• Proceedings of the Korea Air Pollution Research Association Conference
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• 2002.11a
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• pp.197-198
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• 2002

황사는 장거리를 이동해 한반도 둥에 영향을 미치는데, 호흡기 질환, 눈 질환, 알레르기 등 각종 질환을 유발하고, 최근에는 중국의 산업화에 따라 납, 카드뮴 같은 독성금속과 발암물질 둥 유해 오염물질까지 포함하고 있어 건강에 위협을 주고 있다. 나아가 황사에 포함된 미세 입자들이 대기 중에서 화학반응을 일으켜 각종 산화물을 생성하는 까닭에 만성기관지염을 악화시키고, 노인과 영아의 호흡기 질환을 유발하기도 한다 그밖에 황사는 햇빛을 차단해 시정거리를 감소시키고 항공기 운항에도 영향을 미친다. (중략)

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.10 no.1
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• pp.104-114
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• 2000

This study was carried out to estimate current status of dust concentrations in the factories producing non-metallic products in Korea. Data were gathered from the environmental monitoring reports by 40 workplace environmental monitoring institutes and the questionnaire designed for the study by the authors. A total of 1838 dust samples from 368 plants were obtained from the reports and were analyzed with no data modifications. But data on asbestos, rock wool, and welding fumes were excluded in this evaluation. The factories were classified into eight groups according to the standard industrial classification scheme in Korea. The results of this study were as follows; 1. The factories included were glass, non-refractory ceramic, refractory ceramic ware, structural non-refractory clay and ceramic, cement and lime, articles of concretes, and stone. Mean(geometric mean) concentrations of total dust samples ranged from $1.75(0.84)mg/m^3$ to $5.87(2.84)mg/m^3$. Statistically significantly higher dust concentrations were found in the cement and lime industries compared with other industries. 2. The non-compliance rates were 15.2% in glass and 20.6% in other non-metallic mineral products industries. Although all institutions surveyed utilized the identical sampling and classification scheme for dusts as specified in the current occupational exposure limits, wide discrepancies were found in collecting samples and classifying dusts. Further problems were discovered in classifying dusts. A dust sample collected could be classified into any of the three groups regardless of silica content. The results of this study showed that dust concentrations in the non-metallic products industries varied widely. Also discovered was classification errors of dust types among workplace monitoring institutes. These errors could adversely affect the results of exposure assessments and the true nature of dust hazards. Further, no institutions performed respirable dust sampling and analysis of crystalline silica. In order to correct these malpractices, current standards of occupational exposure limits should be revised and tight supervision by the Ministry of Labour be suggested.

• Journal of Korean Society for Atmospheric Environment
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• v.34 no.5
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• pp.668-676
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• 2018

This study has developed a technique to divide the aerosol optical depth of the entire aerosol (${\tau}_{total}$) into the dust optical depth (${\tau}_D$) and the pollution particle optical depth (${\tau}_P$) using the AERONET sun/sky radiometer data provided in Version 3. This method was applied to the analysis of AERONET data observed from 2006 to 2016 in Beijing, China, Seoul and Gosan, Korea and Osaka, Japan and the aerosol optical depth trends of different types of atmospheric aerosols in Northeast Asia were analyzed. The annual variation of ${\tau}_{total}$ showed a tendency to decrease except for Seoul where observation data were limited. However, ${\tau}_D$ tended to decrease when ${\tau}_{total}$ were separated as ${\tau}_D$ and ${\tau}_P$, but ${\tau}_P$ tended to increase except for Osaka. This is because the concentration of airborne aerosols, represented by Asian dust in Northeast Asia, is decreased in both mass concentration and optical concentration. However, even though the mass concentration of pollution particles generated by human activity tends to decrease, Which means that the optical concentration represented as aerosol optical depth is increasing in Northeast Asia.

• Journal of Korean Society for Atmospheric Environment
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• v.20 no.6
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• pp.833-838
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• 2004

The analysis of Pb in both PM$_{2.5}$ and PM$_{10}$ fraction of aerosols was made consecutively for every spring season during four year period of 2001 through 2004. To diagnose the impact of the Asian Dust (AD) on metal concentration levels, we compared our Pb measurement data after dividing the whole data sets into AD and NAD period. The results of our analysis indicated that the concentrations of coarse particles increased significantly during the AD period, whereas an increase in the fine counterpart was of moderate degree. However, when Pb concentrations between AD and NAD were compared, the patterns were quite different. From all particle fractions, the Pb concentrations of NAD were slightly or moderately higher than those of AD. The overall results of our study suggest that an increase in particle concentrations during the AD period can cause a rather slight reduction in Pb concentration levels; this can be explained by the dilution effect associated with the increase of Pb-depleted coarse particles.s.s.

• Particle and aerosol research
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• v.17 no.3
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• pp.71-79
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• 2021

Ultrafine dust, which is emitted from industrial factories or all kinds of vehicles, threatens the human's respiratory system and our environment. In this regard, separating airborne particles is essential to mitigate the severe problem. In this work, an axial cyclone for the effective technology of eliminating harmful dust is investigated by numerical simulation using Ansys 2020, Fluent R2. In addition, the optimized structure of the cyclone is constructed by means of multi objective optimization based on the response surface method which is a representative method to analyze the effect of design parameter on response variables. Among several design parameters, the modified length of the vortex finder and dust collector is a main point in promoting the performance of the axial cyclone. As a result, the optimized cyclone exhibits remarkable performance when compared to the original model, resulting in pressure drop of 307 Pa and separator efficiency of 98.5%.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.2
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• pp.1204-1210
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• 2014

New control methods are proposed for indoor air quality by removing fine airborne dust-particles. As suspended fine dust-particles contain inorganic dust as well as fine organic bacteria, studies for simultaneous control of these contaminants are required. In this study, photocatalytic disinfection of indoor suspended microorganisms such as E. coli and Bacillus subtilis is performed by three types of photocatalysts with UVA irradiation. The UVA irradiation strength was controlled to the minimum $3{\mu}W/cm^2$, and ZnO, $TiO_2$, and ZnO/Laponite ball were used as the catalysts. The results indicate that E. coli was removed over 80 % after about 2 hours of reaction with UVA and all three types of photocatalysts, whereas only with UVA, around 50 % E. coli removal was obtained. Among the catalysts, ZnO/Laponite composite ball was found to have similar sterilizing capacity to $TiO_2$. However, in case of B. subtilis, which has thick cell wall in its spore state, disinfection was not effective under the low UVA irradiation condition, even with the catalysts. Further studies need to figure out the optimal UVA irradiation ranges as well as photocatalysts doses to control airborne dust, to provide healthy clean air environment.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.8 no.1
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• pp.50-66
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• 1998

This study was conducted to estimate crystalline silica contents in airborne respirable dust from various manufacturing industries and to compare analytical performance of two methods of quantifying crystalline silica, X-ray diffraction(XRD) and Fourie transform infrared spectroscopy (FTIR). For this study, various manufacturing industries with a history of having pneumoconiosis cases and also known to generate dusts containing crystalline silica were investigated. These industries include: foundry, brick, potteries, concrete, and abrasive material, etc. Both personal and area respirable dust samples were collected using 10 mm, Dorr-Oliver nylon cyclone equipped with 37mm, $5{\mu}m$ pore size, polyvinylchloride (PVC) filters as collection media. In addition, total dust samples were collected side-by-side to the respirable samples. All samples were weighed before and after sampling and were pretreated according to the NIOSH sampling and analytical methods 0500, 7500, and 7602 for dust collection and quartz analysis. In addition, bulk samples were collected and analyzed by X-ray fluorescence (XRF) for minerals. In this article, only the results obtained from foundry are reported. The results from various other industries will be published in future articles. The respirable dust concentrations from personal samples by cyclone were $0.46-1.06mg/m^3$ and those from area samples were $0.34-0.73mg/m^3$. Dust concentrations of personal samples were significantly higher than those of area samples. The highest dust concentration was obtained from the personal samples of the finishing operation. Total dust concentration ranged $1.24-3.40mg/m^3$. The mean quartz contents estimated by FTIR and XRD in the personal respirable dust samples were 5.12% and 4.41%, respectively, without significant difference between them. For quartz analyses, the two techniques were highly correlated with $r^2$ ranged 0.803-0.920. But the results by FTIR were mostly higher than those by XRD. In addition, cristobalite was not detected by FTIR. Significant correlations between contents of crystalline silica and such minerals as $Al_2O_3$, CaO, $TiO_2$, and $K_2O$ suggest possible interferences from these minerals.

• Journal of Radiation Protection and Research
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• v.41 no.2
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• pp.87-91
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• 2016

Background: A hand-held detector for an emergency response was developed for nuclide identification and to estimate the information of the ambient dose rate in the scene of an accident as well as the radioactivity of the contaminants. Materials and Methods: To achieve this, the most suitable sensor was first selected as a cadmium zinc telluride (CZT) semiconductor and the signal processing unit from a sensor and the signal discrimination and storage unit were successfully manufactured on a printed circuit board. Results and Discussion: The performance of the developed signal processing unit was then evaluated to have an energy resolution of about 14 keV at 662 keV. The system control unit was also designed to operate the CZT detector, monitor the detector, battery, and interface status, and check and transmit the measured results of the ambient dose rate and radioactivity. In addition, a collimator, which can control the inner radius, and the airborne dust sampler, which consists of an air filter and charcoal filter, were developed and mounted to the developed CZT detector for the quick and efficient response of a nuclear accident. Conclusion: The hand-held CZT detector was developed to make the in-situ gamma-ray spectrometry and its performance was checked to have a good energy resolution. In addition, the collimator and the airborne dust sampler were developed and mounted to the developed CZT detector for a quick and efficient response to a nuclear accident.

• Journal of Radiation Protection and Research
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• v.2 no.1
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• pp.9-16
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• 1977

A simple method has been established for determining RaA, RaB and RaC concentrations in airborne dust. This is to evaluate the concentration from measurement of total alpha activities in three selected-time intervals after an air sample is taken from the membrane filter paper (mean pore size: $0.8{\mu}m$). As a preliminary trial, a time-variation of the concentrations has been determined using the single-filter method at the KAERI site (N. Lat. $37^{\circ}38'$ and E. Long $127^{\circ}15'$), Seoul, Korea. It appears that there is a large variation of the concentrations depending on the sampling time. Generally the highest value was observed in the morning that may coincide with the highest density of atmosphere in a day while the lowest value was obtained around fourteen o'clock.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.4 no.2
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• pp.168-179
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• 1994

In some ceramic industries, worker exposure to dust, crystalline free silica and lead were determined and evaluated. The conclusions are as follows. 1. Crystalline silica in bulk samples was 10.5 % in sanitary ware industry, 9.4 % in tile industry, and 2.1 % in ceramic insulator industry respectively. The free silica content of air filter sample was 8.03 % in table ware industry, 5.59 % in sanitary ware industry, and 1.32 % in ceramic insulator industry. Because silica content in ceramic dust is relatively high, it is should be considered silica as important factor in evaluating for ceramic industry. 2. The silica contents in dust from tile, sanitary ware and table ware industries are above 5%, it should be classified as "Type" 2 dust. 3. The airborne concentration of respirable crystalline silica was $27.9{\mu}g/m^3$ in a sanitary ware factory and $5.8{\mu}g/m^3$ in a ceramic insualtor factory. Three of ten samples sampled the above factories were exceeded the occupational exposure levels, $100{\mu}g/m^3$. 4. Geometric mean(GM) of total dust in 11 factories was $1.00mg/m^3$ and GM of respirable dust concentration in 5 factories was $0.33mg/m^3$. Sanitary ware industry had the highest concentration of total dust, $1.62mg/m^3$ and of respirable dust, $0.88mg/m^3$. 5. Average lead concentration in air was $0.05mg/m^3$ in glazing process of 2 factories manufacturing table ware. Five of ten sample(50%) were exceeded $0.05mg/m^3$. Therefore lead exposure in pottery industry should be considered as important problem.