• Particle and aerosol research
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• v.14 no.3
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• pp.73-80
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• 2018

Recently, there has been much research on the effect of ultrafine dust on human body with increasing interest in the ultrafine dust. In the Republic of Korea, there are many old thermal power plants, and the amount of ultrafine dust emitted from the thermal power plants is reported to be about 14% of the total amount of domestic fine dust. Therefore, the amount of fine dust from the flue gas desulfurization facility in the thermal power plant needs be reduced. In this study, we made an experimental setup to simulate a flue gas desulfurization facility and analyzed the physical characteristics of the particles passing through a mist eliminator. Experiments were carried out to investigate the collection efficiency of the mist eliminator by using the Arizona Test Dust in a dry environment, and then spraying limestone slurry into the flue gas desulfurization system equipped with the mist eliminator to examine the size and morphology of limestone particles upstream and downstream of the mist eliminator. Cut-off size of the mist eliminator was formed at about $6{\mu}m$. The result of this study is expected to be helpful for designing an electrostatic precipitator for removing particles passing through the mist eliminator.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.98.1-98.1
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• 2012

We present the results of dust scattering simulations carried out for the Orion-Eridanus Superbubble region by comparing them with observations made in the far-ultraviolet. The albedo and the phase function asymmetry factor (g-factor) of interstellar grains were estimated, as were the distance and thickness of the dust layers. The results are as follows: [0.43]_(-0.04)^(+0.02) for the albedo and [0.43]_(-0.2)^(+0.2) for the g-factor, in good agreement with previous determinations and theoretical predictions. The distance of the assumed single dust layer, modeled for the Orion Molecular Cloud Complex, was estimated to be ~110 pc, and the thickness ranged from ~130 at the core to ~50 pc at the boundary for the region of present interest, implying that the dust cloud is located in front of the superbubble. The simulation result also indicates that a thin (~10 pc) dust shell surrounds the inner X-ray cavities of hot gas at a distance of ~70-90 pc.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.1
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• pp.73.1-73.1
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• 2012

We present the results of dust scattering simulations carried out for the Orion Eridanus Superbubble region by comparing them with observations made in the far-ultraviolet. The albedo and the phase function asymmetry factor (g-factor) of interstellar grains were estimated as well as the distance and thickness of the dust layers. The results are: 0.39-0.45 for the albedo and 0.25-0.65 for the g-factor, in good agreement with previous determinations and theoretical predictions. The distance of the assumed single dust layer, modeled for the Orion Molecular Cloud Complex, was estimated to be -110 pc and the thickness ranged from -130 at the core to -50 pc at the boundary for the region of the present interest, implying that the dust cloud is located in front of the Superbubble. The simulation result also indicates that a thin (-10 pc) dust shell surrounds the inner X-ray cavities of hot gas at a distance of -70-90 pc.

• Journal of the Korean Society of Safety
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• v.30 no.4
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• pp.20-25
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• 2015

In general, the causes of the electrical fire are overcurrent, short circuit, poor contact, etc. This study is aimed to recognize the risk of electric arc to prevent electrical fires due to the conductive dust accumulated on the circuit breaker. The experiment was carried out by the method that conductive metal dust collected from the field is being accumulated on the experimental electrodes with gap of 13 mm until the arc is generated. In case that arc was generated, the amount of conductive dust was measured and the thickness was calculated. This experiments was conducted by particle size. In order to distinguish particle size, mesh size(60~100, 100~150, 150~200, 200~250mesh) was classified using a sieve. As the results of experiment for each of the particle sizes, it was confirmed that there is differences in the generation of arc depending on the thickness of dust accumulated.

• Environmental Engineering Research
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• v.25 no.3
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• pp.409-417
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• 2020

Investigation was carried out to assess the effect of cement dust deposition on the physico-chemical properties of soil near some cement plants in Jaintia Hills, Meghalaya. Soil samples were collected and analysed and compared with the control site. Comparison of various soil physico-chemical parameters revealed that cement dust emanating from cement plants has changed the soil quality in the surrounding areas of cement plants. The normal soil pH in the area is generally acidic. However, due to the continuous deposition of cement dust soil pH was found slightly alkaline near the cement plants. The higher values of soil parameters such as electrical conductivity and bulk density were also noticed near the cement plants. However, lower values of water holding capacity, soil moisture content, soil organic carbon and total nitrogen content were found compared to the control sites. The effect of cement dust deposition on soil is more in areas nearer to the cement plants. At present the changes may not be so serious but if this trend continues, soil properties of a vast area around the cement plants are likely to change leading to multiple effects on flora, fauna and socio-economy of the area.

• Structural Engineering and Mechanics
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• v.65 no.2
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• pp.203-211
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• 2018

This paper introduces the development process of NCC(New Concrete Cutting) system and analyzes first verification test. Based on the first verification test results, some problems of NCC system have been newly modified. We carry out the second verification test. We tried to verify cutting performance and dust control efficiency of NCC system through the cutting test of concrete bridge piers. In particular, this verification test strives to solve the problem of concrete dust, which is the biggest problem of dry cutting method. The remaining dust problems in cutting section tried to solve through this verification test. This verification test of the NCC system shows that the dust problem of dry cutting method is closely controlled and solved. In conclusion, the proposed NCC method is superior to the dry cutting method in all aspects, including cutting performance, dust vacuum efficiency and cooling effect. The proposed NCC system is believed to be able to provide eco-friendly cutting technology to various industries, such as the removal of the SOC structures and the dismantling of nuclear plants, which have recently become a hot issue in the field of concrete cutting.

• Magazine of the Korea Concrete Institute
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• v.7 no.3
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• pp.149-155
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• 1995

An experimental study was carried out to investigate the strength implovlng effect of stone dust in no fines concrete. The cement aggregate ratios of 1:6, 1:8 and 1:10 and several water-cemment ratios between 30% and 56% were chosen for the mix design of no-fines concrete. For the no-fines concrete with stone dust, the weight ratio of cement to stone dust 1:1 was adopted and super plasticizer, 1.5% of cement in weight, was used to obtain proper and workable state of concrete. The compressive and tensile strength test were performed and the results for the different mix designs were compared with each other. The results show that the compressive strength of no-fines concrete can be improved by 38% and the tensile strength by 17%~72% for the same w/c, when the same weight of stone dust as cement is mixed together.

• Journal of Environmental Health Sciences
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• v.13 no.2
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• pp.25-33
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• 1987

This study was carried out to evaluate student exposures to dust in classroom of middle schools. A total of four schools, such as two in an urban and two in a rural area, were selected for this study. In this study, airborne dust concentrations were measured during a period from July 8 to July 18, 1986. Additional measurements of dust concentrations were conducted from November 4 to 7, 1986 to compare the results by seasonal variation. The results of this study were as follows. 1. Respirable dust concentrations were measured by both filtration method (C mg/m$^3$) and Digital Aerosol Monitor (cpm) to calculate anexchange factor K. K- value was 0.159 as follows. $K=\frac{c}{cpm} = \frac{2.71}{17.09} = 0.159$ 2. In summer when windows were opened, the concentrations of airborne respirable dusts measured by filter sampling method were 0.54-1.37 mg/m$^3$ in the morning and 0.79-1.75 mg/m$^3$ in the afternoon. Thus, higher levels were indicated in the afternoon. Meanwhile, the concentrations of airborne respirable dusts measured in winter were approximately twice as high as those in summer. 3. The highest dust concentrations were determined in School D which is a coeducational school with classroom of concrete floor. Walking roads in School D were not paved and students did not wear indoor-shoes. Dust levels in School D were approximately twice as high as levels in School B. All of the measured dust levels in four schools exceeded Korean Standard for outdoor air, 0.3 mg/m$^3$ for 24 hours. Results by Digital Aerosol Monitor indicated that there was no significant difference in dust levels among grades. The concentration of airborne dusts in the classroom was 1.5-3.0 times higher than that in the hall way. The concentration of airborne dusts during recess was 1.3-1.6 times higher than that during class. In winter, the dust concentrations during clean-up exceeded the permissible exposure limit, 10 mg/m$^3$ (as total dusts), for occupational exposures. 4. The concentrations of total dusts measured in winter were 1.5-2.4 times higher than those of respirable dusts measured simultaneously.

• Korean Journal of Agricultural Science
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• v.50 no.4
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• pp.917-925
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• 2023

Efforts for developing the domestic horse industry in South Korea are evident through the various national policies. Proper management of stables for ensuring the health of horses is essential to sustain the growing equine industry. This study aimed to measure the fine dust emissions in stables based on the type and quantity of bedding used for horses, for establishing guidelines pertaining to bedding use in stables. The stables accommodated 12 horses. Sawdust, wood shavings, wood pellet, and straw were chosen as treatments. Three different quantities (approximately 3, 6, and 9 cm in height) were applied for each type. Fine dust measurements were carried out at three time points, with each measuring period lasting for approximately three weeks. Measurements included PM2.5 and PM10 fine dust levels. The initial analysis revealed that, sawdust with 9 cm bedding had the highest dust levels; approximately 54.6 ㎍/m³, for PM2.5 and 95.3 ㎍/m³, for PM10. Sawdust bedding at the highest quantity (9 cm) exhibited significantly higher initial fine dust emissions. These findings suggest that bedding materials with smaller particle size, such as sawdust and wood shavings, tend to produce finer dust. Initially, the fine dust emissions decreased in all bedding types and quantities, possibly due to the increased moisture content of bedding owing to horse manure production. However, emissions increased subsequently due to ammonia production.

• 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.