• 한국산업보건학회지
• /
• 제18권3호
• /
• pp.177-184
• /
• 2008

The purpose of this study was to compare the performance characteristics of Andersen and total suspended particulate (TSP) samplers in terms of particle size distribution (PSD) and mass sampling efficiency. In the present study, two Andersen and four TSP samplers were selected and tested to quantitatively estimate human exposure to fly ash representing industrial particulate matter (PM) in a carefully controlled chamber. The PSD characteristics, a mass median aerodynamic diameter and a geometric standard deviation, were found from the sampled PM of airborne samplers in the chamber. An Andersen sampler was compared with a TSP sampler quantified by a coulter counter multisizer, as a reference sampler, to describe the correlation of mass sampling efficiencies between two types of samplers. Overall results indicate that Andersen samplers overestimated small PM due to particle bounce phenomena between impaction stages. There was reasonably good correlation ($R^2$ = 0.89 and 0.91) between the mass sampling efficiencies of Andersen and TSP samplers during the two tests. However, the lower values of slope (0.71 and 0.72) in two tests showed that the Andersen sampler underestimated PM (> AD $10.1\;{\mu}m$) with sufficient inertia due to a relatively lower Andersen inlet velocity at 0.8 m/s comparing with the operating air velocity at 2.1 m/s in the sampling zone of a chamber.

• 한국분무공학회지
• /
• 제21권4호
• /
• pp.223-236
• /
• 2016

On-road source emissions are major air pollutants and have been associated with serious health effects in Seoul metropolis. Thus, it is of fundamental importance to have an accurate assessment of vehicle emissions in order to implement an effective air quality management policy. As a result, there is a need to overview vehicle emission characteristics of air pollutants. This article discusses vehicle exhaust sampling and chemical analysis, emission characteristics of air pollutants, and emission regulations from passenger cars. The vehicle exhaust sampling and chemical analysis methods were described in particulate matter and gaseous compounds. In this article, chassis dynamometer, measurement instrumentation for nano-particulate matter and carbon compounds analysis device were described. For the gasoline and diesel vehicles, the effective parameters of emissions were average vehicle speed, vehicle mileage and model year. The particle number emissions for diesel nano-particles were sensitive to the sampling conditions. Also, the particle number emissions with a diesel particle filter (DPF) largely reduced rather than those without it. This article also describes different emission characteristics of air pollutants according to biodiesel or bioethanol mixing ratio. The Korean emission standards for passenger cars were compared with those of the US and EU. Finally, the objective is to give an overview of relevant background information on emission characteristics of air pollutants from passenger cars in Korea.

• 한국환경과학회지
• /
• 제1권2호
• /
• pp.25-31
• /
• 1992

Authors Investigated the particulate size distribution in work environment of Banwol and Changwon industry complex. Size distributions of particles exposured to workers in welding and in grounding process were evaluated by personal cascade impactors. Personal air samplers with personal cascade impactor were attached to the workers. The mass median diameter measured in welding sites were 0.3 to 3.BUm and in grinding sites were 1.5 to 2.6htn. Respirable matter fractions were ranged 32.67 to 65.055. Respirable matter fractions were calculated from the sixte distribution data by the respirable particle mass of the ACGIH criteria. The study relating to characteristics of particle of other industries and particulate sixte distribution is more needed in the near future

• 천문학회보
• /
• 제36권2호
• /
• pp.51.2-51.2
• /
• 2011

We have studied the topology of volume-limited galaxy sample selected from the very luminous red galaxies (LRGs) in the completed Sloan Digital Sky Survey. LRGs are predominantly massive elliptical galaxies and tend to reside in massive dark matter halos. We compared the observed genus statistics with predictions from perturbation theory and mock LRG surveys constructed from dark matter halos in a Lambda CDM model. To compare with the observational data, we made 129 mock surveys in the past light cone space by using three different size CDM simulations: 41203 particle 6592 Mpc/h, 60003 particle 7200 Mpc/h, and $7210^3$ particle 10815 Mpc/h.

• Journal of Advanced Marine Engineering and Technology
• /
• 제34권4호
• /
• pp.508-514
• /
• 2010

본 논문은 커먼레일 디젤엔진의 정속운전시 배출되는 나노크기의 입자상 물질을 분석하는데 초점을 두었다. 디젤산화촉매 후단에서 나노입자상 물질의 개수농도 저감수준은 크지 않았으나 매연여과장치 후단에서 분석한 결과 1,000배 정도 저감되는 결과를 확인하였다. 고속 고부하 조건에서는 매연여과장치의 자연재생 효과로 인해 입자상 물질은 증가하였다. 연료분사시기를 BTDC $6^{\circ}CA$ 에서 ATDC $4^{\circ}CA$까지 지각시킨 결과 입자상 물질의 개수농도는 감소하였지만 최지각 조건인 ATDC $9^{\circ}CA$에서는 증가하는 결과를 확인하였다. EGR 적용시 핵화모드 입자상 물질은 저감되는 경향을 보였으며 축적모든 입자는 증가하였다.

• 천문학회보
• /
• 제45권1호
• /
• pp.47.3-48
• /
• 2020

I will present the Sejong Suite, an extensive collection of state-of-the-art high-resolution cosmological hydrodynamical simulations spanning a variety of cosmological and astrophysical parameters, primarily developed for modeling the Lyman-Alpha forest. Adopting a particle-based implementation, we follow the evolution of gas, dark matter (cold and warm), massive neutrinos, and dark radiation, and consider several combinations of box sizes and number of particles. Noticeably, for the first time, we simulate extended mixed scenarios describing the combined effects of warm dark matter, neutrinos, and dark radiation, modeled consistently by taking into account the neutrino mass splitting. Along the way, I will also highlight some new results focused on the matter and flux statistics.

• Environmental Analysis Health and Toxicology
• /
• 제28권
• /
• pp.6.1-6.7
• /
• 2013

Objectives In this study, we investigated the influence of ionic strength and natural organic matter (NOM) on aggregation and soil adsorption of citrate-coated silver nanoparticles (AgNPs). Methods Time-resolved dynamic light scattering measurements and batch adsorption experiments were used to study their aggregation and soil adsorption behaviors, respectively. Results The aggregation rate of AgNPs increased with increasing ionic strength and decreasing NOM concentration. At higher ionic strength, the AgNPs were unstable, and thus tended to be adsorbed to the soil, while increased NOM concentration hindered soil adsorption. To understand the varying behaviors of AgNPs depending on the environmental factors, particle zeta potentials were also measured as a function of ionic strength and NOM concentration. The magnitude of particle zeta potential became more negative with decreasing ionic strength and increasing NOM concentration. These results imply that the aggregation and soil adsorption behavior of AgNPs were mainly controlled by electrical double-layer repulsion consistent with the Derjaguin-Landau-Verwey-Overbeek theory. Conclusions This study found that the aggregation and soil adsorption behavior of AgNPs are closely associated with environmental factors such as ionic strength and NOM and suggested that assessing the environmental fate and transport of nanoparticles requires a thorough understanding of particle-particle interaction mechanisms.

• 한국분무공학회지
• /
• 제19권4호
• /
• pp.182-187
• /
• 2014

As the regulations for Particulate Matter (PM) and Particle Number (PN) emissions from Gasoline Direct Injection (GDI) Vehicle stringent recently, a lot of studies have been made on the emission characteristics of PM and PN. In this study, PM and PN emission characteristics were compared to GDI and Multi Port Injection (MPI) Vehicles using the Condensation Particle Counter (CPC) measurement equipment. And driving mode is divided into normal driving mode (CVS-75, NEDC, NIER 6, NIER 9) and a constant speed driving mode (10 km/h, 35 km/h, 80 km/h, 110 km/h) to evaluate the characteristics in the various operating conditions. In the results, most of the driving mode, PM and PN were emitted from GDI Vehicle more than MPI Vehicle. However, in the constant speed mode of 110 km/h, PM and PN from MPI Vehicle were also a lot of emission. It is determined to cause a difficulty in the fuel injection control of the MPI Vehicle.

• 한국대기환경학회지
• /
• 제15권5호
• /
• pp.657-665
• /
• 1999

Particulate matter produced by diesel engines is of concern to cngine manufactures because of its environmental impact. The majority of diesel particles are in the range of smaller than 1 ${\mu}{\textrm}{m}$. Because of their tiny volume, ultrafine diesel particles contribute very little to the total mass concentration which is currently regulated for automobile emissions. Ultrafinc particles are known to have deleterious effects upon human health cspecially because they penetrate deeply human respiratory tract and have negative effects on the health. In this study, the engine exhaust gas was diluted in a dilution tunnel and the particle size distribution was measured using the scanning mobility particel sizer system. Measurements of the number and the mass concentrations of the diesel exhaust were made under different engine ooperating conditions. The dilution sampling system provided a common basis for collection of the exhaust by cooling and diluting the source emission prior to the measurement. The measurement results showed that the particle size distributions of the exhaust from the diesel vehicles equipment with either heavy-duty or lignt-duty diesel engines, were similar in the particle size range of 0.08~0.2${\mu}{\textrm}{m}$.

• 한국입자에어로졸학회지
• /
• 제10권1호
• /
• pp.1-8
• /
• 2014

In this study, we have developed a real-time monitoring device for measuring $PM_{10/2.5/1}$ of ambient aerosol particles. The real-time PM (Particulate Matter) monitor was based on the light scattering method and had 16 channels in particle size. The laboratory and field tests were carried out to evaluate the performance of the PM monitor developed. Arizona Road Dust particles ranging from diameter of 0.1 to $20{\mu}m$ were generated as test particles in the laboratory test. The field test was carried out at the Seoul Meteorological Observatory. We can obtain the particle size and number concentration (particle size distribution) only from the real-time PM monitor developed. Therefore, the average density of aerosol particles was used to obtain the PM data from the particle size distribution. The $PM_{10/2.5/1}$ results of the PM monitor were compared with the data of the Grimm Dust Monitor (Model 1.108) and a beta ray gauge (Thermo Fisher Scientific). As a result, it was shown that the $PM_{10/2.5/1}$ results obtained by the real-time PM monitor agreed well with the data of the reference devices, and overall, the real-time PM monitor could be used as a PM monitoring device for real-time monitoring of the ambient particles.