• Structural Engineering and Mechanics
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• v.8 no.3
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• pp.273-283
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• 1999

Two physical experiments are performed to verify the effectiveness of beam-particle model for simulating the progressive failure of particulate composites such as sandstone and concrete. In the numerical model, the material is schematized at the meso-level as an assembly of discrete, interacting particles which are linked through a network of brittle breaking beams. The uniaxial compressive tests of cubic and parallelepipedal specimens made of carbon steel rod assembly which are glued together by a mixture are represented. The crack patterns and load-displacement response observed in the experiments are in good agreement with the numerical results. In the application respect of beam-particle model to the particulate composites, the influence of defects, particle arrangement and boundary conditions on crack propagation is approached, and the correlation existing between the cracking evolution and the level of loads imposed on the specimen is characterized by fractal dimensions.

• Korean Journal of Remote Sensing
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• v.27 no.2
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• pp.107-120
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• 2011

Several MODIS AQUA products have been compared with shipboard data to assess the possibility of using remote sensing to estimate particulate organic carbon (POC) concentration in the surface waters of the East Sea. A total of 30 POC profiles obtained in spring and summer seasons of the years of 2006~2010 were compared with remote sensing reflectance at various wavelengths and diffuse attenuation coefficient at 490 nm observed by MODIS AQUA. The algorithm thus established was $POC=266.85^*[R_{rs}(488)/R_{rs}(555)]^{-1.447}$ ($R^2=0.924$) with root mean square error of 20.9 mg $m^{-3}$. Remotely sensed POC contents derived using our algorithm appeared also not to be affected by the presence of non-POC component in suspended particulate matter. Therefore this algorithm could be applied to obtain POC concentration over the East Sea using MODIS Aqua observation.

• Journal of environmental and Sanitary engineering
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• v.17 no.3
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• pp.67-74
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• 2002

Nowadays, a new word called SBS(sick building syndrome) has been come into existence. Since most people spend a large majority of their time indoors, indoor air may affect human health more than outdoor air. This outline survey was carried out to investigate the extent of indoor air pollution in singing room and PC room. The concentrations of major indoor air pollutants(carbon dioxide, total suspended particulate, airborne microbes) and Thermocircumstance(temperature, relative humidity, intensity of illumination) were observed from October 1 to 31, 2001. As results of the survey, the mom values of thermocircumstance in singing room and PC room were $22.1^{\circ}C$ of temperature, 37.1% of humidity, 75 Lux of intensity of illumination and $22.0^{\circ}C$ of temperature, 52.6% of humidity, 135 Lux of intensity of illumination, respectively. The mean concentrations of carbon dioxide were 1589 ppm in singing room and 615 ppm in PC room, respectively The concentrations of carbon dioxide in singing room were higher than the indoor environmental standard of the first clause of Article 45 of public utilization service which is showed at public hygiene of the Ministry of Health and Social Affairs. The mean concentrations of total suspended particulate were $0.33{\;}mg/\textrm{m}^3$ in singing room and $0.57{\;}mg/\textrm{m}^3$ in PC room respectively. The mean concentrations of airborne microbe were $16{\;}CFU/\textrm{m}^3$ in singing room and $12{\;}CFU/\textrm{m}^3$ in PC room, respectively.

• Journal of the Korean Society for Marine Environment & Energy
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• v.5 no.4
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• pp.48-56
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• 2002

It was peformed to estimate the sensitivity analyses and mass balance for tributyltin in Masan Bay, using the model builded by stella program. The results of the sensitivity analysis for dissolved tributyltin and tributyltin in the particulate organic carbon showed that not only organic carbon partition coefficient but also settling rate is important. In the case of tributyltin in phytoplankton, bioconcentration factor of phytoplankton is most important. The results of the mass balance showed that standing stocks of tributyltin in water, in phytoplankton and in particulate organic carbon are 3.29×10⁴g, 1.16×10²g and 3.17×10³g, respectively. In the case of flux, partition to particulate organic carbon showed most high value, 1.64×10³g/4ay, and next were deposition to sediment, 1.64×10³g/day and transportation to open sea by tide, 1.64×10³g/day.

• Journal of the Korean Society of Tobacco Science
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• v.20 no.1
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• pp.124-130
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• 1998

This study was conducted to evaluate the ability of anion generating air cleaner to remove gases, vapor and particles from closed room contaminated with environmental tobacco smoke (ETS). The measurements covered particle sizes of 13.8-542.5nm, particle concentration, surface area, volumes UVPM, FPM, solanesol, and the following gases and vapor; carbon dioxide, carbon monoxide, nicotine, and 3-ethenylpyridine. Tobacco smoke was generated and mixed in a closed room in which the airflow rates were in the range of 0.00-0.04 m/s. The anion generating air cleaner was startedl and the decay rates for the gases, vapor and particles were measured, When the use of anion generating air cleaner, solid components of ETS, such as respirable suspended particle (RSP), utraviolet particulate matter (UVPM, fluorescent particulate matter (FPM) and solanesol was sharply decreased, and vapor phase components of ETS, such as nicotines 3-ethenylpyidine were modelately decreased by time elapse. Even the use of anion generation air cleaner, the decreasing rate of carbon dioxide concentration was similar with control, and the decreasing rate of carbon monoxide was slower than that of control. Our results indicated that the use of anion generting air cleaner had an effect on reduction of solid and vapor components from ETs, but it had no effect on gaseous components of ETS.

• Journal of the Korean Society for Marine Environment & Energy
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• v.9 no.3
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• pp.131-140
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• 2006

Suspended particulate matter and organic carbon were measured in the Mankyoung river estuary in February, May, July and August 2003. There was a large variance in river discharge between the dry season of February and May and the wet season of July and August. The influx of dissolved organic carbon into the estuary was $8.16{\times}10^2tonC\;month^{-1}$ in the dry season and $5.77{\times}10^3tonC\;month^{-1}$ in the wet season. The influx of particulate organic carbon was $9.37{\times}10^2tonC\;month^{-1}$ and $3.14{\times}10^4tonC\;month^{-1}$ in the dry and wet seasons, respectively. Especially, dissolved organic carbon in the northern part of the site inside the dike was increased in July when torrential rainfall was high. In the research, the distribution of dissolved organic carbon showed conservative behavior with the salinity gradient in the estuary, suggesting that physical mixing between seawater and freshwater dominates the distribution pattern of the dissolved organic carbon in the system. However 60 to 90% of the particulate organic carbon introduced into the estuary was removed from the surface water at the upper estuarine mixing zone of low salinities, showing non-conservative behavior similar with suspended particulate matte r. The completion of the Saemangum Dike is likely to inhibit the exchange of materials between open sea and the Mankyoung estuary. This suggests that the oxidation of organic carbon in the bottom of the estuary may exhaust dissolved oxygen in the confined environment.

• Journal of Korean Society for Atmospheric Environment
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• v.19 no.E3
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• pp.99-120
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• 2003

Visibility impairment in an urban area is mainly caused by airborne fine particulate matters. Visibility in a clean air environment is more sensitive to the change of PM$_{2.5}$ particle concentrations. However, a proportionally larger reduction in fine particle concentration is needed to achieve a small increment of visibility improvement in polluted areas. Continuous optical monitoring of atmospheric visibility and extensive aerosol measurements have been made in the urban atmosphere of Kwangju, Korea. The mean for fine particulate mass from 1999 to 2002 at Kwangju was measured to be 23.6$\pm$20.3 $\mu\textrm{g}$/㎥. The daily average seasonal visual range was measured to be 13.1, 9.2, 11.0, and 13.9 km in spring, summer, fall, and winter, respectively. The mean light extinction budgets by sulfate, nitrate, organic carbon, and elemental carbon aerosol were observed to be 27, 14, 22, and 12%, respectively. It is highly recommended that a new visibility standard and/or a fine particle standard be established in order to protect the health and welfare of general public. Much more work needs to be done in visibility studies, including long-term monitoring of visibility, improvement of visibility models, and formulating integrated strategies for managing fine particles to mitigate the visibility impairment and climate change.e.

• Environmental Engineering Research
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• v.23 no.3
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• pp.265-270
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• 2018

This study was to measure the exposure of diesel vehicle drivers to elemental carbon (EC) as an indicator of diesel particulate matter (DPM) emitted from diesel vehicles in an underground coal mine over 3 years as per NIOSH Method 5040. Our study results (range $10{\mu}g/m^3-377{\mu}g/m^3$ for the loader drivers, $19{\mu}g/m^3-162{\mu}g/m^3$ for the SMV drivers) were similar or less than previous study results (range $5{\mu}g/m^3-2,200{\mu}g/m^3$) for normal mine operations. From this study results, it appeared that the exposures decreased in the second and the third year. It is thought that the reasons for the decreased personal DPM (EC) exposures over the 3 years were related to the following recommendations; more frequent monitoring and maintenance of the diesel vehicles and their DPM filtration systems, more consistent monitoring of the mine's ventilation system and changes of work practices such as minimizing the opening of diesel vehicle windows. An educational program on adverse health effects of exposure to DPM and use of respiratory protection (P2 respirators) also assisted in minimizing driver exposure to DPM.

• Journal of the Korean Society of Safety
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• v.35 no.6
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• pp.9-14
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• 2020

This study was to compare the sampling efficiencies for monitoring of diesel particulate matter (DPM) using two different sampling methods; In-House PVC cyclone sampling heads and commercial airborne DPM (EC) sampling heads mounted on Dorr-Oliver cyclone heads. Personal exposure levels of DPM, analysed for elemental carbon (EC) were 0.004 - 0.2 mg/m³ for the loader drivers and 0.005 - 0.34 mg/m³ for the specialised mining vehicle (SMV) drivers were similar to previous study results. The highest result (0.34 mg/m³) might be from an irregular production schedule and multiple job tasks requested. The results using the two sampling heads were not significantly different and it is thought that the In-House PVC cyclone with 37 mm quartz filter could be used in place of the commercial sampler as a preliminary screen in place of using the commercial sampler.

• Journal of the Korean Society of Tobacco Science
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• v.21 no.1
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• pp.102-108
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• 1999

This study was conducted to evaluate the ventilation to remove gases, vapor and particles of environmental tobacco smoke(ETS) in a closed room. The ventilation rate choosed were 0.445 ㎥/min, 0.528 ㎥/min, and 0.625 ㎥/min. ETS components measured were total suspended particle(TSP), ultraviolet particulate matter(UVPM), fluorescent particulate matter(FPM), solanesol, carbon dioxide($CO_2$), carbon monoxide(CO), nicotine, and 3-ethenylpyri-dine(3-EP). The concentration of ETS components measured rapidly decreased as increasing ventilation rate, but the removal efficiency by ventilation was different from each ETS compounds. The $CO_2$, and CO, gaseous components of ETS, were dominant components to be removed from the room by ventilation. The ventilation with 0.528 ㎥/min for 1 hr was enough to remove over 99% of those gaseous components. Nicotine and 3-EP needed the ventilation for 2 hrs to reduce over 95 % of those components. As the same ventilation rate, 99 % of TSP and solanesol concentration were removed from the room within 2 hrs, UVPM and FPM concentration decreased 90 %.