• 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.

• Nutrition Research and Practice
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• v.5 no.6
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• pp.495-502
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• 2011

In this study, antioxidant and free radical scavenging activities of the natural antioxidative compound, pyrogallol-phloroglucinol-6,6'-bieckol (PPB) isolated from brown algae, Ecklonia cava was assessed in vitro by measuring the radical scavenging activities (DPPH, alkyl, hydroxyl, and superoxide) using electron spin resonance (ESR) spectrometry, intracellular reactive oxygen species (ROS) scavenging activity, and DNA damage assay. According to the results of these experiments, the scavenging activity PPB against difference radicals was in the following order: DPPH, alkyl, hydroxyl, and superoxide radicals ($IC_{50}$; 0.90, 2.54, 62.93 and $109.05{\mu}M$). The antioxidant activities of PPB were higher than that of the commercial antioxidant, ascorbic acid. Furthermore, PPB effectively inhibited DNA damage induced by $H_2O_2$. These results suggest that the natural antioxidative compound, PPB, can be used by the natural food industry.

• Journal of environmental and Sanitary engineering
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• v.16 no.3
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• pp.42-53
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• 2001

This study were conducted to estimate property of nitrogen dioxide concentration at industrial areas in Korea. The nitrogen dioxide concentrations were measured for 50 dwellings at Ulsan and Yeochon, respectively using the nitrogen dioxide filter badge forming the passive sampler from summer time 1998 to winter time 1999. The major results obtained from this study were as follows: 1. The mean indoor, outdoor, and personal concentrations of nitrogen dioxide during summer time 1998 in Ulsan were 28.9 ppb, 24.8 ppb, 24.8 pub, respectively. 2. The mean indoor, outdoor, and personal concentrations of nitrogen dioxide during winter time 1999 in Yeochon were 11.4 ppb, 12.5 ppb, 15.5 ppb, respectively. 3. The mean concentration of nitrogen dioxide during winter time 1998 were higher than the corresponding levels during summer time 1997 in Ulsan. 4. The mean concentration of nitrogen dioxide in Ulsan were in general higher than the corresponding levels in Yeochon. 5. This results in slightly positive correlation among indoor, outdoor, and personal nitrogen dioxide concentrations for summer time in Ulsan, then it statistical significance is showed(p <.05). These results suggest that nitrogen dioxide concentrations in industrial areas seem to be affected by traffic density and conditions of industrialization.

• Asian-Australasian Journal of Animal Sciences
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• v.17 no.2
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• pp.259-262
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• 2004

The ability of Modified Glucomannan (MG) to bind T-2 toxin (T-2) in the gastrointestinal tract has been tested in vivo by feeding 120 five-wk-old broiler chicken with the following six treatment diets, 1) Control diet; 2) Control+MG (0.1%); 3) Control+T-2 (500 ppb); 4) Control+T-2 (500 ppb)+MG (0.1%); 5) Control+T-2 (1,000 ppb) and 6) Control+T-2 (1,000 ppb)+MG (0.1%). Twenty birds were assigned to each treatment group, which had five experimental groups. Four birds of each experimental group were sacrificed at an interval of 30 min i.e. at 0, 30, 60, 90 and 120 min after feeding experimental diets. The whole gut contents of each bird were collected, dried and toxin concentration was determined. Percent T-2 recovered from the gut was significantly lower (p<0.05) in the groups fed MG at all the time intervals. The percent T-2 adsorbed by the MG at different T-2 levels (500 and 1,000 ppb) was 15.97 and 14.77, 22.53 and 22.67, 26.88 and 28.03, and 31.50 and 31.83 at 30, 60, 90 and 120 min, respectively.

• Journal of the Korean Chemical Society
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• v.19 no.6
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• pp.428-433
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• 1975

500 ml of a sample water was extracted with 10 ml of 0.01 % dithizone-$CHCl_3$three times. When $CHCl_3$ layer was back extracted with 10 ml of 0.1 N HCl containing mercuric ion, the free metal ions come into aqueous layer. The aqueous layer was added with 2 ml of 2 N KCl and was washed with 10 ㎖ of $CHCl_3$two times in order to remove the trace dithizone, and then was recorded square wave polarogram. The concentration of copper, lead and cadmium can be determined up to 3 ppb and that of zinc up to 14 ppb with an error of 10 %.

• Journal of environmental and Sanitary engineering
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• v.11 no.3
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• pp.47-52
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• 1996

Personal exposure levels of $NO_{2}$ for office workers and housewives Living in A-San and neighboring prefectures were measured in two seasons with $NO_{2}$ filter badge. $NO_{2}$ concentrations in indoor and outdoor air in their offices and houses were also measured in the same periods. Personal exposure levels in winter ranged from 13 to 132 ppb and its distribution pattern was remarkably different from the other seasons (15.2-17.9 ppb). This fact suggests that use of heating apparatus affects largely $NO_{2}$ indoor air pollution in winter seasons. Actually, $NO_{2}$ exposure levels of subjects used Kerosene heater (43.6ppb) and gas heater (33.4ppb) were higher than those of subjects unused heating apparatus (18.0ppb). Personal exposure levels of $NO_{2}$ for man and woman Living in the same houses were correlated well each other. The time spent indoors for office workers and housewives were both longer than 22 hour a day. Home staying time was about 60% of total indoor staying time for office workers and 90% or more for housewives. Personal exposure levels were significantly related to indoor exposure levels at home all seasons. Furthermore, personal exposure levels could be estimated from $NO_{2}$ concentrations and staying times in various Living environment.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.22 no.3
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• pp.209-216
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• 2012

Objectives: Polyurethanes are usually formed by the reactions of liquid diisocyanate components with liquid polyol resin components. Although polyurethanes have advantageous properties, such as their versatility, the manufacturing process generates diisocyanates, which can cause asthma and respiratory irritation in exposed workers. This study compared the differences in diisocyante concentrations between two different (molded foam and slabstock foam) polyurethane foam manufacturing methods. Materials and Methods: Active samples and direct reading samples of diisocyanates (MDI, TDI) were collected in five polyurethane foam manufacturing companies. Results: Workers' exposure concentrations of diisocyanate (GM: 4.078 ppb, range: 1.190~23.770 ppb) in a slabstock foam manufacturing company were much higher than those (GM: 0.011 ppb, range: 0.001~0.055 ppb) in molded foam manufacturing companies. The results of the direct reading samples of diisocyanate indicated that the rapid reaction zone of the slabstock foam processes emitted large amounts of diisocyanates. Conclusions: The exposure levels of diisocyanates for all molded foam workers were much lower than the occupational exposure standard (5 ppb); however, exposure levels for many slabstock foam workers exceeded the standard.

• Nuclear Engineering and Technology
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• v.54 no.9
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• pp.3215-3224
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• 2022

Latest studies found that for 316LN austenitic stainless steel (ASS), its LCF life decreased noticeably in high temperature water containing a great amount of dissolved oxygen (DO) (2 ppm DO), compared with that in the water containing 50 or 100 ppb DO. This finding is different from previous studies about ASSs. This study confirmed that the 316L had similar behavior to 316LN. The LCF life of 316L in water containing 1000 ppb DO water was considerably shorter than that in the water containing 50 ppb DO. Addition of boric acid & lithium hydroxide and pre-soaking did not display noticeable effects on the LCF life of this material in the water with 1000 ppb DO, indicating the discrepancy between the latest studies and previous studies was not caused by the boric acid & lithium hydroxide and pre-soaking. This study also confirmed that similar to 316LN, when a certain amount of DO was added into the water, the amount of hydrogen absorbed into the material decreased significantly compared with that when the DO was less than 5 ppb.

• Journal of Animal Environmental Science
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• v.11 no.1
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• pp.45-54
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• 2005

A field survey was conducted to determine the concentration of odor compounds from pig buildings and that were 20 meters within the boundary area. The odor compounds were measured from large, medium and small farms with enclosed and open housing systems and slurry and sawdust manure fermentation treatment methods. Among the odor compounds investigated, ammonia ($NH_3$) had the highest concentration at 0.9 ${\~}$ 21.0 ppm followed by Hydrogen Sulfide($H_2S$) with a wide variation concentration of 51.9 ${\~}$ 6,712.4 pub, Uethylmercaptan($CH_3SH$) with non-detectable (N. D.) ${\~}$ 12.9 ppb, Dimethylsulphide($(CH_3)_2S$), with N. D. ${\~}$ 5.2 ppb and Dimethyldisulphide($(CH_3)_2S_2$) with N. D. ${\~}$ 2.6 ppb. Considering the prevailing wind direction and air velocity ranging from 0.23 to 0.73 m/s within the boundary area, the odorous matters; $NH_3$, $H_2S$, $CH_3SH$, $(CH_3)_2S_2$ and $(CH_3)_2S$ were 0.2${\~}$4.5 ppm, 0.01 ${\~}$0.06 ppb, N. D. ${\~}$0.009ppb, N. D.${\~}$0.002ppb and N. D. for $(CH_3)_2S$ respectively. These findings suggested that the Odor compounds $(CH_3)_2S_2$ had the lower detection in the boundary area whilst $(CH_3)_2S$ had no detection level within a 20-meter distance only. However, with these results odor compounds from pig buildings has to be further investigated under more controlled environmental factors.

• Journal of Environmental Health Sciences
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• v.9 no.1
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• pp.85-88
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• 1983

캄덴 카운티 청사에 있는 transformer에 화재가 난 후 건물내에 있는 60명의 혈야에서 PCB를 측정하였다. 화재가 발생한 건물내의 공기에서는 거의 검출되지 않았으나 transformer가 있는 방의 Swab Sample에서는 $52.6 \mug/cm^2$가 검출되었다. 건물을 재사용하기 전에 환기를 최대로 시킨후 다시 Swab Sample을 취했을때 12 Sample중 10주에서 PCB가 검출되지 않았다. 또한 혈야에서 PCB수준은 미검출에서 16ppb였으나 일반인에서도 69.2ppb까지 검출된것과 그밖에 17.6ppb까지 검출된 것으로 보아 화재후 PCB가 혈야중에서 증가했다는 증거는 없다고 본다. 이와 같이 혈청내에서 PCB가 증가하지 않은것은 화재후 즉시 청소와 환기를 실시한 결과로 본다.