• Korean journal of applied entomology
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• v.10 no.2
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• pp.77-83
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• 1971

In order to find out the decomposing factors of Sumithion in mineral diluents, the physical and chemical properties of the diluents such as talcs, bentonites, diatomaceous earth and other clay minerals was studied in relation to the decomposition rate of Sumithion in dust formulations. The total base, moisture adsorption capacity, pH, specific surface, water contents, active $Fe^{++}$, ignition loss and cation exchange capacity were analysed as the properties of mineral diluents, and these properties were correlated with the stability of Sumithion in dust formulations. And in hope of finding out the main factors among those properties of diluents, the decomposed products of Sumithion in dust formulations prepared with standard Sumithion were separated by the methods of column chromatography and investigated by thin layer chromatography. The following results were otbained; 1. The total base, moisture adsorption capacity, specific surface, water contents, active $Fe^{++}$ and cation exchange capacity of mineral diluents were found to be highly effective on the rate of decomposition of Sumithion in dust formulations. 2. Decomposed products of Sumithion in dust formulations were found to be dimethylphosphorothionate, 3-methyl-4-nitro phenol and its derivatives. And one fraction was not dissolved in n-hexane and ethylether, but was soluble in methylalcohol and ethylalcohol. 3. The moat highly correlated properties of diluents with the decomposition rate of Sumithion in dust were found to be the total base and water contents. 4. In regard to the kind of diluents, it was found that the rate of decomposition of Sumithion in dust formulations was higher in order of bentonite, diatomaceous earth, kaolin and talc.

• Particle and aerosol research
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• v.5 no.4
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• pp.159-170
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• 2009

A depth filter medium was newly designed in order to achieve high collection of dust and low pressure drop in this work. Multilayer depth filter media consist of an upstream layer of highly porous structure which allows particles to pass through and to follow by one or more downstream layers to hold the particles inside the media. For each filter media, flat sheet and pleated module were made of newly developed depth filter media and filter media of commercial products. Commercial depth filter cartridge for gas turbine air intake cleaning were used as reference for filtration area and pleat geometry of pleated modules. This work attempts to evaluate and compare the newly developed depth filter medium and two commercial filter media in terms of filtration parameters such as air permeability, initial pressure drop, particle retention and pressure drop variation with dust loading. According to the close examination the newly developed depth filter showed better performance compared to the commercial depth filter media.

• Korean Journal of Remote Sensing
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• v.30 no.5
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• pp.597-605
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• 2014

The continuous observations for atmospheric aerosols were conducted during 3 years (2009 to 2011) by using Gwangju Institute of Science and Technology (GIST) multi-wavelength Raman lidar at Gwangju, Korea ($35.10^{\circ}N$, $126.53^{\circ}E$). The aerosol depolarization ratios calculated from lidar data were used to identify the Asian dust layer. The optical properties of Asian dust layer were different according to its vertical distribution. In order to investigate the difference between the optical properties of each individual dust layers, the transport pathway and the transport altitude of Asian dust were analyzed by Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model. We consider that the variation of optical properties were influenced not only their transport pathway but also their transport height when it passed over anthropogenic pollution source regions in China. The lower particle depolarization ratio values of $0.12{\pm}0.01$, higher lidar ratio of $67{\pm}9sr$ and $68{\pm}9sr$ at 355 nm and 532 nm, respectively, and higher ${\AA}ngstr\ddot{o}m$ exponent of $1.05{\pm}0.57$ which are considered as the optical properties of pollution were found. In contrast with this, the higher particle depolarization ratio values of $0.21{\pm}0.09$, lower lidar ratio of $48{\pm}5sr$ and $46{\pm}4sr$ at 355 nm and 532 nm, respectively, and lower ${\AA}ngstr\ddot{o}m$ exponent of $0.57{\pm}0.24$ which are considered as the optical properties of dust were found. We found that the degree of mixing of anthropogenic pollutant aerosols in mixed Asian dust govern the variation of optical properties of Asian dust and it depends on their altitude when it passed over the polluted regions over China.

• Journal of the Korean Ceramic Society
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• v.19 no.1
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• pp.44-50
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• 1982

Drawing optical fibers in a graphite furnace is one of the most convenient and economical means of producing optical fiber. Since the flaw formation on optical fiber is mainly due to dust contaminations during drawing and surface corrosion by water vapor penetration through coating layer, the tensile strength of optical fiber drawn in a graphite furnace is greatly inflenced by the drawing conditions. The important factors found in this investigation were preform treatment (fire polishing), furnace interior environment (dust contamination, inert gas flows), primary coating condition (resin curing temperature, coating materials, method, thickness) and fiber pulling condition (furnace temperature, drawing speed, pulling tension). The tensile strength at optimum drawing conditions turned out to be 5 ~ 6 GPa.

• Proceedings of the KSME Conference
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• 2000.04b
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• pp.740-745
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• 2000

Effects of porous fences on the wind erosion of sand particles from a triangular pile were investigated experimentally. The porous fence and sand pile were installed in a simulated atmospheric boundary layer. The mean velocity and turbulent intensity profiles measured at the sand pile location were well fitted to the atmospheric boundary layer over the open terrain. Particle motion was visualized to see the motion of windblown sand particles qualitatively. In addition, the threshold velocity were measured using a light sensitive video camera with varying the fence porosity ${\varepsilon}$. As a result, various types of particle motion were observed according to the fence porosity. The porous wind fence having porosity ${\varepsilon}=30%$ was revealed to have the maximum threshold velocity, indicating good shelter effect for abating windblown dust particles.

• Journal of Environmental Science International
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• v.23 no.2
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• pp.275-289
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• 2014

Asian dust (or yellow sand) occurring mainly in spring in East Asia is affected by the distribution of weather systems. This study was performed to investigate the characteristics of suspended particulate for Asian dust at Busan, Korea in 20 March 2010, which was one of the extreme case for the last 10 years. There was used the data of weather chart, satellite, automatic weather system (AWS), $PM_{10}$, laser particle counter (LPC), and backward trajectories model. In synoptically, the high pressure was located in the northwestern part and low pressure was located in the northeastern part of Korea. The strong westerly winds from surface to upper layer makes it possible to move air masses rapidly. Air masses passing through Gobi Desert in Mongolia and Inner Mongolia plateau covered the entire Korean peninsula. As the results of aerosol analysis, $PM_{10}$ concentration at Gudeok mountain in Busan was recorded $2,344{\mu}g/m^3$ in 2300 LST 20 March 2010 and their concentration was markedly increased at coarse mode particle. In surface condition, westerly wind about 3 ~ 5 m/s was dominant and small particles of $0.3{\sim}0.5{\mu}m$ were distributed on the whole. In heavy metal components analysis, the elements from the land was predominated.

• Journal of Power System Engineering
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• v.17 no.6
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• pp.63-72
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• 2013

The main purpose of this study is to analyze the collection characteristics of multi-layer multi-stage porous plate system with ionizer and dielectric-substance experimentally. The experiment is carried out to analyze the characteristics of pressure drop and collection efficiency for the present system with experimental parameters such as applied voltage, inlet velocity, stage number and inlet particle concentration, etc. In results, for multi-layer multi-stage porous plate system of inflow type, at 5 stage and $v_{in}$=2.58 m/s, the pressure drop becomes lower 15 $mmH_2O$ as 95 $mmH_2O$ than that of non-inflow type system. It is estimated that for the present system with ionizer and dielectric-substance, the collection efficiency represents 98.5% showing higher 5.2% comparing to that of multi-layer multi-stage porous plate system without ionizer and dielectric-substance at 5 stage, $v_{in}$=2.58 m/s and inlet concentration $3g/m^3$(fly ash).

• Journal of Bio-Environment Control
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• v.31 no.3
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• pp.163-169
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• 2022

This study was conducted to examine an alternative cultivating method that uses coir substrates in a hydroponically cultured system. Three treatment conditions were applied with one-layer substrate (10 cm height) with a coir chip and dust ratio of 5:5 (Treatment A), two-layer coir substrate (20 cm height) with a coir chip and dust ratio of 5:5 (Treatment B), one-layer coir substrate (15 cm height) with a coir chip and dust ratio of 7:3 (Treatment C). The control condition was a plastic container filled with a coir chip and dust ratio of 5:5. Various criteria were measured and compared between the treatments and the control. The yield of strawberry was smaller in the control than in the treatments. No significant difference in growth characteristic was found in the height treatments of the coir substrates. The net photosynthetic rate of the treatments was 14.68-15.76 µmol CO₂·m^-2·s^-1. This does not show a statistically significant difference. The root activity was better in treatment B and C than in treatment A and the control. The length and width of leaves were measured as 4.04-4.13 cm and 3.26-3.34 cm. These results are not statistically significant. The leaf length and width ratio was 1.27 in the control and 1.24 in the treatments. The findings show that no statistically significant benefit was found when utilizing coir substrates with different height treatments in the hydroponic culture system. However, the harvested fruit per plant weights 72.38 g in treatment A and 48.69 g in treatment C. The number of harvested fruit was least in treatment C in which a coir chip and dust ratio of 7:3 was applied. Therefore, further research is needed to examine how the chip and dust ratio in coir substrate affects growth characteristics.

• Journal of Environmental Science International
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• v.16 no.4
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• pp.449-458
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• 2007

Research results for the pressure drop variance depending on operation conditions such as change of inlet concentration, pulse interval, and face velocity, etc., in a pulse air jet-type bag filter show that while at $3kg/cm^2$ whose pulse pressure is low, it is good to make an pulse interval longer in order to form the first layer, it may not be applicable to industry because of a rapid increase in pressure. In addition, the change of inlet concentration contributes more to the increase of pressure drop than the pulse interval does. In order to reduce operation costs by minimizing filter drag of a filter bag at pulse pressure $5kg/cm^2$, the dust concentration should be minimized, and when the inlet dust loading is a lower concentration, the pulse interval in the operation should be less than 70 sec, but when inlet dust loading is a higher concentration, the pulse interval should be below 30 sec. In particular, in the case that inlet dust loading is a higher concentration, a high-pressure distribution is observed regardless of pulse pressure. This is because dust is accumulated continuously in the filter bag and makes it thicker as filtration time increases, and thus the pulse interval should be set to below 30 sec. If the equipment is operated at 1m/min of face velocity, while pressure drop is low, the bag filter becomes larger and thus, its economics are very low due to a large initial investment. Therefore, a face velocity of around 1.5 m/min is considered to be the optimal operation condition. At 1.5 m/min considered to be the most economical face velocity, if the pulse interval increases, since the amount of variation in filter drag is large, depending on the amount of inlet dust loading, the operation may be possible at a lower concentration when the pulse interval is 70 sec. However, for a higher concentration, either face velocity or pulse interval should be reduced.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2011.04a
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• pp.120-123
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• 2011

본 연구는 지하노래방 화재 원인 분석을 수행시 기존의 전기기기들 자체 화재위험성 연구보다 주위 먼지들의 화재 위험성을 중점적으로 연구 하였으며 이를 위하여 국내 화재가 많이 발생되는 곳의 먼지를 수거하여 먼지(dust layer)들의 전기기기 위에서의 발화, 절연저항, 전기적 아크에 의한 착화 가능성을 실험하여 예방대책의 기초자료를 제시하였다.