• Journal of Food Hygiene and Safety
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• v.10 no.2
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• pp.81-87
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• 1995

Daily exposure of aflatoxin B1 (AFB1) was estimated in foods (rice, barley, soybean, peanut, soysauce, soybean paste) by ELISA (enzyme linked immunosorbent assay) using polyclonal antibody R101. Before ELISA, a simple extraction method was applied for the quantitation of AFB1 in foods using chloroform which showed high recovery (70$\pm$12%). AFB1 levels in foods were 0.32 ng/ml (rice), 0.24ng/ml (barley), 0.22 ng/ml (peanut), 0.30~0.78 ng/ml (soysauce), and 0.2 ng/ml (soybean paste). Based on food consumption, we estimated that Koreans were exposed to AFB1 at the level of 1.86$\pm$0.46 ng/kg/day and liver cancer incidence attributed to AFB1 exposure (assuming that AFB1 as a single hepatocarcinogenic agent) might be calculated to be 13.1 per 100, 000 population. Our data demonstrate that AFB1 levels in foods were below the regulation of 10 ppb in foods and might not be the major risk factor for the high incidence of lover cancer in Korea.

• Journal of Korean Society for Atmospheric Environment
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• v.27 no.1
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• pp.50-62
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• 2011

Temporal trends and spatial distributions of ozone concentrations in Pohang were investigated using data measured at 4 air quality monitoring stations (i.e., Daedo, Jukdo, Jangheung, and Desong) during 2002-2006. The monthly mean ozone concentrations were highest during April and June and decreased during July and August, which follows the typical trend in the Northeast Asia region. The high springtime ozone concentration might have been strongly influenced by the enhanced photochemical ozone production of accumulated precursors during the winter under increased solar radiations. In July and August, ozone levels were decreased by frequent and severe precipitation that caused lower mean monthly solar radiation and efficient wash-out of ozone precursors. This suggests that precipitation is extremely beneficial in the aspect of ozone pollution control. High ozone concentrations exceeding 80ppb dominantly occurred in May and June during the late afternoon between 16:00~17:00. Ozone concentrations were higher in Jangheung and Daesong relative to Daedo and Jukdo, whereas total oxidants $(O_3+NO_2)$ were higher in Jangheung and Daedo. In the suburban area of Daesong, ozone concentrations seem to be considerably higher than those in urban sites of Daedo and Jukdo due to lower ozone loss by NO titration with lower local NO level.

• Child Health Nursing Research
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• v.10 no.1
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• pp.108-116
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• 2004

Purpose: There has been a number of reports on elution of bisphenol-A, an endocrine disrupting chemical, from milk bottles, all concerning the potential health effect of the substance. In this study, we measured the elution of bisphenol-A from milk bottles during boiling-water sterilization, to suggest a safe sterilization method. Method: Through the survey of 200 mothers, 78.5％ of them expressed their concern on the possible harmful effect of bisphenol-A, which might be eluted from the bottles. And it was found that most mothers use boiling-water to sterilize bottles; duration of boiling bottles could be divided into three groups of 3, 5, and 10 minutes. We measured the elution of bisphenol- A from three different brands of bottles, subject to various mode of sterilization found in the survey. Result: In all the measurements, the concentration of the eluted bisphenol-A was in the range of 0.3 - 0.7 ppb, far below 2.5ppm, the level set up by Korea Food ％amp; Drug Administration(KFDA) for a potential harmful effect. Conclusion: Although trace amount of bisphenol -A can be eluted from polycarbonate milk bottles during sterilization, and bottle feeding, the amount is found to be too small to cause any health related impact for infants.

• Environmental Analysis Health and Toxicology
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• v.23 no.2
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• pp.113-117
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• 2008

Biomonitoring of nonylphenol (NP), an endocrine disrupting chemical, is required in Korea to perform its proper regulation. Thus, we analyzed exposure levels of nonlyphenol (NP) in breast milk from the mothers who delivered babies within 10 days (N=325). We analyzed free and total forms of NP in breast milk with LC/MS/MS (LOD, 0.5 ppb). In addition, we obtained questionnaires concerning lifestyle from the subject. As results, ranges of total NP were ${\mu}g/L$ (median, $3.51{\pm}4.98{\mu}g/L$ vs. normal, N=281, $2.07{\pm}3.76{\mu}g/L$; p<0.05). In conclusion, we suggest that exposure monitoring of NP should be continuously performed, even though the risks of NP are not clear, yet.

• 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 Korean Society for Atmospheric Environment
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• v.19 no.E4
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• pp.157-168
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• 2003

This study evaluated the technical feasibility of the application of titanium oxide (TiO$_2$) photocatalysis for the removal of VOCs in low ppb concentrations commonly associated with non -occupational indoor air quality issues. A series of experiments were conducted to evaluate four parameters (relative humidity (RH), hydraulic diameter (HD), photocatalytic oxidation (PCO) reactor material (RM), and inlet port size (IPS) of PCO reactor) for the PCO destruction efficiencies of the selected target VOCs. None of the target VOCs presented significant dependency on the RH, which is inconsistent with a few previous studies. However, it is noted that the three parameters (HD, RM and IPS) should be considered for better VOCs removal efficiencies for the application of TiO$_2$ photocatalytic technology for cleansing non -occupational indoor air. The PCO destruction of VOCs at concentrations associated with non-occupational indoor air quality issues can be up to nearly 100％. The amount of CO generated during PCO would be negligible in comparison to the indoor CO levels. These results can make the PCO reactor an important tool in the effort to improve non-occupational indoor air quality.

• Korean Journal of Materials Research
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• v.25 no.4
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• pp.183-190
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• 2015

Fatigue crack growth rate tests were conducted as a function of temperature, dissolved hydrogen (DH) level, and frequency in a simulated PWR environment. Fatigue crack growth rates increased slightly with increasing temperature in air. However, the fatigue crack growth rate did not change with increasing temperature in PWR water conditions. The DH levels did not affect the measured crack growth rate under the given test conditions. At $316^{\circ}C$, oxides were observed on the fatigue crack surface, where the size of the oxide particles was about $0.2{\mu}m$ at 5 ppb. Fatigue crack growth rate increased slightly with decreasing frequency within the frequency range of 0.1 Hz and 10 Hz in PWR water conditions; however, crack growth rate increased considerably at 0.01 Hz. The decrease of the fatigue crack growth rate in PWR water condition is attributed to crack closure resulting from the formation of oxides near the crack tips at a rather fast loading frequency of 10 Hz.

• Proceedings of the Korean Society for Applied Microbiology Conference
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• 2000.04a
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• pp.94-99
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• 2000

Bioluminescence is being used as a prevailing reporter of gene expression in microorganisms and mammalian cells. Bacterial bioluminescence draws special attention from environmental biotechnologists since it has many advantageous characteristics, such as no requirement of extra substractes, highly sensitive, and on-line measurability. Using bacterial bioluminescence as a reporter of toxicity has replaced the classical toxicity monitoring technology of using fish or daphnia with a cutting-edge technology. Fusion of bacterial stress promoters, which control the transcription of stress genes corresponding to heat-shock, DNA-, or oxidative-damaging stress, to the bacterial lux operon has resulted in the development of novel toxicity biosensors with a short measurement time, enhanced sensitivity, and ease and convenient usage. Therefore, these recombinant bioluminescent bacteria are expected to induce bacterial bioluminescence when the cells are exposed to stressful conditions, including toxic chemicals. We have used these recombinant bioluminescent bacteria in order to develop toxicity biosensors in a continuous, portable, or in-situ measurement from for air, water, and soil environments. All the data obtained from these toxicity biosensors for these environments were found to be repeatable and reproducible, and the minimum detection level of toxicity was found to be ppb (part per billion) levels for specific chemicals.

• Food Science and Biotechnology
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• v.15 no.1
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• pp.112-116
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• 2006

Levels of ethyl carbamate, by-product produced naturally during fermentation, in Korean alcoholic beverages were determined by Gas Chromatography/mass spectrometry/selected ion mode (GC/MS/SIM), and their daily intake by Korean adult group was estimated. In GC/MS/SIM analysis 0.8-10.1, 0.5-0.8, 0.4-0.9, 3.5-689.9, 8.4-30.3, 13.9-30.0, and 1.7-11.7 ppb of ethyl carbamate were detected in soju, beer, takju, fruit wine, cheongju, whiskey, and grape wine, respectively. Maximum daily exposure of ethyl carbamate through alcoholic beverage consumption was 7.41 ng/kg body weight/day for average Korean male, with one soju brand and two fruit wine brands showing high ethyl carbamate level.

• Journal of Environmental Health Sciences
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• v.31 no.4 s.85
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• pp.260-265
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• 2005

Indoor air quality might be affected by source strength of indoor pollutants, ventilation rate, decay rate, outdoor level, and so on. Although technologies measuring these factors exist directly, direct measurements of all factors are not always practical in most field studies. The purpose of this study was to develop an alternative method to estimate the source strength and deposition constant by application of multiple measurements. For the total duration of 60 days, indoor and outdoor $NO_2$ concentrations every 3 days were measured in 30 houses in Seoul, Asan and Daegu. Using a compartment model by mass balance and linear regression analysis, penetration factor (ventilation divided by sum of air exchange rate and deposition constant) and source strength factor (emission rate divided by sum of air exchange rate and deposition constant) were calculated. Subsequently, the source strength and deposition constant were estimated. Natural ventilation was $1.80{\pm}0.42\;ACH,\;1.11{\pm}0.50\;ACH,\;0.92{\pm}0.26\;ACH$ in Seoul, Asan and Daegu, respectively. Calculated deposition constant(K) and source strength of $NO_2,$ in this study were $0.98{\pm}0.28\;hr^{1}\;and\;16.28{\pm}7.47\;ppb/h,$ respectively.