• Environmental Analysis Health and Toxicology
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• v.17 no.2
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• pp.125-133
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• 2002

Volatile disinfection by-products (DBPs) contained in chlorinated tap water are released into household air during indoor activities (showering, cooking, dish -washing, etc.) associated with tap water uses and may cause adverse health effects on humans. Twenty seven subjects were recruited and their homes were visited during the winter of 2002. Tap water, household air, and exhaled breath samples were collected and analyzed for five volatile DBPs (chloroform, bromodichloromethane, dichloroacetonitrile, 1,1 -dichloropropanone and 1,1,1 trichloropropanone). Chloroform was a major DBP found in most samples. Tap water chloroform concentrations were not statistically correlated with its household air concentrations, probably due to individual variability in indoor activities such as showering, cooking, and dish - washing as well as household ventilation. Correlation of breath chloroform concentration with household air chloroform concentration showed its possible use as a biomarker of exposure to household air chloroform. Exposure estimates suggested that inhalation during household stay be a major route of exposure to volatile DBPs and that ingestion of tap water be a trivial contributor to the total exposure in Koreans.

• Journal of Mushroom
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• v.19 no.1
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• pp.14-22
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• 2021

This study investigated the changes in the antioxidant activity, nitrite scavenging activity, and ��-glucan content of processed raw materials (Pleurotus eryngii, Pleurotus ostreatus, Lentinula edodes, and Flammulina velutipes) brought about by storage at room temperature (20-25℃) and low temperature (4℃). The results indicated that DPPH free radical scavenging activity was the lowest in air-dried and roasted samples that were stored at room temperature, k with the exception of the air-dried samples of P. eryngii and L. edodes. For total polyphenol contents, all roasted samples of the edible mushrooms stored at room and low temperature decreased compared with the samples pre-storage, except for the air-dried samples of P. eryngii, P. ostreatus, and L. edodes. Furthermore, the ferric reducing antioxidant power and reducing power of the air-dried and roasted samples stored at room temperature and low temperature tended to increase compared to that before storage. Moreover, the ��-glucan content in the air-dried and roasted samples stored at room temperature was significantly lower compared to that before storage, as well as to that in the samples stored at low temperature (p<0.05). The results of this study may help predict the degree to which biological activities in processed edible mushrooms change when stored at room temperature and/or low temperature conditions.

• Journal of Korean Society for Atmospheric Environment
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• v.14 no.3
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• pp.163-176
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• 1998

In this study, airborne particle samples were obtained to determine the concentrations of particulate air pollutants in indoor and outdoor air of public facilities in Taegu area. Total of 12 public facilities, regulated by the Public Sanitary Law, were selected as sampling sites, which include three underground arcades, one railway and two bus terminals, three general hospitals, and three department stores. In each place, sampling was carried out seasonally during the period of October 1994 to July 1995, and four samples per each site per season were collected both indoors and outdoors simultaneously. After determination of suspended particulate matter (SPM) mass concentrations, the particle samples were divided into two parts for subsequent chemical analysis: one for the analysis of trace elements and the other for water soluble ions. Seasonal levels of SPM appeared to be the highest in spring and the lowest in summer both indoors and outdoors, while locational variations of highest in statioyterminals, and lowest in department stores . SPM concentrations indoors and outdoors did not show any significant differences each other in most places . However, there were significant correlations between indoor and outdoor levels of SPM and other chemical species . These results indicates that indoor SPM levels are likely to be significantly affected by outdoor sources in many places. The most significant source of SPM was estimated to be the resuspension of soil/road dust both indoors and outdoors . The concentrations of toxic heavy metals (Pb, Cd, Cr, Cu) in underground arcades appeared to be very much lower than the established air quality guidelines for underground environments. In addition, it is likely that micro-environmental parameters such as temperature, humidity, and air velocity, play a less significant role than outdoor air quality as a factor affecting the levels of particulate pollutants in indoor environments of public facilities in Taegu area.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.12
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• pp.6072-6081
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• 2013

In this study, experiments were performed on air heater samples with three different shapes (chevron, wave and dimple type) to reduce the plumes from cooling towers. The tests were conducted for a range of frontal air velocities of 1~3 m/s and water flow rate 0.19~0.33 kg/s. The results showed that the heat transfer rate increased with increasing air velocity or water flow rate. The air-side pressure drop also increased with increasing air velocity. At the same frontal air velocity, the highest heat transfer rate was obtained for the chevron sample (1.5~1.7 times compared to that of the plate sample), followed by the dimple, wave and plate samples. The heat transfer rate per unit power consumption was also 15% larger than that of the dimple sample. On the other hand, there was no noticeable difference between the other samples.

• Analytical Science and Technology
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• v.18 no.5
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• pp.431-435
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• 2005

In order to evaluate the hazardous effects of environmental tobacco smoking (ETS), we measured the concentrations of major aromatic VOC from those who decided to participate in a program to quit smoking. By acquiring the air samples both before and after quitting smoking (QS), we were able to compare their BTEX concentration levels in their breathing air. The results of our study clearly showed that BTEX levels in respiring air samples were significantly high prior to the QS period. It was found that toluene maintained the highest concentration levels both before and after the QS period. However, the level of reduction was most significant in the case of benzene, as it was decreased 10 times from 4.8 to 0.46 ppb. When their reduced BTEX levels are compared to those who never smoked before, differences were not significant enough to distinguish in statistical terms. The overall results of this preliminary study suggest that BTEX levels in breathing air samples can be used as one of the most sensitive signals to judge the effect of QS.

• Korean Journal of Food Science and Technology
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• v.33 no.2
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• pp.245-251
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• 2001

This research was conducted to study the changes in physical characteristics of mushrooms (Agaricus bisporus) as influenced by drying methods. Samples were dried using either hot air drying, vacuum drying, or freeze drying and changes in the color, browning index, hardness and rehydration rate were evaluated by response surface methodology. Hot air drying resulted in the fastest drying of sample as compared to other methods. The rate of drying was most affected by the environmental temperature rather than air velocity or vacuum pressure. The overall color difference increased as the temperature and air velocity increased. The overall color changes of the freeze dried samples were minimal as compared to those of fresh mushrooms. The hot air dried samples showed the greatest changes in the overall color, browning index as well as hardness. The freeze dried samples showed the best rehydration characteristic and maintained the best overall quality after drying.

• Biomedical Science Letters
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• v.29 no.4
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• pp.363-370
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• 2023

Human respiratory viral infections such as COVID-19 are highly contagious, so continuous management of airborne viruses is essential. In particular, indoor air monitoring is necessary because the risk of infection increases in poorly ventilated indoors. However, the current method of detecting airborne viruses requires a lot of time from sample collection to confirmation of results. In this study, we proposed a system that can monitor airborne viruses in real time to solve the deficiency of the present method. Air samples were collected in liquid form through a bio sampler, in which case the virus is present in low concentrations. To detect viruses from low-concentration samples, viral RNA was concentrated and extracted using silica-magnetic beads. RNA binds to silica under certain conditions, and by repeating this binding reaction, bulk samples collected from the air can be concentrated. After concentration and extraction, viral RNA is specifically detected through real-time qPCR (quantitative polymerase chain reaction). In addition, based on liquid handling technology, we have developed an automatic machine that automatically performs the entire testing process and can be easily used even by non-experts. To evaluate the system, we performed air sample collection and automated testing using bacteriophage MS2 as a model virus. As a result, the air-collected samples concentrated by 45 times then initial volume, and the detection sensitivity of PCR also confirmed a corresponding improvement.

• Safety and Health at Work
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• v.3 no.3
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• pp.235-240
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• 2012

The objectives are to compare the airborne asbestos concentrations resulted from mitering of abestos cement roof sheets by a high-speed motor and a hand saw, and to monitor whether other workers near the test sites are vulnerable to the fibers exceeding the occupational exposure limit. Four test cases were carried out and altogether 7 personal and 4 area air samples were collected. The NIOSH method 7400 was employed for the air samplings and analysis. Using the phase contrast microscopy, fiber counting was conducted under Rule A. The study showed that the fiber concentration medians for personal air samples gathered from the two tools were 4.11 fibers/cc (ranged: 1.33-12.41 fibers/cc) and 0.13 fibers/cc (ranged: 0.01-5.00 fibers/cc) respectively. The median for the area samples was 0.59 fibers/cc (ranged: 0.14-3.32 fibers/cc). Comparing each study case, the concentration level caused by the high-speed motor saw was more than twice that of the hand saw. According to the area samples, the workers nearby the test site are at risk from high exposure to asbestos.

• Journal of Korean Society for Atmospheric Environment
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• v.21 no.3
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• pp.285-293
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• 2005

This study was aimed at estimation of gas-particle partitioning of polychlorinated biphenyls (PCBs) in ambient air. The samples were collected at urban site in Japan from March 2002 to January 2003. The concentration of total PCBs (from 4 CB to 10 CB) and TEQ (Toxic equivalent) ranged from 62 to $247\;pg/m^3$ and from 2 to $14\;fgTEQ/m^3 $, respectively. The average contribution $(\%)$ of gas phase to total PCBs concentration was above $80\%$, which suggests that in the atmosphere PCBs predominantly existed in the gas phase. The weak correlations between total PCBs concentration and temperature was found. However this result was due to a typhoon during summer and raining during sampling period. The gas-particle partition coefficient (Kp) was obtained as a function of temperature. The partition ratio of gaseous and particulate phase PCBs can be estimated for an arbitrary temperature. The plot of gas/particle partition coefficient (log Kp) vs. sub-cooled liquid vapor pressure $(log\;P_L)$ had reasonable correlations for individual samples but the slope varied among the samples (coefficients of determination for log Kp versus log $P_L$ plot were> 0.76 $(p<0.0001)$, except for 3 samples). As a result, the variations in the slope among the sampling period may be due to change of temperature, raining during sampling period and wind in this study.

• Geomechanics and Engineering
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• v.2 no.4
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• pp.321-335
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• 2010

This article describes a laboratory research on stabilizing tropical peat using ordinary Portland cement (OPC) as a binding agent, and polypropylene and steel fibres as chemically inert additives. California bearing ratio (CBR) and unconfined compressive strength (UCS) tests were carried out to evaluate the increase in the strength of the stabilized samples compacted at their optimum moisture contents and air cured for up to 90 days. The results show that the UCS values of stabilized peat samples increased by as high as 748.8% by using OPC (5%), polypropylene fibres (0.15%), and steel fibres (2%). The CBR values of the samples stabilized with OPC (5%), polypropylene fibres (0.15%), and steel fibres (4%) showed an increase of as high as 122.7%. The stabilized samples showed a shrinkage in volume upon air curing and this shrinkage was measured by an index called, volume shrinkage index (VSI). The highest VSI recorded was 36.19% for peat without any additives; and the minimum was 0% for the sample containing 30% OPC, 0.15% polypropylene fibres and 2% steel fibres. The technique of stabilizing peat with OPC, polypropylene and fibres, coupled with air curing, appears to be cost-effective compared with other frequently used techniques.