• Particle and aerosol research
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• v.18 no.3
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• pp.51-59
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• 2022

In this work, virion concentration and its dose changes by HVAC and air cleaners were estimated in a subway station platform to control airborne infection of SARS-CoV-2. Collection efficiencies with particle size were measured for the air filter equipped in a HVAC in one subway station in Daejeon. Indoor PM_2.5 changes according to outdoor PM_2.5 with time were also measured to estimate air infiltration rate in the subway station platform. When infected persons generate virions by 10⁴, 10⁵, 10⁶, 3 × 10⁶ and 5 × 10⁶ h^-1 in a 2,400 m³ volume platform, the concentration and dose were estimated as 9, 92, 275 and 458 virions/m³ and 4, 43, 130 and 217 virions after 1 hour exposure, respectively. The concentration and dose were reduced by 70%, and 64%, respectively by operations of both HVAC (with a flow rate of 16,000 m³/h, MERV 11) and ten air cleaners(with total CADR 10,740 m³/h) compared to those without operation of both HVAC and air cleaners. However, virion dose in the platform was estimated to be too low at the general conditions due to a large space, a high air infiltration (3 h^-1) and a short residence time (usually < 10 mins) in the platform irrespective of the operations of HVAC or air cleaners. HVAC with filters and air cleaners would be more necessary in the concourse or shopping areas in the subway stations to reduce the infection dose from a few hundred to several tens virions in a hour.

• Analytical Science and Technology
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• v.20 no.6
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• pp.474-482
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• 2007

Daycare centers are an important indoor environment for pre-school children and exposure area with potential harmful health effects for infants and children who spend most of their daily life. Sampling was undertaken at 29 daycare centers located Seoul in Korea from January, 2006 to December 2006. The target compounds were 7 individual volatile organic compounds (benzene, toluene, ethylbenzene, m,p-xylene, styrene, o-xylene, TVOC). The mean concentrations of TVOC, toluene, m ,p-xylene, ethylbenzene, benzene and styrene in daycare centers were $318.7{\mu}g/m^3$, $51.6{\mu}g/m^3$, $11.7{\mu}g/m^3$, $6.5{\mu}g/m^3$, $4.2{\mu}g/m^3$, $3.6{\mu}g/m^3$, respectively. Toluene occupied 17.6 % of the concentration of individual VOCs. The ratio of indoor and outdoor (I/O) of TVOC and toluene were 2.0 and 1.6, respectively. The results of characteristics according to a season of a year, the concentration of TVOC were measured $433.9{\mu}g/m^3$, and these concentrations during third quarter of the year in summer were higher than the other season. In the other four seasons, TVOC were measured 280.5 in winter, 298.3 in spring and $264.6{\mu}g/m^3$ in fall, respectively.

• Journal of Environmental Health Sciences
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• v.50 no.2
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• pp.146-156
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• 2024

Background: Children who use playground facilities are exposed to potential risks due to the high concentration of heavy metals contained in the finishing materials of facilities in children's playgrounds. Objectives: The purpose of this study was to investigate the concentration of heavy metals in the finishing materials of outdoor children's playgrounds where harmful heavy metals exist in Gwangju and to conduct human risk assessment for children and adults by age to find the risks and limitations. Methods: The bottom and top layers of double-painted paint were peeled off and collected together from the finishing materials of children's play facilities such as slides, swings, and seesaws in 147 children's parks in Gwangju. Heavy metals were analyzed using ICP-OES, etc., and human risk assessment was performed using the concentrations of heavy metals. Results: Based on 1.0E-04, which requires legal regulation, CTE was found to pose a carcinogenic risk for preschool children and no carcinogenic risk for the rest of the age groups. However, RME showed that both men and women of all ages had a carcinogenic risk. For reference, when the carcinogenic risk was based on 1.0E-06, CTE was found to pose a carcinogenic risk from infants to elementary school students, and RME was found to have a carcinogenic risk in all age groups. It was judged that there is a non-carcinogenic risk if the non-carcinogenic risk exceeds 1 based on the hazard index (HI) 1. In CTE, there was no non-carcinogenic risk, and RME for preschooler males (1.49E+00) and females (1.56E+00) were found to have non-carcinogenic risk. Conclusions: This study was meaningful in that it examines the differences in the current management of heavy metals concentration standards and potential carcinogenic and non-carcinogenic risks to the human body and discusses the relationship between heavy metals and human health effects.

• The Korean Journal of Pesticide Science
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• v.13 no.1
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• pp.39-44
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• 2009

This study was conducted to evaluate the actual risk of fipronil on worker honey bees (Apis mellifera L.) through acute contact toxicity test, acute oral toxicity test, toxicity of residues on foliage test, and small scale field test. The $48h-LD_{50s}$ of fipronil SC on honeybee were $0.005{\mu}g$ a.i./bee in acute contact toxicity test and $0.004{\mu}g$ a.i./bee in acute oral toxicity test, respectively. In toxicity of residues on foliage test, fipronil showed over 90% of mortality during 28days after treatment at recommended application rate. The $DT_{50}$ of dislodgeable foliar residue was 9 days. Finally, In small scale field test, fipronil showed similar toxicity in the residues on foliage test. It was concluded that fipronil has very high acute toxicity and long residual toxicity to honeybee. Therefore, fipronil is highly toxic to bees exposed to direct treatment or residues on blooming crops or weeds. Do not apply this product or allow it to drift to blooming crops or weeds if bees are visiting the treatment area. To protect honeybee and wild pollinators from outdoor use of fipronil, ultimately it should need to limit for only indoor use to prevent pollinators from unintentionally exposure of fipronil.

• Journal of the Korean Institute of Landscape Architecture
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• v.45 no.4
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• pp.1-10
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• 2017

This study investigated indoor temperature and humidity control and PM1 and PM10 mitigation effects of a single green wall (Case 1), two green walls (Case 2), and two green walls plus a waterfall (Case 3) in comparison with a control without either a green wall or waterfall. Experiments were conducted in the office of Chungbuk National University from August to September, 2015. Experiments were carried out sequentially in the order of control, Case 1, Case 2, and Case 3. Data collected from August 17 to August 20, 2015 (Experiment 1), and from August 31 to September 3, 2015 (Experiment 2), when outdoor temperature was relatively constant, were analyzed. Plant volume ratios by indoor landscaping of the control, Case 1, Case 2 and Case 3 were 0.0, 0.6, 1.2, and 1.4%, respectively. Compared to the control, average temperatures of Case 1, Case 2 and Case 3 were decreased by 0.3~0.7, 0.7~0.9 and $1.0^{\circ}C$, respectively, and relative humidity was increased by 1.8~8.7, 9.2~14.6 and 14.8~21.9%, respectively. Three hundred minutes after exposure to mosquito repellent incense particles, the ratio of the remaining PM1 of the control, Case 1, Case 2 and Case 3 were 25.0, 22.0%, 21.2%, 17.3%, respectively, in Experiment 1 and 42.3, 28.9, 23.1, and 30.9%, respectively, in Experiment 2. As indoor greening increased the effect of indoor temperature, PM1 and PM10 mitigation were greater, and temperature and humidity were lower. The greater the relative humidity was, the faster PM1 and PM10 mitigation tended to be.

• Korean Journal of Heritage: History & Science
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• v.54 no.1
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• pp.206-219
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• 2021

The warming of the climate is increasing the damage caused by termites to wooden buildings, cultural properties and houses. A group removal system can be installed around the building to detect and remove termite damage; however, if the site is not visited regularly, every one to two months, you cannot observe whether termites have spread within, and it is difficult to take prompt effective action. In addition, since the system is installed and operated in an exposed state for a long period of time, it may be ineffective or damaged, resulting in a loss of function. Furthermore if the system is installed near a cultural site, it may affect the aesthetic environment of the site. In this study, we created a detection system that uses wood, cellulose, magnets, and magnetic sensors to determine whether termites have entered the area. The data was then transferred to a low power LoRa Network which displayed the results without the necessity of visiting the site. The wood was made in the shape of a pile, and holes were made from the top to the bottom to make it easier for termites to enter and produce a cellulose sample. The cellulose sample was made in a cylindrical shape with a magnet wrapped in cellulose and inserted into the top of a hole in the wood. Then, the upper part of the wood pile was covered with a stopper to prevent foreign matter from entering. It also served to block external factors such as light and rainfall, and to create an environment where termites could add cellulose samples. When the cellulose was added by the termites, a space was created around the magnet, causing the magnet to either fall or tilt. The magnetic sensor inside the stopper was fixed on the top of the cellulose sample and measured the change in the distance between the magnet and the sensor according to the movement of the magnet. In outdoor experiments, 11 cellulose samples were inserted into the wood detection system and the termite inflow was confirmed through the movement of the magnet without visiting the site within 5 to 17 days. When making further improvements to the function and operation of the system it in the future, it is possible to confirm that termites have invaded without visiting the site. Then it is also possible to reduce damage and fruiting due to product exposure, and which would improve the condition and appearance of cultural properties.