• Journal of Environmental Science International
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• v.22 no.3
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• pp.347-358
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• 2013

The aerosol number concentration have measured with an aerodynamic particle sizer spectrometer(APS) at Gosan in Jeju Island, which is known as background area in Korea, from March 2010 to February 2011. The obtained results of asian dust events and non-asian dust period have been compared. The results show that the entire averaged aerosol number concentration from APS measurement during asian dust events and non-asian dust period are about 341 particles/$cm^3$ and 240 particles/$cm^3$, respectively. During asian dust events, the number concentration in small size ranges(${\leq}0.4{\mu}m$) are similar to non-asian dust period, however, those in large size ranges(${\geq}0.7{\mu}m$) are very higher than non-asian dust period. The contributions of the size resolved number concentration(23 channel in $0.25{\sim}10.0{\mu}m$) to total number concentration in that range are dramatically decreased with increased particle size. The contributions of smaller size ranges(${\leq}0.4{\mu}m$) during asian dust events are very low compared with non-asian dust period, on the other hand, those of larger size ranges(${\geq}0.4{\mu}m$) are higher than non-asian dust period. The number concentration in each size range are strongly correlated with the concentration in adjacent size range. And the total aerosol number concentration are depended on the number concentration in range of smaller than $0.58{\mu}m$ during non-asian dust period and asian dust events. On the other hand, $PM_{10}$ mass concentration has mainly affected with the number concentration in range of smaller than $1.0{\mu}m$ during non-asian dust period, however, during asian dust events, the mass concentration has mainly affected with the number concentration in range of $0.65{\sim}3.0{\mu}m$.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.9 no.2
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• pp.145-157
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• 1999

Wood dust is created when machines are used to cut or shape wood materials. Industries of high risk of wood dust exposure are sawmills, dimension mills, furniture industries, and carpenters, etc. Health effects associated with wood dust exposure includes dermatitis, allergic respiratory effects and cancer. Health effects of wood dus t are mainly depend on the concentration, dust size and exposure time. This study were carried out to evaluate the concentration and particle size distribution of wood dust during working processes. The subjects of this study were 53 workers exposed to wood dust in 7 furniture factories and 5 musical instruments, and 5 sawmill factories. The average total wood dust concentrations measured by personal cascade impactor were $1.82{\pm}2.31mg/m^3$ in primary manufacture, $3.59{\pm}1.72mg/m^3$ in s econdary manufacture, $5.09{\pm}1.46mg/m^3$ in sanding operation. Mass median diameters of hardwoods dust were $3.36{\mu}m$ in primary manufacture, $4.25{\mu}m$ in secondary manufacture, $4.21{\mu}m$ in sanding operation. softwoods dust were $3.39{\mu}m$ in primary manufacture, $4.34{\mu}m$ in secondary manufacture. Particle size distributions showed a nearly the same pattern in each working processes. The sample concentration of all hardwood dust exceeded the Threshold Limit Value(TLV) and 20.8% of the softwood dust exceeded the Threshold Limit Value. The range of size distribution were $0.5-10{\mu}m$ in the soft and hardwood dust. The respirable dust of soft and hardwood took up 59% and above. Therefore new threshold limit value for wood dust should be needed in Korea. Also, it should be done for various studies on health effects related to occupational exposure of wood dust.

• Journal of environmental and Sanitary engineering
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• v.14 no.4
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• pp.93-98
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• 1999

We had investigated combustion properties of rice bran dusts. Decomposition of rice bran dusts with temperature were investigated using DSC and the weight loss according to temperature using TGA in order to find the thermal hazard of rice bran dusts, and the properties of dust explosion in variation of their dust with the same particle size. Using Hartman's dust explosion apparatus which estimate dust explosion by electric ignition after making dust disperse by compressed air, dust explosion experiments have been conducted by varying concentration and size of rice bran dust.According to the results for thermodynamic stability of rice bran dust, there are little change of initiation temperature of heat generation and heating value for used particle size. But initiation temperature of heat generation decreased with high heating rate whereas decomposition heat increased with particle size. Average maximum explosion pressure was $10kgf/cm^2$ for 60/70 mesh and $1.5mg/cm^2$ dust concentration.

• Particle and aerosol research
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• v.5 no.2
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• pp.63-70
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• 2009

The size distribution and number concentration of atmospheric aerosol were measured and compared using APS 3321 and Dust Monitor 1.108. The particle size distribution and number concentration measured by two devices were also compared at a particle generation system of standard PSL and fly ash. The number concentration of atmospheric aerosol measured by APS was higher than that by Dust Monitor in particle size range of less than $3.0{\mu}m$, but there was good accordance between them in particle size range of over $3.0{\mu}m$. In the particle generation system of PSL and fly ash, different measurement results were shown because the particle concentration was higher than that of atmospheric aerosol. The number concentration measured by Dust Monitor was higher than that by APS in most particle size ranges. However, the peak concentration of PSL particles measured by Dust Monitor was lower than that by APS. The difference of the collection efficiency in a scrubber by APS and Dust Monitor measurement was less than 10%, but in the particle size of $1.5{\mu}m$, it was over 20%.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.30 no.1
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• pp.10-17
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• 2020

Objectives: This study was performed to evaluate the total dust, size-selective dust, and heavy metal concentrations generated inside and outside toll booths on an expressway and to identify the source through analysis of the components of the deposited dust. Methods: A total of 32 samples were collected from eight expressway toll booths. Each total dust sample was collected using a 37 mm PVC filter attached to a personal air sampler. Heavy metal samples were collected according to NIOSH method 7300. The size-selective dust concentrations were identified using a DustMate, and deposited dust was analyzed by WD-XRF and UHR-FE-SEM. Results: The geometric mean concentrations of the total dust inside and outside the toll booths were 337.5 ㎍/㎥ and 342.7 ㎍/㎥, respectively. The overall concentrations of TSP, PM₁₀, PM_2.5, and PM1 were higher on the outside of the toll booths, as the particle size of dust was larger, and higher in the underground passage as the dust size was smaller. The real-time analysis of the dust concentrations of TSP, PM₁₀, PM_2.5, and PM1 revealed to be higher at morning and evening times than other times because of heavy traffic. The element components of deposited dust in the toll booth were related to natural sources rather than artificial sources. Among the chemical components in the deposited dust analyzed by WD-XRF, SiO₂ was the highest. For the elements analyzed by UHR-FE-SEM, C was the highest, followed by O, and Si. Conclusions: In order to reduce the dust concentrations around toll booths on an expressway, it is necessary to periodically clean surrounding areas such as underground passages, and it is also necessary to remove deposited dust inside the toll booth from time to time.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.5 no.2
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• pp.212-225
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• 1995

This study was performed in a diatomite factory located at Pohang City, Kyeongsangbuk-Do. The major objectives were to evaluate sampling and analytical methods of diatomaceous earth dust. Concentrations of total and respirable diatomaceous earth dust were measured. Size distribution of dust was analyzed by a personal cascade impactor and the particle size analyzer which is an application of multiple diffraction method. Also crystalline silica in respirable and total dust samples was analyzed quantitatively by X-ray diffraction and Fourie Transform Infrared Spectroscopy(FTIR). The results were as follows: The airborne total and respirable dust concentrations, particle size distribution, and cristalline silica(quartz) concentrations showed approximately a log-normal distribution. The means of totaldust concentrations at flour maufacturing, fire brick grinding and packaging processes exceeded the Korean and American Conference of Governmental Industrial Hygienists standards, $10mg/m^3$. The size distribution of diatomaceous earth dust was log-normal and identified as the rspirable particle mass and thoracic particle mass. The crystalline silica in respirable and total dust samples was identified to quartz and contained about 10 % in those samples. Finally, it is necessary to study the applicability of multiple diffraction for particle size distribution to compare the ACGIH's size selective sampling with other materials containing crystalline silica. Also, advanced quantitative study to X-ray diffraction and FTIR methods shoud be carried out 10 verify general and specific characteristics for respirable crystalline silica.

• Analytical Science and Technology
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• v.25 no.6
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• pp.476-482
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• 2012

Asian dust particles are known to have sizes ranging from a few nanometers up to about a few micrometers. The environmental and health effects depend on the size of the dust particles. The smaller, the farther they are transported, and the deeper they penetrate into the human respiratory system. Sedimentation field-flow fractionation (SdFFF) provides separation of nano to microparticles using a combination of centrifugal force and parabolic laminar flow in a channel. In this study, the steric mode of SdFFF (Sd/StFFF) was tested for size-based separation and characterization of Asian dust particles. Various SdFFF experimental parameters including flow rate, stop-flow time and field strength of the centrifugal field were optimized for the size analysis of Asian dust. The Sd/StFFF calibration curve showed a good linearity with $R^2$ value of 0.9983, and results showed an excellent capability of Sd/StFFF for a size-based separation of micron-sized particles.The optical microscopy (OM) was also used to study the size and the shape of the dust particles. The size distributions of the samples collected during a thick dust period were shifted towards larger sizes than those of the samples collected during thin dust periods. It was also observed that size distribution of the sample collected during dry period shifts further towards larger sizes than that of the samples collected during raining period, suggesting the sizes of the dust particle decrease during raining periods as the components adsorbed on the surface of the dust particles were removed by the rain water. Results show Sd/StFFFis a useful tool for size characterization of environmental particles such as the Asian dust.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.21 no.5
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• pp.40-45
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• 2022

In recent years, indoor air pollution has become a crucial environmental problem. Hence, the purification of indoor air is an important issue. Typical physical filters show relatively high dust collection efficiency at a dust particle size of more than 5.0 ㎛ but extremely low efficiency at an ultrafine size of less than 2.5 ㎛. In this study, an electric field filter was proposed to capture ultrafine dust with a size of less than 5.0 ㎛. Simulation results showed that the electric field filter effectively removed ultrafine dust. In addition, sufficient dust collection efficiency was obtained even with a simple plate-shaped filter without bending the Chevron filter.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.24 no.4
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• pp.462-470
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• 2014

Objectives: The purpose of this study was to evaluate quartz concentrations in airborne respirable dust and particle size-related quartz concentrations. Methods: Respirable dust samples were collected using a 10 mm Dorr-Oliver nylon cyclone equipped with a 37 mm, $5{\mu}m$ pore size PVC filter. Dust samples were collected with a Marple's personal cascade impactor from stone grinding operations in five stone-related business located in the Gyeongsangbuk-do area. Results: The geometric mean of quartz concentration in the respirable dust was $0.170mg/m^3$, and the rate of exceeding the Korean Occupational Exposure Limit(KOEL) was 93.3%. The quartz concentration by particle size shows that it was the highest($0.115mg/m^3$) in stage 5($3.50-6.00{\mu}m$), which corresponds with the size of respirable particle. The smaller the particle sizes were, the higher quartz the content became. The mass fractions of inhalable, thoracic, and respirable dust were 72.1%, 36.0%, and 14.4%. Conclusions: The rate of the quartz concentration in respirable dust from stone grinding operations exceeding the American Conference of Governmental Industrial Hygienists Threshold Limit Values was 100%, which means proper work environmental management is required through regular working environmental measurements. Given that the stone grinding operations had a higher small size dust concentrations, there is a need to reduce respirable dust, such as through wet operation and local exhaust ventilation.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2002.04a
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• pp.159-160
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• 2002

Soil dust particles transported from loess regions of the Asian continent, called Asian dust, highly influences the air quality of north-eastern Asia and the northern Pacific Ocean. The effects of these dust storms, on the chemical composition of atmospheric aerosol particles with different size, was investigated. Measurements of size distributions of total aerosol and major ion species were carried out on Jeju Island, Korea. (omitted)