• Journal of the Korean earth science society
• /
• v.35 no.1
• /
• pp.1-18
• /
• 2014

The purpose of this study was to analyze the sensitivity of meteorological fields and the variation of concentration of particulate matters (PMs) due to aerosol schemes and dust options within the WRF-Chem model to estimate Asian dusts affected on 29 May 2008 in the Korean peninsula. The anthropogenic emissions within the model were adopted by the $0.5^{\circ}{\pm}0.5^{\circ}$ RETRO of the global emissions, and the photolysis option was by Fast-J photolysis. Also, three scenarios such as the RADM2 chemical mechanism and MADE/SORGAM aerosol, the MOSAIC 8 section aerosol, and the GOCART dust erosion were simulated for calculating Asian dust emissions. As a result, the scenario of the RADM2 chemical mechanism & MADE/SORGAM aerosol depicted higher concentration than the others' in both Asian dusts and the background concentration of PMs. By comparing of the daily mean of PM10 measured at each air quality monitoring site in Seoul with the scenario results, the correlation coefficient was 0.67, and the root mean square error was $44{\mu}gm^{-3}$. In addition, the air temperature, the wind speed, the planetary boundary layer height, and the outgoing long-wave radiation were simulated under conditions of no chemical option with these three scenarios within the WRF or WRF-Chem model. Both the spatial distributions of the PBL height and the wind speed of u component among the meteorological factors were similar to those of the Asia dusts in range of 1,800-3,000 m and $2-16ms^{-1}$, respectively. And, it was shown that both scenarios of the RADM2 chemical mechanism and MADE/SORGAM aerosol and the GOCART dust erosion were interacted on-line between meteorological factors and Asian dusts or aerosols within the model because the outgoing long-wave radiation was changed to lower than the others.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.27 no.11
• /
• pp.1542-1547
• /
• 2003

Although dielectric barrier discharge (DBD) in air has been applied to a wider range of aftertreatment processes for HAPs (Hazardous Air Pollutants), due to its high electron density and energy, its potential use as precharging dust particles is not well known. In this work, we measured size distributions of bimodal aerosol particles and estimated collection efficiency of the particles by an electrostatic precipitator (ESP) using DBD as particle charger. To examine the particle collection with DBD charger, nano size particles of NaCl(20∼100nm) and DOS (50∼500nm) were generated by a tube furnace and an atomizer, respectively. For experimental conditions of 60㎐, 11㎸ and 60 lpm, the particle collection efficiency for the hybrid system was over 85%, based on the number of particles captured.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.24 no.10
• /
• pp.1351-1358
• /
• 2000

Two dimensional aerosol dynamics considering the effects of particle generation, coagulation, thermophoresis, sintering and convection has been studied to obtain the growth of non-spherical silica particles in conjunction with determining flame temperature by performing combustion analysis of premixed flat flame. Heat and mass transfer analysis includes 16 species, 29 chemical reaction steps together with oxidation and hydrolysis of SiCl4. The effect of radiation heat loss has also been included. The predictions of flame temperatures and the evolution of particle size distributions were in a reasonable agreement with the existing experimental data.

• Proceedings of the KSME Conference
• /
• 2003.04a
• /
• pp.1435-1440
• /
• 2003

Although Dielectric Barrier Discharge (DBD) in air has been applied to a wider range of aftertreatment processes for HAPs(Hazardous Air Pollutants), due to its high electron density and energy, its potential use as precharging dust particles is not well known. In this work, we measured size distributions of bimodal aerosol particles and estimated collection efficiency of the particles by electrostatic precipitator(ESP) using DBD as particle charger. To examine the particle collection with DBD charger, nano size particles of NaCl($20{\sim}100$ nm) and DOS($50{\sim}800$ nm) were generated by tube furnace and atomizer, respectively. For experimental conditions of 60 Hz, 11 kV, and 60 lpm, the particle collection efficiency for the hybrid system comprising DBD charger and ESP was over 85 %, based on the number of particles captured.

• New & Renewable Energy
• /
• v.7 no.1
• /
• pp.22-28
• /
• 2011

The surface solar radiations were calculated and analyzed with spatial resolutions (4 km and 1 km) using by GWNU (Gangneung-Wonju National University) solar radiation model. The GWNU solar radiation model is used various data such as aerosol optical thickness, ozone amount, total precipitable water and cloud factor are retrieved from Moderate Resolution Imaging Spectrometer (MODIS), Ozone Monitoring Instrument (OMI), MTSAT-1R satellite data and output of the Regional Data Assimilation Prediction System(RDAPS) model by Korea Meteorological Administration (KMA), respectively. The differences of spatial resolutions were analyzed with input data (especially, cloud factor from MTSAT-1R satellite). And the Maximum solar radiation by GWNU model were found in Andong, Daegu and Jinju regions and these results were corresponded with the MTSAT-1R cloud factor.

• The KSFM Journal of Fluid Machinery
• /
• v.10 no.5
• /
• pp.27-33
• /
• 2007

Rarefied gas flows through two-dimensional micro channels are studied numerically for the performance optimization of a nanomembrane-based Knudsen compressor. The effects of the wall temperature distributions on the thermal transpiration flow patterns are examined. The flow has a pumping effect, and the mass flow rates through the channel are calculated. The results show that a steady one-way flow is induced for a wide range of the Knudsen number. The DSMC(direct simulation Monte Carlo) method with VHS(variable hard sphere) model and NTC(no time counter) techniques has been applied in this work to obtain numerical solutions. A critical element that drives Knudsen compressor Is the thermal transpiration membrane. The membranes are based on aerosol or machined aerogel. The aerogel is modeled as a single micro flow channel.

• Journal of Environmental Health Sciences
• /
• v.22 no.4
• /
• pp.55-61
• /
• 1996

Measurements of the seasonal variations of concentration and size distribution of TSP, $SO_4^{2-}, NO_3^-, Cl^-, NH_4^+, Na^+, K^+, Ca^{2+}$ and $Mg^{2+}$ were made by Andersen air sampler from May 1995 to April 1996 in Seoul. The size distribution of these ions was divided into four patterns. 1) Distribution was concentrated on fine particles over a year such as $NO_3^-$ component, 2) Distribution was predominated in coarse particles fraction over a year such as $Mg^{2+}$ and $Ca^{2+}$ components, 3) Distribution was differerent from various seasons such as $NH_4^+, SO_4^{2-}, Cl^-$ and $K^+$ components, 4) Distribution was bi-modal such as $Na^+$.

• Particle and aerosol research
• /
• v.10 no.2
• /
• pp.61-75
• /
• 2014

Five on-road measurements were made using a mobile laboratory (ML) to characterize spatial and temporal air pollutant distributions over roads around a day-care center in urban area on 30 August 2013. Fixed monitoring was also done near the day-care center using the ML during the periods between on-road measurements. On-road air pollution monitoring route was classified into seven sections and three zones to identify severe polluted roads among many roads having different traffic volumes and directions. Typical pollutants emitted from vehicles such as $NO_x$, black carbon, particle-bound polycyclic aromatic hydrocarbons, and submicron particles including nanoparticles were monitored using real-time instruments. Peak concentration episodes were frequently observed during the on-road measurements and most peaks were simultaneously monitored at four pollutants. Colored on-road air pollution map for each pollutant provides an insight on spatial air pollution distribution, showing heavily polluted roads and sections. Average on-road $NO_x$ concentration of each run was similar to that monitored at the nearest roadside air monitoring station.

• Journal of Korean Society for Atmospheric Environment
• /
• v.34 no.3
• /
• pp.447-456
• /
• 2018

Elemental carbon (EC) and organic carbon (OC) thermal/optical methods for the analysis of ambient particulate matter were used to analyze twenty-two $PM_{2.5}$ samples along collected from May 28 to June 20 of 2016 at the Anmyeon measurement site ($36.32^{\circ}N$; $126.19^{\circ}E$). The three laboratory OCEC protocols, which are the National Institute of Occupational Safety and Health (NIOSH5040), the Interagency Monitoring of Protected Visual Environments_A(IMPROVE_A), and European Supersites for Atmospheric Aerosol Research2 (EUSAAR2), were utilized for the aerosol characterization experiment as in intercomparisons between three protocols. There are excellent agreement for total carbon (i.e. sum of EC and OC), but statistically significant differences were observed in the split between the measured EC and OC. IMPROVE_A EC values were always larger than both NIOSH5040 and EUSAAR2 protocols. These methods exhibited significantly different temperature-distributions based on thermogram analysis, which is normalized to total carbon. In this study, a protocol for carbonaceous analysis is suggested for the Korean Peninsula.

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