• Journal of Korean Society for Atmospheric Environment
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• v.19 no.5
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• pp.491-502
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• 2003

In the present work, the distribution characteristics of ambient volatile organic compounds (VOCs) were investigated at high temporal resolution from a monitoring station located in a mid-eastern area of Seoul. A total number of 587 samples were collected during December 2002 to January 2003. The measurements of VOC were conducted by a combination of on-line air sampling and thermal desorption unit (TDU) coupled with capillary GC/FID analysis. A total of five aromatic compounds (BTEX: benzene, toluene, ethylbenzene, m, p-xylene, and o-xylene) were measured routinely at hourly intervals during the whole study period. The mean concentrations of BTEX measured in our study period were found in the order: toluene (8.99 $\pm$5.38 ppb) > benzene (0.92$\pm$0.52 ppb) > m, p-xylene (0.51$\pm$0.34 ppb) > 0- xylene (0.48$\pm$0.35 ppb) > ethyl benzene (0.43$\pm$ 0.32 ppb). The BTEX concentrations were generally higher during the daytime than the nighttime, exhibiting certain patterns on a weekly basis. Results of our analysis indicate that the unusually high concentrations of toluene, while showing good correlations with other VOCs, can be a good indicator of air pollution in the study area.

• Journal of the Korean Society of Safety
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• v.22 no.2 s.80
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• pp.47-52
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• 2007

The flash points and the fire points for the m-xylene+n-propionic acid and n-butanol+n-pentanol systems were measured by using Tag open-cup apparatus(AS1M D 1310-86). The experimental flash points of two binary systems were compared with the values calculated by the Raoult's law, Van Laar equation and Wilson equation. The calculated values based on the Raoult's law on m-xylene+n-propionic acid system were found to be better than those based on Van Laar and Wilson equations. The calculated values based on Van Laar equation on n-butanol+n-pentanol system were found to be better than those based on the Raoult's law and Wilson equation. The the fire points for the m-xylene+n-propionic acid system were about $7{\sim}8^{\circ}C$ above the flash points. In the case of n-butanol+n-pentanol system, the flash points and the fire points had been found to be identical.

• Korean Chemical Engineering Research
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• v.58 no.4
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• pp.658-664
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• 2020

Zeolite HY is wet impregnated with Ni (0.1, 0.3, 0.4, 0.5 wt%), Pt (0.1 wt%) and reduced in presence of hydrogen to form nanosized particles of Ni and Pt. All the catalysts were characterized by XRD, TEM, ESCA, NH₃-TPD, Pyridine adsorbed FT-IR and BET. Characterization results confirm that the Ni and Pt fractions effectively rehabilitated the physio-chemical properties of the zeolite HY catalysts. Further, all the reduced catalyst were screened with hydroisomerization of m-xylene at LHSV = 2.0 h^-1 in the temperature range 250-400 ℃ in steps of 50 ℃ in hydrogen atmosphere (20 ml/g). The addition of Ni to Pt catalyst increases hydroisomerization conversion, as well as maximizes p-xylene selectivity by restricting the pore size. The increasing trend in activity continues up to 0.3 wt% of Ni and 0.1 wt% Pt addition over zeolite HY. The increasing addition of Ni increases the total number of active metallic sites to exposed, which increases the metallic sites/acid sites ratio towards the optimum value for these reactions by better balance of synergic effect for stable activity. The rate of deactivation is pronounced on monometallic catalysts. The results confirm the threshold Ni addition is highly suitable for hydroisomerization reaction for product selectivity over Ni-Pt bimetallic/support catalysts.

• Carbon letters
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• v.10 no.4
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• pp.305-313
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• 2009

In this study, the adsorption of toxic pollutants onto cetyltrimethylammonium kaolin (CTAB-Kaolin) is investigated. The organo-kaolin is synthesized by exchanging cetyltrimethylammonium cations (CTAB) with inorganic ions on the surface of kaolin. The chemical analysis, the structural and textural properties of kaolin and CTAB-kaolin were investigated using elemental analysis, FTIR, SEM and adsorption of nitrogen at $-196^{\circ}C$. The kinetic adsorption and adsorption capacity of the organo-kaolin towards o-xylene, phenol and Cu(II) ion from aqueous solution was investigated. The kinetic adsorption data of o-xylene, phenol and Cu(II) are in agreement with a second order model. The equilibrium adsorption data were found to fit Langmuir equation. The uptake of o-xylene and phenol from their aqueous solution by kaolin, CTAB-kaolin and activated carbon proceed via physisorption. The removal of Cu(II) ion from water depends on the surface properties of the adsorbent. Onto kaolin, the Cu(II) ions are adsorbed through cation exchange with $Na^+$. For CTAB-kaolin, Cu(II) ions are mainly adsorbed via electrostatic attraction with the counter ions in the electric double layer ($Br^-$), via ion pairing, Cu(II) ions removal by the activated carbon is probably related to the carbon-oxygen groups particularly those of acid type. The adsorption capacities of CTAB-kaolin for the investigated adsorbates are considerably higher compared with those of unmodified kaolin. However, the adsorption capacities of the activated carbons are by far higher than those determined for CTAB-kaolin.

• Journal of Environmental Science International
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• v.14 no.3
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• pp.351-358
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• 2005

The research in this paper was carried out to examine the BTEX(Benzene, Toluene, Ethylbenzene, Xylene) concentrations in Seongseo Industrial Complex. These compounds are the major constituents, more than $60\%$ in composition of total VOCs, mainly charging in ambient air. BTEX samples were collected from the 38 sites, 10 for the source points and 18 for the boundary sites, and were analyzed by canister-GC/MS. The mean concentrations of BTEX were 33 ppbv for benzene, 214 ppbv for toluene, 89 ppbv for ethyl benzene, 77 ppbv for xylene. Among the BTEX, toluene had the highest concentration in the source points and boundary sites. In the source points, BTEX concentration of incineration facility for hazardous wastewater appeared highly in the range of 220­350 ppbv. BTEX concentrations in source boundary sites appeared in the order of toluene>ethylbenzene>xylene>benzene. As a result of the correlation analysis, the concentration of the source points was related to those of the boundary sites. Correlation of ethylbenzene and xylene was presented to 0.7991(P<0.0 1),\;0.6329(P<0.05) as the correlation coefficient, respectively.

• Journal of Korean Society for Atmospheric Environment
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• v.17 no.6
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• pp.463-474
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• 2001

In this study, the concentrations of major anthropogenic volatile organic compounds(VOCs) which include benzene, toluene, m, p-xylene, o-xylene, and ethylbenzene were measured at the Nan-ji-do landfill site during the spring and fall season of 2000. the temporal distribution characteristics of these VOCs were investigated over varying time scale. According to our study, the mean concentration of those species were computed to be 1.65$\pm$2.68(benzene), 9.62$\pm$9.32(toluene), 1.84$\pm$2.90(m, p-xylene), 0.83$\pm$1.43(o-xylene), and 1.17$\pm$1.21 ppb(ethylbenzene). The VOCs levels in the study area are not distinctively higher than the level typically found in urban area that can be subject to the influence of various anthropogenic source processes. Inspection of their temporal trends exhibited various patterns for the diurnal(and seasonal) cycle. Although each species showed distinctive patterns in temporal distribution trends, we were able to find the strong correlations among most concurrently measured VOCs except for benzene.

• Journal of Life Science
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• v.24 no.1
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• pp.81-85
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• 2014

Pseudomonas sp. BCNU 106 isolated from industrial wastewater was able to produce indigo from indole by utilizing various organic solvents. BCNU 106 produced indigo effectively when grown in the presence of a large volume of p-xylene, propylbenzene, and mesitylene and a high level of indole. The present study demonstrated that the maximal yield was achieved with 20% (v/w) p-xylene and 4 g/l indole. Under these conditions, the indigo yield and the transformation efficiency of indole were 315.5 mg/l and 97%, respectively. The results suggest that Pseudomonas sp. BCNU 106 might be a potential candidate for industrially important indigo production.

• The Journal of Korean Medicine
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• v.16 no.2 s.30
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• pp.271-280
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• 1995

The experimental studies were done to research the clinical effects of lnsambaekhabtang and Insambaekhabtanggamibang on the xylene-poisoned-lung damage and hypoprothrombinemia induced by warfarin injection in rats and mice. The results are as follows: 1. As to the hemostatic time in mice, lnsambaekhabtang was recongnized no significance but Insambaekhabtanggamibang was recognized significance( P<0.02 ). 2. As to the prothrombine time in rats. lnsambaekhabtang and lnsambaekhabtanggamibang Were recognized significance ( P<0.05, P<0.05 ). 3. As to the recalcification in rats, Insambaekhabtang and lnsambaekhabtanggamibang Were recognized significance ( P<0.05, P<0.02). 4. As to the lung TBA values in Xylene intoxicated rats, Insambaekhabtang was recognized significance but Insambaekhabtanggamibang was no recognized significance ( P<0.05). 5. As to the oxygen consumption in Xylene intoxicated rats, Insambaekhabtang and lnsambaekhabtanggamibang were no recognized significance. According to the above findings, it is suggested that the solid extract of Insambaekhabtang and Insambaekhabtanggamibang revealed effects on the xylene-poisoned-Iung damage and hypoprothrombinemia induced by warfarin injection in rats and mice.

• Biomedical Science Letters
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• v.18 no.1
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• pp.42-48
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• 2012

This study was performed to investigate the urinary methyl hippuric acid (UMHA) excretion among aircraft maintenance workers exposed to xylene by examination of blood test, urine test and biochemical tests. Study subjects (301) were divided into 2 groups; non-exposed group (n=123, who were not exposed to xylene), and exposed group (n=178, who were exposed to xylene). The average of blood level and MHA level was normal. The ${\gamma}$-GTP level was 35.5 IU/L (45.7%) in the exposed group and 27.9 IU/L (44.7%) in the non-exposed (control) group. The proportion of total cholesterol (TG) level higher than 150 mg/dl were 34.3% in the exposed group and 21.1% in the non-exposed group. These results were showed statistically significant difference (${\chi}^2$ = 6.10, P<0.05). Other items showed no statistically significant differences. The results of urine tests were no statistically significant differences in protein, occult blood and glucose level.

• Bulletin of the Korean Chemical Society
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• v.17 no.10
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• pp.919-924
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• 1996

Crystal structure of two inclusion compounds Cd(pn)Ni(CN)4·0.25G (G=toluene and p-xylene, pn=1,2-diaminopropane) have been determined from single-crystal X-ray diffraction data; toluene clathrate: monoclinic P21/n, a=13.838(6), b=26.893(5), c= 7.543(5) Å, γ=90.92(3)°, Z=4, R=0.0616; p-xylene clathrate: monoclinic P21/n, a=13.895(2), b=26.900(3), c=7.613(1) Å, γ=91.06(1)°, Z=4, R=0.0486. The host structures determined for toluene- and pxylene-guest clathrates are substantially identical to the U-type structures observed for the straight chain aliphatic-guest clathrates. However, the alternating arrangement of occupied channels with the guest molecules and vacant channels appears in the host structure. The non-centrosymmetric toluene molecules are distributed about the inversion center to give an image like p-xylene molecule. The guests, toluene and p-xylene, prefer the U-type channel, favoring the interaction between the π-electrons of the aromatic ring and the pn-amino groups to hold the aromatic ring vertical to the cyanometallate meshes.