• Fire Science and Engineering
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• v.19 no.2 s.58
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• pp.37-44
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• 2005

We have conducted a numerical simulation under three-dimensional unsteady conditions in order to analyze the characteristics of flow and the distribution of $CO_2$ agent concentration according to the number of $CO_2$ agent nozzle. The engine room of a ship was selected as a protection space, and flow fields and $CO_2$ concentration fields were measured. In case of increasing the number of $CO_2$ nozzle from 2 nozzles to 4 nozzles, the distribution of CO2 concentration showed low, and in case of increasing the number of $CO_2$ nozzle to above 6 nozzles, the recirculating flow affected to all region was generated. In case of increasing the number of $CO_2$ agent nozzle to above 4 nozzles, the iso-concentration line below 0.36 expanded or contracted slightly. Therefor, the proper number and the arrangement of $CO_2$ agent nozzle are considered when $CO_2$ fire fighting system is designed.

• Fire Science and Engineering
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• v.20 no.2 s.62
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• pp.44-53
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• 2006

We have conducted a numerical simulation under two-dimensional unsteady conditions in order to analyze the effect according to the injection angle and velocity of the $CO_2$ agent nozzle which is one of the elements for the fixed type $CO_2$ fire extinguishing system installed in a ship on the characteristics of flow and $CO_2$ concentration distribution. The flow fields and concentration fields were measured and analyzed. We can found that the difference of flow patterns according to the conditions of $CO_2$ agent injection nozzle, and in all the conditions of $CO_2$ agent injection nozzle, the iso-concentration line was expanded from the region at which vortex was generated to the surroundings. We can expected that the intensity of the wall jet on the bottom floor was generated differently and the iso-concentration lines were expanded or shrunk according to the angle of $CO_2$ agent injection nozzle. In case of increasing $CO_2$ agent injection velocity maintaining the flow quantity of the $CO_2$ agent injection equally, the iso-concentration line of $CO_2$ agent on bottom floor can be formed more higher than in case of decreasing $CO_2$ agent injection velocity.

• Journal of computational fluids engineering
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• v.7 no.2
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• pp.33-42
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• 2002

Numerical estimation for concentration of mono-carbon oxygen (CO) gas inside an underground parking lot with auxiliary jet fans for enhancement of ventilation is carried out by using a commercial program. Main interest lies on the diagnosis of the present ventilation system including position and selection of auxiliarly fans in addition to main suppliers and exhausts. Details of both flows and concentration of CO gas that is most important component among car exhaust gases are illustrated in this investigation and those are presented for engineering construction of an underground parking pool. Prediction data of computational work is also validated by real measurements of concentration of CO gas.

• Journal of Korean Society for Atmospheric Environment
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• v.19 no.2
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• pp.167-177
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• 2003

The number size distribution of urban aerosols ranging from 0.02 to 20 ${\mu}{\textrm}{m}$ in diameter was measured by using a scanning mobility particle sizer (SMPS) system and an aerodynamic particle sizer spectrometer (APS) at Seoul from November 30,2001 to January 14, 2002. The gaseous species such as CO, NO, NO$_2$, and $O_3$ were also continuously monitored. The daily average concentration of urban aerosols sorted into three groups (0.02~0.1 ${\mu}{\textrm}{m}$, 0.1~1 ${\mu}{\textrm}{m}$ and 1~10 ${\mu}{\textrm}{m}$) and the typical number, surface, and volume distributions of urban aerosols were discussed in this paper. The weekly variation of aerosol concentration was compared with those of gaseous concentrations. relative humidity, and visibility. The results showed that the particle number concentration seemed to increase in the morning and the number concentration of fine particles less than 1 fm in diameter seemed to increase when the concentrations of CO, NO, and NO$_2$ were high. The number concentration of fine particles was relatively high when the relative humidity was greater than 70％ during the increasing period of relative humidity. The visibility was weakly correlated with the concentration of aerosols ranging 0.1 to 1 ${\mu}{\textrm}{m}$, and the number size distribution for high visibility episode was apparently different from that for low visibility episode.

• Journal of Korean Society for Atmospheric Environment
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• v.28 no.1
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• pp.12-21
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• 2012

The purpose of this study is to understand distribution of ozone concentration in the south coastal region of Korea by evaluating ozone spatial distribution in the upper air using aircraft. Sampling was carried out from May to August in 2009. The average concentration of ozone in the upper air was ranged from 32.3~90.8 ppb with its maximum concentration of 132 ppb. When it comes to the spatial distribution of ozone, ambient concentration was high in the air, 1,000 m and 500 m above the southern sea near the Gwangyang Bay area and emission sources, respectively. Daily mean concentration of NOy was 6.7~24.2 ppb and that of CO was 0.152~0.487 ppm. In addition, the concentration was appeared to be relatively high in the upper air of industrial regions and the southern seas. Meanwhile, the concentration of both $NO_y$ and CO was high in the upper air of the emission sources regardless of latitude. As for PAN, its daily mean concentration ranged between 0.1 and 0.6 ppb with overall mean concentration of 0.2 ppb. The average concentration of VOCs was 48 ppb, and the concentration of toluene and m,p-Xylene were higher than other components.

• Journal of the Korean Society of Safety
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• v.31 no.4
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• pp.48-54
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• 2016

The prediction of various emissions from coal combustion is an important subject of researchers and engineers because of environmental consideration. Therefore, the development of the models for predicting pollutants very fast has received much attention from international research community, especially in the field of safety assessment. In this work, response surface method was introduced as a design of experiment, and the database for RSM was set with the numerical simulation of a drop tube furnace (DTF) to predict the spatial distribution of pollutant concentrations as well as final ones. The distribution of carbon dioxide in DTF was assumed to have Boltzman function, and the resulted function with parameters of a high $R^2$ value facilitates predicting an accurate distribution of $CO_2$. However, CO distribution had a difference near peak concentration when Gaussian function was introduced to simulate the CO distribution. It might be mainly due to the anti-symmetry of the CO concentration in DTF, and hence Extreme function was used to permit the asymmetry. The application of Extreme function enhanced the regression accuracy of parameters and the prediction was in a fairly good agreement with the new experiments. These results promise the wide use of statistical models for the quantitative safety assessment.

• Journal of Korean Tunnelling and Underground Space Association
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• v.14 no.6
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• pp.607-616
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• 2012

The need for management of tunnel air quality is imminent considering the rapid increase of number and span of tunnels in Korea. To investigate spatial distribution of $CO_2$ within tunnels, $CO_2$ were measured and model simulations were performed in Namsan 1 tunnel. Results show that $CO_2$ concentrations were 250 ppm to 400 ppm higher in the exit than tunnel entrance. Also, $CO_2$ concentrations were 200 ppm to 300 ppm lower inside no ventilating vehicle than in the tunnel. Both experimental and model simulation results show that spatial distribution and concentration gradient of air pollutant inside tunnel are highly dependent on traffic density.

• Journal of Environmental Science International
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• v.3 no.4
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• pp.357-365
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• 1994

Air pollution characteristics and the influence of sea breeze on air pollution concentration were studied using the data measured at 7 air quality continuous monitoring stations in Pusan, 1993. Maximum air pollution concentration in Pusan was Gamjeondong for $SO_2$, Sinpyeongdong for TSP, Daeyeondong for $O_3, Kwangbokdong for $NO_2$, Beomcheondong for CO and all substances were under annual ambient air quality standards. Increased rate of concentration for sea breeze was 24.4% for 502, 31.5% for TSP, 8.0% fort $O_3, 26.7% for $NO_2$, 15.7% for CO. Frequencies distribution of $SO_2$, TSP, $O_3$, $NO_2$, and CO concentration for sea breeze moved toward high concentration class.

• Journal of Environmental Health Sciences
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• v.32 no.4 s.91
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• pp.324-335
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• 2006

Five sampling sites were selected to investigate the distribution characteristics of air pollutants with pollution sources and weather conditions in Ulsan. $SO_2,\;NO_2,\;O_3,\;CO,\;PM_{10}$ concentrations and weather conditions with time were analyzed by using several statistical methods. Also, the distribution characteristics of ambient air quality were estimated by pollution-rose and multi-regression analysis. As a result of the analysis, $NO_2,\;CO\;and\;PM_{10}$ concentrations were high in winter season, whereas $SO_2\;and\;O_3$ concentrations were high in summer season. This concentration distribution was caused by the unfavorable geographical location, which the residential area was located at the downwind direction to industrial area. From the pollution-rose, we confirmed that each pollutant influenced the downwind residential areas because of seasonal wind direction. $SO_2$ concentration has shown positive correlation of $0.2{\simm}0.3$ for $NO_2,\;PM_{10}$ and temperature, while $O_3$ concentration has shown negative correlation. Also, $NO_2$ and CO concentrations, pollutants generated by combustion, have shown positive correlation, while $O_3$ concentration and temperature have shown negative correlation. Therefore, it could be suggested that a seasonal air quality policy and a new guideline of air quality was necessary in each season with wind directions to reduce the air pollution level in Ulsan.

• Fire Science and Engineering
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• v.18 no.2
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• pp.41-48
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• 2004

We have conducted a numerical simulation under three-dimensional unsteady conditions in order to analyze the characteristics of $CO_2 $;, extinguishant transfer by varying the location of the injection nozzle, which affects the effect of a $CO_2 $;, fire fighting system used in the form of fixed systems for the marine engine room. Flow fields and $CO_2 $;, concentration fields were measured according to the location of the injection nozzle. In the case of arranging the injection nozzle on the center of the ceiling, the low-normal concentration distribution was developed along the $CO_2 $;, jet due to the downward flow created by impinging ceiling jets in the symmetric plane. The concentration line reaches its peak due to the mass transfer of $CO_2 $;, at the comer.