• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.12
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• pp.2662-2669
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• 2002

Recently structural applications of adhesive bonding method have been increased extensively in automobile industry. Adhesively-bonded joints which are used in automobile field are exposed to various environmental conditions. In this study, several environmental factors were concerned to evaluate their effects on the adhesive strength such as air temperature, water temperature, exposed time in water. The specimens are exposed for 1, 10 and 100 hours at various air temperatures to evaluate the effects of the air and water temperature on the adhesive strength. It is proved that the adhesive strength decrease with rising the air and water temperature, and the adhesive strength decrease steeply at the higher temperature with increasing the exposure time in water.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.22 no.2
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• pp.91-99
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• 2012

Airborne chlorpyrifos concentrations in formulation workplaces have not been determined in Korea. The aim of the study was to evaluate chlorpyrifos concentrations of air in a formulation workplace and recognize the RBC cholinesterase activities for the formulation workers. 30 air samples (personal or area sampling) were collected and bood samples from 10 workers were collected for RBC chlorinesterase (RBC AChE) activity in a factory on May 2008. Air samples were collected by the National Institute for Occupational Safety and Health (NIOSH) method and were analyzed by GC-MS. Airborne chlorpyrifos concentrations ranged from 0.003 to $12.90mg/m^3$ and geometric mean (GM) was $0.15\;mg/m^3.$ Compared to Korean Occupational Exposure Limit (KOEL) of 0.1 (2011) or $0.2\;mg/m^3$ (2008), at 95% confidence, airborne concentrations exceeded the KOEL 69.7% or 56.1% of the time or less, indicating that this concentration level was unacceptable according to exposure assessment using a LogNorm2$^{(R)}$. Since the workers were continually at work on the organophosphate or carbamate pesticides formulation, individual baseline for RBC AChE activity was not determined. As the results of comparison with reference average value of RBC AChE activity, it was found that a worker was below 70% RBC AChE activity and five workers were abnormal.

• Journal of Korean Society for Atmospheric Environment
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• v.32 no.6
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• pp.575-582
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• 2016

Seoul city has high population density as well as high traffic congestion, which are vulnerable to exposure of environmental pollutions caused by car traffic. However, recent studies are only on local regions about road traffic and air pollution or health effect of road traffic on residents. Thus, comprehensive study data are needed in terms of overall Seoul regions. In this study utilized the nitrogen dioxide concentration through the national air pollution monitoring network data, 2012 to 2013. It also divided regions into high and low exposure districts via the Origin destination data developed by the Korea transport institute to quantify and evaluate the effect of transport policies and analyzed a correlation of asthma symptoms with high and low exposure districts through raw data of community health survey from the Korea centers for disease control and prevention. Based on the collected data, the pearson's correlation analysis was conducted between air pollution substance concentration and high exposure district and multiple logistic regression analysis was conducted to determine the effect of traffic environment and factors on asthma symptoms of residents. Accordingly, the following results were derived. First, the high exposure district was higher concentrations of nitrogen dioxide ($NO_2$) as per time compared to those of the low exposure district (p<0.01). Second, analysis on correlation between average daily environmental concentration in the air pollution monitoring network and road traffic showed that nitrogen dioxide had a significant positive correlation (p<0.01) with car traffic and total traffic as well as with truck traffic (p<0.05) statistically. Third, an adjusted odds ratio about asthma doctor's diagnosis in the high and low exposure districts was analyzed through the logistic regression analysis. With regard to an adjusted model 2 (adjusted gender, age, health behavior characteristics, and demographic characteristics) odds ratio of asthma doctor's diagnosis in the high exposure district was 1.624 (95% CI: 1.269~2.077) compared to that of the low exposure district, which was significant statistically (p<0.001).

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.26 no.3
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• pp.301-306
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• 2016

Objectives: Direct-reading instrument(Photoionization detectors, PID) and quantitative analysis using active type air sampling (Gas chromatography-flame ionization detector, GC-FID) were tested to evaluate their ability to detect volatile organic compounds(VOCs) in a semiconductor manufacturing plant. Methods: The organic compounds used were acetone and ethanol which are normally used as cleaning solutions in the semiconductor manufacturing. The evaluation was based on the preparation of test solutions of known acetone and ethanol concentration in a chamber($600{\times}600{\times}1150mm$). Samples were prepared that would be equivalent to 5~100 ppm for acetone and 10~ 200 ppm ethanol. GC-FID and PID were evaluated simultaneously. Quantitative analysis was performed after sampling and the direct-reading instrument was checked using real-time data logging. Results: Positive correlations between PID and GC-FID were found for acetone and ethanol at 0.04~2.4% for acetone(TLV: 500 ppm) and 0.1~8.3% for ethanol(TLV: 1000 ppm). When the sampling time was 15 min, concentration of test solution was the most similar between measurement methods. However, the longer the sampling time, the less similar the results. PID and GC-FID had similar exposure patterns. Conclusions: The results indicate that PID and GC-FID have similar exposure pattern and positive correlation for detection of acetone and ethanol. Therefore, PID can be used for exposure monitoring for VOCs in the semiconductor manufacturing industry. This study has significance in that it validates measuring occupational exposure using a portable device.

• Journal of Preventive Medicine and Public Health
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• v.14 no.1
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• pp.23-31
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• 1981

This study was conducted to investigate the effects of passive inhalation of cigarette smoke and the correlation between change of flicker value and active or passive smoking in poorly ventilated room. Forty five male students were tested by divided into four experimental groups composed of active and passive smokers and three control groups. Each four experimental groups were exposed to smoke for Two hours in enclosed room. Vital capacities, flicker values, blood carboxyhemoglobin levels and carbon monoxide concentration in room air were estimated before, during and after the exposure, and amounts of smoking or smoke exposure during two hours were also noted. The results obtained were as follows; 1. Concentration of carbon monoxide in air and increase of blood carboxyhemoglobin level (% COHb) were positively correlated with smoking amount. 2. Increase of blood carboxyhemoglobin in passive smokeres, in average, were about seventy six percent of that in smokers, as 2.2% vs. 2.9%. 3. Comparison with published data showed that Peterson's equation gave most similar result to this study in estimation of increase of blood carboxyhemoglobin level. 4. During the exposure, flicker values fell steadily in both experimental groups and control groups as time passed. Flicker values were, however, elevated again in experimental groups after exposure, despite the fact that values still fell in control groups. 5. Blood carboxyhemoglobin and flicker value were negatively correlated and this correlationship was stronger in passive smoker than in active smoker. 6. Multiple regression equation between flicker value and exposure time and blood carboxyhemoglobin level was expressed as: Flicker value=41.6-0.2 COHb%-0.9Hour, 7. In general, it is suggested that biological criteria would be more preferrable than chemical criteria in establishment of statutory limitation of smoking in enclosed spaces.

• Corrosion Science and Technology
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• v.17 no.5
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• pp.231-241
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• 2018

Atmospheric corrosion is generally an electrochemical degradation process of metal. It can be caused by various corrosion factors of atmospheric component, weather, and air pollutants. Moisture, particles of sea salts, and sulfur dioxide are major factors in atmospheric corrosion. Galvanizing coating is one of the most efficient ways to protect iron from corrosion by zinc plating on the surface of the iron. Galvanized steels are being widely used in automobiles, building structures, roofing, and other industrial structures due to their high corrosion resistance compared to bare iron. Atmospheric corrosion of galvanized steel has shown complex corrosion behavior depending on coating process, coating thickness, atmospheric environment, and air pollutants. In addition, different types and kinds of corrosion products can be produced depending on the environment. Lifespan of galvanized steels is also affected by the environment. Therefore, the objective of this study was to determine the corrosion behavior of galvanized steel under atmospheric corrosion at six locations in Korea. When the exposure time was increased, content of zinc from GA surface decreased while contents of iron and oxygen tended to increase. On the other hand, content of iron was constant even after 36 months of exposure of GI.

• Journal of the Korean Medical Association
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• v.61 no.12
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• pp.749-755
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• 2018

Particulate matter is an air pollutant emitted from both natural and anthropogenic sources, and its adverse health effects have been well documented in time-series analyses and cohort studies. The effect size of particulate matter exposure-a roughly 0.5% increase in mortality for each $10{\mu}g/m^3$ increment of short-term exposure to particulate matter with aerodynamic diameter ${\leq}10{\mu}m$ and approximately a 10% increase for each $10{\mu}g/m^3$ increment of long-term exposure to particulate matter with aerodynamic diameter ${\leq}2.5{\mu}m$-is small compared to other risk factors, but the exposure is involuntary and affects the entire population, which makes particulate matter pollution an important public health issue. The World Health Organization and Korean government have both established guidelines for particulate matter concentrations, but the Korean guideline is less stringent than that of the World Health Organization. The annual mean concentration of particulate matter in Korea is decreasing, but the trend seems to be slowing. In addition to policy efforts to reduce particulate matter emission, personal approaches such as the use of face masks and air purifiers have been recommended. Personal approaches may not solve the fundamental problem, but can provide temporary mitigation until efforts to reduce emission make progress.

• Journal of Aquaculture
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• v.16 no.4
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• pp.229-232
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• 2003

Survival with various conditions (water temperature, salinity and air exposure) and sand immersion ability for release of surf clam, Spisula sachalinensis spats, which were artificially seed produced, were investigated. Survival with water temperature conditions of spats showed no difference within the range of 4∼28 $^{\circ}C$ for 10 days. In salinity conditions, survival (%) of spats showed more than 50% in over 22 psu. In air exposure conditions, survival (%) of spats air exposed for 12 hours was no difference within below 2$0^{\circ}C$, however, that of spats air exposed for 16 hours showed below 50% at $25^{\circ}C$. In sand immersion ability, the immersion time was increased with the increase of shell length, and the immersion rate was decreased. Spats of below 15 mm in shell length were emersed more than 90% within 10 min. There was no difference in the immersion time and the immersion rate with the grain sizes of the sand bottom.

• Journal of Radiation Protection and Research
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• v.19 no.1
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• pp.69-80
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• 1994

The TCMI(Three-Compartment Model for iodine) computer code has been developed, which is based on the three-compartment model and the respiratory model recommended in ICRP publication 54. This code is able to evaluate the thyroid burden, dose equivalent, committed dose equivalent and urinary excretion rate as time-dependent functions from the input data: working time and the radioiodine concentration in air. Using the TCMI code, the time-dependent thyroid burdens, the thyroid doses and the urinary excretion rates were calculated for three specific exposure patterns : acute, chronic and periodic. Applicability as an internal dose evaluation method has been assessed by comparing the results with some operational experiences. Simple equations and tables are provided to be used in the evaluation of the thyroid burden and the resulting doses for given I-131 concentration in air and the working time.

• Journal of the Korean Society of Safety
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• v.35 no.1
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• pp.70-78
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• 2020

Nitrox diving was introduced by the NOAA (National Oceanic and Atmospheric Administration) to increase the oxygen content and lower the nitrogen content in respiratory gases. The commercial diving sector specializing in underwater operations has recently introduced regulations on the use of Nitrox. Because the respiratory gas for Nitrox diving has a lower nitrogen content than the normal air, the amount of nitrogen dissolved in the body is small, which not only significantly reduces the decompression time compared to air diving, but also reduces the chance of exposure to decompression sickness. In this study, we applied the VPM (Varying Permeability Model) algorithm to virtual diving with air and Nitrox as a respiratory gas, respectively, to study the optimal Nitrox diving for the safety at the underwater works. The results showed that Nitrox diving had a longer NDL (No-Decompression Limit), a much shorter depression time. In other words, Nitrox diving in underwater works is safer from decompression sickness than commonly used air diving.