• Journal of the korean society of oceanography
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• v.32 no.3
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• pp.112-119
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• 1997

Coastal sediments collected near the Youngkwang Nuclear Power Plant were analysed for major(Al$_2$O$^_3$, Fe$^_2$O$^_3$, MgO, CaO, Na$^_2$O, K$^_2$O, TiO$^_2$, MnO), trace (Ba, Sr, V, Co, Cr, Cu, Ni, Zn, Pb) metal, and P$^_2$O$^_5$ contents. The composition of bulk metals from most stations fits within the range as those in the average crustal and sedimentary rocks, suggesting that the anthropogenic perturbation of these components is insignificant. The abundance and distribution of total contents for the majority of metals in the surface sediment could be explained by the grain size and were associated with mud (<63 ${\mu}$m) contents. However, distributions of Ca, K, Sr and Ba did not have any significant association with the sediment grain size. This may be due to the geochemical coherence among these metals in certain minerals abundant in coarse grained fractions. The distribution of Pb appears to be partly affected by the contribution from aerosol fallout. Using the R'-mode factor analysis, we show that the variance of the metal contents could be explained by four factors which account for 93.7% of the total variance. It appears that texturally controlled and/or sorting factors influenced by fine fraction are the most dominant factors which determine the relative abundance and distribution of metals in the study area.

• Korean Journal of Remote Sensing
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• v.20 no.2
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• pp.77-89
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• 2004

The spatial and temporal variations of aerosol optical depth (AOD) over Northeast Asia regions have special importance in the aerosol research for estimation of aerosol radiative forcing parameters and climate change. Aerosol optical and physical properties (AOD and ${\AA}$ngstrom parameter) have been investigated by using Moderate Resolution Imaging Spectroradiometer (MODIS) and Total Ozone Mapping Spectrometer (TOMS) Aerosol Index (AI) to estimate aerosol characteristics over the study region during 2001. Additionally, aerosol characteristics over the Korean peninsular during Aerosol Characteristic Experiment in Asia (ACE-Asia) Intensive Observation Period (IOP) have been investigated by using satellite observations. The results showed that the daily-observed aerosol data indicate seasonal variations with relatively higher aerosol loading in the spring and very low during the winter. The typical Asian dust case showed higher AOD (>0.7) with lower Angstrom exponent (<0.5) and higher AI (>0.5) that is mainly due to the composition of coarse particles in the springtime. Mean AOD for 2001 at 4 different places showed 0.65$\pm$0.37 at Beijing, 0.31$\pm$0.19 at Gosan, 0.54$\pm$0.26 at Seoul, and 0.38$\pm$0.19 at Kwangju, respectively. An interesting result was found in the present study that polluted aerosol events with small size dominated-aerosol loading around the Korean peninsular are sometimes observed. The origin of these polluted aerosols was thought to East China. Aerosol distribution from satellite images and trajectory results shows the proof of aerosol transport. Therefore, aerosol monitoring using satellite data is very useful.

• Journal of Environmental Health Sciences
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• v.29 no.3
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• pp.91-96
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• 2003

This study was intended as an investigation of characteristics of background site atmospheric respirable particulate matters(RPM), and fine particles(<2.5 ${\mu}{\textrm}{m}$). The particle size distributions during the phenomenon of Yellow Sand(YS) occurs from April, 2001. Atmospheric aerosol particulate matter was directly collected on the Jeju island between 1 to 30, April, 2001 using an eight-stage cascade impacter(particle size range: 0.43-11 ${\mu}{\textrm}{m}$), and cyclone separator(cut size: 2.5, 10 ${\mu}{\textrm}{m}$). The episode of YS observed in background monitoring site, Kosan and appeared 2 times at sampling period. The mass concentrations of fine and coarse particles for YS episode were 34.2 and 59.6 $\mu\textrm{g}$/㎥, respectively, which were significantly increased amounts compared to 13.3 and 13.0 $\mu\textrm{g}$/㎥ for NonYS(NYS). Most size distributions had two peaks, one at 0.43∼.65 ${\mu}{\textrm}{m}$ and the other at 3.3${\mu}{\textrm}{m}$4.7 ${\mu}{\textrm}{m}$. The result of analysis of water-soluble ion component indicated that sulfate was mainly ion component, but nitrate and calcium ion was significantly increased at the YS episode.

• Proceedings of the KSME Conference
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• 2000.04b
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• pp.416-421
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• 2000

We have developed a simple model for describing the non-spherical particle growth phenomena using modified 1-dimensional sectional method. In this model, we solve simultaneously particle volume and surface area conservation sectional equations which consider particles' irregularities. From the correlation between two conserved properties of sections, we can predict the evolution of the aggregates' morphology. We compared this model with a simple monodisperse-assumed model and more rigorous two dimensional sectional model. For the comparison, we simulated silica and titania particle formation and growth in a constant temperature reactor environment. This new model shows a good agreement with the detailed two dimensional sectional model in total number concentration, primary particle size. The present model can also successfully predict particle size distribution and morphology without costing very heavy computation load and memory needed for the analysis of two dimensional aerosol dynamics.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.7
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• pp.1020-1027
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• 2000

A simple model for describing the non-spherical particle growth phenomena has been developed. In this model, we solve simultaneously particle volume and surface area conservation sectional equations that consider particles' non-sphericity. From the correlation between two conserved properties of sections, we can predict the evolution of the aggregates' morphology. This model was compared with a simple monodisperse-assumed model and more rigorous two-dimensional sectional model. For comparison, formation and growth of silica particles have been simulated in a constant temperature reactor environment. This new model showed good agreement with the detailed two-dimensional sectional model in total number concentration and primary particle size. The present model successfully predicted particle size distribution and morphology without costing very heavy computation load and memory needed for the analysis of two dimensional aerosol dynamics.

• 한국연소학회:학술대회논문집
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• 1997.06a
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• pp.61-68
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• 1997

The morphology and size distribution of chromium oxides and the concentration measurement of atomic arsenic have been studied in laminar diffusion flames. Nitrogen was added to vary flame temperatures in hydrogen flames. Ethene flames were used in order to investigate the potential for interaction between the soot aerosol that is formed in these flames and the chromium aerosol. Two sources of chromium compounds were introduced: chromium nitrate and chromium hexacarbonyl. A detailed investigation of the morphology was carried out by scanning electron microscopy (SEM). The amounts of Cr(VI) and total Cr were determined by a spectrophotometric method and by X-ray fluorescence spectrometry, respectively. Also, LIF was used for the measurement of atomic arsenic, which was excited at 197.2 nm and was detected at 249.6 nm. Results showed that the morphology of the particles varied with the flame temperature and with the chromium source. The particles were characterized by porous structures, cenospheres and agglomerated dense particles when chromium nitrate solution was added to the flames. At low to moderate temperatures, porous sintered cenospheric structures were formed, in some cases with a blow hole. At higher temperatures, an agglomerated cluster which was composed of loosely sintered submicron particles was observed. It was also found that the emission of Cr(VI) from the undiluted $H_2$ flame was more than 10 times larger than in the 50% $H_2$ / 50% $N_2$ flame on a mass basis. Single point LIF measurement of atomic arsenic indicated that arsenic exist only in the low temperature, fuel rich region.

• Particle and aerosol research
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• v.11 no.3
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• pp.87-92
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• 2015

MCM-41 (Mobil Composition of Matter) and SBA-15 (Santa Barbara Amorphous) were used as a supported catalyst for ethylene polymerization due to their combination of large surface area and wide range of pore size distribution. The morphology of supports was used to control the morphology of the resulting polymer. Different molar ratios of Al/Ti were used for ethylene polymerization at $60^{\circ}C$ under atmospheric pressure. The effect of different mass ratios of MCM-41/SBA-15 and 1-hexene concentration on polymerization activity and polymer properties was investigated. The catalytic activity and the crystallinity reached the highest value at Al/Ti of 480. Upon incorporation of MCM-41 and SBA-15 into $MgCl_2/TiCl_4$ catalyst, the molecular weight and crystallinity of polyethylene were enhanced. The obtained polyethylene showed melting temperature between 130 and $135^{\circ}C$. The polyethylene with replication structure of support and bimodal MWD was expected.

• Journal of Korean Society for Atmospheric Environment
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• v.24 no.4
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• pp.404-414
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• 2008

A Transient Differential Mobility Particle Spectrometer (TR-DMPS) with a short response time was recently developed to monitor high concentration of ultrafine particles emitted from vehicles. To investigate the availability of the TR-DMPS for monitoring transient roadside aerosols, the number size distribution of ultrafine particles was monitored at the Cheongnyangni roadside in Seoul on March 23, 2007 together with a Scanning Mobility Particle Sizer (SMPS). The roadside aerosols were monitored every 5 min and 0.1 sec by using the SMPS and the TR-DMPS, respectively. The concentration of ultrafine particles at the roadside was highly fluctuated for a short duration. From the comparison of particle number concentrations and size distributions between two instruments, it was confirmed that the SMPS provided fairly good time-averaged number size distribution although it did not follow rapid change of particle number concentration at the roadside. The TR-DMPS quickly responded to a rapid change of particle number concentration due to abrupt traffic flow. However, the TR-DMPS frequently showed electrical noise events, resulting in underestimated particle contamination. A more stable operation of the TR-DMPS is needed in application of roadside aerosol monitoring.

• Journal of Korean Society for Atmospheric Environment
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• v.1 no.1
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• pp.71-82
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• 1985

The effect on the particulate matters in the atmosphere was investigated in Seoul area from March, 1984 to Aprill, 1985. Aerosols were collected by filters on nine stages Andrsen Air Sampler, and size distribution and total concentration of the aerosols, Fe and Pb were measured. In spring with Yellow Sand the concentration of particles in aerosols was 185.55$\mug/m^3$ and CP/TA was 65.9%. But in spring without Yellow Sand those of particles was 135.45$\mug/m^3$ and CP/TA was 58.6%. Accordingly the concentration of coarse particles with Yellow Sand was higher than without them in Spring. Above results indicate that in Seoul Area the main source of air pollution originated from natural burdens, especially from soil. The concentration of Pb was similarly valued through both seasons in Seoul area but fine particles valued above coarse particles. On the other hand, in urban area, the natural and anthropogenic sources have influenced on the concentration of Pb. With referred to particle size distribution for Fe, the concentration of coarse particles was 0.168$\etag/m^3$ (CP/TA: 74.3%) in Spring with Yellow Sand, 0.096$\mug/m^3$ (CP/TA: 71.6%) without Yellow Sand and 0.083$\mug/m^3$ (CP/TA: 67.4%) in winter, respectively. Compared with fine particles, all of them were higher. It indicated that the origin of coarse particles in urban air was not related to anthropogenic source. The concentration of Fe was influenced by Yellow Sand and contributed to air pollution.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.4 no.2
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• pp.180-188
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• 1994

This study was designed to investigate qualitatively whether respirators now being used in workplaces tit workers iflfaces well or not. Leak sites were determined after exposing the subjects to fluorescent aerosol and were analyzed by gender, brand and manufacturing nation. The results were as follows ; 1. Among those leak sites which were classified into four areas(nose, cheek, lip and chin), test aerosol was mostly deposited on the nose and the cheek areas. 2. The mean number of leak sites observed from the female subjects were 2.3 while the number were 2.2 from the male subjects. The most frequently observed leak site was nose and followed by chin, lip and cheek in descending order of frequency. 3. Among different brands of respirators, different leak sites were observed. Test subjects wearing the Sand N brands were more heavily exposed than those of wearing the D and M brands. 4. No significant difference of the number of leak sites were found between Korean-made and American-made masks. However, the most frequent leak site observed for the Korean-made ones was the nose area while it was the chin area for the American-made ones. 5. Analyses of 97 leak sites by shape showed that 27(27.8%) were point types, 54(55.7%) diffuse types and 16(16.5%) streamline types. 6. Test subjects indicated that the facepieces of Korean-made respirators were harder and smaller in size than those of American-made one. The most comfortable respirator selected was the respirator by the N Co. and the most uncomfortable one was the respirator by the D Co. This study suggests that many half-mask respirators now being used in the workplaces may not fit to workers well. Therefore, when selecting respirators, employers are advised to test respirators if they fit to workers well. And manufacturers are recommended to produce effective and comfortable respirators tested qualitatively and quantitatively not only in the laboratory but also in the field.