The purpose of this study is to create a new odor analysis technology that combines the separation technology of GC and the measurement of MOS sensors. The detector of the GC system is replaced with the MOS sensor to analyze various odor compounds. Carrier gas also used air in the normal atmosphere through a micro pump. Therefore, it is possible to develop a portable odor analysis device since no additional cylinder is needed. Retention times for H2S, C7H8, and C2H4O analyzed by the combined GC/MOS system were identified as 1.28 minutes, 3.88 minutes and 1.77 minutes, respectively. Measurement reproducibility of odorous RT was very good at less than 1.2 %RSD. Also, the magnitude of the peak as a result of changes in the concentration of each odor showed a linear proportional relationship. Thus, a new method could be proposed to analyze various odorous substances with the combined GC/MOS system.

This study was performed to investigate the contamination characteristics of water in the scrubber with the aim of stably maintaining the scrubber, and to comprehend the removal characteristics of sulfur compounds, which are odorous substances, when microbubbles were supplied to the circulation water tank of a scrubber. The results of our analysis found that 63 kinds of gas compounds were detected from the scrubber, and thus it could be determined that Sulfur compounds, Ammonia (base compounds), Aldehyde compounds, and Pyrazine compounds were generated from the process for the production of sesame oil. About 93% of ammonia was removed in the scrubber; however, it was hard to remove Sulfur compounds, Aldehyde compounds and Pyrazine compounds using the scrubber. The efficiency of hydrogen sulfide, methylmercaptan and dimethydisulfide removal using only water in the scrubber was 79.8%, 79.7%, and 81.0%, respectively. However, when microbubbles were supplied to the scrubber, the removal efficiency for each was 83.7%, 91.1%, and 96.1%, respectively. Therefore, it was confirmed that the efficiency of sulfur compound removal was improved by supplying microbubbles to the circulation water tank of the scrubber. In addition, the amount of removal that could be achieved by using microbubbles was 1.05- 1.19 times higher than using only water. In terms of supplying microbubbles, it was confirmed that the saturation time required to absorb odorous gases was about 2.8 times longer than the time without microbubbles because the OH radicals generated when the microbubbles are shrinking partly oxidized organic matter. When there was no chemical in the circulation water tank, the conductivity and CODCr concentration were highly correlated. Therefore the system, which can replace circulation water by using real-time conductivity data, can be considered to be applicable.

In this study, 40 residents of the Gwangyang and Yeosu areas were assessed for their level of exposure to heavy metals (As, Cd, Ni) from April 2017 to June 2018. The aim was to understand the differences in levels of indoor exposure to heavy metals (As, Cd, Ni), and a health risk assessment was conducted to determine whether there was any fatal cause from carcinogenic elements. The mean concentrations of PM10 particles indoors were As 0.24 μg/m3, Cd 0.07 μg/m3, and Ni 0.89 μg/m3. The health risk assessment for the arsenic, cadmium, and nickel in indoor air confirmed that the mean values exceeded the cancer risk tolerances specified by the U.S. EPA, for As (males 3.07 × 10−4, females 3.35 × 10−4), Cd (males 3.83 × 10−5, females 4.18 × 10−5), and Ni (males 6.36 × 10−5, females 6.95 × 10−5).

A pilot-scale biocover was installed at a sanitary landfill for municipal waste, and the removal of volatile organic compounds (VOCs) by the biocover was evaluated for a long period of 550 days. The biocover (2.5 m W × 5 m L × 1 m H) was constructed with the mixture of soil, perlite, earthworm cast and compost (6:2:1:1, v/v). The total VOCs concentration of the inlet gas into the biocover was 820.3 ppb~7,217.9 ppb, and the total VOCs concentration of the outlet gas from the surface of the biocover was 12.6 ppb~1,270.1 ppb. The average removal efficiency of total VOCs was 87.6 ± 11.0% (60.5% for minimum and 98.5% for maximum). Toluene concentration was the highest among the inlet VOCs, followed by ethylbenzene, m, p-xylene and o-xylene. These aromatic VOCs accounted for more than 50% of the total VOCs concentration. Other than these aromatic VOCs, hexane, cyclohexane, heptane, benzene, and acetone were major VOCs among the inlet VOCs. Compared with the VOC profiles in the inlet gas, the relative contribution of dichloromethane to the outlet VOCs emitted from the biocover layer increased from 0.1% to 15.3%. The average removal efficiencies of BTEX in the biocover were over 84% during the operation period of 550 days. The average removal efficiencies of hexane, cyclohexane and heptane in the biocover were 86.0 ± 18.9%, 85.4 ± 20.4% and 97.1 ± 4.0%, respectively. The removal efficiency of VOCs in the biocover decreased not only when the ambient temperature had fallen below 5oC, but also when the ambient temperature had risen above 23oC. Information on the VOCs removal characteristics of the biocover installed in the landfill field can be useful for commercializing the biocover technology for the treatment of VOCs.

This study was conducted to determine the absorption properties of silicone oil, liquid paraffin, and silicone rubber as absorbents for hydrophobic volatile organic compounds (VOCs) mainly emitted from the printing and publishing industry through VOCs absorption efficiency and partition coefficient. Also, changes in absorbability were tested through blending of absorbents and load of target VOCs mixtures. The results obtained can be used as fundamental data to choose an appropriate absorbent. All of the three absorbents showed an excellent absorption efficiency of above 98% for each 5 wt% load of the target VOCs including toluene, xylene, methyl ethyl ketone (MEK), isopropyl alcohol (IPA), 1,2,4-trimethylbenzene (124-TMB), and n-Nonane. In terms of toluene load, all absorbents showed good absorption efficiency of above 95% to a high load of 15 wt%. The air-absorbent partition coefficient of each target compound (P value) exhibited the highest value of 9.8 × 10−5 for 124-TMB in silicone rubber and the lowest value of 1.6 × 10−2 for IPA in liquid paraffin. These results indicate that the target VOCs had high affinity for the three absorbents. Absorption efficiency for the target VOCs at various absorbent blending ratios using three kinds of absorbents was improved to 99.9% regardless of the absorbent type or blending ratio. This result suggests that the shortcomings of single absorbents can be overcome through absorbent blending, enabling cost reduction and applicability to a dry-type treatment process. In treatment for mixture of the target VOCs to mimic an actual VOCs treatment, the absorption performances of silicone oil showed an absorption efficiency of 99% for 16 wt% of total VOCs load. These results indicated that silicone oil could be considered as a good absorbent.

Charcoal canisters are broadly used for radon detection because of their handiness and short sampling period. Radon detection using charcoal canisters are known to be susceptible to surrounding conditions such as temperature and humidity. Public radon inspectors cannot handle extreme temperature, and the relative humidity can differ in districts due to the use of different types of construction. Thus, if relative humidity can be controlled at the entrance of a charcoal canister, radon inspectors will be able to procure more reliable data. The purpose of this study was to assess the efficiency of existing filters in a charcoal canister and to apply a new type of filter (Super Absorbent Polymers, SAP) that can control the moisture penetrating into the charcoal canister. Based on adequate case studies using the new filter, radon data have shown over 98% close to the reference data irrespective of varying moisture levels. Meanwhile, basic filters showed 88% similarity compared to the reference data, which means that charcoal canisters were affected by moisture. The SAP filter is reasonably inexpensive and once it turns into its gel shape (which, in turn, is saturated by moisture), it can be easily replaced. This filter will not only be able to provide more accurate radon data, but also apply to other gas phase material detections that are sensitive to moisture in the air.

A number of studies on airborne pollutants and microorganisms using ultraviolet sterilization have been conducted. Countermeasures are also needed to be taken against contamination and damage that occur on indoor surfaces in addition to indoor air. In this study, a method to predict UV-C intensity distribution using radiance calculation was introduced for the purpose of surface sterilization using UVGI systems and compared with the measured UVC intensities in a kitchen model room. The results of calculations showed a similar distribution of ultraviolet intensity with the measured intensities, although there was some discrepancy, probably due to different reflectance of building materials. And some bacteria and viruses occasionally identified in kitchens were predicted to be sterilized 99.9% only after about 30 minutes of UV-C irradiation with the figure 90% for fungi. The sterilization performance of UVGI and exposure time to UV-C were reasonably predicted using the radiance calculation method, and UV sterilization can be achieved with great effect even after a short period of time.

In this study, we measured the concentration of total volatile organic compounds (TVOCs) in four different seasons from 2016 to 2017 in order to determine seasonal variation of indoor air quality in relation to public transportation modes (subways, trains, and express buses). The measurement was carried out both during rush hour when traffic was congested as well as during non-rush hour when traffic was not congested. Effects by season, degree of congestion, and characteristics of public transportation were analyzed on the basis of 295 items of data during the periods of congestion and 295 items of data during the periods of non-congestion. The average TVOCs concentration in winter was the highest with 226.4 μg/m 3 . The average TVOCs concentration on an express bus was the highest with a seasonal average of 142.3 μg/m 3 . The TVOCs concentration in the period of congested traffic was higher than in the period of non-congested traffic for all public transportation modes. For the average TVOCs concentration by season and transportation, there was no data that exceeded the guidelines regarding maintaining indoor air quality. However, 2.5% of all sample measured data (TVOCs) exceeded the guidelines regarding maintaining indoor air quality. Therefore, the continuous monitoring of public transport vehicles is required.

This study was performed to assess particulate matter removal efficiency of domestic air cleaner products in a field condition. The assessment also included air cleaners with different air removal mechanisms. The particulate matter (PM2.5) removal test with a different air removal mechanism using air cleaners showed that the electrostatic precipitation technique showed better performance compared with HEPA filters and other types of systems. Its removal efficiency was almost 95% in one of our operation times in the given test condition. It was assumed that not only the type of removal system but also the individual design, supply and exhaust system, and the automatically controlled air volume are involved in the removal efficiency. With respect to the area of application, tests with air cleaners for 40 m2, 60 m2, and 80 m2 areas revealed that particulate matter removal efficiency increased with the air cleaner that had a broad area of application. However, particulate matter removal efficiency by air cleaners did not correspondingly increase with the increase of the area of application. Moreover, the installation location did not influence particulate matter removal efficiency. Our results are expected to be used as the basic information for indoor air quality improvement and prediction using air cleaners.

To reduce subway passengers’ exposure to PM 10 (particulate matter less than 10 micrometers), management of PM 10 concentration in underground stations is critical. In this study, we attempted to investigate the distribution of airflow PM 10 concentration in an underground station. The numerical simulations were performed using computational fluid dynamics. In order to apply to CFD, measurement of air volume (supplied and exhausted air) and PM 10 concentration were conducted at the concourse and platform areas of the underground station. The results of the simulation agreed with the actual PM 10 concentration, and we confirmed the distribution of PM 10 concentration depending on air volume conditions. This result will be helpful to reduce the PM 10 in an underground station when using ventilation system.