• Transactions of the Korean hydrogen and new energy society
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• v.27 no.4
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• pp.357-364
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• 2016

Recently, the world faces the environmental problem such as air pollution due to harmful gas discharged from car and abnormal climate due to the green-house gases increased by the discharge of $CO_2$. Compressed Natural Gas (CNG), one of alternative for this problem, is less harmful, compared to the existing fossil fuel, as gaseous fuel, and less carbon in fuel ingredients and carbon dioxide generation rate relatively favorable more than the existing fuel. However, CNG fuel has the weakness of slow flame propagation speed and difficult fast burn. On the other hand, hydrogen does not include carbon in fuel ingredients, and does not discharge harmful gas such as CO and HC. Moreover, it has strength of quick burning velocity and ignition is possible with small ignition energy source and it's has wide Lean Flammability Limit. If using this hydrogen with CNG fuel, the characteristics of output and discharge gas is improved by the mixer's burning velocity improved, and, at the same time, is possible to have stable lean combustion with the reduction of $CO_2$ expected. Therefore, this research tries to identify the characteristics of engine and emission gas when mixing CNG fuel and hydrogen in each portion and burning them in spark igniting engine, and grasp the combustion stability and emission gas characteristics according and use it as the basic data of hydrogen-CNG premixed engine.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.21 no.8
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• pp.1068-1076
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• 1997

Emission control of acid exhaust gases from coal-fired power plants and waste incinerators has become an increasing concern of both industries and regulators. Among those gaseous emissions, SO$_{2}$ has been eliminated by a Spray Drying Absorber (SDA) system, where the exhaust gas is mixed with atomized limestone-water slurry droplets and then the chemical reaction of SO$_{2}$ with alkaline components of the liquid feed forms sulfates. Liquid atomization is necessary because it maximizes the reaction efficiency by increasing the total surface area of the alkaline components. An experimental study was performed with a laboratory scale SDA to investigate whether the scrubbing efficiency for SO$_{2}$ reduction increased or not with the application of a DC electric field to the limestone-water slurry. For a selected experimental condition SO$_{2}$ concentrations exited from the reactor were measured with various applied voltages and liquid flow rates. The applied voltage varied from -10 to 10 kV by 1 kV, and the volume flow rate of slurry was set to 15, 25, 35 ml/min which were within the range of emission mode. Consequently, the SO$_{2}$ scrubbing efficiency increased with increasing the applied voltage but was independent of the polarity of the applied voltage. For the electrical and flow conditions considered a theoretical study of estimating average size and charge of the atomized droplets was carried out based on the measured current-voltage characteristics. The droplet charge to mass ratio increased and the droplet diameter decreased as the strength of the applied voltage increased.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.9
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• pp.973-980
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• 2015

With their wide geographical distribution, unconventional resources are continuously compared against conventional resources, but their development is expanding because TRRs (Technical Recoverable Resources) are similar to conventional resources. In particular, there is active development of unconventional gas resources such as shale gas, tight gas, CBM (coalbed methane) and gas hydrate. However, it is difficult to calculate the material properties of unconventional resources, especially the gas content, with current geophysical logging technology. Additionally, some overseas companies have monopolies on related equipment and materials. Therefore, this study developed a reservoir PCS (Pressure Core Sampler). It can collect core samples without gaseous loss by maintaining high pressure from the moment the core is sampled and record pressure and temperature in real time. Successful performance testing was also carried out for official verification of the manufactured PCS. The reservoir PCS will contribute to the acquisition of geophysical well logging data as well as accurate and reliable cores.

• Asian-Australasian Journal of Animal Sciences
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• v.16 no.3
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• pp.380-383
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• 2003

The gas dilution technique was used to evaluate the possibility of estimating the volume of gaseous phase in the rumen from its composition in sheep given rice whole crop silage (RWS) or dent corn silage (DCS) at a level of maintenance (M) or 2 M, and in the course of fasting. The rumen gas composition was determined at 2 and 7.5 h after morning feeding. Nitrogen gas was injected by using an airtight syringe into the rumen immediately after collecting the rumen gas sample as a control. Then rumen gas samples were collected at 5, 10, 20, 40 and 60 min. after injection. Dry-matter intakes were $42g/kg^{0.75}$ and $57g/kg^{0.75}$ for DCS, and $36g/kg^{0.75}$ and $59g/kg^{0.75}$ for RWS, at 1 M and 2 M levels, respectively. Animals ingested both silages about 20% less than expected at 2 M level. The rumen gas composition did not differ significantly between 2 h and 7.5 h after feeding except for $N_2$. Content of $CO_2$ in gas composition was significantly higher at 2 M level than at 1 M (p<0.05) for both RWS and DCS, whereas $CH_4$ showed no significant difference between feeding levels. At both feeding levels, $CO_2$ showed a higher (p<0.05) percentage in DCS than RWS. A dilution technique by using $N_2$ injection is not appropriate for the determination of gas production in vivo, unless the rate of rumen gas turnover is considered. Changes in composition at fasting indicate that the rumen fermentation may reach the lowest level after 72 h fasting for sheep given silage as their sole diet.

• Clinical and Experimental Pediatrics
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• v.60 no.7
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• pp.232-236
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• 2017

Pulmonary alveolar proteinosis (PAP) is a rare disease in children characterized by intra-alveolar accumulation of surfactant proteins, which severely reduces gaseous exchange. Whole lung lavage (WLL) is the preferred technique for the treatment of severe PAP. Herein, we present a pediatric case of PAP treated with WLL. An 11-year-old boy was admitted with the chief complaint of a dry cough lasting 6 months. He developed symptoms of dyspnea on exertion and had difficulty in climbing stairs. He was ultimately diagnosed with PAP through video-assisted thoracoscopic lung biopsy. As first-line of treatment for PAP, he underwent therapeutic WLL for each of his lungs on separate days. After a brief recovery, his symptoms gradually worsened; therefore, he underwent a second WLL. This is the first pediatric case of PAP relapse despite successful WLL in Korea.

• Journal of Korean Society for Atmospheric Environment
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• v.22 no.4
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• pp.440-450
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• 2006

PM10, NOx, and $O_3$ were measured at six locations, of which each three is horizontally and vertically distributed respectively, in an apartment complex around the heavily traffic road. Those were measured seven times a day with two hours interval starting from 8 o'clock in the morning for 15 days during May 2005 $\sim$ September 2005. PM10 and NOx showed high concentrations in rush hours while low concentrations in midday due to the direct emissions from automobiles in operation. Temporal variations of 01 showed very much similar trend appeared in normal urban atmospheres. The spatial distributions of PM10, NOx and $O_3$ showed that almost all of concentrations were higher in a row of Roadside > Surface at 130 m apart from the road > Surface at 230 m apart from the road > 3rd floor of apartment building > 15th floor of apartment building > 27th floor of apartment building. Model equations, which can project spatial concentration distributions, were constructed by combining the horizontal and the vertical linear regression equations derived from six mean values corresponding to six measuring locations. According to inter-comparison of PM10, NOx, and $O_3$ with the constructed model equations, concentration gradients were higher in a row of Vertical direction of NOx > Vertical direction of PM10 > Horizontal direction of NOx > Horizontal direction of PMIO > Vertical direction of $O_3$ > Horizontal direction of $O_3$. Why concentration gradient of particulate PM10 is lower than that of gaseous NOx is in question, and should be studied.

• Journal of Korean Society for Atmospheric Environment
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• v.7 no.1
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• pp.1-16
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• 1991

In this study, sampling and analytical procedures were evaluated for the determination of ambient levels of atmospheric PAH, both in gaseous and particulate phase. The method involves low-volume sampling and Soxhlet extraction of the filters and Tenax absorbent, followed by a clean-up stage using a silica column prior to analysis by reversed-phase HPLC with wavelength programmable fluorescence and UV detection. A total of 18 PAH were identified and quantified, all of which have been of environmental concern. In order to validate the methodology and to ensure compatibility of the results, the analytical method used for the determination of PAH was evaluated with respect to the efficiencies of extraction and clean-up procedure, HPLC separation, and lower limits of detection. In addition, substrate dependency of PAH recovery was investigated for the two types of fiters, i.e. glass fiber and PTFE filters.

• Journal of Korean Society for Atmospheric Environment
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• v.23 no.E1
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• pp.16-28
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• 2007

An improved method was developed to determine gas-phase hydrogen peroxide($H_2O_2$) and organic hydro-peroxides (ROOH) in real-time, The analytical system for $H_2O_2$ is based on formation of hydroxybenzoic acid (OHBA), a strong fluorescent compound. OHBA is formed by a sequence of reactions, photoreduction of Fe(III)-EDTA to Fe(II)-EDTA, the Fenton reaction of Fe(II)-EDTA with $H_2O_2$, and hydroxylation of benzoic acid. By use of this analytical method rather than a previous similar method, Fenton reaction time was reduced from 2 min. to 30s. Air samples were collected by a surfaceless inlet to prevent inlet line losses. With a special arrangement of the sampling apparatus, sample delivery time was drastically reduced from ${\sim}5\;min\;to\;{\sim}20\;s$. The automated system was found to be sensitive, capable of continuous monitoring, and affordable to operate. A comparison of this method with a well-established one showed an excellent linear correlation, validating applicability of this technique to $H_2O_2$ determination. The system was applied to field measurements conducted during summertime of 2004 in Gwangju, South Korea. $H_2O_2$ was found to be a predominant species of peroxides. The diurnal variation of $H_2O_2$ displayed the maximum in early afternoon and the broad minimum throughout night. $H_2O_2$ was correlated positively with ozone, photochemical age, and temperature, however, negatively with $NO_x$ and relative humidity.

• Journal of Korean Society for Atmospheric Environment
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• v.33 no.2
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• pp.139-158
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• 2017

CMAQ (Community Multiscale Air Quality Model) simulations were carried out to estimate the potential range of contributions on surface $PM_{2.5}$ concentrations over the Seoul Metropolitan Area (SMA) with the gaseous precursors and Primary Particulate Matters(PPM) available from a recent national emissions inventory. In detail, on top of a base simulation utilizing the 2013 Clean Air Policy Supporting System (CAPSS) emission inventory, a set of Brute Force Method (BFM) simulations after reducing anthropogenic $NO_x$, $SO_2$, $NH_3$, VOCs, and PPM emissions released from area, mobile, and point sources in SMA by 50% were performed in turn. Modeling results show that zero-out contributions(ZOC) of $NH_3$ and PPM emissions from SMA are as high as $4{\sim}5{\mu}g/m^3$ over the region during the modeling period. On the contrary, ZOC of local $NO_x$ and $SO_2$ emissions to SMA $PM_{2.5}$ are less than $1{\mu}g/m^3$. Moreover, model analyses indicate that a wintertime $NO_x$ reduction at least up to 50% increases SMA $PM_{2.5}$ concentrations, probably due to increased HNO3 formation and conversion to aerosols under more abundant ozone and radical conditions after the $NO_x$ reduction. However, a nation-wide $NO_x$ reduction decreased SMA $PM_{2.5}$ concentrations even during winter, which implies that nation-wide reductions would be more effective to curtail SMA $PM_{2.5}$ concentrations than localized efforts.

• Journal of the Korean Institute of Landscape Architecture
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• v.29 no.3
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• pp.38-45
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• 2001

This study quantified annual $CO_2$, SO$_2$ and NO$_2$ uptake and annual $O_2$ production by trees in Yongin´s urban ecosystem, and explored values of urban tree plantings in atmospheric purification. Woody plant cover was only 7.7% with planting density of 1. trees/100$m^2$, and the tree-age structure was largely characterized by a young, growing tree population. Annual per capita pollutant emissions from fossil fuel consumption were 7.3t/yr for $CO_2$, 7.6kg/yr for SO$_2$, and 26.6kg/yr for NO$_{x}$. Carbon dioxide storage per unit urban area by trees was 13.1t/ha and the economic value for $CO_2$ storage was ￦6.6millions/ha. Annual atmospheric purification was 2.0t/ha/yr for $CO_2$ uptake, 2.0kg/ha/yr for SO$_2$ uptake, 4.0kg/ha/yr for NO$_2$ uptake and 1.5t/ha/yr for $O_2$ production, and the annual economic value for the atmospheric purification was ￦1.5millions/ha/yr. Urbantrees stored an amount of $CO_2$ equivalent to about 3.1% of the total annual $CO_2$ emissions, and annually offset total $CO_2$ emissions by 0.5%. Annual SO$_2$ and NO$_2$ uptake by trees equaled 0.5% of total SO$_2$ emissions and 0.3% of total NO$_{x}$ emissions, respectively. Urban trees also played an important role through producing annually 9.2 of the $O_2$ requirement for Yongin´s total population, despite relatively poor tree plantings. Future active plantings and greenspace enlargement in the study city could enhance the role of atmospheric purification by urban trees. The results from this study are expected to be useful in emphasizing environment benefits of urban trees, and in urging the continuous necessity for tree planting and management budget.get.