• 한국대기환경학회지
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• 제33권3호
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• pp.277-288
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• 2017

Previous studies of health effects of $PM_{2.5}$ performed spatial monitoring campaigns to assess spatial variability of $PM_{2.5}$ across people's residences. Highly reliable portable and cost-effective samplers will be useful for such campaigns. This study aimed to investigate applicability of the Deployable Particulate Impact Sampler(DPIS), one of the compact impact samplers, to spatial monitoring campaigns of $PM_{2.5}$ in Seoul, Korea. The investigation focused on the consistency of $PM_{2.5}$ concentrations measured by DPISs compared to those by the Low-volume Cyclone sampler (LCS). LCS has operated at a fixed site in the Seoul National University Yeongeon campus, Seoul, Korea since 2003 and provided qualified $PM_{2.5}$ data. $PM_{2.5}$ sampling of DPISs was carried out at the same site from November 17, 2015 through February 3, 2016. $PM_{2.5}$ concentrations were quantified by the gravimetric method. Using a duplicated DPIS, we confirmed the reliability of DPIS by computing relative precision and mean square error-based R squared value ($R^2$). Relative precision was one minus the difference of measurements between two samplers relative to the sum. For accuracy, we compared $PM_{2.5}$ concentrations from four DPISs (DPIS_Tg, DPIS_To, DPIS_Qg, and DPIS_Qo) to those of LCS. Four samplers included two types of collection filters(Teflon, T; quartz, Q) and impaction discs(glass fiber filter, g; pre-oiled porous plastic disc, o). We assessed accuracy using accuracy value which is one minus the difference between DPIS and LCS $PM_{2.5}$ relative to LCS $PM_{2.5}$ in addition to $R^2$. DPIS showed high reliability (average precision=97.28%, $R^2=0.98$). Accuracy was generally high for all DPISs (average accuracy=83.78~88.88%, $R^2=0.89{\sim}0.93$) except for DPIS_Qg (77.35~78.35%, 0.82~0.84). Our results of high accuracy of DPIS compared to LCS suggested that DPIS will help the assessment of people's individual exposure to $PM_{2.5}$ in extensive spatial monitoring campaigns.

• 한국대기환경학회지
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• 제33권4호
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• pp.411-423
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• 2017

The spacial potential source contribution function (PSCF) method was utilized by considering topography and height of back trajectories based on the measurement of organic typo matter (OM), $NO_3{^-}$, $SO{_4}^{2-}$, and $NH_4{^+}$ at the Baegryungdo Super Site ($37^{\circ}57^{\prime}N$, $124^{\circ}37^{\prime}E$, 135 m a.s.l. (above sea level)) for three selected periods (i.e., January~April, May~August, and September~December) in 2013. The PSCF were calculated on the contributions of trans-boundary transport to the hourly mean concentrations using a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS). The cluster analysis using back trajectories was performed to identify the major airflows to the sampling site. The upper atmosphere in the Tianjin area of China and the lower atmosphere in the western coast area of Korea can be the major source of trans-boundary pollution to the sampling site during January~April resulted from PSCF. The area in Lianyungang-city and Liaoning-sheng, China can be responsibile for the nitrogen related secondary compounds during May~August, and Shandong Peninsula in China is the major source area during September~December. In addition, relationships between the cluster analysis of back trajectories and PSCF were investigated for the statistically significance level for the source areas.

• 한국대기환경학회지
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• 제23권5호
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• pp.596-611
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• 2007

Resuspended dust from paved roads in Seoul and Incheon metropolitan areas is regarded as one of the major $PM_{10}$ sources in these areas, according to the recent emission estimates using the emission factors compiled in AP-42. It is well known that the AP-42 model for estimating $PM_{10}$ emissions from paved roads requires information on silt loadings of particular paved roads. The conventional AP-42 method (vacuum swept method) for road silt sampling, however, is expensive, time consuming, and dangerous. These drawbacks led us to develop a Mobile Dust Monitoring System (MDMS) capable of doing real time measurements of silt loading of paved roads, thereby we could get higher resolution silt loading data both in terms of time and space without too much human efforts and danger. In this study, for the real-time measurement of silt loading of paved roads, the principle used in the TRAKER method of U.S. Desert Research Institute was employed and the entire sampling systems including data acquisition system were designed for theses purpose and mounted on a SUV. The correlation between the silt loading measured by vacuum swept method and the speed corrected ${\Delta}Dust$ was derived for the vehicle-based silt loading measurements, and then the variations of silt loading on paved roads were surveyed using the MDMS in test routes of Seoul and Incheon. From the results of real-time measurements, temporal and spatial variations of silt loading data together with the existence of hot spots were observed for paved roads in Seoul and Incheon. The result of this study will be employed to estimate fugitive dust emissions from paved roads.

• 한국대기환경학회지
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• 제17권6호
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• pp.475-485
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• 2001

The presence of airborne particles in the earth atmosphere expert important controls on the global climate because of their effects on the radiative balance. However, there are major uncertainties associated with the direct and indirect radiative effects of aerosols. In addition, their physicochemical properties cannot only the decline of air quality but also damage human health. Airborne particles were collected by two different commercial air samples, high volume sampler(for TSP) and low volume sampler(for P $M_{10}$ ) at the campus of Kunsan National University during February to September, 2000. In most cases, TSP and P $M_{10}$ were sampled once a week for the duration of 24 hours from 9:00 a.m. In addition samples were collected more intenisve, when the yellow dust was expected. Each sample was analyzed for pH and major ions concentration (C $l^{[-10]}$ , S $O_4$$^{2-}$, N $O_3$$^{[-10]}$ , N $a^{+}$, N $H_4$$^{+}$, $K^{+}$, $Mg^{2+}$, $Ca^{2+}$) by ion chromatography and atomic absorption spectrophotometry. Acidity (pH) of TSP and P $M_{10}$ ranged from 5.09 to 8.51 and from 6.22 to 7.54, respectively. The concentrations of airborne particles were found to satisfy both the short and long-term air quality standards during the sampling period. If the ratio of ionic concentrations originating from None sea salt(Nss) to sea salt(ss) in aerosol samples was concerned, it was found that the ionic concentrations from marine environment contributed dominantly in total mass concentration in the airborne particles. When seasonal trends were examined, the TSP concentrations in spring were higher than those of other seasons. It may result form frequent occurrences of yellow dust and during the spring season. The concentration ratio of P $M_{10}$ to TSP ranged from 0.78 to 1 during the sampling period. pH in the airborne particle was highest during spring, but the other seasons maintained almost same level. These results suggest that alkaline species in yellow dust can directly neutralize aerosol acidity. During spring season, yellow dust could be a positive factor that can defer the acidification of surface soil and water by neutralizing acidic aerosols in the atmosphere.osphere.

• 한국대기환경학회지
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• 제20권3호
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• pp.381-396
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• 2004

In order to understand the precipitation acidity and chemical composition of ion species in Iksan area as well as to know the difference of chemical characteristics in precipitation samples from the viewpoint of precipitation sampling method, precipitation samples were collected by wet-only automatic precipitation sampler and bulk manual precipitation sampler in Iksan, from March 2003 to August 2003. The mean pH of precipitation was 5.0. There was a little significant difference in the mean value of pH between automatic and manual sampler. However, pH values of some precipitation samples were lower in automatic sampler than in manual sampler, especially in case of precipitation samples with small rainfall for March 2003. The mean concentrations of each ions in precipitation were generally a little higher in precipitation samples collected by the manual sampler than in those collected by the automatic sampler because of accumulation of dry deposition on the surface of glass funnel installed at the manual sampler during the sampling period or no rainfall. Dominant species determining the acidity of precipitation, were N $H_4$$^{[-10]}$ and nss-C $a^{2+}$ for cations and nss-S $O_4$$^{2-}$ and N $O_3$$^{[-10]}$ for anions. The mean concentration of N $H_4$$^{+}$ and nss-C $a^{2+}$ were 31 $\mu$eq/L and 9 $\mu$eq/L for the automatic sampler and 40 ueq/L and 16 ueq/L for the manual sampler, respectively. In addition, nss-S $O_4$$^{2-}$ and N $O_3$$^{[-10]}$ were 27 $\mu$eq/L and 13 $\mu$eq/L for the automatic sampler and 32 $\mu$eq/L and 17 $\mu$eq/L for the manual sampler, respectively. Although the concentrations of the acidifying ions of nss-S $O_4$$^{2-}$ and N $O_3$$^{[-10]}$ were about 3 times higher than those for foreign pristine sites, precipitation acidity were estimated to be natural due to the neutralization reaction of the alkaline species of N $H_4$$^{+}$ and nss-C $a^{2+}$ with its higher concentrations. Considering the ratios of nss-S $O_4$$^{2-}$/N $O_4$$^{[-10]}$ nss-S $O_4$$^{2-}$, it was found that ammonium sulphate was dominant in Iksan precipitation. The major non-sea salt ions were maximum concentrations for March, but decreased with increasing of precipitation amount.on amount.

• Current Optics and Photonics
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• 제2권3호
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• pp.269-279
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• 2018

We are currently investigating the feasibility of a 1.6 m telescope with a laser-guide star adaptive optics (AO) system. The telescope, if successfully commissioned, would be the first dedicated adaptive optics observatory in South Korea. The 1.6 m telescope is an f/13.6 Cassegrain telescope with a focal length of 21.7 m. This paper first reviews atmospheric seeing conditions measured over a year in 2014~2015 at the Bohyun Observatory, South Korea, which corresponds to an area from 11.6 to 21.6 cm within 95% probability with regard to the Fried parameter of 880 nm at a telescope pupil plane. We then derive principal seeing conditions such as the Fried parameter and Greenwood frequency for eight astronomical spectral bands (V/R/I/J/H/K/L/M centered at 0.55, 0.64, 0.79, 1.22, 1.65, 2.20, 3.55, and $4.77{\mu}m$). Then we propose an AO system with a laser guide star for the 1.6 m telescope based on the seeing conditions. The proposed AO system consists of a fast tip/tilt secondary mirror, a $17{\times}17$ deformable mirror, a $16{\times}16$ Shack-Hartmann sensor, and a sodium laser guide star (589.2 nm). The high order AO system is close-looped with 2 KHz sampling frequency while the tip/tilt mirror is independently close-looped with 63 Hz sampling frequency. The AO system has three operational concepts: 1) bright target observation with its own wavefront sensing, 2) less bright star observation with wavefront sensing from another bright natural guide star (NGS), and 3) faint target observation with tip/tilt sensing from a bright natural guide star and wavefront sensing from a laser guide star. We name these three concepts 'None', 'NGS only', and 'LGS + NGS', respectively. Following a thorough investigation into the error sources of the AO system, we predict the root mean square (RMS) wavefront error of the system and its corresponding Strehl ratio over nine analysis cases over the worst ($2{\sigma}$) seeing conditions. From the analysis, we expect Strehl ratio >0.3 in most seeing conditions with guide stars.

• 대한원격탐사학회지
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• 제31권6호
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• pp.549-560
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• 2015

지구 온난화와 기후 시스템에 가장 강력한 영향을 미치는 인자 중 하나인 대기 중 이산화탄소 농도 변화를 지속적으로 모니터링하는 것은 중요하며, 현재 지상 관측과 더불어 위성을 통한 모니터링이 이루어지고 있다. 본 연구에서는 동북아시아 지역 중에서도 1999년부터 주요 대기질 관측소로 운영되어 온 안면도와 고산에서의 대기 중 이산화탄소 농도 변화에 대한 경향성을 전구 월별 평균 값과 비교해 보았으며, 이를 대표적인 온실 기체 관측 위성인 Greenhouse Gases Observing Satellite (GOSAT)과 Atmospheric Infrared Sounder (AIRS)에서 산출되는 값을 안면도와 고산 관측소의 농도 값과 비교하였다. 1999년 1월 대기 중 평균 농도가 371.87 ppm이었던 안면도에서의 이산화탄소 농도는 2013년 12월 405.50 ppm으로 지난 15년간 지속적으로 증가하였다(KMA, 2013). 플라스크 공기 샘플링 방법에 의해 관측된 안면도의 이산화탄소 농도는 같은 기간 전구의 계절 변동성 및 증가 추이가 동일했으나, 동북아시아에서의 이산화탄소 농도의 증가폭이 전구보다 평균 4 ppm 더 높게 나타났다. GOSAT과 AIRS에서 산출된 이산화탄소는 안면도 관측소의 지상 농도와 비교되었으며, 이를 통해 두 위성 자료들의 정확도가 비교하고자 하였다. GOSAT과 AIRS 모두 월별 이산화탄소 농도는 지상 관측소인 안면도의 관측 값보다는 낮은 분포 경향을 보였으나, 계절 변동성과 증가 추이는 동일하게 나타났다. GOSAT과 AIRS에서 산출되는 이산화탄소 농도는 위성별 정확도 분석을 위해 두 위성의 관측 기간 중 동일 관측이 수행된 2011년 1월부터 2012년 12월까지의 자료를 비교하였다. GOSAT은 r이 0.947, RMSD가 5.610, bias가 -5.280으로 r이 0.737, RMSD가 8.574, bias가 -7.316으로 나타난 AIRS보다 동북아시아를 대표하는 안면도 관측소에서의 정확도가 더 높게 나타났다.

• 한국대기환경학회지
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• 제32권6호
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• pp.603-612
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• 2016

The objective of this study was to estimate the emission characteristics for PM, $PM_{10}$, and $PM_{2.5}$ in the various stationary sources. The particulate matters collected in the various stationary sources such as power plants (Coal and B-C oil), incinerators(municipal and industrial waste), and glass furnaces. The PM and $PM_{10}$, PM and $PM_{2.5}$, $PM_{10}$ and $PM_{2.5}$ samples were collected using the cyclone type $PM_{10}$, $PM_{2.5}$ samplers and 30 species(19 inorganic species, 9 ionic species, OC and EC) were analyzed by ICP, IC, and TOR/IMPROVE methods. The mass concentrations of PM, $PM_{10}$, $PM_{2.5}$ from nine stationary sources ranged $0.63{\sim}9.58mg/Sm^3$, $0.26{\sim}7.47mg/Sm^3$ and $0.13{\sim}6.34mg/Sm^3$, respectively. The level of $PM_{10}$, $PM_{2.5}$ portion in PM calculated 0.63~0.99, 0.38~0.94, respectively. In the case of emission trend for species, power plant showed high concentrations for Al, Mg, Na, Si, V and $SO_4{^{2-}}$, respectively. Also, Ca, Fe, K, Si, $Cl^-$, and $K^+$ showed high in incinerator. In the case of glass furnace, Na, Pb, K, Si, $Na^+$ and $SO_4{^{2-}}$ represented high concentrations. Power plant showed higher EC/OC concentrations than other sampling sites. These results suggest the possible role for complement establishment process of emission inventory and emission management for PM.

• 한국대기환경학회지
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• 제15권4호
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• pp.393-402
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• 1999

Precipitation samples were collected by the wet-only sampling method in Iksan in the northwest of Chonbuk from March 1995 to February 1997. These samples were analyzed for the concentration of ion components, in addition to pH and electrical conductivity. The annual mean pH of precipitation was 4.8 and the seasonal trend of pH was shown to be low in Fall and Winter(4.5), middle-ranged in Spring(4.7) and high in Summer(5.0). The frequency of pH below 5.6 was about 71%. The seasonal pattern of pH frequency was found to be different in each season. In the case of the pH less than 5.0, the frequency was higher in Spring, Fall and Winter than in Summer, especially higher in Fall than in other seasons. The concentrations of analysed ions showed a pronounced seasonal pattern. However, major ion species for all seasons were $NH^+_4,;Ca^{2+};and;Na^+$ among cations and $SO^{2-}_4,;Cl^-;and;NO^-_3$ among anions. The major acidifying species appeared to be $nss-SO^{2-}_4;and;NO^-_3$, and the main bases responsible for the neutralization of precipitation acidity were $nss-Ca^{2+};and;NH^+_4$. The potential acidity of precipitation, pAi, was found to be between 3.0 and 5.0 for total samples, while the measured pH was approximately between 3.9 and 7.8. The seasonal trend of pAi showed a decreasing order: Summer (4.3), Winter(4.0), Spring and Fall(3.8). During the Fall, both pAi and pH were especially very low, which indicated that during this period the potential acidity of precipitation was high but the neutralizing capacity was low. For Spring, pAi was very low but pH was slightly high. This was likely due to the large amount of $CaCO_3$ in the soil particles transported over a long range from the Chinese continent that were incorporated into the precipitation, and then neutralized the acidifying species with its high concentraton.

• Journal of Korean Society for Atmospheric Environment
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• 제20권E2호
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• pp.53-59
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• 2004

The roadway tunnels in urban areas give rise to problems such as a localized air pollution. Here, we report the results of a case study of an urban roadway tunnel measurement. The size-resolved particle sampling was carried out with a two 2-stage filter pack samplers and an Andersen impactor sampler at the center of Buk-Ak tunnel in November 2001. Particle Induced X-ray Emission (PIXE) was applied to determine the elemental composition of size-resolved particles divided into soluble and insoluble fractions. The Thermal/Optical Reflectance (TOR$^{(R)}$) method was also employed in analyzing of elemental carbon (EC) and organic carbon (OC). Mass concentrations of fine (< 1.2 ${\mu}{\textrm}{m}$) and coarse (> 1.2 ${\mu}{\textrm}{m}$) particles are 165 and 48 $\mu\textrm{g}$ m$^{-3}$ , respectively. Total elemental mass concentration (the sum of insoluble coarse, soluble coarse, insoluble fine, and soluble fine) is found to be 24$\mu\textrm{g}$ m$^{-3}$ and comprises only 11 % of total particle mass concentration. The concentrations of EC, OC, and mass show the clear dependency on particle size with the maximum between 0.1 and 0.43 ${\mu}{\textrm}{m}$ aerodynamic diameters. Total carbon (sum of EC and OC) accounts for approximately 70% of mass concentration.n.