr^{-1}$), accounting for approximately 82% of the total VOC emissions. Out of solvent usages, the emission from painting was the most dominant ($22,733ton\;yr^{-1}$), comprising 52% of the total emissions from solvent usages. The most dominant VOC species emitted from their sources in Busan was toluene, followed by xylene, butane, ethylbenzene, n-butanol, isopropyl alcohol, and propane. The major emission sources of toluene and xylene were found to be painting of coil coating and ship building, respectively. The value of POCP for the off-road mobile source (61) was the highest in ten major activity sectors of VOC emissions. Since the POCP value of ship transport of off-road mobile source (72) was also high enough to affect ozone concentration, the ship emission can play a significant role in ozone production of the port city like Busan.

• The Korean Journal of Food And Nutrition
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• v.36 no.4
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• pp.334-339
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• 2023

To suppress mold generation of yujacheong, Penicillium chrysogenum LB31 was cultured, and spores were harvested and put into yujacheong. Antioxidant activity, useful ingredients, mold size and incidence were investigated while storing yujacheong for 30 days, after sterilization with different methods (nontreatment, ozone gas emission, heating after ozone gas emission and heating). The results showed that the content of narirutin, naringin, hesperidin, or neohesperidin, which are functional components of yuzu, increased as the storage period increased in all the treatment units. In addition, mold generation was not observed until the 15th day in the heat treatment group after ozone gas emission. As the treatment group emitted ozone gas. molds of 34.8 and 112 mm2 in size were observed on the 30th day. These results suggested that ozone sterilization can prevent microbial contamination, further extending the shelf life of yuzacheong and maintaining a fresh state.

• Journal of Korean Society for Atmospheric Environment
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• v.27 no.6
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• pp.772-790
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• 2011

In this paper, we use the HDDM (High-order Decoupled Direct Method)-driven ozone sensitivity to predict change in ozone concentrations in response to domain-wide $NO_x$(Oxides of Nitrogen) and VOC (Volatile Organic Compound) emission controls over the Seoul Metropolitan Area during June 11~19, 2007. In order to validate the applicability of HDDM to $NO_x$ and VOC control scenarios, the HDDM results are compared to Brute Force Method (BFM). For VOC controls, NME (Normalized Mean Error) between BFM and HDDM remains less than 2% until the domain-wide VOC emissions are reduced by 80%. The NME for a 40% reduction in the domain-wide $NO_x$ emissions is less than 5% but increases abruptly after further reductions in the $NO_x$ emissions (i.e., 80% reduction). The results indicates that it may be inaccurate to use ozone sensitivity coefficients estimated at a given base emission condition in predicting ozone after $NO_x$ reductions larger than ~50% of the domain total in the SMA. Therefore, HDDM application on piecewise emissions is desirable to predict ozone response to emission controls with accuracy (i.e., truck emissions rather than the domain total). For computational efficiency, HDDM shows approximately 30% faster than the BFM sensitivity approach.

• Journal of Information Display
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• v.7 no.1
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• pp.1-6
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• 2006

A 10" carbon nanotube field emission display device was fabricated with a novel structure with a hopping electron spacer (HES) by screen printing technique. HES plays a role of preventing the broadening of electron beams emitted from carbon nanotubes without electrical discharge during operation. The structure of the novel tetrode is composed of carbon nanotube emitters on a cathode electrode, a gate electrode, an extracting electrode coated on the top side of a HES, and an anode. HES contains funnel-shaped holes of which the inner surfaces are coated with MgO. Electrons extracted through the gate are collected inside the funnel-shaped holes. They hop along the hole surface to the top extracting electrode. In this study the effects of the addition of HES on emission characteristics of field emission display were investigated. An active ozone treatment for the complete removal of residues of organic binders in the emitter devices was applied to the field emission display panel as a post-treatment.

• Journal of Environmental Impact Assessment
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• v.5 no.1
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• pp.69-77
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• 1996

The variations of ozone concentration and the sensitivity test for VOC emission intensities was investigated by means of a PBM(Photochemical Box Model). Compared to monitoring data, the typical variations of $NO_2$, CO, $O_3$ for days were successfully reproduced. Model results revealed that maximum ozone concentration got increased with the increase of VOC emission, that is, VOC played the important role in producing the photochemical smog.

• Asian Journal of Atmospheric Environment
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• v.11 no.1
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• pp.29-32
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• 2017

Ozone concentration in Tokyo Metropolitan area is one of the most serious issues of the local air quality. Tropospheric ozone is formed by radical reaction including volatile organic compound (VOC) and nitrogen oxides ($NO_x$). Reduction of the emission of reactive VOC is a key to reducing ozone concentrations. VOC is emitted from anthropogenic sources and also from vegetation (biogenic VOC or BVOC). BVOC also forms ozone through $NO_x$ and radical reactions. Especially, in urban area, the BVOC is emitted into the atmosphere with high $NO_x$ concentration. Therefore, trees bordering streets and green spaces in urban area may contribute to tropospheric ozone. On the other hand, not all trees emit BVOC which will produce ozone locally. In this study, BVOC emissions have been investigated (terpenoids: isoprene, monoterpenes, sesquiterpenes) for 29 tree species. Eleven in the 29 species were tree species that did not emit BVOCs. Three in 12 cultivars for future planting (25 %) were found to emit no terpenoid BVOCs. Eight in 17 commonly planted trees (47%) were found to emit no terpenoid BVOC. Lower-emitting species have many advantages for urban planting. Therefore, further investigation is required to find the species which do not emit terpenoid BVOC. Emission of reactive BVOC should be added into guideline for the urban planting to prevent the creation of sources of ozone. It is desirable that species with no reactive BVOC emission are planted along urban streets and green areas in urban areas, such as Tokyo.