• 한국학교보건학회지
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• 제23권1호
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• pp.29-40
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• 2010

Purpose: The purposes of this study were: (a) to assess indoor air quality such as $PM_{10}$, $CO_2$ concentrations in child daycare centers, (b) to compare the levels with each standard, and (c) to identify teachers' awareness of indoor air quality in child care centers. Methods: Data were obtained from seventeen child daycare centers and ninety-eight teachers in a district of Seoul, from April 3 to May 12, 2009. Collected data were analyzed by SAS 8.2, and descriptive statistics, $x^2$ test, student t-test, Pearson correlation analysis, and Spearman rank correlation were used. Results: The mean of $PM_{10}$ and $CO_2$ level were $50.3{\mu}g/m^3$ and 792.1ppm. Sixteen child daycare centers (94.2%) met the guidelines of the $PM_{10}$ level, so did thirteen child daycare centers (76.5%) in the $CO_2$ level. $CO_2$ levels were significantly low in child daycare centers using air cleaners than those do not using them (t=-6.03, p<.001). Types of child daycare centers were significantly correlated to the levels of $CO_2$, which public child daycare centers were low in $CO_2$ levels than those of private child daycare centers (t=-2.54, p=.013). There was no significant correlation between teachers' awareness and management attitude of indoor air quality while teachers' awareness of indoor air quality significantly raised the frequency of carpet cleaning. Methods of cleaning routines were significantly correlated with $PM_{10}$, and $CO_2$ levels. Conclusion: The $PM_{10}$ and $CO_2$ concentrations in child daycare centers were satisfactory. Those conditions are affected by general characteristics of child daycare centers and teachers' attitude regarding management of indoor air quality.

• 대한임상독성학회지
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• 제10권2호
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• pp.122-125
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• 2012

Alocasia was originally distributed throughout subtropical and tropical areas. Recently, in Korea, it has been used in air cleaners and in control of humidity. Despite easy access in Korea, there are few reports on Alocasia toxicity. We report on two cases of Alocasia intoxication. One patient was a 16-month-old male, who was admitted with a complaint of irritability after biting leaves of Alocasia. Four hours later, he was discharged without any symptoms. Another patient, a 52-year-old female, complained of oral pain, numbness on the perioral area, dysphonia, swallowing difficulty, and chest and abdominal pain after eating root stuck of alocasia odora. She underwent gastrointestinal fibroscopy (GIF) due to lasting chest and abdominal pain. Finding on GIF showed erythema and swelling in the aryepiglottic fold and larynx. Her symptoms lasted 13 days; she was then discharged without any complications or sequelae.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.1423-1428
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• 2003

We investigated the amount of the toxic gases emitted from the Electrostatic Precipitators(ESPs), which were currently used by indoor air cleaners. We used the wire-to-plate(WTP) type and the needle-to-plate(NTP) type corona discharger in our study. Using the voltage, the polarity of wire, the number of needles of NTP as the input variables, we studied the characteristic of Ozone and $NO_x$ generation in the ESPs. As the results, we found out that the concentration of Ozone, $NO_2$ and $NO_x$ is increased, but the amount of NO is decreased with increasing the voltage and the number of needles. And we knew that the generation rate of ozone and $NO_x$ is very related with the corona region.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2009년도 춘계학술대회 논문집
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• pp.1970-1976
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• 2009

This paper describes a series arc detection algorithm in a low-voltage wiring system. We designed and fabricated an arc detection circuit which consists of a high-pass filter with the low cut-off frequency of 170 kHz to attenuate power frequency. The series arcing phenomena was simulated by an arc generator specified in UL1699. In the experiment, various loads such as resistive loads, resistive loads controlled by a dimmer, and vacuum cleaners were used. Whether the signal is arc or noise is discriminated by pulse counts and periodicity of the detected signal.

• Environmental Engineering Research
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• 제12권5호
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• pp.203-210
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• 2007

Since the emissions composition from the household products have potentially been associated with health risks for building occupants, the chemical composition emitted from the products should be surveyed. The current study identified the emission composition for 42 liquid household products, using a purge-and-trap method. This evaluation was done by classifying the household products into five product classes (deodorizers, household cleaners, color removers, pesticides, and polishes). Nineteen compounds were chosen on the basis of selection criteria. The quality control program for purge-and-trap and analytical systems included tests of laboratory blank Tenax traps and blank water samples, and the determination of calibration equation, measurement precision, method detection limit (MDL), and recovery. The number of chemicals varied according to the product categories, ranging from 4 for the product category of bleaches to 12 for the product categories of air fresheners and nail color removers. For all product categories, the emission composition and concentrations varied broadly according to product. It is noteworthy that most household products emit limonene: 19 of 25 cleaning products; 5 of 6 deodorizers; 1 of 3 pesticides; 3 of 3 color removers; and 4 of 5 polishes. It was suggested that the use of household products sold in Korea could elevate the formation of secondary toxic pollutants in indoor environments, by the reaction of limonene with ozone, which entered indoor environments or might be generated by indoor sources such as electronic air cleaning devices and copying machines.

• 설비공학논문집
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• 제23권2호
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• pp.126-131
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• 2011

Cyclone, a type of particle collector widely used in the field of ambient sampling and industrial particulate control, is the principal type of gas-solids separator that uses a centrifugal force. The goal of this study is to design and evaluate the cyclone that can be used for the household vacuum cleaners. A multi cyclone with a 1st cyclone and several 2nd cyclones is designed to improve dust collection efficiency. The dust collection efficiency and the suction power of 1st cyclone are evaluated. And the dust collection efficiency and the suction power of multi cyclone are evaluated according to various sizes of inlet and vortex finder. As a result, a cone shape porous filter has better dust collection efficiency than a cylinder shape porous filter. The dust collection efficiency of a multi cyclone is 3.5% greater than that of a single cyclone.

• 수산해양기술연구
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• 제53권3호
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• pp.302-307
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• 2017

An electric steam boiler equipped with a condensate recovery system, which stores the condensate generated after using steam in steam washers, steam cookers, steam irons, and steam cleaners in a condensate tank and supplies compressed air to the condensate tank so that the condensate is recovered to the boiler by the pressure of the compressed air, was studied. In the results of this study, the heat energy balance between the quantity of the heat generated by the non-metallic surface heating element and the quantity of the heat absorbed by the water was good in a range of ${\pm}5%$. In addition, the heat transfer rate increased in proportion to the electric power of the surface heating element heater, the waste heat energy was normally recovered by the recovery of the condensate of the steam boiler equipped with the high compression waste heat recovery system, and the recovery rate of the waste heat exhibited 23%.

• 한국산업보건학회지
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• 제15권1호
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• pp.71-81
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• 2005

The purposes of this study was to collect, analyze, and describe the MF exposure levels from subways in Korea and to measure and evaluate the MF levels generated from electric appliances used at general homes. The target subway lines were Seoul Metropolitan Line 1 to Line 8, Bundang Line, Incheon Line, Daegu Line, Gwangju Line, and Busan Line 1 and Line 2. We measured at each station in those subway lines and, all the train types (pantograph-equipped, motor-equipped, and common), and platform types(facing and isolating) were investigated by the distance(80, 200, 400 cm) from the train on 19 targeted subway lines using 3 magnetic field measuring devices (EMDEXII, Enertech Co.) during the survey from January till October, 2004. On the other hand, the levels of the 60Hz magnetic fields generated from 14 items of home electric appliances such as electric blankets, hair dryers, electric razors, etc. were measured at 10 general homes using 5 EMDEXII meters with a sampling interval of 1.5 second by the distance(surface, 30, 50, 100, 300cm ) from the target electric appliances. The survey results in the whole subway lines examined in this study were as follows; Seoul Metropolitan Line 4 using AC(alternating current) power source showed the highest mean value of $2.85{\mu}T$, followed by Seoul Metropolitan Line 1 running between Seoul and Incheon using AC($2.78{\mu}T$), Seoul Metropolitan Line 1 between Seoul and Uijongbu using AC($2.73{\mu}T$), Bundang Line using AC($1.79{\mu}T$), Seoul Metropolitan Line 1 connected from Yongsan using AC($1.67{\mu}T$), Seoul Metropolitan Line 1 between Seoul and Suwon using AC($0.79{\mu}T$), and so on. In general, the intensity of the magnetic field in the subway systems in Korea was significantly higher when using AC($2.14{\pm}0.91{\mu}T$) than when using DC($0.29{\pm}0.44{\mu}T$) power source. Among the home electric appliances examined, microwave ovens showed the highest mean value of $7.69{\mu}T$, followed by hair dryers($6.47{\mu}T$), vacuum cleaners($5.27{\mu}T$), televisions ($2.26{\mu}T$), electric blankets($1.38{\mu}T$), personal computers ($0.81{\mu}T$), and so on. Two items of electric appliances showed the excess value of $0.2{\mu}T$ at the distance of 30cm in the MF exposure level; electric razors $1.58{\pm}2.13{\mu}T$ and vacuum cleaners $0.48{\pm}0.44{\mu}T$. As a whole, this study showed a tendency that the shift of the MF levels according to the increase of distance from the electric appliances was lower than those of the results surveyed in UK and USA. As a result, this study is expected to suggest meaningful data for the future study in exposure assessment of magnetic fields and for the establishment of guidelines for subways and electric appliances in Korea. More detailed and large scaled exposure assessment studies should be performed continuously to get the various and useful information on health risk assessment of MFs in Korea.

• 대한기계학회논문집B
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• 제27권10호
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• pp.1442-1449
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• 2003

We investigated the amount of the toxic gases emitted from the Electrostatic Precipitators(ESPs), which are currently used as the indoor air cleaners. The existing wire-to-plate(WTP) and neddle-to-plate(NTP) types of ESP designs are considered as the experimental corona dischargers. Using the voltage, the polarity of wire, the number of needles of NTP as the input variables, we studied the generation characteristics of ozone and $NO_{x}$ and the particle removal efficiency in the ESPs. As the results, we found out that the concentration of ozone, $NO_{2}$ and $NO_{x}$ is increased with increasing the voltage and the number of needles, but the amount of NO is decreased. And we observed that the generation rates of ozone and $NO_{x}$ are mainly related with the corona region through the photographs. Finally the experimental results showed that the particle removal efficiency of ESP with WTP type charger is more superior to that with NTP type chargers at the same voltage.

• Safety and Health at Work
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• 제10권3호
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• pp.377-383
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• 2019

Objectives: Exposure to fine particles in urban air has been associated with a number of negative health effects. High levels of fine particles have been detected at underground stations in big cities. We investigated the exposure conditions in four occupational groups in the Stockholm underground train system to identify high-exposed groups and study variations in exposure. Methods: $PM_1$ and $PM_{2.5}$ were measured during three full work shifts on 44 underground workers. Fluctuations in exposure were monitored by a real-time particle monitoring instrument, pDR, DataRAM. Qualitative analysis of particle content was performed using inductively coupled plasma mass spectrometry. Nitrogen dioxide was measured using passive monitors. Results: For all underground workers, the geometric mean (GM) of $PM_1$ was $18{\mu}g/m^3$ and of $PM_{2.5}$ was $37{\mu}g/m^3$. The particle exposure was highest for cleaners/platform workers, and the GM of $PM_1$ was $31.6{\mu}g/m^3$ [geometric standard deviation (GSD), 1.6] and of $PM_{2.5}$ was $76.5{\mu}g/m^3$ (GSD, 1.3); the particle exposure was lowest for ticket sellers, and the GM of $PM_1$ was $4.9{\mu}g/m^3$ (GSD, 2.1) and of $PM_{2.5}$ was $9.3{\mu}g/m^3$ (GSD, 1.5). The $PM_1$ and $PM_{2.5}$ levels were five times higher in the underground system than at the street level, and the particles in the underground had high iron content. The train driver's nitrogen dioxide exposure level was $64.1{\mu}g/m^3$ (GSD, 1.5). Conclusions: Cleaners and other platform workers were statistically significantly more exposed to particles than train drivers or ticket sellers. Particle concentrations ($PM_{2.5}$) in the Stockholm underground system were within the same range as in the New York underground system but were much lower than in several older underground systems around the world.