• Journal of Korean Society for Atmospheric Environment
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• v.20 no.1
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• pp.111-118
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• 2004

In order to compare the NVOC (Natural Volatile Organic Compound) emission rates from oak trees, the emission rates of isoprene were quantitatively measured in situ based on tree species and region. As a result, the emission rates from Quercus serrata T. were found to be 1000 times greate. than those from Quercus acutissima C. However, the emission rates at the Chili and Gumsung mountain sites did not show any significant differences in summer. Cuvette tests using four different oak species also supported that there was a tremendous difference in emission rates between Quercus serrata T. and Quercus acutissima C. It was found that the emission rates from the trees were highest on the order of Quercus serrata T., Quercus aliena B., Quercus acutissima C. and Quercus variabilis B.

• Particle and aerosol research
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• v.14 no.4
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• pp.171-180
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• 2018

To optimize the shape of the electrostatic precipitator for the removal of particulate matter in subway environments, the wind-tunnel experiments were carried out to characterize collection efficiency and ozone emission rate. As a standardized parameter, power consumption divided by the square of flow velocity, was increased, the $PM_{10}$ collection efficiency increased. If the standardized parameter is higher than 1.0 due to high power consumption or low flow velocity, increase in thickness of electrodes from 1 to 2 mm, or increase in distance of collection plates from 5 to 10 cm did not change the $PM_{10}$ collection efficiency much. Increase in thickness of high-voltage electrodes, however, can cause decrease in $PM_{10}$ collection efficiency by 28% for low power consumption and high flow velocity. The ozone emission rate decreased as distance of collection plates became wider, because the ozone emission rate per unit channel was constant, and the number of collection channels decreased as the distance of collection plates increased. When the distance of collection plates was narrow, the ozone emission rate increased with the increase of the thickness of electrodes, but the difference was negligible when the distance of collection plates was wide. It was found that the electrostatic precipitator having a thin high-voltage electrodes and a narrow distance of collection plates is advantageous. However, to increase the thickness of high-voltage electrodes, or to increase the distance of collection plates is needed, it is necessary to increase the applied voltage or reduce the flow rate to compensate reduction of the collection efficiency.

• KIEAE Journal
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• v.13 no.5
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• pp.79-88
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• 2013

This study creates the evaluation criteria to analyze the $CO_2$ emission quantity in the complex of apartment house among domestic buildings and proposes how to calculate the $CO_2$ emission quantity by the only simple information of apartment house. The study shows that in order to create the index of carbon emission evaluation criteria, $CO_2$ emission quantity for its input materials in these 27 apartment houses are 445,412g-$CO_2/m^2$ for apartment building, 474,322g-$CO_2/m^2$ for the basement parking lot, 483,523g-$CO_2/m^2$ for welfare facility, 729,957g-$CO_2/m^2$ for sales facility, 743,560g-$CO_2/m^2$ for other facility, 26,782g-$CO_2/m^2$ for public facility, 43,659g-$CO_2/m^2$ for landscape, 1,113g-$CO_2/m^2$ for indoor facility, 11,251g-$CO_2/m^2$ for outdoor facility and 891g-$CO_2/m^2$ for common temporary based on the average $CO_2$ emission by facility. We can also see the analysis data that in case of using the selected factors only, the rate of error is 7.51% comparing with the emission quantity by using simplified LCA method this study suggests for the whole range of apartment houses and the rate of error is average 3.24% using selective and main materials. And this it is evaluated that we can get the result which is similar to the actual $CO_2$ emission quantity with only the simple information about the apartment house.

• Journal of Korean Society for Atmospheric Environment
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• v.20 no.2
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• pp.175-183
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• 2004

In order to investigate the composition ratio and the emission rate of monoterpenes emitted from coniferous trees during summer, the enclosure chamber experiments were carried out for two tree species (Pinus densiflora and Pinus rigida). The major monoterpenes from the pine trees were $\alpha$-pinene, $\beta$-pinene, myrcene and $\beta$-phellandrene. There was no difference of the composition ratio between two sites for P. densiflora, but the difference was observed for P. rigida. Clearly, the ratio of $\beta$-pinene (26.1 %) for P. rigida was higher than that of $\beta$-phellandrene (12%) at the Gumsung mountain site, but the ratio of $\beta$-phellandrene (22.2%) was higher than that of $\beta$-pinene (9.9%) at the Chiri mountain site. Particularly, the composition ratio of $\beta$-phellandrene was higher than that of $\beta$-pinene for P. densiflora, and the opposite trend was found for P. rigida at the Gumsung mountain site. The characteristics of the composition ratio between two species were similar at the Chiri mountain site. As a result of the emission rate measurements, it was observed that both sites did not show any significant $\beta$ value (slope between emission rate and temperature) and ERs (Standard Emission rate at 3$0^{\circ}C$) difference. However, the $\beta$ value and ERs at the Chiri mountain site were slightly greater than those of Gumsung mountain site for both pine species. P. densiflora (1.703 and 1.971 $\mu\textrm{g}$C/gdw/hr) showed the higher monoterpene ERs than those of P. rigida (0.572 and 0.698 $\mu\textrm{g}$C/gdw/hr) at both sites.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.1
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• pp.24-31
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• 2002

An experimental study was conducted to investigate the effects of EGR (Exhaust Gas Recirculation) variables on performance and emission characteristics in a 2-liter 4-cylinder spark-ignition LPG fuelled engine. The effects of EGR on the reduction of thermal loading at exhaust manifold were also investigated because the reduced gas temperature is desirable for the reliability of an engine in light of both thermal efficiency and material issue of exhaust manifold. The steady-state tests show that the brake thermal efficiency increased and the brake specific fuel consumption decreased with the increase of EGR rate in hot EGR and with the decrease of EGR temperature in case of cooled EGR, while the stable combustion was maintained. The increase of EGR rate or the decrease of EGR temperature results in the reduction of NOx emission even in the increase of HC emission. Furthermore, decreasing EGR temperature by $180^{\circ}C$ enabled the reduction of exhaust gas temperature by $15^{\circ}C$ in cooled EGR test at 1600rpm/370kPa BMEP operation, and consequently the reduction of thermal load at exhaust. The optimization strategy of EGR application is to be discussed by the investigation on the effect of geometrical characteristics of EGR-supplying pipe line.

• Journal of the Korean Society of Combustion
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• v.4 no.1
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• pp.49-57
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• 1999

An experimental study on double-concentric diffusion flame has been carried out in order to investigate the shape, the flame length, and the other characteristics of the flame. Flow visualization of the flame by the $TiO_2$ particles and also the emission measurements are conducted. The commercial grade LP gases are used as fuel. The inverse diffusion flames are formed at the center when the central air flow rate is about 0.1 L/min. With a larger flow rate of the central air jet than 0.2 L/min the flame turns to be an annular-shaped flame, which is very bright. When the central air flow rate increases over 2.4 L/min, the flame turns to blue and the flame tips are opened because of the lifting of the inner part of the flame. Because of this lifting and the incomplete combustion, the CO emission increases abruptly from 25 ppm to more than 150 ppm. On the contrary, the NOx emission is decreased.

• Journal of ILASS-Korea
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• v.20 no.4
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• pp.254-260
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• 2015

The objective of this study is to investigate the effect of multi-hole nozzle on the performance of small CRDI engine. Combustion and exhaust emission characteristics of engine were studied by using CFD simulation with ECFM-3Z combustion model. The conditions of simulation were varied with nozzle geometry, injection timing and injection quantity. In addition, the results were compared in terms of combustion pressure, rate of heat release, $NO_x$ and soot emissions. It was found that combustion pressure was increased when injection timing was advanced. The rate of heat release of 6 hole nozzle was higher than that of 12 hole nozzle since the quantity of fuel impinged at the bottom of piston rim was different under different injection timing conditions. In the case of $NO_x$ emission, 6 hole nozzle generated more $NO_x$ emission than 12 hole nozzle. On the other hand, in the case of soot emission, 12 hole nozzle showed higher value than 6 hole nozzle because injected fuel droplets from multi-hole nozzle were coalesced.

• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.277-282
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• 2006

In order to predict the indoor air pollutant, the VOCs emission rate is used through small chamber in the design process. However, the small chamber method has limitations as the convective mass transfer coefficient, the most important factor when predicting VOCs contamination of indoor air, is different between the small chamber result and the measured data in the actual building. Furthermore, the existing studies which analyzed mass transfer coefficient in the small chamber were directed on the small chambers developed at the time and FLEC(Field and Laboratory Emission Cell), thus, are different from the current small chamber which has been changed with improvements. The purpose of this study is to determine the emission rate of pollutant in double-layered building materials through the CFD(Computational of Fluid Dynamics) and Numerical analysis based on the mass transfer coefficient on singled-layered building material by using the current small chamber widely used in Korea. Futhermore, this study used the new convective mass transfer coefficient($h_m'$) which indicates the existing convective mass transfer coefficient($h_m$) including VOC partition coefficient(k). Also, formaldehyde was selected as target pollutant.

• Transactions of the Korean hydrogen and new energy society
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• v.33 no.4
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• pp.400-412
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• 2022

Hydrogen with high chemical reactivity and combustion efficiency, is expected to reduce greenhouse gas and CO emission. However, there is a problem of increase in NOx emission due to hydrogen combustion. MILD combustion technology has been proposed to resolve NOx emission. In this study, the characteristics of MILD combustion and NOx formation by flue gas recirculation (KV) in CH₄-H₂ mixture were analyzed and predicted using 0D premixed combustion model. The ignition delay time became shorter as the hydrogen co-firing rate increased, and longer as the recirculation rate increased. For NOx emission, EINO decreased as the KV increased, but EINO increased as the hydrogen co- firing rate increased. In particular, EINO was predicted to increase significiently above 80% hydrogen. Through the pathway analysis of NO formation, it was found that the influence of N₂O intermediate route and NNH route was enhanced for hydrogen co-firing.

• Journal of Korean Society of Transportation
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• v.31 no.6
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• pp.90-105
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• 2013

There are lots of variations on speed, acceleration and engine power during vehicle driving. It is well known that Green House Gas emissions by these dynamic driving properties are not precisely estimated by the average speed based emission estimation model which has been currently used in Korea. MOVES are selected as an appropriate transferable model among Micro-level emission estimation models. Based on MOVES, a novel emission estimation model can be used in Korea is developed. In this model, MOVES concept of emission estimation method and the MOVES method of estimating the Micro-level emission rate map is adopted. The results from the proposed model were compared with those from the average speed based emission model. The comparison results show the estimated base emission maps are good to be applied in Korea, but needed to be adjusted to consider the vehicle size differences between the two countries. Therefore, the factors for calibrating vehicle size difference were calculated and applied to acquired the micro-level emission maps for the Korean standard vehicle types.