• Journal of Environmental Science International
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• v.32 no.7
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• pp.503-520
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• 2023

In this study, numerical simulations using community multiscale air quality (CMAQ) were conducted to analyze the change in ozone (O₃) concentration due to the reduction in nitrogen oxides (NO_x)andvolatile organic compounds (VOCs) emissions in Busan. When the NO_x and, VOCs emissions were reduced by 40% and, 31%, respectively, the average O₃ concentration increased by 4.24 ppb, with the highest O₃ change observed in the central region (4.59 ppb). This was attributed to the decrease in O₃ titration by nitric oxide (NO) due to the reduction of NO_x emissions in Busan, which is classified as a VOCs-limited area. The distribution of O₃ concentration changes was closely related to NO_x emissions per area, and inland emissions were highly correlated with daily maximum concentrations and 8-h average O₃ concentrations. Contrastingly, the effect of emission reduction depended on the wind direction. This suggests that the emission reduction effects may vary depending on the environmental conditions. Further research is needed to comprehensively analyze the emission reduction effects in Busan.

• Environmental Engineering Research
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• v.23 no.1
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• pp.107-113
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• 2018

Air quality and pollution have recently become a major concern; vehicle emissions significantly pollute the air, especially in large and crowded cities. There are various factors that affect vehicle emissions; this research aims to find the most influential factors affecting $CO_2$ and $NO_x$ emissions using Adaptive Neural Fuzzy Inference System (ANFIS) as well as a systematic approach. The modified ANFIS (MANFIS) was developed to enhance modelling and Root Mean Square Error was used to evaluate the model performance. The results show that percentages of $CO_2$ from trucks represent the best input combination to model. While for $NO_x$ modelling, the best pair combination is the vehicle delay and percentage of heavy trucks. However, the final MANFIS structure involves two inputs, three membership functions and nine rules. For $CO_2$ modelling the triangular membership function is the best, while for $NO_x$ the membership function is two-sided Gaussian.

• Journal of Environmental Health Sciences
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• v.49 no.4
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• pp.190-200
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• 2023

Background: Gunsan has been constantly affected by pollutants generated by the Saemangeum development and the construction industry since the completion of the Saemangeum seawall on April 27, 2010. However, there are limitations to its study, such as taking into consideration weather conditions, geographical factors, and foreign inflows. Objectives: In this study, we compared the Existing-CAPSS emissions of Gunsan with Recalculated-CAPSS emissions data to analyze the differences in emissions characteristics by year (2016~2019). Methods: Using Existing data on CAPSS emissions (2016~2019) and Recalculated-CAPSS emissions (2016~2019) for Gunsan, which were Recalculated following the improvement of emissions calculations for 2020, we organized CO, NO_X, SO_X, PM₁₀, VOC_S, and NH₃ emissions by substance and investigated the differences and characteristics of the Recalculated emissions by year. Results: For Re-CO and Re-PM₁₀, the emission characteristics of CO were examined as energy industry combustion and PM₁₀ emission characteristics were examined as ship cargo from non-road transportation sources, as ship leisure sources were excluded from non-road transportation source emissions. Conclusions: Comparing the emissions of Existing-CAPSS and Recalculated-CAPSS in Gunsan, the emissions of Recalculated-CAPSS by substance decreased by 39.76% for CO, 9.98% for PM₁₀, 5.53% for VOC_S, and 9.24% for NH₃, while Re-NO_X increased by 2.86% and Re-SO_X increased by 1.97%. On the other hand, when comparing the emissions characteristics of Existing-CAPSS and Recalculated-CAPSS in Gunsan, Jeonju, and Iksan, the emission characteristics of Re-NO_X, Re-SO_X, Re-VOC_S and Re-NH₃ were similar to those of Ex-NO_X, Ex-SO_X, Ex-VOC_S, and Ex-NH₃. As such, Gunsan, Iksan, and Jeonju, showed differences in the comparison of different emission characteristics due to the geographical characteristics of the region (population, area, topography, weather factors) and the characteristics of the industrial complex (metal, petrochemical).

• Journal of Korean Society for Atmospheric Environment
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• v.25 no.5
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• pp.369-381
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• 2009

The objective of this study was to simulate surface air pollutants and to examine reliability of mobile emission for CMAQ system using an observation-based approach in the Seoul Metropolitan Area. Accurate assessment of emissions from mobile source is one of the most debatable parts in the entire emissions inventory process. For this study, we evaluated the official emission inventories of Volatile Organic Compounds (VOCs) and nitrogen oxides ($NO_x$) using an observation-based approach. In this paper, we achieved VOCs/CO and $NO_x$/CO ratios derived from ambient measurements taken from June to August of 2005 in early morning (07:00~08:00). And we compared them with those derived from the emission inventory. Based on these ratios and on the assumption that official inventory of CO emissions is reasonably accurate, mobile emissions of $NO_x$ seem to be slightly overestimated and VOCs emissions significantly underestimated. The results of simulations using modified emission of mobile source were in closer agreement with the observation results except NO. Predicted NO values based on revised $NO_x$ emissions were considerably lower than the observed values. Using modified emission inventories brings the modeled values into closer agreement with observed ozone levels in Seoul. Especially in case of CO, $NO_x$ and VOCs emission, the modified values were suitable for simulating ozone levels in Seoul and Gyeonggi. However, ozone values predicted using the modified emissions were higher than the observed and predicted values based on original emissions. According to the 95 percentile ozone concentrations, emission revised by CO, $NO_x$ and VOCs from mobile source was the best for predicting high concentration.

• 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.

• International Journal of Automotive Technology
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• v.7 no.7
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• pp.763-768
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• 2006

Emission reduction in the cold start period of SI engines is crucial to meet stringent emission regulations such as SULEV Emissoin reduction is the starting point of the study in the which the variable valve timing (VVT) technology may be one promising method to minimize cold start emissions while maintaining engine performance. This is because it is possible to change valve overlap and residual gas fraction during cold start and idle operations. Our previous study showed that spark timing is another important factor for reducing cold-start emissions since it affects warm-up time of close-coupled catalysts (CCC) by changing exhaust gas temperature. However, even though these factors may be favorable for reduction of emissions, they may deteriorate combustion stability in these operating conditions. This means that the two variables should be optimized for best exhaust emissions and engine stability. This study investigated the effects of valve and spark timings in idle performance such as combustion stability and exhaust emissions. Experiments showed that valve timings significantly affected engine stability and exhaust emissions, especially CO and $NO_x$, due to change in residual gas fraction within the combustion chamber. Spark timing also affects HC emissions and exhaust gas temperature. Yet it has no significant effects on combustion stability. A control strategy of proper valve timing and spark timing is suggested in order to achieve a reduction in exhaust emissions and a stable operation of the engine in a cold start and idle operation.

• Journal of Korean Society for Atmospheric Environment
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• v.13 no.2
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• pp.123-135
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• 1997

An air pollutant emission inventory system for the input preparations of photochemical dispersion model was developed. Using the system, anthropogenic emissions as well as biogenic emissions in the Seoul metropolitan area were calculated. Anthropogenic emission by fuel combustion using regional cosumption data, and the laundries and so forth was estimated. The biogenic emission was estimated based upon meteorological data and the distribution of land use type in the study area. The anthropogenic emission of pollutants was highest in Seoul, and the second highest in Inchon. TSP and $SO_2$ were found large quantities during the winter due to increased consumption of heating oil. NOx and THC were emitted without seasonal variation. Among biogenic emissions, PAR was very common while NO was the least common. PAR, OLE, and ALD2 were emitted in large volumes in coniferous forest areas, while ISOP was emitted in deciduous forest areas. Generally, most biogenic emissions increased during daytime, and peaked between oen and two o'clock. Because of strong solar radiation, emission during the summer was high. Biogenic NO emissions were found to be lower compared to anthropogenic emissons, and other VOC was indicated relatively high. In the study area, among biogenic emissions PAR was found to be 3 times, OLE 8 times,and ALD2 12 times more common than among anthropogenic emissions.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.4
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• pp.547-554
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• 2002

We are facing the serious environmental pollution difficulties such as acid rain, green house effects, etc. The gaseous matter NOx, SOx, VOCs which are regarded as main factors for these current pollutions are mainly emitted from power plants and vehicles. Therefore several leading countries are regulating the emissions strictly, especially the exhaust emissions from a Diesel engine without an aftertreatment device. The objective of this study is to find out soot and NO removal characteristics focused on the emissions of a Diesel engine by using nonthermal plasma for each engine speeds and loads. Electrostatic precipitator(wire-to-plate type reactor) is used for soot removal. Radicals generated from outer air and put into a mixing chamber in the end of exhaust line are used for NO removal. Concentration of exhaust emissions is analyzed from the gas analyzer(KaneMay) and FTIR to estimate by-products.

• Journal of Environmental Science International
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• v.17 no.12
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• pp.1413-1419
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• 2008

The Kyoto Protocol, that had been in force from February 16, 2005, requires significant reduction in $CO_2$ emissions for all anthropogenic sources containing transportation, industrial, commercial, and residential fields, etc, and automotive emission standards for air pollutants such as particulate matter (PM) and nitrogen oxides $(NO_x)$ become more and more tight for improving ambient air quality. This paper has briefly reviewed homogeneous charge compression ignition (HCCI) combustion technology offering dramatic reduction in $CO_2,\;NO_x$ and PM emissions, compared to conventional gasoline and diesel engine vehicles, in an effort of automotive industries and their related academic activities to comply with future fuel economy legislation, e.g., $CO_2$ emission standards and corporate average fuel economy (CAFE) in the respective European Union (EU) and United States of America (USA), and to meet very stringent future automotive emission standards, e.g., Tier 2 program in USA and EURO V in EU. In addition, major challenges to the widespread use of HCCI engines in road applications are discussed in aspects of new catalytic emissions controls to remove high CO and unburned hydrocarbons from such engine-equipped vehicles.

• Journal of Korean Society for Atmospheric Environment
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• v.27 no.4
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• pp.460-471
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• 2011

A port has been regarded as a significant contributor to air pollution in the surrounding areas. Port-related air pollutants are released from not only marine vessels, but also various land-side sources at ports, which include cargo handling equipment, vehicles, locomotives, and fugitive dust sources by port activities such as bulk handling and vehicle movements. However, most studies in Korea have only focused on vessel emissions and there is a lack of information on the emissions from other sources at port. In this study, in order to establish the port-related emission inventory and evaluate the relative contribution of these sources to air emissions from the Port of Incheon, the emissions from land-side sources were estimated and the CAPSS (Clean Air Policy Support System) data for vessel emissions were used. In particular, the detailed information and activity data for the cargo handling equipment source were collected and the emission factors and emissions by equipment types were calculated using U.S. EPA methodologies. Total HC, CO, $NO_x$, $PM_{10}$, and $SO_2$ emissions from port-related sources including the vessel in 2007 were calculated as 229 ton/year, 638 ton/year, 4,861 ton/year, 307 ton/year, and 3,995 ton/year, respectively. It was found that the vessel was the largest contributor to air pollutant emissions from the port, the cargo handling equipment was responsible for about from 8% to 13% of HC, CO, and $NO_x$ emissions and the resuspended road dust contributed about 39% for $PM_{10}$ emissions. The results of this study will be used to establish the management and reduction strategies of air pollution in the port.