• Journal of Environmental Health Sciences
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• v.20 no.1
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• pp.62-67
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• 1994

Introduction : Recently, water and environmental pollution becomes serious social problem and high technology makes this pollution accelerate. Hydrogen sulfide, the main subject of our research, is one of the most dangerous air pollutant like SO$_x$ and NO$_x$. The major contaminant in coal gasification is H$_2$S, which is very toxic, hazardous and extremely corrosive. Therefore, control of hydrogen sulfide to a safe level is essential. Although commercial desulfurization process called liquid scrubbing is effective for removal of H$_2$S, it has drawbacks, the loss of sensible heat of the gas and costly wastewater treatment. Many investigations are carried out about high-temperature removal ol H$_2$S in hot coal-derived gas using metal oxide or mixed metal qxide sorbents. It was reported that ZnO was very effective sorbent for H2S removal, but it has big flaw to vaporize elemental zinc above 600\ulcorner \ulcorner As alternative, metal oxides such as CaO, $Fe_2O_3$, TiO$_2$ and CuO were added to ZnO. Especially, different results are reported for $Fe_2O_3$ additive. Tamhankar et al. reported SiO$_2$ with 45 wt% $Fe_2O_3$ sorbent is favorable for removal of H$_2$S and regeneration.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.6
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• pp.167-175
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• 2018

Natural gas is a clean fuel that discharges almost no air-contaminating substances. This study examined the simultaneous reduction of $CH_4$ and NOx of NGOC/LNT catalysts for CNG buses related to the improvement of the $de-CH_4/NOx$ performance, focusing mainly on identifying the additive catalysts, loading of the washcoat, stirring time, and types of substrates. The 3wt. % Ni-loaded NGOC generally exhibited superior $CH_4$ reduction performance through $CH_4$ conversion, because Ni is an alkaline, toxic oxide, and exerts a reducing effect on $CH_4$. A excessively small loading resulted in insufficient adsorption capacity of harmful gases, whereasa too high loading of washcoat caused clogging of the substrate cells. In addition, with the economic feasibility of catalysts considered, the appropriate amount of catalyst washcoat loading was estimated to be 124g/L. The NOx conversion rate of the NGOC/LNT catalysts stirred from $200^{\circ}C$ to $550^{\circ}C$ for 5 hours showed 10-15% better performance than the NGOC/LNT catalysts mixed for 2 hours over the entire temperature range. The NGOC/LNT catalysts exhibitedapproximately 20% higher $de-CH_4$ performance on the ceramic substrates than on the metal substrates.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.1
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• pp.35-41
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• 2014

Trihalomethanes (THMs) are formed as a results of the reaction of residual chlorine, used as a disinfectant in drinking water, with the organic matter in raw water. Although chlorinated and brominated THMs are the most common disinfection byproducts (DBPs) reported, iodinated THMs (I-THMs) can be formed when iodide is present in raw water. I-THMs have been usually associated with several medicinal or pharmaceutical taste and odor problems and is a potential health concern since they have been reported to be more toxic than their brominated and chlorinated analogs. Currently, there is no published standard analytical method for I-THMs in water. An automated headspace-gas chromatography/electron capture detector (GC/ECD) technique was developed for routine analysis of 10 THMs including 6 I-THMs in water samples. The optimization of the method is discussed. The limits of detection (LOD) and limits of quantification (LOQ) range from 12 ng/L to 56 ng/L and from 38 ng/L to 178 ng/L for 10 THMs, respectively. Matrix effects in river water, sea water and wastewater treatment plant (WWTP) final effluent water were investigated and it was shown that the method is suitable for the analysis of trace levels of I-THMs, in a wide range of waters. The method developed in the present study has the advantage of being rapid, simple and sensitive.

• Tunnel and Underground Space
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• v.28 no.1
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• pp.38-58
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• 2018

The ventilation system plays a crucial role in underground mine safety. The main objective of the ventilation system is to supply sufficient air to dilute the contaminated air at working places and consequently provide tenable environment during the normal operation, while it also should be capable of controlling the fire propagation and facilitate rescue conditions in case of fire in mines. In this study, a smoke control fan was developed for the auxiliary ventilation as well as the fire smoke exhaust. It works as a free-standing auxiliary fan without tubing to dilute or exhaust the contaminated air from the working places. At the same time, it can be employed to extract the fire smoke. This paper aims to examine the smoke control efficiency of the fan when combined with the current ventilation system in mines. A series of the site experiments and numerical simulations were made to evaluate the fan performance in blind entry development sites. The tracer gas method with SF6 was applied to investigate the contaminant behavior at the study sites. The results of the site study at a large-opening limestone mine were compared with the CFD analysis results with respect to the airflow pattern and the gas concentration. This study shows that in blind development entry, the most polluted and risky place, the smoke fan can exhaust toxic gases or fire smoke effectively if it is properly combined with an additional common auxiliary fan. The venturi effect for smoke exhaust from the blind entry was also observed by the numerical analysis. The overall smoke control efficiency was found to be dependent on the fan location and operating method.

• Journal of the Korean Institute of Gas
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• v.21 no.1
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• pp.43-51
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• 2017

Recently, ammonia leak occurred frequently in the domestic refrigeration manufacturing facilities. Ammonia caused great damage to the environment and human health in the event of an accident as combustible gases and toxic gases. After considering the types of ammonia accidents of domestic refrigeration manufacturing facilities and selected accident scenarios and to analyze the risk analysis through Impact range estimates and frequency analysis and there was a need to establish measures to minimize accident damage. In this study, depending on the method of analysis quantitative risk assessment we analyzed the risk of the receiver tank of ammonia system. Scenario analysis conditions were set according to the 'Technical guidelines for the selection of accident scenario' under the chemicals control act and 'Guidelines for chemical process quantitative risk analysis' of center for chemical process safety. The risk estimates were utilized for consequence analysis and frequency analysis by SAFETI program of DNV, event tree analysis methodology and part count methodology. The individual risk of ammonia system was derived as 7.71E-04 / yr, social risk were derived as 1.17E-03 / yr. The derived risk was confirmed to apply as low as reasonably practicable of the national fire protection association and through risk calculation, it can be used as a way to minimize accidents ammonia leakage accident damage.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.50 no.2
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• pp.143-151
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• 2024

Ozone is a colorless, toxic gas that is produced when nitrogen oxides and hydrocarbons undergo a photochemical oxidation reaction in the sun's rays. Even at low concentrations, it affects the respiratory system, causing coughing and other harmful effects. It was confirmed that ozone was generated from nitrogen plasma among cosmetic raw materials, and it was found that the concentration of ozone decreased after 1 day. On the other hand, ozone was not detected in ozone-free plasma generated with argon gas. Therefore, we aimed to produce ozone-free cosmetics by utilizing ozone-free plasma. For efficient plasma processing, the non-sinking method was utilized to inject the plasma into layer separation mists, toners, and ampoules, and the stability was observed. It was found that the successful injection of plasma in the layer separation mist was higher than the other two formulations, but decreased sharply compared to the toner and ampoule. It was found that the ozone-free plasma used did not affect the stability of the layer separation mist, toner, and ampoule under low temperature (4 ℃), room temperature (25 ℃), and high temperature (37 ℃, 50 ℃) conditions. Therefore, this study suggests the importance of ozone-free plasma for cosmetic potential and stability of each formulation.

• Analytical Science and Technology
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• v.23 no.2
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• pp.187-195
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• 2010

To assess health risk for the intake among residents after the Hebei Spirit oil spill, 16 Polycyclic Aromatic Hydrocarbons (PAHs) in seafood samples from oil contaminated bay were determined by Gas Chromatography-Mass Spectrometry (GC-MSD) and samples were personally collected and purchased by residents. Samples were hydrolyzed with KOH and extracted with methylene chloride. The extracted solution were cleaned up using silica/florisil column and 16 PAHs were eluted by methylene chloride : n-hexane (1:9) mixture and determined by GC-MSD in Selected Ion Monitoring (SIM) mode. The mean recoveries for 16 PAHs ranged from 79% to 85%. The 16 PAHs levels in 126 samples ranged from 0.17 to $6.04\;{\mu}g$/kg and the TEQBaP (Toxic EQuivalents) levels in 126 samples were calculated using benzo(a)pyrene toxic equivalency factor for individual 16 PAHs and ranged from 0 to $0.91\;{\mu}gTEQ$/kg. The average Benzo(a)pyrene dietary exposure of residents was $5.5{\times}10^{-8}\;mg/kg$ bw/day and the average PAHs chronic dietary exposure was $1.3{\times}10^{-5}\;mg$ TEQ/kg bw/day. The margin of exposure (MOE) and the excess cancer risk and were $1.8{\times}10^6$ and $9.8{\times}10^{-8}$, respectively. Therefore, the assessment result was considered as low concern for health risk.

• Proceedings of the KSR Conference
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• 2011.05a
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• pp.1701-1708
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• 2011

A typical day in the subway transportation is used by hundreds of thousands are also concerned about the safety of the various workrooms with high underground fire or other less than in the subway users could be damaging even to be raised and there. In 2010, in fact, room air through vents in the fire because smoke and toxic gas accident victims, and train service suspended until such cases are often reported. In response to these incidents in subway stations, even if the latest IT technology, wireless sensor network technology and intelligent video surveillance technology by integrating fire and structural integrity, such as a comprehensive integrated surveillance system to monitor the development of intelligent urban transit system and are under study. In this study, prior to the application of the monitoring system into the field stations, authors carried out the ZigBee-based wireless sensor networks performance analyzation in the Chungmuro station. The test results at a communications room and ventilation room of the station are summarized and analyzed.

• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.42.2-42.2
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• 2010

Transparent conducting oxides (TCOs) are of significant importance for their applications in various devices, such as light-emitting diodes, thin-film solar cells, organic light-emitting diodes, liquid crystal displays, and so on. In order for TCOs to contribute to the performance improvement of these devices, TCOs should have high transmittance and good electrical properties simultaneously. Sn-doped $In_2O_3$ (ITO) is the most commonly used TCO. However, indium is toxic and scarce in nature. Thus, ZnO has attracted a lot of attention because of the possibility for replacing ITO. In particular, group III impurity-doped ZnO showed the optoelectronic properties comparable to those of ITO electrodes. Al-doped ZnO exhibited the best performance among various doped ZnO films because of the high substitutional doping efficiency. However, in order for the Al-doped ZnO to replace ITO in electronic devices, their electrical and optical properties should further significantly be improved. In this connection, different ways such as a variation of deposition conditions, different deposition techniques, and post-deposition annealing processes have been investigated so far. Among the deposition methods, RF magnetron sputtering has been extensively used because of the easiness in controlling deposition parameters and its fast deposition rate. In addition, when combined with post-deposition annealing in a reducing ambient, the optoelectronic properties of Al-doped ZnO films were found to be further improved. In this presentation, we deposited Al-doped ZnO (ZnO:$Al_2O_3$ = 98:2 wt%) thin films on the glass and sapphire substrates using RF magnetron sputtering as a function of substrate temperature. In addition, the ZnO samples were annealed in different conditions, e.g., rapid thermal annealing (RTA) at $900^{\circ}C$ in $N_2$ ambient for 1 min, tube-furnace annealing at $500^{\circ}C$ in $N_2:H_2$=9:1 gas flow for 1 hour, or RTA combined with tube-furnace annealing. It is found that the mobilities and carrier concentrations of the samples are dependent on growth temperature followed by one of three subsequent post-deposition annealing conditions.

• Journal of the Korean Applied Science and Technology
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• v.34 no.1
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• pp.12-24
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• 2017

The main purpose of this research is for the investigation on the impact of engine oil aging on PM and DPF. It is widely known that lubricant specifications and consumption from an ICE have significantly influenced on the regulated and unregulated harmful emissions as the engine operating conditions. Considering DPF clogging phenomena with lubricant-derived soot/ash components, simulated aging mode for the DPF was newly designed for engine dynamometer testing. PM/ash accumulation cycle were developed in reflecting real-world engine operating conditions for the increment of engine oil consumption and natural DPF regeneration for the ash accumulation. The test duration for DPF aging reached around 100hrs with high- and low-SAPS engine oils, respectively. Using high SAPs engine oil made more PM/ash accumulation compared with low SAPs engine oils and it could accelerate fouling of EGR in engine. Fouling of EGR made effects on more harmful exhaust gases emissions. The test results on engine lubricant under engines operating conditions will deliver for the establishment of regulated and unregulated toxic emissions policy, lubricant quality standard.