• Resources Recycling
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• v.21 no.3
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• pp.21-27
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• 2012

In order to make high-purity ferro-manganese from $Mn_3O_4$ dust, the application of aluminothermy process to the reduction of $Mn_3O_4$ dust was investigated in previous work. The result showed the fact that can be obtained high purity ferro-manganese which have over about 93% of manganese content and lower impurities such as C, P, S than those of KS D3712 specification. The addition of silicon powder instead of aluminum powder was investigated as reductant in the thermite reaction process of $Mn_3O_4$ dust in this work because its production cost is lower than that of aluminum powder. In case of addition of silicon powder only as reductant, the experimental result showed the unstable ignition and no thermite reaction of mixture, but in case of simultaneous addition of silicon and aluminum powders as reductant, showed the fact that can be obtained high purity ferro-manganese which have much low content of impurities such as C, P, S component.

• Explosives and Blasting
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• v.36 no.4
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• pp.48-61
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• 2018

This case study is concerned with the project of the explosive demolition for the KOGAS office building located in Bundang district in Seongnam city. Since the office building was a kind of long-span beam structures, a mechanical demolition method using jacking support systems was considered in the beginning of the project. With consideration of the excessive reinforcement cost, uncertainty of safety, and prolonged construction period, however, the original plan was later changed to use an explosive demolition method. For the purpose of protecting nearby buildings and facilities during the collapse process, the explosive initiation sequence was elaborately designed to bring down the building structure towards its front left corner. A total of over 550 electronic detonators (Unitronic 600) was used to sequentially initiate the explosives installed at appropriate columns in the first, second, and fifth floors. To diminish dust production, water bags of small and large sizes were respectively installed at each column and on the floors to be blasted. As such, every effort was exercised to mitigate overall noise, dust, and shock vibrations that could be generated during the explosive demolition process for the office building.

• Land and Housing Review
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• v.12 no.3
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• pp.39-50
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• 2021

This research aims to provide guidelines with the appropriate type of smart bus stop to reduce the concentration of fine dust. To this end, we divided smart bus stops into two types: closed and open bus stops. The estimated reduction effect was compared and analysed by measuring the estimated PM₁₀ and the estimated PM_2.5 at five locations inside and outside a smart bus stop located in Gangnam gu, Seoul. The effect of reducing the amount of the fine dust concentration in external space was insignificant for both types of bus stops. The different effect of reducing the concentration of the amount between in internal space was relatively significant: the fine dust concentration was 26.0 ㎍/m³ for PM₁₀ and 20.2 ㎍/m³ for PM_2.5 at open-type bus stops; whilst was 2.4 ㎍/m³ for PM₁₀ and 1.8 ㎍/m³ for PM_2.5 at closed type bus stops. Based on the findings, a closed type bus stop is recommended when considering the cost of reducing fine dust. In addition, due to the ineffectiveness of reducing the amount of fine dust from the outside of the bus stop, additional provision of smart bus stops is required particularly in locations where demand exceeds the capacity of the inside. A clear definition of smart bus stop and it's minimum standard should also be considered.

• Electronics and Telecommunications Trends
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• v.34 no.2
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• pp.83-91
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• 2019

In this article, we introduce examples and technologies relating to particulate matter (PM) reduction technology, for the purpose of reducing PM that harms health and affects the entire industry such as dust-sensitive semiconductor industry. First, the definition of PM and how it is generated is explained, including its effects on the human body. In addition, various methods for measuring PM are described, including examples of the restrictions on the operation of polluting vehicles and emission reduction devices. Finally, we describe techniques relating to the reduction and forecasting of PM.

• Resources Recycling
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• v.2 no.4
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• pp.27-32
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• 1993

A process has been studied to recover gallium from steelmaking dust which had several hundreds ppm of gallium. Aqueous solution containing 38 mg/l gallium was obtained by leaching of dust with 2.25 mol/l sulfuric acid. The leach liquor contained iron and zinc about 1,000 times greater than gallium. Gallium was then concentrated by ion exchanger of chelating resin with functional group of amino carboxylic acid after reduction of ferric ion to ferrous ion and pH adjustment. Gallium was concentrated to be 13 g/l in the resulting eluate by double ion exchanges. The liquor was further treated to remove impurities by solvent extraction technique empolying TOMAC as extractant. The galluim with 99% purity was finally obtainable.

• 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.

• Korean Journal of Environment and Ecology
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• v.38 no.2
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• pp.217-226
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• 2024

This study aimed to investigate the influence of anions in the air on the purification of fine dust (PM10 and PM2.5) and to evaluate the effects of plants on the generation of anions in the air and the purification of fine dust. Subsequently, the fine dust reduction models were compared according to each factor and plant volume. The characteristics of anion generation by each factor were observed to be in the order of Type N.I (negative ion generator; 204,133.33 ea/cm³) > Type P₃₀ (plant vol. 30%; 362.55 ea/cm³) > Type C (control; 46.22 ea/cm³), indicating that the amount of anion generation in the anion generator treatment group and the plant arrangement group were approximately 4,417 times and 7 times higher, respectively, than that in the untreated group. Consequently, the fine dust reduction characteristics by anion generation source showed that for PM10, Type NI had a purification efficiency 2.52 times higher than Type C, and Type P₃₀ was 1.46 times higher, while for PM2.5, Type NI had a purification efficiency 2.26 times higher than Type C, and Type P₃₀ was 1.31 times higher. The efficiency of fine dust purification by plant volume was in the order of Type P₂₀ (84.60 minutes) > Type P₃₀ (106.50 minutes) = Type P₂₅ (115.50 minutes) = Type P₁₅ (117.60 minutes) > Type P₅ (125.25 minutes) = Type P₁₀ (129.75 minutes), and for ultrafine dust, Type P₂₀ (104.00 minutes) > Type P₃₀ (133.20 minutes) = Type P₂₅ (144.00 minutes) = Type P₁₅ (147.60 minutes) > Type P₅ (161.25 minutes) = Type P₁₀ (168.00 minutes). Thus, a quantitative analysis of the anions and plants for purifying fine dust and suggested matters to be considered for future green space planning and plant planting considering fine dust purification.

• Advances in concrete construction
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• v.11 no.3
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• pp.207-217
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• 2021

This study relates to a production of Quaternary Cement Concrete (QCC) prepared by using Micro Silica (MS), Marble Dust (MD) and Rice Husk Ash (RHA), followed by an investigation towards fresh and hardened properties of blended concrete. A total of 39 mixes were cast by incorporating different percentages of MS (6%, 7% and 8%), MD (5%, 10% and 15%) and RHA (5%, 10%, 15% and 20%) as partial replacement of Ordinary Portland Cement. The workability of fresh concrete was maintained in the range of 100±25 mm by adding 0.7% of Super Plasticizer in the mix. Optimum mechanical strength was observed at combination of 8% MS+5% MD+10% RHA. Marble dust replacement from 10 to 15% and Rice husk ash replacements from 15 to 20% depicted a substantial reduction in compressive strength at all ages. Durability parameter with respect to water absorption at 28 days shows an increasing trend as the percentage of blending increases.

• Journal of Platform Technology
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• v.11 no.6
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• pp.28-33
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• 2023

With the development of the beauty industry, the nail art industry is expanding, and through this, nail culture is becoming more popular. However, some products used in the nail art field may produce harmful substances, so great caution is required. In this paper, an air purification system was designed to reduce harmful air. The air purification system uses a harmful gas sensor to measure the level of pollution in the surrounding air and then turns the fan on/off to remove harmful gases and fine dust. Two types of filters and two fans can be driven and controlled respectively so that harmful gases are absorbed into the charcoal filter and fine dust is absorbed into the HEPA filter. In addition, filters, fans, and piping were appropriately placed to remove contaminated surrounding air as quickly as possible during nail procedures.

• Korean Journal of Remote Sensing
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• v.25 no.1
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• pp.45-59
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• 2009

This research presents the effect of Asian dust on the derived sea surface temperature (SST) from measurements of the Advanced Very High Resolution Radiometer (AVHRR) instrument flown onboard NOAA polar orbiting satellites. To analyze the effect, A VHRR infrared brightness temperature (TB) is estimated from simulated radiance calculated from radiative transfer model on various atmospheric conditions. Vertical profiles of temperature, pressure, and humidity from radiosonde observation are used to build up the East Asian atmospheric conditions in spring. Aerosol optical thickness (AOT) and size distribution are derived from skyradiation measurements to be used as inputs to the radiative transfer model. The simulation results show that single channel TB at window region is depressed under the Asian dust condition. The magnitude of depression is about 2K at nadir under moderate aerosol loading, but the magnitude reaches up to 4K at slant path. The dual channel difference (DCD) in spilt window region is also reduced under the Asian dust condition, but the reduction of DCD is much smaller than that shown in single channel TB simulation. Owing to the depression of TB, SST has cold bias. In addition, the effect of AOT on SST is amplified at large satellite zenith angle (SZA), resulting in high variance in derived SSTs. The SST depression due to the presence of Asian dust can be expressed as a linear function of AOT and SZA. On the basis of this relationship, the effect of Asian dust on the SST retrieval from the conventional daytime multi-channel SST algorithm can be derived as a function of AOT and SZA.