• Particle and aerosol research
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• v.7 no.1
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• pp.21-30
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• 2011

The spatial distributions of air pollutants, in particular, ultrafine particles near traffic congestion roads at urban areas need to reduce human exposure levels for protecting public health. In this study, the number concentrations of ultrafine particles larger than 5 nm were measured every second during driving on the major roads of Nowon-gu, Seoul for 1.6 h using a mobile emission laboratory on October 5, 2010. The ultrafine particle number concentrations ranged from 7,009 to $265,600particles/cm^3$ with an average of $55,570particles/cm^3$, and these levels were comparable to concentrations of ultrafine particles larger than 3 or 7 nm on the arterial roads at urban areas in Los Angeles, USA and Zurich, Switzerland. It was frequently observed that the ultrafine particle number increased rapidly when vehicle speed was accelerated and it decreased sharply when vehicle speed was decelerated. The high peak events of ultrafine particle concentration larger than $200,000particles/cm^3$ were observed seven times during the measurement period. From the three repeated measurements during the short period of 50 min, it was concluded that the ultrafine particle number concentration on the road was significantly time-dependent. This on-road measurement approach can be utilized to manage vehicle-related air pollution in urban.

• Journal of Korean Society for Atmospheric Environment
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• v.26 no.5
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• pp.543-553
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• 2010

Almost five million citizens a day are using subways as a means of traffic communication in the Seoul metropolitan. As the subway system is typically a closed environment, indoor air pollution problems frequently occurs and passengers complain of mal-health impact. Especially $PM_{10}$ is well known as one of the major pollutants in subway indoor environments. The purpose of this study was to compare the indoor air quality in terms of $PM_{10}$ and to quantitatively compare its source contributions in a Seoul subway platform before and after installing platform screen doors (PSD). $PM_{10}$ samples were collected on the J station platform of Subway Line 7 in Seoul metropolitan area from Jun. 12, 2008 to Jan. 12, 2009. The samples collected on membrane filters using $PM_{10}$ mini-volume portable samplers were then analyzed for trace metals and soluble ions. A total of 18 chemical species (Ba, Mn, Cr, Cd, Si, Fe, Ni, Al, Cu, Pb, Ti, $Na^+$, $NH_4^+$, $K^+$, $Mg^{2+}$, $Ca^{2+}$, $Cl^-$, and ${SO_4}^{2-}$) were analyzed by using an ICP-AES and an IC after performing proper pre-treatments of each sample filter. Based on the chemical information, positive matrix factorization (PMF) model was applied to identify the source of particulate matters. $PM_{10}$ for the station was characterized by three sources such as ferrous related source, soil and road dust related source, and fine secondary aerosol source. After installing PSD, the average $PM_{10}$ concentration was decreased by 20.5% during the study periods. Especially the contribution of the ferrous related source emitted during train service in a tunnel route was decreased from 59.1% to 43.8% since both platform and tunnel areas were completely blocked by screen doors. However, the contribution of the fine secondary aerosol source emitted from various outside combustion activities was increased from 14.8% to 29.9% presumably due to ill-managed ventilation system and confined platform space.

• Journal of Korean Society of Transportation
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• v.19 no.4
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• pp.35-47
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• 2001

Traffic represents one of the largest sources of primary air pollutants in urban area. As a consequence. numerous abatement strategies are being pursued to decrease the ambient concentration of pollutants. A characteristic of most of the these strategies is a requirement for accurate data on both the quantity and spatial distribution of emissions to air in the form of an atmospheric emission inventory database. In the case of traffic pollution, such an inventory must be compiled using activity statistics and emission factors for vehicle types. The majority of inventories are compiled using passive data from either surveys or transportation models and by their very nature tend to be out-of-date by the time they are compiled. The study of current trends are towards integrating urban traffic control systems and assessments of the environmental effects of motor vehicles. In this study, a methodology of motor vehicle emission calculation by using real-time traffic data was studied. A methodology for estimating emissions of CO at a test area in Seoul. Traffic data, which are required on a street-by-street basis, is obtained from induction loops of traffic control system. It was calculated speed-related mass of CO emission from traffic tail pipe of data from traffic system, and parameters are considered, volume, composition, average velocity, link length. And, the result was compared with that of a method of emission calculation by VKT(Vehicle Kilometer Travelled) of vehicles of category.

• Asian Journal of Atmospheric Environment
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• v.5 no.4
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• pp.237-246
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• 2011

To explore the sources of carbonaceous material in the airborne particulate matter (PM), comprehensive PM sampling was performed (3 to 14 January 2010) at a traffic hot spot site (HS), Farm Gate, Dhaka using several samplers: AirMetrics MiniVol (for $PM_{10}$ and $PM_{2.5}$) and MOUDI (for size fractionated submicron PM). Long-term PM data (April 2000 to March 2006 and April 2000 to March 2010 in two size fractions ($PM_{2.2}$ and $PM_{2.2-10}$) obtained from two air quality-monitoring stations, one at Farm Gate (HS) and another at a semi-residential (SR) area (Atomic Energy Centre, Dhaka Campus, (AECD)), respectively were also analyzed. The long-term PM trend shows that fine particulate matter concentrations have decreased over time as a result of government policy interventions even with increasing vehicles on the road. The ratio of $PM_{2.5}/PM_{10}$ showed that the average $PM_{2.5}$ mass was about 78% of the $PM_{10}$ mass. It was also found that about 63% of $PM_{2.5}$ mass is $PM_1$. The total contribution of BC to $PM_{2.5}$ is about 16% and showed a decreasing trend over the years. It was observed that $PM_1$ fractions contained the major amount of carbonaceous materials, which mainly originated from high temperature combustion process in the $PM_{2.5}$. From the IMPROVE TOR protocol carbon fraction analysis, it was observed that emissions from gasoline vehicles contributed to $PM_1$ given the high abundance of EC1 and OC2 and the contribution of diesel to $PM_1$ is minimal as indicated by the low abundance of OC1 and EC2. Source apportionment results also show that vehicular exhaust is the largest contributors to PM in Dhaka. There is also transported $PM_{2.2}$from regional sources. With the increasing economic activities and recent GDP growth, the number of vehicles and brick kilns has significantly increased in and around Dhaka. Further action will be required to further reduce PM-related air pollution in Dhaka.

• Journal of Preventive Medicine and Public Health
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• v.37 no.3
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• pp.225-231
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• 2004

Objectives : This study was performed to examine the influence of smoking on the blood cadmium concentration in university students. Methods : The study included 300 university students. A questionnaire interview was used to collect data. The urine cotinine and blood cadmium levels were measured as biological exposure indices. The data were analyzed using t-tests ANOVA and ANCOVA. Results : The median value of blood cadmium concentration was equal in both males and females ($0.8{\mu}g/l$). This level was relatively low in comparison with the reference value suggested by WHO (2001). ANCOVA showed that smoking related variables, urine cotinine and smoking amount, were significantly associated with the blood cadmium level (P=0.004, 0.015). However, the values with regard to traffic related air pollution were not significantly associated with the blood cadmium level. Conclusions : Smoking is an important source of nonoccupational cadmium exposure in young people. The Blood cadmium level is at least 10% higher in active smokers than in passive or nonsmokers. The level of urine cotinine can be used as an indicator of non-occupational exposure of respirable cadmium due to smoking, as there is a good correlation bestween smoking amount and the urine cotinine level.

• Journal of the Korean Society of Safety
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• v.38 no.6
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• pp.50-59
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• 2023

As the diversity of disasters continues to increase, the concept of "complex disasters" has gained prominence in various policies and studies related to disaster management. However, there has been a certain limitation in the availability of the systematic statistics or data in advancing policies and research initiatives related to complex disasters. This study aims to analyze the macro-level characteristics of the complex disasters that have occurred domestically utilizing a 30-year span of a news data. Initially, we categorize the complex disasters into the three types: "Natural disaster-Natural disaster", "Natural disaster-Social disaster", and "Social disaster-Social disaster". As a result, the "natural diaster-social disaster" type is the most prevalent. It is noted that "natual disaster-natural disaster" type has increased significantly in recent 10 years (2011-2020). In terms of specific disaster types, "Storm and Flood", "Collapse", "Traffic Accident", "National Infrastructure Paralysis", and "Fire⋅Explosion" occur the most in conjunction with other disasters in a complex manner. It has been observed that the types of disasters co-ocuuring with others have become more diverse over time. Parcicularly, in recent 10 years (2011-2020), in addition to the aforementioned five types, "Heat Wave", "Heavy Snowfall⋅Cold Wave", "Earthquake", "Chemical Accident", "Infectious Disease", "Forest Fire", "Air Pollution", "Drought", and "Landslide" have been notable for their frequent co-occurrence with other disasters. These findings through the statistical analysis of the complex disasters using long-term news data are expected to serve as crucial data for future policy development and research on complex disaster management.

• Journal of Korean Society for Atmospheric Environment
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• v.32 no.4
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• pp.422-434
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• 2016

This study was conducted to understand roles of $NO_x(=NO+NO_2)$ on high $O_3$ episodes at an urban monitoring station in Seoul. Concentrations of NO, $NO_2$, $NO_y$ and $O_3$ were measured intensively at KIST monitoring station which located at urban center in Seoul metropolitan area during May 18~June 13, 2015. Sampling period was planed because high $O_3$ and PM occurred frequently during from late spring to early summer months in Seoul. The experimental site locates in NW from center of Seoul and is surrounded by residential area. Belt highway of the city runs from north to west side nearby experimental site. Vehicle exhaust emissions due to heavy traffic influenced $NO_x$ concentration at the site during northwesterly wind. Specific $NO_2$ concentration was measured by Blue Light photolytic converter, and it was compared to $NO_2$ concentration measured by molybedenum converter. $[NO_2]_{phtolysis}$ was usually lower than $[NO_2]_{molybedenum}$ during the experiment period; however their diurnal variations were very similar. The linear relationship between these $NO_2$ concentrations was found to be $[NO_2]_{phtolysis}$=0.64 $[NO_2]_{molybedenum}$ - 2.6, $r^2$=0.83 during May 16~8, 2015. The difference between $NO_2$ by molybdenum converter and by photolytic converter (${\Delta}NO_2=[NO_2]_{molybedenum}-[NO_2]_{phtolysis}$) accounted for residual $NO_y$ which can represent $NO_z$ (=$NO_y-NO_x$). $O_3$ concentration showed typical daily trend which has maximum at late afternoon and minimum during the night. $O_3$ increased at a rate of 7 ppb/hr since 8 am. and reached the maximum concentration (~80 ppb) at 3 pm.. The diurnal pattern of $O_3$ was inversely related with that of $NO_2$, suggesting that the formation of $O_3$ was the result of photochemical activity of $NO_2$.

• Advances in aircraft and spacecraft science
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• v.3 no.3
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• pp.243-257
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• 2016

The increase of air traffic volume has brought an increasing amount of issues related to carbon and NOx emissions and noise pollution. Aircraft manufacturers are concentrating their efforts to develop technologies to increase aircraft efficiency and consequently to reduce pollutant discharge and noise emission. Ultra High By-Pass Ratio engine concepts provide reduction of fuel consumption and noise emission thanks to a decrease of the jet velocity exhausting from the engine nozzles. In order to keep same thrust, mass flow and therefore section of fan/nacelle diameter should be increased to compensate velocity reduction. Such feature will lead to close-coupled architectures for engine installation under the wing. A strong jet-wing interaction resulting in a change of turbulent mixing in the aeroacoustic field as well as noise enhancement due to reflection phenomena are therefore expected. On the other hand, pressure fluctuations on the wing as well as on the fuselage represent the forcing loads, which stress panels causing vibrations. Some of these vibrations are re-emitted in the aeroacoustic field as vibration noise, some of them are transmitted in the cockpit as interior noise. In the present work, the interaction between a jet and wing or fuselage is reproduced by a flat surface tangential to an incompressible jet at different radial distances from the nozzle axis. The change in the aerodynamic field due to the presence of the rigid plate was studied by hot wire anemometric measurements, which provided a characterization of mean and fluctuating velocity fields in the jet plume. Pressure fluctuations acting on the flat plate were studied by cavity-mounted microphones which provided point-wise measurements in stream-wise and spanwise directions. Statistical description of velocity and wall pressure fields are determined in terms of Fourier-domain quantities. Scaling laws for pressure auto-spectra and coherence functions are also presented.

• Journal of Korean Society of Transportation
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• v.34 no.5
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• pp.377-393
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• 2016

Vehicle emissions have been known as a critical factor to give a negative impact on the public health. In particular, particulate matters(PM) and NOx are highly related with respiratory diseases such as asthma. This study aimed at analyzing spatio-temporal patterns of PM and NOx generated from urban freeway traffic. MOVES, which is a well-known emission analysis tool presented by US Environmental Protection Agency(EPA), was applied to estimate PM and NOx based on traffic volume and speed data obtained from Seoul Outer Ring Expressway during January~June, 2012. K-means clustering analysis was used for categorizing the Level of Vehicle Emissions(LOVE) to support more systematical identification of the significance of emissions. Then, spatio-temporal analyses of estimated emissions were conducted by LOVE. Finally, this study proposed a set of strategies to reduce both PM and NOx to enhance public health based on analysis results.

• Journal of Preventive Medicine and Public Health
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• v.18 no.1
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• pp.113-127
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• 1985

This paper was carried out for comparison of respiratory symptoms between urban and rural residents that is somewhat related to air pollution. And as urban residents, 470 persons of Daegu (Taegu) and 364 of Pohang were selected and 472 rural residents were also, in Eusong-Gun, those who were responded to questionnaire distributed from April 10, 1984 to April 30 through students of middle or high school. The subjects were families of the student. The questionnaire was appropriately modified the item B of Cornell Medical Index by author. Looking into the rate of complaints about each part, generally, the rate in urban is higher than that in rural. Particulary it is higher to 'feeling a choking lump or swelling of throat', 'the sputum' and 'the asthma' in the city (p<0.05). On the contrary, women in the farm village, to 'caught a severe cold' as compared with the city. In men under nineteen yearn of age, it is higher than the farm village to 'feeling a choking lump or swelling of throat' of Pohang (p<0.05). But in men forties, it is higher than the city that farm people are 'soaking sweat at night' and 'foreign body sensation on throat'. Students hardly differ between the two areas, while the group having occupation in Pohang felt more in 'feeling a choking lump or swelling of throat' than the farm residents. As the result, I consider that the rural residents were much affected by physical fatigue and pestisides, and the urban, by some problems of industrial fuel, traffic gas and various dusts.