• Particle and aerosol research
• /
• v.6 no.2
• /
• pp.91-103
• /
• 2010

Size-segregated number concentration and scattering coefficient of urban aerosols were measured using an SMPS (scanning mobility particle sizer) and a nephelometer, respectively in Seoul, Korea, during the winter season of 2003. The average number concentrations of ultrafine particles (20~100 nm) and accumulation mode particles (100~600 nm) were $2,170\;particles\;cm^{-3}$ and $1,521\;particles\;cm^{-3}$, respectively. The scattering coefficient at the wavelength of 550 nm ranged from $62.6Mm^{-1}$ to $330.1Mm^{-1}$ and average value was $163.4Mm^{-1}$. The peak concentrations of ultrafine particles and accumulation mode particles were simultaneously recorded between 6:00 and 9:00 A.M., indicating the effect of vehicle emissions which are major air pollution sources in the urban atmosphere. On average, the number concentration of ultrafine particles was 1.4 times higher than that of accumulation mode particles, although it was a little higher during the morning peak time. The variation of aerosol scattering coefficient was in good agreement with that of accumulation mode particle number concentration rather than that of ultrafine particle number concentration.g coefficient was in good agreement with that of accumulation mode particle number concentration rather than that of ultrafine particle number concentration.

• Journal of Korean Society for Atmospheric Environment
• /
• v.21 no.3
• /
• pp.295-301
• /
• 2005

The fine particles in the range of $30\~500nm$ are monitored at Hanyang University campus in Ansan using house made DMA (differential mobility analyzer) and commercial CPC (condensation particle counter, TSI inc.) in SMPS mode. The monitoring period is March 16th 2004 through May 7th, 2004. During the monitoring period, Aitken nuclei mode $(30\~100nm)$ particle concentration has a tendency of increase in the morning and evening hours. However, the accumulation mode $(100\~500nm)$ particle concentration stays rather stable than that of Aitken mode.

• Particle and aerosol research
• /
• v.17 no.3
• /
• pp.43-54
• /
• 2021

Size distributions of atmospheric particulate matter (PM) and its water-soluble organic and inorganic components were measured between January and February 2021 at an urban site in Gwangju in order to identify the major factors that determine their size distributions. Their size distributions during the study period were mainly divided into two groups. In the first group, PM, NO₃^-, SO₄^2-, NH₄⁺ and water-soluble organic carbon (WSOC) exhibited bi-modal size distributions with a dominant condensation mode at a particle size of 0.32 ㎛. This group was dominated by local production of secondary water-soluble components under atmospheric stagnation and low relative humidity (RH) conditions, rather than long-range transportation of aerosol particles from China. On the other hand, in the second group, they showed tri-modal size distributions with a very pronounced droplet mode at a diameter of 1.0 ㎛. These size distributions were attributable to the local generation and accumulation of secondary aerosol particles under atmospheric conditions such as atmospheric stagnation and high RH, and an increase in the influx of atmospheric aerosol particles by long-distance transportation abroad. Contributions of droplet mode NO₃^-, SO₄^2-, NH₄⁺ and WSOC to fine particles in the second group were significantly higher than those in the first group period. However, their condensation mode contributions were about two-fold higher in the first group than in the second group. The significant difference in the size distribution of the accumulation mode of the WSOC and secondary ionic components between the two groups was due to the influx of aerosol particles with a long residence time by long-distance transport from China and local weather conditions (e.g., RH).

• Proceedings of the Korea Air Pollution Research Association Conference
• /
• 2003.05b
• /
• pp.43-44
• /
• 2003

스모그 챔버는 대기화학 반응을 물리적 변수를 제어할 수 있는 공간 내에서 재현하여 스모그 현상을 체계적으로 규명하기 위해 가장 많이 사용되는 방법이다(Dodge, 2000). 대기화학 반응을 통해 생성된 입자상 물질(secondary particles) 또는 초미세 입자(ultrafine particle, 〈0.1 $\mu\textrm{m}$)는 연속된 물리화학 반응을 통해 accumulation mode(0.1~l.0 $\mu\textrm{m}$) 입자로 성장한다. 특히, 대도시의 시정(visibility)은 accumulation mode 입자의 산란(scattering)과 흡수(adsorption)가 주요한 원인이기 때문에 이러한 물질의 생성에 영향을 주는 가스상 물질의 전화(gas-to-particle conversion) 반응과 초미세 입자의 성장 현상을 규명하는 것은 매우 중요하다. (중략)

• Journal of Advanced Marine Engineering and Technology
• /
• v.34 no.4
• /
• pp.508-514
• /
• 2010

The objective of this work presented here was experimental study of steadystate and cold start exhaust nano-sized particle characteristics from common rail diesel engine. The effect of the diesel oxidation catalyst (DOC) on the particle number reduction was insignificant, however, particle number concentration levels were reduced by 3 orders of magnitude into the downstream of diesel particulate filter (DPF). In high speed and load conditions, natural regeneration of trapped particle occurred inside DPF and it was referable to increase particle number concentration. As fuel injection timing was shifted BTDC $6^{\circ}CA$ to ATDC $4^{\circ}CA$, particle number concentration level was slightly reduced, however particle number and size was increased at ATDC $9^{\circ}CA$. Nucleation type particle reduced and accumulation type particle was increased on EGR condition.

• Journal of Korean Society for Atmospheric Environment
• /
• v.34 no.3
• /
• pp.418-429
• /
• 2018

Measurements of 24-hr size-segregated ambient particles were made at an urban site of Gwangju under high pressure conditions occurred in the Korean Peninsula late in March 2018. The aim of this study was to understand the effect of air stagnation on mass size distributions and formation pathways of water-soluble organic and inorganic components. During the study period, the $NO_3{^-}$, $SO_4{^{2-}}$, $NH_4{^+}$, water-soluble organic carbon (WSOC), and humic-like substances(HULIS) exhibited mostly bi-modal size distributions peaking at 1.0 and $6.2{\mu}m$, with predominant droplet modes. In particular, outstanding droplet mode size distributions were observed on March 25 when a severe haze occurred due to stable air conditions and long range transport of aerosol particles from northeastern regions of China. Air stagnation conditions and high relative humidity during the study period resulted in accumulation of primary aerosol particles from local emission sources and enhanced formation of secondary ionic and organic aerosols through aqueous-phase oxidations of $SO_2$, $NO_2$, $NH_3$, and volatile organic compounds, leading to their dominant droplet mode size distributions at particle size of $1.0{\mu}m$. From the size distribution of $K^+$ in accumulation mode, it can be inferred that in addition to the secondary organic aerosol formations, accumulation mode WSOC and HULIS could be partly attributed to biomass burning emissions.

• Proceedings of the KSR Conference
• /
• 2002.05a
• /
• pp.561-566
• /
• 2002

As the air pollution caused by diesel vehicles goes worse, so non-road vehicles exhaust gas standards are more strict in an foreign countries. There is growing evidence that diesel vehicles could play the important role in determining health effects. Most of the particle number emitted by diesel engines is in the nanopaticle range, D$\_$p/ < 50nm, while most of the mass is in the accumulation mode, 50nm < D$\_$p/ < 1000nm range. The aim of this work was to investigate pollutants in the exhaust of railroad diesel rolling stock under load tests.

• Environmental Engineering Research
• /
• v.24 no.4
• /
• pp.690-698
• /
• 2019

Air pollution has attracted ever-increasing attention because of its substantial influence on air quality and human health. To better understand the characteristics of long-range transported pollution, the single particle chemical composition and size were investigated by the single particle aerosol mass spectrometry in Fuzhou, China from 17th to 22nd January, 2016. The results showed that the haze was mainly caused by the transport of cold air mass under higher wind speed (10 m·s^-1) from the Yangtze River Delta region to Fuzhou. The number concentration elevated from 1,000 to 4,500 #·h^-1, and the composition of mobile source and secondary aerosol increased from 24.3% to 30.9% and from 16.0% to 22.5%, respectively. Then, the haze was eliminated by the clean air mass from the sea as indicated by a sharp decrease of particle number concentration from 4,500 to 1,000 #·h^-1. The composition of secondary aerosol and mobile sources decreased from 29.3% to 23.5% and from 30.9% to 23.1%, respectively. The particles with the size ranging from 0.5 to 1.5 ㎛ were mainly in the accumulation mode. The stationary source, mobile source, and secondary aerosol contributed to over 70% of the potential sources. These results will help to understand the physical and chemical characteristics of long- range transported pollutants.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.34 no.8
• /
• pp.755-760
• /
• 2010

In this study, we mainly focused on the PM (Particulate Matter) emission characteristics of a diesel engine. To analyze particle behavior in the tail-pipe, particle emission was measured on the engine-out (downstream of turbocharger), each upstream and downstream both of DOC (Diesel Oxidation Catalyst) and DPF (Diesel Particulate Filter). Moreover, particle emission contours on each sampling point were constructed. The reduction efficiency of particle number concentration and mass through the DOC and DPF was studied. Parameters such as EGR (Exhaust Gas Recirculation) and the main injection timing were varied in part load conditions and evaluated using the engine-out emissions. The DMS500 (Differential Mobility Spectrometer) was used as a particle measurement instrument that can measure particle concentrations from 5 nm to 1000 nm. Nano-particles of sizes less than 30 nm were reduced by oxidation or coagulated with solid particles in the tail-pipe and DOC. The DPF has a very high filtration efficiency over all operating conditions except during natural regeneration of DPF.

• Asian Pacific Journal of Cancer Prevention
• /
• v.14 no.4
• /
• pp.2461-2476
• /
• 2013

To assess environmental contamination with carcinogens, carbonaceous compounds, water-soluble ionic species and trace gaseous species were identified and quantified every three hours for three days st three different atmospheric layer at the heart of chiang-Mai, bangkok and hat-Yai from December 2006 to February 2007. A DRI model 2001 Themal/Optical Carbon Analyzer with the IMPROVE thermal/optical reflectance (TOR) protocol was used to quantify the organic carbon(OC) and elemental carbon content in $PM_{10}$. Diurnal and vertical variability was also carefully investigated. In general, OC and EC contenttration shoeed the highest values at the monitoring period o 21.00-00.00 as consequences of human activities at night bazaar coupled with reduction of mixing layer, decreased wind speed and termination of photolysis nighttime. Morning peaks of carboaceous compounds were observed during the sampling period of 06:00 -09:00, emphasizing the main contribution of traffic emission in the three cities. The estimation of incremental lifetime partculate matter exposure (ILPE) raises concern of high risk of carbonaceous accumulation over workers and residents living close to the observatory sites. The average values of incremental lifrtime particulate matter exposure (ILPE) of total carbon at Baiyoke Suit Hotel and Baiyoke Sky Hotel are approsimately ten time shigher then those air sample collected at prince of songkla University Hat-Yai campus corpse incinerator and fish-can maufacturing factory but only slightly higher than those of rice straw burnig in Songkla province. This indicates a high risk of developing lung cancer and other respiratory diseases across workers and residents living in high buildings located in Pratunam area. Using knowledge of carbonaceous fractions in $PM_{10}$, one can estimate the gas-particle partitioning of polycyclic aromatic hydrocarbons (PAHs). Dachs-Eisenreich model highlights the crucial role of adsorption in gas-particle partitioning of low molecular weight PAHs, whereas both absorption and adsorption tend to account for gas-particle partitioning of high molecular weight PAHs in urban residential zones of Thailand. Interestingly, the absorption mode alone plays a minor role in gas-partcle partitiining of PAHs in Chiang-Mai, Bangkok and hat-Yai.