• Asian-Australasian Journal of Animal Sciences
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• v.28 no.6
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• pp.816-826
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• 2015

The present experiment evaluated the influence of moisture level and anaerobic fermentation on aerobic stability of total mixed ration (TMR). The dynamic changes in chemical composition and microbial population that occur after air exposure were examined, and the species of yeast associated with the deterioration process were also identified in both non-fermented and fermented TMR to deepen the understanding of aerobic deterioration. The moisture levels of TMR in this experiment were adjusted to 400 g/kg (low moisture level, LML), 450 g/kg (medium moisture level, MML), and 500 g/kg (high moisture level, HML), and both non-fermented and 56-d-fermented TMR were subjected to air exposure to determine aerobic stability. Aerobic deterioration resulted in high losses of nutritional components and largely reduced dry matter digestibility. Non-fermented TMR deteriorated during 48 h of air exposure and the HML treatment was more aerobically unstable. On dry matter (DM) basis, yeast populations significantly increased from $10^7$ to $10^{10}cfu/g$ during air exposure, and Candida ethanolica was the predominant species during deterioration in non-fermented TMR. Fermented TMR exhibited considerable resistance to aerobic deterioration. Spoilage was only observed in the HML treatment and its yeast population increased dramatically to $10^9cfu/g$ DM when air exposure progressed to 30 d. Zygosaccharomyces bailii was the sole yeast species isolated when spoilage occurred. These results confirmed that non-fermented and fermented TMR with a HML are more prone to spoilage, and fermented TMR has considerable resistance to aerobic deterioration. Yeasts can trigger aerobic deterioration in both non-fermented and fermented TMR. C. ethanolica may be involved in the spoilage of non-fermented TMR and the vigorous growth of Z. bailii can initiate aerobic deterioration in fermented TMR.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.3
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• pp.1265-1271
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• 2014

The lamp cooling system of the exposure has effect on the exposure efficiency and device lifetime. In this paper, we performed the numerical analysis about the thermal flow in the lamp housing of the exposure apparatus for the cooling air inflow rate. We set up the velocity of cooling air of side and bottom as the independent variables because cooling performance of the lamp housing is affected by the velocity of the cooling air side and bottom. The cooling state of lamp housing depend on three dependent variables; the temperature at top mirror and exhaust gas, ellipsoidal mirror. Response surface methodology was used in order to establish the efficient cooling analysis plan. The regression equation predicting the variables temperature of lamp housing according to the cooling air velocity were drawn. The velocity of cooling air to reach the optimum temperature of the lamp housing were derived.

• Journal of Environmental Health Sciences
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• v.48 no.1
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• pp.44-51
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• 2022

Background: Air pollution is increasing together with industrialization and urbanization. In order to reduce air pollution, public transportation is recommended rather than private cars, and the number of passengers using public transportation is increasing accordingly. This study observes the concentration of indoor pollutants in city buses over time. Through this means, we intend to suggest a plan to manage the indoor air quality in city buses. Objectives: The concentration of indoor pollution in public transportation was investigated from April 2021 to January 2022. Based on this, we evaluated the exposure to indoor pollutants. Methods: Six city bus lines in an industrial city were selected for the research, and indoor pollution was measured through IoT (Internet of Things)-based sensor-type measuring devices. The concentration of pollutants was measured every minute, and statistical data were constructed based on the measurement results. Results: In all the city buses studied, the average concentration of pollutants were below the guidelines. However, some measurement results showed cases of exceeding the guidelines. As a result of the analysis by time zone, there were more cases in which pollutants exceeded the standard value during rush hour compared to at other times. A risk assessment for PM₁₀ was performed by evaluating the excess mortality risk from exposure and the risk from inhalation exposure. Conclusions: All measured indoor pollutants in the city buses did not exceed the guidelines. Also, the risk assessment results were found to be within the level of safety. However, if a city bus is used for a long time, there is a possibility that there may be an impact on the human body due to inhalation exposure, so additional management is required.

• Proceedings of the Korean Society of Toxicology Conference
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• 2003.10b
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• pp.112-112
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• 2003

Air pollution is made up by complex mixture exhausted from cars, industries and incinerators etc. Those pollutants come from everywhere without border and contain phototoxic and photogenotoxic chemicals including PAHs exhausted in the air. We have published that the chemicals which show phototoxicity and photogenotoxicity are closely related in mechanistic and the PAHs react as a strong photocatalyzer by radical productions under UV exposure.(omitted)

• Journal of Radiation Protection and Research
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• v.38 no.4
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• pp.234-236
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• 2013

Some of radioactive contamination is unavoidable in the facilities using the unsealed radioactive material. The primary purpose of radioactive contamination control in the workplace with contamination concern is the effects from the potential intake of radioactive material into the body. This paper provides procedures to estimate the level of internal exposure for the worker based on the conservative assumptions and simple calculations. They consist of two processes; to calculate air concentration of radioactive material and annual intake by inhalation with contaminated air and to compare each of them to Derived Air Concentration and Annual Limit on Intake mentioned in the related notification. The procedures are applicable to make a decision on practical requirements for monitoring air contamination and internal exposure of worker as follows; needs for measurement of air contamination and internal exposure and acquisition of information on the design of the ventilation system.

• Journal of Preventive Medicine and Public Health
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• v.39 no.1
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• pp.53-58
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• 2006

Objectives: We wanted to evaluate the main route of exposure to lead and cadmium for the general population in Korea by using multi-route and multi-media exposure assessment Methods: Samples of air at the homes, samples of the food and water and peripheral blood samples were collected from thirty volunteers living in Seoul (the metropolitan area), Yong-in (the suburban area) and Ansan (the industrial area) in 2001. Graphite furnace atomic absorption spectrometric methods were used for the determination of the Pb and Cd levels in the air, food, water and blood samples. Results: The average intake of lead through the air, drinking water and food were $5.06{\mu}g/day\;(26.3%)\;0.002{\mu}g/day\;(0.1%),\;and\;16.4{\mu}g/day\;(73.6%)$, respectively. The average intake of cadmium through the air, drinking water and food were $0.082{\mu}g/day\;(0.9%),\;0.001{\mu}g/day\;(0.007%),\;and\;12.61 {\mu}g/day\;(99.0%)$, respectively. The blood lead level was statistically higher in the male subjects than in the female subjects (3.39 and $2.22{\mu}g/dl$, respectively), and only gender was a significant variable on the multiple regression analysis for blood lead. Conclusions: This study showed that the intake of lead and cadmium through food was the major route of exposure. A policy to reduce the pollutants according to the exposure routes should be established. However, more studies will be needed to support these data for the general population.

• Journal of Environmental Health Sciences
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• v.33 no.4
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• pp.227-234
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• 2007

Recent epidemiologic studies show that gestational exposure to air pollution adversely affects pregnancy outcomes including low birth weight in preform birth. In this study, we evaluated the effect of air pollutants on LBW (low birth weight) on firstborn fetus throughout the gestational period using the birth cohort between 1999 and 2003 in Seoul. Using birth cohort data from the National Statistics Office of Korea we identified 288,346 firstborn births (excluded missing data on lack of information for birth weight and discordance between residential and certificated address from a total of 316,451) during 1999 to 2003 with complete covariate (gender, parity, date of birth, gestational age, parental age and educational level, maternal occupation etc.) and maternal residential history data. Our subjects were defined as more than 37 weeks and less than 44 weeks of completed gestation and we identified 5,457 persons (1.89%) by low birth weight (<2.5 kg) in this study. Using logistic regression, we estimated the risk of mean (entire pregnancy and trimester period) air pollution concentrations for CO, $O_3,\;PM_{10},\;NO_2\;and\;SO_2$. In terms of trimester-specific exposure, we found that some air pollutants exposure in each trimester would increase the risk for LBW. Results also showed that the effect size of air pollutants exposure during the first and third trimester is higher than during the second trimester. In all trimester, the estimated risk of LBW was 1.831 (95% CI=1.573-2.132) with unit increase for CO, 1.139 (95% CI=1.107-1.172) for 50, and 1.009 (95% CI=1.001-1.017) for $O_3$. Our results suggest that exposure during the gestation period to relatively low levels of some air pollutants may be associated with a reduction in birth weight on first-born fetus. These findings implicate the effective risk management strategies should be applied to minimize the public health impacts for pregnant women.

• Journal of Environmental Health Sciences
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• v.43 no.2
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• pp.157-166
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• 2017

Objectives: Exposure to hazardous air pollutants could be affected by sociodemographic factors such as age, gender and more. Information on time spent in microenvironments has a critical role in exposure assessment. The purpose of this study was to analyze the exposure pathways which influence personal exposure through time-activity patterns and sociodemographic factors. Methods: A total of 379 subjects were collected from the second term of the Korean National Environmental Health Survey. A questionnaire survey in relation to sociodemographic factors and a time-activity diary were carried out for personal exposure to toluene. Focusing on personal exposure to toluene, factors affecting personal exposure were analyzed using multiple regression analysis. Results: Participants spent their time in an indoor house for $16.8{\pm}4.0hr$, workplace or school $2.3{\pm}3.5hr$, and other indoor $2.1{\pm}2.2hr$. Sociodemographic factors were significantly different among each personal exposure and microenvironment. Time of staying at an office turned out to be a main factor from point of exposure in exposure pathway using multiple regression analysis. As a result, this means that exposure may be different according to the time of staying in each microenvironment. Conclusions: Personal exposure to air pollutants might be decided by time-activity pattern indicating when, where, and which activities people pursue, as well as individual sociodemographic factors.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.20 no.2
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• pp.102-110
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• 2010

Personal exposure relies on characteristics of time activity patterns of the population of concern as human activities impact the timing, location, and level of personal exposure. The information about time spent in microenvironments plays a critical role for personal exposure to air pollutants. It is useful to determine the precise times of the day that the subjects are in certain locations or engaging in specific activities because exposure to some air pollutants can depend on temporal trends. This study investigated time activity pattern for workers of Korean population over 19 years old with 8,778 workers in weekday. The residential indoor times were 12 hours. Time activity was different by gender and the mean times stayed at home in weekday were 12.9 hours in female and 11.42 hours in male, respectively. The major factors on residential indoor time and workplace time were age, monthly income, occupation and industry type, work position, education, and gender. Considering shorter than those in other countries, Korean workers spent less time at home after the working hours. Determinants of time activity pattern need to be taken into account in exposure assessment, epidemiological analyses, exposure simulations, as well as in the development of preventive strategies. Since there are substantial difference of Korean worker activity pattern, this information can be critical for exposure assessment in Korea.

• Journal of Korean Society for Atmospheric Environment
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• v.16 no.6
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• pp.625-631
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• 2000

Practical devices for measuring personal exposure to nitrogen dioxide(NO$_2$) have been made for epidemiological studies of the health effects of air pollution Standard methods for NO$_2$ measurement such as the chemiluminescent method and Saltzman method are not suitable for personal exposure because they are heavy, large and complicated to operate. In this study, a passive monitor was tested for the measurements of indoor and outdoor NO$_2$ level. Through a comparative analysis of data sets obtained by on-site chemiluminescence system, we assessed the accuracy and precision of NO$_2$ passive monitors. We also examined the possibility of passive monitor in the study of indoor, outdoor and personal NO$_2$ exposure. The accuracy and precision of NO$_2$ passive monitor were analyzed assuming measurements of on-site chemiluminescence system is reference value and using duplicated measure- ments, respectively. From these analysis the NO$_2$ passive monitor was useful for measuring indoor, outdoor and personal exposure. And NO$_2$ level from on-site chemiluminescence systems could not properly represent the personal NO$_2$ exposure as well as indoor and outdoor level of ones house. Personal exposures were correlated more strongly with indoor NO$_2$ concentrations than with outdoor NO$_2$ concentrations. Since activity pattern of each person is different, it was considered that personal daily behavior and life-style might prevent the air pollutant exposure.