• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.1
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• pp.66-71
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• 2004

Airborne contaminant particles are intruded into optical disk drive(ODD) due to the flow caused by disk rotation and can be adhered to objective lens, which causes read/write errors. Such a phenomenon can be a serious problem for high-density storage devices. The purpose of this paper is to understand the effect of particle contamination of objective lens in a CD-ROM drive on laser diode power and photo diode RF signal. The measurements of laser power and readout RF signal were carried out by using a laser power meter and a time interval analyzer, respectively. The parameters for estimating a readout-signal' distortion were its jitter and amplitude. Alumina(Al$_2$O$_3$) particles were used as test dust particles. The results show that the failure for data access happened as the degree of lens contamination was greater than 20％.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.11 no.3
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• pp.359-368
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• 1999

The outdoor and indoor air quality surrounding highway have been measured, and the study on the design of the booth shape and the air-conditioning system also has been carried out. For the first step of the work, the air quality at the Seoul tollgate on the Kyeong-bu highway was monitored over a year. The measured indoor air quality shows seasonal average concentration 85.6-92.1ppb of >;$NO_2$and the $SO_2$and CO lower than the EAQS(Environmental Air Quality Standards). The measured TSP concentration was much higher than the EAQS. In conclusion, there is necessity to improve the working environment of the tollbooths on highways, and the current air-conditions need to be modify for the purpose. In the process of modifying the air-conditioning system, particulate pollutants needs to be considered processing and the priority needs to be put on the booths for big vehicles.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.447-450
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• 2005

This paper describes an implementation of system based on ZIGBEE wireless communication technique to prevent for diseases of skin ailments and respiratory ailments as sensing the air pollutions that breaks out in the inside and purifying. ZIGBEE wireless communication technique has features - low battery consumption, low cost, acceptance of the maximum 256 node and simple protocol structure of below 32Kbyte. Hardware platform is implemented by using ATmega128L in ATmel corporation and 2.4GHz RF-IC CC2420 in Chipcon corporation and dust sensor(GP2Y1010AU) and gas sensor(GSBT11) that confirm degree of inside air pollution for ZIGBEE wireless communication technique.

• Journal of the Korean Chemical Society
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• v.58 no.3
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• pp.267-276
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• 2014

The collection of $PM_{10}$ and $PM_{2.5}$ fine particulate matter samples was made at the 1100 m site of Mt. Halla of Jeju Island, located at the atmospheric boundary layer (ABL) of background area, during the fall of 2012. Their ionic and elemental species were analyzed, in order to investigate the chemical compositions and size distribution characteristics. In $PM_{2.5}$ fine particles ($d_p$ < $2.5{\mu}m$), the concentrations of the secondary formed nss-$SO{_4}^{2-}$, $NH_4{^+}$ and $NO_3{^-}$ species were 4.84, 1.98, and $1.27{\mu}g/m^3$, respectively, showing 58.2% of the total $PM_{2.5}$ mass. On the other hand, their concentrations in $PM_{10-2.5}$ coarse particles (2.5 < $d_p$ < $10{\mu}m$) were 0.63, 0.21 and $1.10{\mu}g/m^3$, respectively, occupying 22.8% of the total $PM_{10-2.5}$ mass. The comparative study of size distribution has resulted that $NH_4{^+}$, nss-$SO{_4}^{2-}$, $K^+$ and $CH_3COO^-$ are mostly existed in fine particles, and $NO_3{^-}$ is distributed in both fine and coarse particles, but $Na^+$, $Cl^-$, $Mg^{2+}$ and nss-$Ca^{2+}$ are rich in coarse particle mode.

• Journal of the Korean Society for Railway
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• v.20 no.4
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• pp.433-439
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• 2017

Urban railway tunnels are polluted by resuspension of deposited bottom dust or newly generated wear dust. A hybrid type dust collector consisting of a baffle and an electrostatic precipitator was developed to remove these types of airborne dust when trains are running in the tunnel. Since dust collection efficiency of the hybrid dust collector is inversely proportional to the airflow rate, the relationship between airflow rate and dust collection efficiency was experimentally investigated for two baffle models. Collection efficiencies for dust larger than $0.5{\mu}m$ for the hybrid dust collector model A1, operated at 3.4 m/s, were greater than 30%; those for the hybrid dust collector model A2, operated at 4.7 m/s, were higher than 20%. When the applied voltage was 13 kV, the amounts of $PM_{10}$ collected with model A1 and model A2 dust collectors were estimated at $253{\mu}g$ and $242{\mu}g$ per hour, respectively.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.2
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• pp.443-449
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• 2017

The imbalance of air supply and the exhaust on subway platforms has led to the installation of platform screen doors in underground subway stations. This imbalance causes the accumulation of pollutants on the platform and loss of comfort due to the lack of ventilation. In this study, a floor exhaust system was optimized using computational fluid dynamics (CFD) and an optimization program. The optimized floor exhaust system was manufactured and tested experimentally to evaluate the particle collection efficiency. CFX 17.0 and HEEDS were used to analyze the flow field and optimize the principal dimensions of the exhaust system. As a result of the three-step optimization, the optimized floor exhaust system had a total height of 1.78 m, pressure drop of 430 Pa, and particle collection capability of 61%. A fine dust particle collection experiment was conducted using a floor exhaust system that was manufactured at full scale based on the optimized design. The experiment indicated about 65% particle collection efficiency. Therefore, the optimized design can be applied to subway platforms to draw in exhaust air and remove particulate matter at the same time.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.4
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• pp.2876-2882
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• 2015

The object of this study is to identify changes in air pollution in the maximum ground level concentration and the surrounding area when air pollution control facilities are improved in the thermal power plants. The effects of improved facilities are analyzed by comparing air quality after applying improved air pollution control facilities. For prediction of air quality, the change of wind field can be represented with movement of Puff and CALPUFF Model, air pollution diffusion models which can implement abnormal conditions. Major air pollutants of thermal power plants such as $SO_2$, $NO_2$, and $PM_{10}$ are selected as prediction items. That results show that improvement of air pollution control facilities is significantly effective in reduction of air pollution of $SO_2$ and $NO_2$ in the maximum ground level concentration and areas around of thermal power plants. In the case of $PM_{10}$, it is found that the effect of reduction in pollution is high in the maximum ground level concentration, but the effect of reduction in air pollution is somewhat low in the area around of the thermal power plant.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.10
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• pp.756-766
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• 2011

In order to investigate the degree of apartment parking lot dust contamination, total 72 samples of parking lot dust (36 from ground parking lots and 36 from the underground parking lots) were collected in Daegu city from the end of March to the early June 2010. The dust samples were sieved below $100{\mu}m$, and analysed by ICP for 14 elements after an acid extraction. Results obtained from the source assessment of trace element using enrichment factor showed that Fe, K, Mg, Mn, Na and V were influenced by natural sources, while Cd, Cr, Cu, Ni, Pb and Zn were influenced by anthropogenic sources in both the ground parking lot and the underground parking lot. And results showed that Ca were influenced by natural sources in the ground parking lot, but influenced by anthropogenic sources in the underground parking lot. The measured values were remarkably higher in components from natural sources than in components from anthropogenic sources. Underground parking lot dust was more affected by anthropogenic sources and contaminated compared with the ground parking lot dust. Pollution index of heavy metals revealed that underground parking lot dust was 5.5 times more contaminated with heavy metal components than the ground parking lot dust. The results of correlation analysis among trace elements indicated that components in the ground parking lot were more correlated than those in the underground parking lot, and especially more correlated with natural sources-natural sources. Analysis for correlations between components and influencing factors in the underground parking lot showed that concentrations of heavy metals were higher with smaller number of parking spaces and no ventilation system, and older apartments in last paint and cleaning had relatively higher contents of heavy metals than those of recently painted and cleaned.

• Journal of the Korean earth science society
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• v.24 no.8
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• pp.711-720
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• 2003

To study characteristics of the heavy metal pollution, sediment samples were collected at 67 sites on the roadside of Jeonju city during summer and winter, 2002. The total concentration of metals including Cd, Co, Cr, Cu, Ni, Pb, Zn, and Mn in the sediment samples were determined. The results indicate that the roadside sediments in Jeonju city have lower (1/2 to 1/7 times) concentrations of Zn, Cu, Pb and Cd than the metal concentrations previously reported for roadside soil, dust and sewage sludges in Seoul. However, the metal concentrations are higher than environmental quality criteria in soil suggested from several countries, and Zn, Cu, Pb and Cd contents are usually 2-7 times higher than the world average contents of the metals in natural soil. Although pollution index and concentrations of Cr, Ni, Pb and Zn in the roadside sediments at industrial area were usually higher than those of downtown and residential area, the metal having small vehicle- and steel-related industries had high concentrations of metals. The results of chemical partitioning analysis showed that Pb, Zn and Mn are mainly associated with carbonate/adsorbed and Fe-Mn oxide phases but that Cu is largely associated with the organic and sulfide fractions. It thus indicates that both large and small (vehicle- and steel-related) industries are main sources of heavy metal contamination. Due to high solubility of the carbonate phases by natural leaching episodes, the carbonate/adsorbed Cd, Co, Ni, Pb, Zn and Mn in the roadside sediments may serve as a potential source of contamination.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.9
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• pp.3615-3620
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• 2010

This study is development of UV-cured coating compounds which has more improved anti-stain and anti-biosis, about surface prevention of PVC Tile. We added water-soluble anti-static and anti-microbial agent to the resin. The process has prevented electrostatic and bacterial contagious disease. The result, which added 15wt% of water-soluble anti-static and 1wt% anti-microbial agent and coated with No.12 Bar-coater, coating composition had optimum surface property. It appear electric resistance($10^9{\Omega}/cm^2$), anti-stain (Ink Test, Dust Test), anti-biosis (99.99%), and adhesive power(100%).