• Proceedings of the KSR Conference
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• 2011.05a
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• pp.613-618
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• 2011

More than 7 million persons use Seoul Metropolitan Subways (SMS) everyday and the number has been in increasing trend. With the increasing trend of concerns on indoor air quality(IAQ), the management of IAQ has become an important issue, especially in case of subway operators, because most of subway lines are placed underground with poor ventilation condition. The ultimate object of study develop independent cleaning device that reduce efficient fine particle and $CO_2$. Urban subway has characteristics about proper clean air flow, must be installed in narrow space and maintenance cycle has enough time. Two layered electrically pre-charged filters were used for removing particulate matters and gas absorbers are packed between two layer filters for removing gases pollutants such $CO_2$, VOCs and HCHO. Urban subway has characteristics about proper clean air flow, must be installed in narrow space and maintenance cycle has enough time. SCAP prototype is producted as all in one method which decrease fine dust, $CO_2$ and noxious gas. and basic test carry out with quantity of wind, a gap of pressure, sampling efficiency.

• Journal of environmental and Sanitary engineering
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• v.18 no.4
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• pp.64-69
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• 2003

Recently, Indoor air quality(IAQ) in workplace, residential environments and office has been concern of people, scientists and related the public. The oxygen in air was very important and essential element in every aspect of life. This study was performed on a questionnaire survey of 400 people about their awareness of indoor air quality, oxygen generators and measured of oxygen concentration in indoor environment. The results obtained were as follows; As respondents are having their 90% of daytime indoors a day, and 80% of them can feel indoor air pollutions degrees directly by particle matters. The control of most important problems of IAQ was the poor ventilation. We know that 22% of the respondents was recognized the oxgen generator. And for the installation of indoor pollution control equipment, 20% of all respondents installed oxygen generators because almost respondents was not satified the trust of ability purified indoor air pollutants. In the experimental results, it was found that the oxygen concentration of sampling sites were in the range of 20~23.5%. Therefore, it was recommended that the government related IAQ was suggested the guideline and control of oxygen generators. Finally, it appeared that the oxygen generators using indoor environment can be applied to new technology for cleaning of indoor air.

• Proceedings of the KSME Conference
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• 2000.11b
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• pp.532-537
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• 2000

The purpose of this study is to determine the performance of a commercial air cleaner in removing tobacco smoke indoors. Following injection of tobacco smoke in a room, decay rates for particle concentrations were obtained far mass concentration at each point. The size distribution of the tobacco smoke particles was approximately $1.266{\mu}m$ in mass median diameter with a geometric standard deviation of 1.313. The air cleaner consisted of an electrostatic filtration unit and a fan operated at a flow rate of 5.98 CMM. The collection efficiency for $>1\;{\mu}m$ was more than 99%. Without air cleaner operation, tobacco smoke concentration ratio in room decreased to 30% of initial values within 30 minutes and with air cleaner operation, decreased to 90% of initial values in the test chamber, volume $51.27\;m^3$. Without air cleaner operation, tobacco smoke concentration ratio in room decreased to 10% of initial values within 30 minutes and with air cleaner operation, decreased to 30-70% of initial values in the test chamber, volume $149.2\;m^3$.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.1238-1243
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• 2009

As Social Overhead Capital(SOC) has been expanded, the highway road construction has been accelerated and city road system has been more complicated. So, long road tunnels have been increased and traffic flow rate also has been raised. Accordingly, the exhausting gas of vehicle cars seriously deteriorates the tunnel inside air quality and driving view. In order to improve tunnel inside air quality, it is needed to introduce a compulsory ventilation system as well as natural ventilation mechanism. The former, that is, a special compulsory ventilation facility is very useful and helpful to prevent a tunnel of being contaminated by traffic in most case. In the case of obtaining clearer and longer driving view, the ventilation systems have to be considered in order to remove floating contaminants or exhaust gas from engines. In this paper, discharge electrode design technology will be discussed.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.10
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• pp.1251-1256
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• 2014

The use of lubrication oil is of many purposes and one among them is to drive the engine mounted on a ship. Hence the supply of clean lubrication oil is important. And an oil purifier is one of key components in marine diesel engines. At present, the element type full-flow oil filter has been widely used for cleaning the engine oil. The self-driven centrifugal oil purifier is a device which is used to remove the impurities in lubrication oil using a jet flow. The flow characteristics and the physical behaviors of particles in this self-driven oil purifier were investigated numerically and the filtration efficiencies were evaluated. For calculations, a Computational Fluid Dynamics method is used and the Shear Stress Transport turbulence model has been adopted. The Multi Frames of Reference method is used to consider the rotating effect of the flows. The influence of centrifugal forcehas been numerically investigatedto improve filtration efficiency of tiny particles. As a result of this research, it was found that the particle filtration efficiency using the only center axis rotating and outer wall rotating system are higher than that of the fully rotating system in the self-driven oil purifier.

• Journal of Korean Society for Atmospheric Environment
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• v.29 no.4
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• pp.378-389
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• 2013

In Korea, studies on the indoor air quality have been conducted since mid of 1980s. The turning point occurred in 2003 by establishing the act of the indoor air quality management for public facilities. According to the law, the basic plan for indoor air quality management is prepared by government every five years, affecting greatly governmental policy and related academia and industries. Indoor air quality survey was mostly carried out among indoor air quality researches. After then, assessment of health effect and air cleaning technology were studied. Although various control technologies for particle, bioaerosol, odor, and hazardous chemicals have been applied to indoor environments, breakthrough technologies are needed to solve real problems facing at the applied environments. In the future, issue of indoor air quality is more interested and both management policy and control technology are key factors in order to realize comfort and healthy indoor environments.

• Membrane Journal
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• v.23 no.2
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• pp.185-188
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• 2013

This study was carried out for microfiltration tubular membrane module equipped with self-designed air injection nozzle in order to determine the permeate flux due to the effect of membrane fouling reduction. The 0.1 wt% yeast particle solution was used as a feed solution and permeation tests were performed for the cases with and without air injection. Permeation fluxes were measured and analyzed to examine the effect of membrane fouling reduction. While the permeation flux without air injection decreased continuously, that with air injection was improved more than 30 percent than that of no air injection case.

• Membrane Journal
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• v.18 no.1
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• pp.65-74
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• 2008

NOM and fine particles are the main target materials in water treatment using membranes. Particularly, humic substances extracted from soils are frequently used in many fundamental studies representing natural organic matter in raw water for drinking water treatment. In this study, ultrafiltration (UF) of artificial humic water and natural river water was conducted and the characteristics of removal efficiency and permeability were compared. In the UF of river water, the transmembrane pressure increased in the same pattern with that of 5 mg/L humic water. For the removal of organic matter and fine particles, however, two types of feed water had shown different trends. Kaolin particles and humic acids added to artificial water were better removed, while colloids and organics in natural water were relatively poorly removed. From the $UV_{254}$ and GPC analyses, it seemed that the hydrophobicity and size of humic substances contributed to the greater removal of organic matter. The UF membrane applied for humic water also showed a higher flux recovery by caustic chemical cleaning than that for river water.

• Journal of the Mineralogical Society of Korea
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• v.23 no.3
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• pp.235-242
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• 2010

Froth flotation using the residual water in the end of flotation process has been performed through controlling of pH. IEP (isoelectric point) of molybdenite and quartz in distilled water was below pH 3 and pH 2.7, respectively and the stabilized range was pH 5~10. In case of a suspension in reusing water, zeta potential of molybdenite decreased to below -10 mV or less at over pH 4 due to residual flocculants. As result of pH control, flotation efficiency in the alkaline conditions was deteriorated by flocculation, resulting from expanded polymer chain, ion bridge of the divalent metal cations ($Ca^{2+}$), and hydrophobic interactions between the nonpolar site of polymer/the hydrophobic areas of the particle surfaces. However, the weak acid conditions (pH 5.5~6) improved the efficiency of flotation as hydrogen ions neutralize polymer chains and then weakened its function. In cleans after rougher flotation, the Mo grade of 52.7% and recovery of 90.1% could be successfully obtained under the conditions of 20 g/t kerosene, 50 g/t AF65, 300 g/t $Na_2SiO_3$, pH 5.5 and 2 cleaning times. Hence, we developed a technique which can continuously supply waste water filtered from tailings into the grinding-rougher-cleaning processes.

• Korean Journal of Materials Research
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• v.8 no.8
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• pp.751-756
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• 1998

Effects of remote hydrogen plasma cleaning process parameters on the removal of Fe impurities on Si surfaces and the Fe removal mechanism were investigated. Fe removal efficiency is enhanced with decreasing the plasma exposure time and increasing the rf-power. The optimum plasma exposure time and rf-power are 1 min and 100W. respectively, in the range below 10 min and 100W. Fe removal efficiency is better under lower pressures than higher pressures, and the optimum $\textrm{H}_2$ flow rate was found to be 20 and 60sccm, respectively, under a low and a high pressure. The post-RHP(remote hydrogen plasma) annealing enhanced metallic contaminants removal efficiency, and the highest efficiency was achieved at $600^{\circ}C$. According to the AFM analysis results Si surface roughness was improved by 30-50%, which seems to be due to the removal of particles by the plasma cleaning. Also. Fe impurities removal mechanisms by remote hydrogen plasma are discussed.