• Proceedings of the SAREK Conference
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• 2008.11a
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• pp.537-540
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• 2008

A numerical study has been carried out on the optimization of an air cleaning system which was installed in a heating, ventilation and air conditioning system (HVAC) system of subway station for particle removal. Required particle removal efficiencies of three different air cleaning systems were calculated from ventilation rate, and indoor/outdoor concentration of PM10. Mass balance equations of PM10 were used to solve the required particle removal efficiencies. Fibrous filter was considered as an air cleaning system. Calculations were carried out about two different places which were waiting area and platform of subway station, respectively. This study proposed optimized design and operation condition of each air cleaning system.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.17
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• pp.7769-7779
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• 2015

Background: This study was conducted with the purpose of evaluating the effect of skin cancer training provided to maritime high school students on their knowledge and behaviour. Materials and Methods: The study had a quasi-experimental design with pre-test and post-test intervention and control groups. Two maritime high schools located in the city of Antalya were included within the scope of the study between March and June 2013, covering a total of 567 students. Results: While the knowledge mean scores of students regarding skin cancer and sun protection did not vary in the pre-test ($6.2{\pm}1.9$) and post-test ($6.8{\pm}1.9$) control group, the knowledge mean scores of students in the experimental group increased from $6.0{\pm}2.3$ to $10.6{\pm}1.2$ after the provided training. Some 25.4% of students in the experimental group had low knowledge level and 62.2% had medium knowledge level in the pre-test; whereas no students had low knowledge level and 94.3% had high knowledge level in the post-test. It was determined that tenth grade students, those who had previous knowledge on the subject, who considered themselves to be protecting from the sun better, had higher knowledge levels and their knowledge levels increased as the risk level increased. It was found that the provided training was effective and increased positively the knowledge, attitude and behaviour levels of students in the experimental group in terms of skin cancer and sun protection. Conclusions: Along with the provided training which started to form a lifestyle, appropriate attitudes and behaviours concerning skin cancer and sun protection could be brought to students who will work in outdoor spaces and are members of the maritime profession within the risk group.

• Korean Journal of Environmental Biology
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• v.31 no.4
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• pp.347-352
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• 2013

Outdoor cultivation experiment was conducted with artificial seeds using free-living gametophytes and zoospores of Ecklonia cava to develop FLG (free-living gametophyte) seeding technique. Growth of thalli between FLG and zoospore seeding groups was compared monthly from May to October 2009 at culture farm in Wando, Korea. In September 2009, thalli in the FLG seeding experimental group were $35.9{\pm}0.8$ cm in length, $24.1{\pm}2.62$ g in weight, $2.32{\pm}0.26$ kg $m^{-1}$ in biomass and $22.0{\pm}2.8$ individuals $m^{-1}$ in density. There were no significant differences in length, weight, biomass and density between FLG and zoospore seeding group. Therefore, the FLG seeding technique could replace the zoospore seeding method which would eventually contribute in restoration and conservation of natural resources.

• Journal of Environmental Health Sciences
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• v.45 no.1
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• pp.1-8
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• 2019

Objectives: The purpose of this study was to estimate the ventilation rate of residential homes in Korea through tracer gas methods using indoor and outdoor concentrations of carbon dioxide ($CO_2$) and $CO_2$ generation rates from breathing. Methods: In this study, we calculated the number of occupants in a home by time through data on the average number of people per household from the Korean National Statistical Office and also measured the amount of $CO_2$ generation by breathing to estimate the indoor $CO_2$ generation rate. To estimate the ventilation rate, several factors such as the $CO_2$ generation rate and average volume of residential house provided by the Korean National Statistical Office, indoor $CO_2$ concentrations measured by sensors, and outdoor $CO_2$ concentrations provided by the Korea Meteorological Administration, were applied to a mass balance model for residential indoor environments. Results: The average number of people were 2.53 per household and Koreans spend 61.0% of their day at home. The $CO_2$ generation rate from breathing was $13.9{\pm}5.3L/h$ during sleep and $15.1{\pm}5.7L/h$ in a sedentary state. Indoor and outdoor $CO_2$ concentrations were 849 ppm and 407 ppm, respectively. The ventilation rate in Korean residential houses calculated by the mass balance model were $42.1m^3/h$ and 0.71 air change per hour. Conclusions: The estimated ventilation rate tended to increase with an increase in the number of occupants. Since sensor devices were used to collect data, sustainable data could be collected to estimate the ventilation rate of Korean residential homes, which enables further studies such as on changes in the ventilation rate by season resulting from the activities of occupants. The results of this study could be used as a basis for exposure and risk assessment modeling.

• Horticultural Science & Technology
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• v.33 no.5
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• pp.647-657
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• 2015

To investigate a method for calculation of the heating load for environmental designs of horticultural facilities, measurements of total heating load, infiltration rate, and floor heat flux in a large-scale plastic greenhouse were analyzed comparatively with the calculation results. Effects of ground heat exchange and infiltration loss on the greenhouse heating load were examined. The ranges of the indoor and outdoor temperatures were $13.3{\pm}1.2^{\circ}C$ and $-9.4{\sim}+7.2^{\circ}C$ respectively during the experimental period. It was confirmed that the outdoor temperatures were valid in the range of the design temperatures for the greenhouse heating design in Korea. Average infiltration rate of the experimental greenhouse measured by a gas tracer method was $0.245h^{-1}$. Applying a constant ventilation heat transfer coefficient to the covering area of the greenhouse was found to have a methodological problem in the case of various sizes of greenhouses. Thus, it was considered that the method of using the volume and the infiltration rate of greenhouses was reasonable for the infiltration loss. Floor heat flux measured in the center of the greenhouse tended to increase toward negative slightly according to the differences between indoor and outdoor temperature. By contrast, floor heat flux measured at the side of the greenhouse tended to increase greatly into plus according to the temperature differences. Based on the measured results, a new calculation method for ground heat exchange was developed by adopting the concept of heat loss through the perimeter of greenhouses. The developed method coincided closely with the experimental result. Average transmission heat loss was shown to be directly proportional to the differences between indoor and outdoor temperature, but the average overall heat transfer coefficient tended to decrease. Thus, in calculating the transmission heat loss, the overall heat transfer coefficient must be selected based on design conditions. The overall heat transfer coefficient of the experimental greenhouse averaged $2.73W{\cdot}m^{-2}{\cdot}C^{-1}$, which represents a 60% heat savings rate compared with plastic greenhouses with a single covering. The total heating load included, transmission heat loss of 84.7~95.4%, infiltration loss of 4.4~9.5%, and ground heat exchange of -0.2~+6.3%. The transmission heat loss accounted for larger proportions in groups with low differences between indoor and outdoor temperature, whereas infiltration heat loss played the larger role in groups with high temperature differences. Ground heat exchange could either heighten or lessen the heating load, depending on the difference between indoor and outdoor temperature. Therefore, the selection of a reference temperature difference is important. Since infiltration loss takes on greater importance than ground heat exchange, measures for lessening the infiltration loss are required to conserve energy.

• Journal of Environmental Health Sciences
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• v.48 no.2
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• pp.59-65
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• 2022

Background: Since people move through microenvironments rather than staying in one place, they may be exposed to both indoor and outdoor PM_2.5 concentrations. Objectives: The aim of this study was to assess the exposure level of each sub-population group and evaluate the contribution rate of the major microenvironments. Methods: Exposure scenarios for sub-population groups were constructed on the basis of a 2019 Time-Use survey and the previous literature. A total of five population groups were classified and researchers wearing MicroPEM simulated monitoring PM_2.5 exposure concentrations in real-time over three days. The exposure contribution for each microenvironment were evaluated by multiplying the inhalation rate and the PM_2.5 exposure concentration levels. Results: Mean PM_2.5 concentrations were 33.0 ㎍/m³ and 22.5 ㎍/m³ in Guro-gu and Wonju, respectively. When the exposure was calculated considering each inhalation rate and concentration, the home showed the highest exposure contribution rate for PM_2.5. As for preschool children, it was 90.8% in Guro-gu, 94.1% in Wonju. For students it was 65.3% and 67.3%. For housewives it was 98.2% and 95.8%, and 59.5% and 91.7% for office workers. Both regions had higher exposure to PM_2.5 among the elderly compared to other populations, and their PM_2.5 exposure contribution rates were 98.3% and 94.1% at home for Guro-gu and Wonju, respectively. Conclusions: The exposure contribution rate could be dependent on time spent in microenvironments. Notably, the contribution rate of exposure to PM_2.5 at home was the highest because most people spend the longest time at home. Therefore, microenvironments such as home with a higher contribution rate of exposure to PM_2.5 could be managed to upgrade public health.

• Journal of Environmental Health Sciences
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• v.44 no.2
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• pp.143-152
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• 2018

Objectives: The purpose of this study was to provide basic data for air pollutant exposure modelling and understanding the contribution of respective microenvironments by assessing the time-activity patterns of Korean students according to variables such as grade, sex, weekday, and weekend. Methods: In this study, we compared the residential time of 521 (both weekday and weekend) lower elementary students, 1,735 (1,054 on weekdays, 681 on weekends) upper elementary students, 2,210 (1,294 on weekdays, 916 on weekends) middle school students, and 2,366 (1,387 on weekdays, 979 on weekends) high school students in different microenvironments according to grade, sex, weekday, and weekend. We used data from the 2014 Time-Use Survey by the Korean National Statistical Office for upper elementary students through high school students, and surveyed time-activity patterns of 521 lower elementary students aged 7-9 years. Each microenvironment was divided into indoor, outdoor, and transport. Indoor environments were divided into home, school, and other places. In addition, the results of previous studies were compared to this study. Results: Weekday time-activity patterns of Korean students indicated that lower elementary students spent $16.02{\pm}2.53hr$ in the home and $5.37{\pm}2.32hr$ in school. Upper elementary students spent $14.11{\pm}1.79hr$ in the home and $6.27{\pm}1.37hr$ in school. Middle school students spent $12.83{\pm}2.22hr$ in the home and $7.48{\pm}1.88hr$ in school. High school students spent $10.65{\pm}2.86hr$ in the home and $10.23{\pm}2.86hr$ in school on weekdays. High school students spent the least amount of time in the home and the most time in school compared to other grades Conclusions: Students spent most of their time indoors, including in the home, school, and other indoors. On weekdays, as the grade increases, home residential times were decreased and school residential times were increased. Differences in time-activity patterns according to sex were not found for either weekdays or weekends. It is estimated that Korean students could be affected by school indoor air quality. High school students could be most affected by school indoor air quality since they spent the most time at school.

• Journal of Environmental Health Sciences
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• v.47 no.5
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• pp.410-424
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• 2021

Background: Subway stations have the characteristics of being located underground and are a representative public-use facility used by an unspecified number of people. As concerns about indoor air quality (IAQ) increase, various management measures are being implemented. However, there are few systematic studies and cases of long-term continuous measurement of underground station air quality. Objectives: The purpose of this study is to analyze changes and factors influencing IAQ in subway stations through real-time continuous long-term measurement using IoT-based IAQ sensing equipment, and to evaluate the IAQ improvement effect of a bio-filter system. Methods: The IAQ of a subway station in Seoul was measured using IoT-based sensing equipment. A bio-filter system was installed after collecting the background concentrations for about five months. Based on the data collected over about 21 months, changes in indoor air quality and influencing factors were analyzed and the reduction effect of the bio-filter system was evaluated. Results: As a result of the analysis, PM₁₀, PM_2.5, and CO₂ increased during rush hour according to the change in the number of passengers, and PM₁₀ and PM_2.5 concentrations were high when a PM warning/watch was issued. There was an effect of improving IAQ with the installation of the bio-filter system. The reduction rate of a new-bio-filter system with improved efficiency was higher than that of the existing bio-filter system. Factors affecting PM_2.5 in the subway station were the outdoor PM_2.5, platform PM_2.5, and the number of passengers. Conclusions: The IAQ in a subway station is affected by passengers, ventilation through the air supply and exhaust, and the spread of particulate matter generated by train operation. Based on these results, it is expected that IAQ can be efficiently improved if a bio-filter system with improved efficiency is developed in consideration of the factors affecting IAQ and proper placement.

• Asian-Australasian Journal of Animal Sciences
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• v.6 no.2
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• pp.305-311
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• 1993

A total of thirty male Holstein calves were reared outdoors with simple housings or in warmed pens in three experiments conducted in three consecutive midwinters in Hokkaido. Average outdoor air temperatures during the experiments were between -5.3 and $-6.1^{\circ}C$, and average minimum air temperatures were between -9.7 and $-10.6^{\circ}C$. The age of calves at the start of the experiments were $16{\pm}6$ hours. There was no difference in the liquid feed intake, while the solid concentrate (artificial milk) intake by the calves in the simple housing systems (outdoors, calf hutch and open shed) tended to be higher than those in the warmed pen. No significant differences in the daily gain or the monthly development of wither height were observed among housing systems. There were no serious cases of diarrhea. However, coughing was observed in several of the calves reared in the poorly ventilated warmed pens.

• Journal of Environmental Science International
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• v.16 no.9
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• pp.1019-1026
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• 2007

This study was performed in 30 selected apartments in Seoul, Asan and Daegu area which were constructed within 4 years and over 4 years, to measure the concentration of VOCs(benzene, toluene, xylene) from July, 2004 to September. Mean ratios of indoor to outdoor VOCs concentrations in the construction under 4 years were higher in 1 than average, I/O ratio of over 4 years were lower in 1. This was considered that the VOCs density influences indoor pollutant. For the indoor air quality estimation, the deposition constant and the source strength factor of toluene were $1.49{\pm}2.05\;hr^{-1}\;and\;36.95{\pm}52.26\;ppb/h$, respectively.