• Transactions of the Korean Society of Automotive Engineers
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• v.9 no.6
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• pp.103-111
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• 2001

During cold-start period, the reduction of exhaust emissions is a challenging task. To decrease harmful gaseous substances such as HC, it is necessary to realize a fast catalyst warm-up. In this study, the performance of dual pipe exhaust system have been carried out through different test mode. From measurement of gas temperature and HC concentration, the following conclusions were derived ; 1) Compared with single pipe, dual pipe exhaust system remarkably increase temperature of exhaust gas going through M.C.C(Main Catalytic Converter). 2) W.C.C.(Warm-up Catalytic Converter) also decreases HC emission. To reduce HC emission, it is helpful to use W.C.C. as well as dual pipe exhaust system. 3) Using finite element method, it is shown that inner parts have much higher distribution of temperature than outer parts.

• Journal of Korean Society for Atmospheric Environment
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• v.15 no.2
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• pp.201-210
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• 1999

Cyclones have been extensively used in the industry for removing fine particles from the gaseous streams, based on simplicity in design and construction in association with low cost and flexibility to operate in extreme and harsh environments. However, industrial cyclones are typically not very efficient for particles smaller than 10μm. In this work, in order to improve the separation efficiency of reverse flow cyclones, a simple device named Post Cyclone(Poc) in installed on the top of an existing cyclone. Thereby the residual swirl present at the outlet (vortex finder) of a conventional cyclone has been used to capture the escaped dust from the cyclone in the PoC. The performance of PoC was closely evaluated by changing configuration of the PoC and operation condition. In addition, the dust behaviour in th PoC was investigated based on the hypothesis of residual vortex.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2126-2130
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• 2008

Gasoline engine have proved its utility in light, medium and heavy duty vehicle in every sector of the world community. The concern about long term availability of petroleum and the increasing threat for the environment by the increasing load of vehicular emission, compel the technology to upgrade itself for meeting the challenges. CNG is environmentally clean alternative to the existing SI Engines with out much change in the hardware. Many researchers have found this as a potential substitute to meet the energy requirement. Higher octane number and higher self ignition temperature make it a good gaseous fuel. Although power output is slightly lesser than the gasoline it's thermal efficiency is better than the gasoline for the same SI Engine. Results showed that reduced CO, hydrocarbon emissions is a favorable outcome, with slight increase in $NO_x$ emission when compared with gasoline fuel to dual fuel mode in the existing SI Engines.

• Transactions of the Korean Society of Automotive Engineers
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• v.19 no.2
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• pp.133-141
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• 2011

The effect of payload on fuel consumption and emission of light duty freight truck during acceleration driving has been analyzed. Running tests were carried out with various payload conditions on chassis dynamometer. A typical driving pattern for urban cities was used. Real time emission measurement systems for gaseous and soot emission were utilized to investigate the real time dynamic of fuel use and exhaust emissions. It was observed that fuel use and pollutant emissions were increased as payload was increased. Under the same payload condition, the increased amount of acceleration driving is much higher than that of steady state driving. The results demonstrated the advantages of eco-driving, which is an environmentally friendly driving manner, could be emphasized in heavier payload condition. Inertial tractive power was introduced for considering the parameters affecting emission during acceleration driving, which are speed, acceleration and payload. Fuel use and emission in various driving conditions were expressed as functions of inertial tractive power. The estimated result by these functions well predicted measured result within 10 % deviation.

• Journal of The Korean Society of Agricultural Engineers
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• v.64 no.1
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• pp.99-110
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• 2022

In this study, the generation and emission characteristics of particulate matter and gaseous matter in a mechanically ventilated layer house were evaluated. Each concentration of PM₁₀, PM_2.5, inhalable dust, respirable dust, and NH₃ was measured and compared with occupational limit considering seasons and respiratory disorder. CAPPS (Clean Air Policy Support System) of the Ministry of Environment proposes the emission factors of PM₁₀, PM_2.5, and NH₃ for a layer houses however, emission factors are still calculated from foreign factors such as CONINAIR values. As a result, it is urgent to develop national emission factors for domestic layer house. Emission coefficients of the studied mechanically-ventilated layer house in a summer season were calculated as 0.052 kg/head/year for PM₁₀, about 12% lower than that of CAPSS, and 0.0068±0.0038 kg/head/year for PM_2.5, showing no significant difference. Emission factor of NH₃ was calculated as 0.159±0.031 kg/head/year, about 51% lower than that of CAPSS.

• Asian Journal of Atmospheric Environment
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• v.11 no.3
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• pp.202-216
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• 2017

Nitrogen (N) is an essential macronutrient. Thus, evaluating its flows and stocks in rice paddy ecosystems provides important insights into the sustainability and environmental loads of rice production. Among the N sources of paddy fields, atmospheric deposition and irrigation inputs remain poorly understood. In particular, insufficient information is available for atmosphere-rice paddy exchange of gaseous and particulate reactive N (Nr, all N species other than molecular N) which represents the net input or output through dry deposition and emission. In this study, we assessed the N inputs via atmospheric deposition and irrigation to a Japanese rice paddy area by weekly monitoring for 2 years with special emphasis on gas and particle exchange. The rice paddy during the cropping season acted as a net emitter of ammonia ($NH_3$) to the atmosphere regardless of the N fertilizer applications, which reduced the effects of dry deposition to the N input. Dry N deposition was quantitatively similar to wet N deposition, when subtracting the rice paddy $NH_3$ emissions from N exchange. The annual N inputs to the rice paddy were 3.2 to $3.6\;kg\;N\;ha^{-1}\;yr^{-1}$ for exchange, 8.1 to $9.8\;kg\;N\;ha^{-1}\;yr^{-1}$ for wet deposition, and 11.1 to $14.5\;kg\;N\;ha^{-1}\;yr^{-1}$ for irrigation. The total N input, 22.8 to $27.5\;kg\;N\;ha^{-1}\;yr^{-1}$, corresponded to 38% to 55% of the N fertilizer application rate and 53% to 67% of the brown rice N uptake. Monitoring of atmospheric deposition and irrigation as N sources for rice paddies will therefore be necessary for adequate N management.

• Journal of Environmental Science International
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• v.21 no.7
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• pp.883-890
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• 2012

Emission characteristics of gaseous odor compounds emitted from the charcoal manufacturing process were investigated, and evaluated the odor removal efficiency of odor control devices. It was found that the measured odor dilution ratio of emission gases ranged from 10,000 to 44,814, which exceed largely the emission standard in the stack. Methylmercaptan, trimethylamine, hydrogen sulfide, acetaldehyde were turned out as major odor compounds of the charcoal manufacturing process. It was revealed that the odor removal ratio of odor control devices were very low due to the its improper maintenance and wrong design.

• Journal of Korean Society for Atmospheric Environment
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• v.29 no.1
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• pp.1-9
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• 2013

Hazardous Air Pollutants (HAPs) are difficult to measure, analyze and assess for risk because of low ambient concentrations and varieties. Types of HAPs are Volatile organic compounds (VOCs), Polycyclic aromatic hydrocarbon (PAHs) and Aldehydes. HAP emissions from vehicles are a contributor to serious adverse health effects in urban areas. In this study, hazardous air pollutant emissions from road transport vehicles by Non-methane volatile organic compounds (NMVOC) weight fraction and PAHs emission factors are estimated in 2008. The top-five-most hazardous air pollutant emissions were estimated to toluene 864.3 ton/yr, acrolein 690.6 ton/yr, acetaldehyde 554.5 ton/yr, formaldehyde 498.7 ton/yr, propionaldehyde 421.6 ton/yr in 2008. The results for a cancer and non-cancer risk assessment of HAPs emissions show that the major cancer driver is formaldehyde and the non-cancer driver is acrolein.

• Journal of Korean Society for Atmospheric Environment
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• v.16 no.6
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• pp.585-594
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• 2000

Through an application of Micrometerorological methods, we conducted measurements of Hg fluxes from Nan-Ji-Do which is well known as one of the major local areal sources in Seoul metropolitan area during Match/April of 2000. In the course of our study, we determined the concentration gradients of total gaseous Hg(between 20 and 2000 cm heights) and combined these data with Micrometerorological components to derive is fluxes. It turned out that emission from and dry deposition to soil surfaces occurred at the ratio of 72:27 from a total of 271 hourly measurements. The validity of measured concentration gradients( or resulting fluxes) was evaluated in terms of percent gradient. Accordingly, about more than 95% of gradient data derived were statistically significant. The mean fluxes of Hg across soil-air interface, when computed using the concentrations gradients and relevant parameters, were found at 253(during emission) and -846ng/$m^2$/h(during dry deposition) The occurrences of abnormalously high exchange rates appear to be the combined effects of enormously high gradient values and high transfer coefficients. While the emissions of Hg occurred constantly during the whole study periods, the occurrences of dry deposition events were observed most intensively during very limited time periods(3/29 and 4/3). The results of our study cleary indicated that the studied area is a strong local areal source, while exhibiting great potential as a major sink simultaneously.

• 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.