• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.16 no.3
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• pp.222-232
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• 2006

Objectives: The objective of this study was to propose the total isocyanate analytical method which involves derivation of 2,4-toluene diisocyanate(2,4-TDI), 2,6-toluene diisocyanate(2,6-TDI), 4,4'-methylenediphenyl diisocyanate(4,4'-MDI) and 1,6-hexamethylene diisocyanate(1,6-HDI) using 2-chlorobenzyl alcohol(2-CBA) or 2,4-dichlorobenzyl alcohol(2,4-DCBA), and analyzing of hydrolysate of the synthesized urethane with the gas chromatography(GC)/flame ionization detector(FID), GC/pulsed discharge ionization detector-electron capture detector(PD-ECD) and GC/mass selective detector(MSD). Methods: Urethanes were synthesized by reacting 2,4-TDI, 2,6-TDI, 4,4'-MDI and 1,6-HDI to 2-CBA or 2,4-DCBA. Urethanes was verified by TLC, HPLC/UVD and GC/MSD. For field application, the most suitable condition that 2-CBA coated in glass fiber filter removed completely and urethanes were not removed was searched. 2-CBA generated from hydrolysis of urethanes according to hydrolysis conditions. Diisocyanates were collected on field air and analyzed. Results: Urethanes which were white and solid phase synthesized by reacting 2,4-TDI, 2,6-TDI, 4,4'-MDI, 1,6-HDI and 2-CBA or 2,4-DCBA. And urethanes were verified by TLC, HPLC/UVD and GC/MSD. The most suitable conditions to remove 2-CBA coated in glass fiber filter were $87^{\circ}C$ and 20 mmHg and urethanes were not removed under same condition. Hydrolysis yields of urethanes were 99 % to 111 %. 2-CBA, the hydrolysate of urethanes was analyzed by GC/FID, GC/PD-ECD and GC/MSD. Conclusions: Simultaneous analysis of 2,4-TDI, 2,6-TDI, 4,4'-MDI and 1,6-HDI deriving with 2-CBA and 2,4-DCBA, along with a total isocyanate analysis, was feasible with GC/FID, GC/PD-ECD and GC/MSD. This result will be a guide of further study on total isocyanate analysis.

• Korean Chemical Engineering Research
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• v.50 no.2
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• pp.317-327
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• 2012

The average specific cake resistance, the most important indicator for cake filtration and solid-liquid separation, is measured by filtration experiment. But the exact value is difficult to measure because of the other influences such as sedimentation during filtration. This study, a little more stable method named filtration-permeation is proposed for measuring average specific cake resistance. The filtration-permeation is composed of permeation of particle eliminated water through pre-formed cake by filtration. Using 1 wt% calcium carbonate suspension, the filtration-permeation experiments were performed for 8 kinds of filter media at the conditions of 0.5 atm and 0.2 atm, 1 and 3 sheets of filter media. At each specific condition, three to five times filtration-permeation were accomplished. As a result, stable permeation speed is measured. According to this experimental result, the characteristics of permeation and the effect of sedimentation are analyzed with Ruth's equation. The one way analysis of variance (one way ANOVA) is applied to the average specific cake resistances of filtration and permeation obtained with the selected three kinds of filter media. The average specific cake resistances between 0.5 atm and 0.2 atm by filtration do not distinguished, but those by permeation is perfectly distinguished. The experimental results during permeation have a very narrow distribution than that measured during filtration. The analysis of filtration experiments, it was verified that the resistance of filter medium by traditional method is of no significance. Finally, the migration of small particles through the medium composed of fiber glass at low pressure was studied.

• KSBB Journal
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• v.15 no.2
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• pp.214-218
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• 2000

A hepatitis B Surface Antigen(HBsAg)-screening kit using immunochromatographic assay(ICA) method was developed by e employing two kinds of antibodies. One is mouse monoclonal anti-HBs for tracer antibody and the other is goat p이yclonal a anti-HBs for capture antibody. This capture antibody was immobilized on the surface of nitroceliulose(NC) membrane and the t tracer antibody was conjugated with g미d particles. When serum sample was added to the sample well, the $\infty$njugates d deposited in a dry state on the surface of glass fiber filter were reconstituted and then combined with HBsAg in serum. In 5 5 min after adding, the assay result was visible through the window, that is, the complexes composed of HBsAg and the c conjugates appeared as maroon line on the lower part of the NC membrane. The detection limit of the ICA kit was 2 ng/ml w when being tested with the reference HBsAg.

• Tribology and Lubricants
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• v.38 no.4
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• pp.121-127
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• 2022

This study presents the development of an integrated oil purification system consisting of moisture removal, oil flushing, and oil filtering devices. In this system, the oil flushing device is combined with a micro-bubble generator. Oil purification is necessary for ensuring the high performance of the lubricant through the efficient removal of contaminants and thus enables good maintenance of mechanical systems. The developed purification system removes moisture, varnish, and solid particles. Moreover, during oil purification, the oil flushing device separates foreign materials and contaminants remaining in the lubricating oil piping or mechanical systems. The microbubble generator, which is combined with the oil flushing device, can separate harmful contaminants, such as sludge, wear particles, and rust, from piping or lubrication systems through the cavitation effect. Moisture is removed using a double high-vacuum chamber, while sludge and varnish are removed via electro-absorption using a high-voltage generator. Additionally, the total maintenance cost of the system is reduced through the use of domestically fabricated cartridge filters composed of glass fiber and cellulose. The heater, which maintains the temperature of the lubricant at 60℃, can process 41,000 L of lubricant simultaneously. Multiple tests confirmed that the proposed integrated purification system exhibits good performance in oil flushing and removal of water and varnish.

• Journal of the Korean Ceramic Society
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• v.46 no.6
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• pp.587-591
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• 2009

Lithium salt have been used mainly as electrolyte of thermal battery for electricity storage. Recently, The 3phase lithium salt(LiCl-LiF-LiBr) is tried to use as electrolyte of thermal battery for high electric power. It is reported that LiCl-LiF-LiBr salt have high ion mobility due to its high lithium ion concentration. Solid lithium salt is melt to liquid state at above $500{^{\circ}C}$. The lithium ion is easily reacted with support materials. Because the melted lithium ion has small ion size and high ion mobility. For the increasing mechanical strength of electrolyte pellet, the research was started to apply ceramic filter to support of electrolyte. In this study, authors used SiOC web and glass fiber filter as ceramic mat for support of electrolyte and impregnated LiCl-LiF-LiBr salt into ceramic mat at above $500{^{\circ}C}$. The fabricated electrolyte using ceramic mat was washed with distilled water for removing lithium salt on ceramic mat. The washed ceramic mat was observed for lithium ion reaction behavior with XRD, SEM-EDS and so on.

• Journal of the Korean Electrochemical Society
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• v.14 no.3
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• pp.171-175
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• 2011

Lithium secondary batteries using lithium metal count electrode are easy to use and to analyze the specific characteristics of working electrode. Nevertheless, during the charge operation internal electrical short circuit could be caused by the dendritic growth of lithium. The cell failure by the short circuit depends on the condition of separator such as constitutive material and thickness. To prevent the cell failure caused by the dendritic growth of lithium, the electrochemical properties of the cell of lithium metal count electrode were evaluated for four different kinds of separator. Among the tested separators, GMF (glass micro-fiber filter, $300{\mu}m$) was the most promising one because it could effectively prevent the cell failure during the charge. The cell using GMF separator had relatively low impedance. Generally the cell using thicker separator than $50{\mu}m$ could effectively avoid the cell failure by internal short circuit and had the good cycleability. The highest rate capability by the signature method was acquired in the case of GMF separator.

• Journal of Korean Society for Atmospheric Environment
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• v.25 no.2
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• pp.108-121
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• 2009

The suspended particulate matters have been collected on membrane filters and glass fiber filters by an 8-stage cascade impactor for 2 years (Sep. 2005${\sim}$Sep. 2007) in Kyung Hee University-Global Campus located on the border of Yongin and Suwon. The 20 chemical species (Al, Mn, Si, Fe, Cu, Pb, Cr, Ni, V, Cd, Ba, $Na^+$, ${NH_4}^+$, $K^+$, $Mg^{2+}$, $Ca^{2+}$, $Cl^-$, ${NO_3}^-$, and ${SO_4}^{2-}$) were analyzed by an ICP-AES and an IC after performing proper pre-treatments of each sample filter. Based on these chemical information, the PMF receptor model was applied to identify the source of ambient size-by-size particulate matters. The receptor modeling is the one of the statistical methods to achieve resonable air pollution management strategies. A total of 10 sources was identified in 9 size-ranges such as long-range transport, secondary aerosol, $NH_{4}NO_{3}$ related source, coal combustion, sea-salt, soil, oil combustion, auto emission, incineration, and biomass burning. Especially, the secondary aerosol source assorted in fine and coarse modes was intensively studied.

• Toxicological Research
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• v.34 no.2
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• pp.163-172
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• 2018

Air pollution is increasing, along with consumption of fossil fuels such as coal and diesel gas. Air pollutants are known to be a major cause of respiratory-related illness and death, however, there are few reports on the genotoxic characterization of diverse air pollutants in Korea. In this study, we investigated the mutagenic activity of various particles such as diesel exhaust particles (DEP), combustion of rice straw (RSC), pine stem (PSC), and coal (CC), tunnel dust (TD), and road side dust (RD). Ultra-fine particles (UFPs) were collected by the glass fiber filter pad. Then, we performed a chemical analysis to see each of the component features of each particulate matter. The mutagenicity of various UFPs was determined by the Ames test with four Salmonella typhimurium strains with or without metabolic activation. The optimal concentrations of UFPs were selected based on result of a concentration decision test. Moreover, in order to compare relative mutagenicity among UFPs, we selected and tested DEP as mutation reference. DEP, RSC, and PSC induced concentration-dependent increases in revertant colony numbers with TA98, TA100, and TA1537 strains in the absence and presence of metabolic activation. DEP showed the highest specific activity among the particulate matters. In this study, we conclude that DEP, RSC, PSC, and TD displayed varying degrees of mutagenicity, and these results suggest that the mutagenicity of these air pollutants is associated with the presence of polycyclic aromatic hydrocarbons (PAHs) in these particulate matters.

• Journal of Korean Society for Atmospheric Environment
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• v.25 no.1
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• pp.46-56
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• 2009

The main purpose of this study was to investigate air quality trends of ambient aerosol with obtaining size-fractionated information. The suspended particulate matters were continuously collected on membrane filters and glass fiber filters by an 8-stage cascade impactor for 2 years (Sep. 2005 $\sim$ Sep. 2007) in Kyung Hee University-Global Campus. 8 ionic species ($Na^+$, ${NH_4}^+$, $K^+$, $Mg^{2+}$, $Ca^{2+}$, $Cl^-$, ${NO_3}^-$, and ${SO_4}^{2-}$) were analyzed by an IC after performing proper pretreatments of each sample filter. The average concentration levels of each ion were $9.24{\mu}g/m^3$ of ${SO_4}^{2-}$, $7.35{\mu}g/m^3$ of ${NO_3}^-$, $2.81{\mu}g/m^3$ of ${NH_4}^+$, $2.11{\mu}g/m^3$ of $Ca^{2+}$, $1.65{\mu}g/m^3$ of $Cl^-$, $1.87{\mu}g/m^3$ of $Na^+$, $0.80{\mu}g/m^3$ of $Mg^{2+}$, and $0.54{\mu}g/m^3$ of $K^+$, respectively. The distribution pattern of $Na^+$, $Mg^{2+}$, $Ca^{2+}$, $Cl^-$, and ${NO_3}^-$ was bi-modal and two peaks appeared in the range of $0.4{\sim}0.7{\mu}m$ and $3.3{\sim}4.7{\mu}m$, respectively. On the other hand, ${SO_4}^{2-}$, ${NH_4}^+$, and $K^+$ showed patterns of uni-modal distribution, mostly abounded in the fine mode group.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.23 no.4
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• pp.412-420
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• 2013

Objectives: This study was conducted in order to evaluate personal and area exposure to airborne total dust and endotoxin during harvest and planting tasks at cucumber, yellow melon and potato farms Materials and Methods: Total dust was measured with NIOSH method 0500. Endotoxin were measured using a 37 mm glass fiber filter which was connected to an air pump calibrated to 2 LPM, and then analyzed with a Turbidmetric kinetic method. Results: The average(arithmetic mean) concentrations of total dust in the personal samples were $0.10-3.81mg/m^3$ for cucumbers, $0.21-1.19mg/m^3$ for yellow melon, and $0.08-2.72mg/m^3$ for potato. There was a significant difference in the harvest task among the three farm types(p=0.019 of personal sample, p=0.048 of area sample), in which the air concentration for potatoes was higher than with cucumbers and yellow melons. Conclusions: It was found that potatoes(planting and harvest) should be considered the first priority for studying and reducing total dust exposure.