This study examines the effects of surrounding outdoor environmental characteristics in multi-use public facilities that are used by the susceptible population, on the concentration and distribution of indoor airborne bacteria. For this study, areas were divided into ‘factory area,’ ‘city area,’ and ‘forest area.’ The research was conducted from October 2017 to April 2018, and the selected target facilities were daycare centers, hospitals, postpartum care centers, and nursing homes for the elderly. In order to measure airborne bacteria, indoor air samples were collected using a six-stage viable particulate cascade impactor, and airborne bacteria samples were collected using MCE (Mixed cellulose esters) filters. Moreover, the outdoor airborne bacteria concentration was also measured to determine the concentration ratio (I/O ratio) of the total indoor airborne bacteria and total outdoor airborne bacteria concentrations. The results showed that the total outdoor airborne bacteria concentration was highest in the city area, with 74.2 ± 60.0 CFU/m3, and the lowest in the factory area, with 45.9 ± 35.8 CFU/m3. Furthermore, the distribution of the total outdoor airborne bacteria concentrations significantly differed across each surrounding environment (p < 0.05). On the other hand, no statistically significant difference in total indoor airborne bacteria concentrations, according to surrounding environments, was observed (p > 0.05). These findings suggest that the concentration of outdoor airborne bacteria differs across surrounding environments, unlike that of the indoor airborne bacteria.

Mold is one of the harmful biological pollutants in the indoor environment. To investigate how the contamination degree of mold existing in the indoor environment differs according to the characteristics of the house, the concentration of mold in the indoor air was investigated for the houses damaged by leakage or flooding. As a result of a survey of 20 houses located in Gyeonggi-do and Chungcheong-do, the concentration of mold in indoor air surprisingly exceeded more than two times the recommended indoor air quality standard of 500 CFU/m3 in all the houses investigated. The fungal concentration was high in houses with condensation and mold odors. As for the housing type, the pollution degree was higher in detached houses than in row houses. As for the type of water damage, mold contamination was higher in the leaky houses than in the flooded houses. The degree of mold concentration was 1,237 CFU/ m3 in the leaky houses. In terms of housing age, pollution was very high in houses over 20 years old. The occurrence of these measured mold concentrations was correlated at a significant level with respect to the properties of the house. This study shows that in the case of water damaged houses, careful management of mold contamination is required.

Mold grows more easily when humidity is higher in indoor spaces, and as such is found more often on wetted areas in housing such as walls, toilets, kitchens, and poorly managed spaces. However, there have been few studies that have specifically assessed the level of mold in the indoor spaces of water-damaged housing in the Republic of Korea. We investigated the levels of airborne mold according to the characteristics of water damage types and explored the correlation between the distribution of mold genera and the characteristics of households. Samplings were performed from January 2016 to June 2018 in 97 housing units with water leakage or condensation, or a history of flooding, and in 61 general housing units in the metropolitan and Busan area, respectively. Airborne mold was collected on MEA (Malt extract agar) at flow rate of 100 L/min for 1 min. After collection, the samples were incubated at 25oC for 120 hours. The cultured samples were counted and corrected using a positive hole conversion table. The samples were then analyzed by single colony culture, DNA extraction, gene amplification, and sequencing. By type of housing, concentrations of airborne mold were highest in flooded housing, followed by water-leaked or highly condensed housings, and then general housing. In more than 50% of water-damaged housing, the level of airborne mold exceeded the guideline of Korea's Ministry of Environment (500 CFU/m3). Of particular concern was the fact that the I/O ratio of water-damaged housing was greater than 1, which could indicate that mold damage may occur indoors. The distribution patterns of the fungal species were as follows: Penicillium spp., Cladosporium spp. (14%), Aspergillus spp. (13%) and Alternaria spp. (3%), but significant differences of their levels in indoor spaces were not found. Our findings indicate that high levels of mold damage were found in housing with water damage, and Aspergillus flavus and Penicillium brevicompactum were more dominant in housing with high water activity. Comprehensive management of flooded or water-damaged housing is necessary to reduce fungal exposure.

봄철 천식환자 가정집 9곳에서 실내 공기를 포집하여 부유진균의 농도 및 다양성을 조사하였다. 조사된 천식환자 가정집의 평균 부유진균 농도는 거실 143 CFU/m³, 방 142 CFU/m³ 이었으며 외기보다 낮았다. 이는 다중이용시설 실내공기질 기준법의 권고기준 기준치 500 CFU/m³를 초과하지 않았음을 보여준다. 총 59균주를 분리하였으며 5속 33종으로 동정하였다. 이 중 병원균으로서 인체에 위해성을 가지고 있는 진균은 4속 12종이었다. 동정된 종 중 Cladosporium crousii, Penicillium maximae, Aspergillus protuberus는 국내에 보고되지 않은 미기록 진균 종으로 확인하였다. 이 중 A. protuberus는 국외에서 인체에 질병을 유발시키는 균으로 알려진 진균이다. 이상의 결과는 천식환자 가정에서 진균의 관리는 정량적 수준에서뿐만 아니라 유해종을 파악하여 관리하는 정성적인 수준에서도 이루어져야 함을 제시한다. 본 연구는 봄철 천식환자 가정집에 존재하는 실내 공기 중 부유진균의 농도 및 다양성에 대한 최초의 연구이다.

한반도 주변 해상사고가 증가함에 따라 원격탐사 자료를 활용한 선박탐지 연구의 중요성이 점점 더 강조되고 있다. 이 연구는 고해상도 광학영상에 의존하는 기존 선박탐지 분야에 수백 개 채널의 분광정보를 포함하는 초분광영상을 활용하여 새로운 선박탐지 알고리즘 제시하였다. 두 차례의 현장관측을 통해 측정한 선박 선체의 반사 스펙트럼과 AVIRIS (Airborne Visible/Infrared Imaging Spectrometer) 초분광센서 영상의 선박 및 해수 반사 스펙트럼 간의 분광정합 기법을 적용하였다. 총 다섯 개의 탐지 알고리즘 spectral distance similarity (SDS), spectral correlation similarity (SCS), spectral similarity value (SSV), spectral angle mapper (SAM), spectral information divergence (SID)를 사용하였다. SDS는 선박 일부가 해수로 탐지되는 오차를 나타내었고, SAM은 선박과 해수 사이에 약 1.8배의 차이를 나타내어 명확한 분류 결과를 보여주었다. 이와 더불어 본 연구에서는 각 기법의 최적 임계값을 제시하여 초분광 영상에 포함되어 있는 선박을 분류하였으며 그 결과 SAM, SID가 다른 탐지 알고리즘에 비해 우수한 선박탐지 능력을 보여주었다.

This study aims to analyze the effects of 4 directions of wind, wind speed, year of construction of slate roofs, installation area and other factors on the concentration and size distribution of airborne fiber particles in farmhouses with a slate roof containing asbestos. Airborne fiber particle samples were collected from the air in six houses with a slate roof containing asbestos using a high flow rate pump (10 L/min) for 2 hours, three times a day with a different condition, 72 times in total. The airborne fiber particle concentrations were measured using a phase contrast microscope, and the size of fiber particles of 72 samples in total was estimated using the mean value of those in each sample measured at 100 with a field of view. The total average concentration of fiber particles collected from in the air in four directions of the targeted farmhouses was 2.83 fiber/L, and its maximum concentration was 5.75 fiber/L, which means that among all samples there was no place that exceeded 10 fiber/L, a recommended indoor air quality standard. The average size of the fiber particles was 11.55 μm, and the maximum size was 40 μm. A multiple regression analysis of factors affecting the concentration and size of fiber particles in the air collected from the farmhouses with a slate roof containing asbestos found that the closer to the main wind direction (p<0.001) and the faster the average wind speed (p<0.05), the fiber particles concentration became significantly higher. In this case, the coefficient of determination was 52.8%. It was also found that the wider the total area of the slate roof (p<0.001) and the slower the average wind speed (p<0.05), the longer the fiber particles; the coefficient of determination for this finding was 19.6%. The concentration of fiber particles in the air of farmhouses with a slate roof appeared to be the highest under the main wind direction, and became significantly higher as the wind speed became faster. This proved that fiber particles were leaked from the slate roof. The size of the fiber particles became significantly longer as the area of the slate roof became wider and the wind speed became slower.

The aim of this study was to examine indoor fungal concentration and fungal volatile organic compounds(VOCs) in single-person households. A total of 22 houses occupied by one person were investigated in this study. 19 VOCs detected in the field were estimated as fungi-derived VOCs through a review of the literature, and 11 VOCs were confirmed as fungal VOCs by laboratory experiments. Exposure to fungal VOCs in the indoor environment has been confirmed to be highly influenced by airborne fungal concentration and indoor humidity. 3-octanone was characterized by a clear generation profile in Aspergilus versiocolor, and n-decane in Pencillum chrysogenum. ntetradecane emitted by Stachybotrys chartarum exhibited a tendency to occur consistently. The observations made in this study demonstrated that single-person households can easily be exposed to fungi, and MVOCs can be used as an indicator of fungal exposure in indoor environments.

In this study, we analyzed the factors affecting the concentration of airborne asbestos fiber in the indoor and outdoor environment of a slate roofing house, and performed a health risk assessment of residents living in houses with slate roofs. Sampling was conducted at ten houses with slate roofs on 3 different days under different weather conditions. A high flow rate pump was used for sampling. The specimen was assessed using a phase-contrast microscope. The degree of risk of exposure to asbestos was assessed using EPA’s carcinogen risk assessment method. Asbestos fiber concentrations for slate roofing houses were 2.43 fiber/L inside and 2.46 fiber/L outside, respectively. The correlation between the indoor and outdoor asbestos fiber concentration was 0.486. But on both sides, the asbestos fiber concentrations did not exceed the standard (10 fiber/L) for ambient air in Korea. The factors affecting the concentration of asbestos fiber were year of construction (p<0.05), total roof area (p<0.05) and average wind velocity (p<0.01). According to EPA’s ELCR (Excess Lifetime Cancer Risk) on air pollution substances, a level of 1.0E-04~1.0E-06 should be maintained. However, the ELCR level of 6 out of 10 houses was over 1.0E-04. Therefore, a risk management plan for residents of slate roofing houses must be prepared immediately.

Per capita nail-products use and airborne VOCs emission in four techniques of nail care (full coat coloring, UVgel polish, repair silk, and acrylic overlay) are estimated in this study. These assessments were carried out in a sealed test chamber using artificial hand and nails. A polish remover and a gel cleanser as cleanser and acrylic liquid as solvent were the most commonly used nail products in all 4 of the nail care techniques. Acetone, isopropyl alcohol, and methanol, which are major components of a polish remover, were commonly detected in all nail care techniques while acetone was detected the most. In addition to these airborne VOCs, a variety of other components such as ethyl acetate, cyclohexane, and toluene were identified in full coat coloring technique. In the process of UV-gel polish care technique, the main airborne VOCs were caused by solvents and were not involved in the curing process of UV gels (base gel and top gel) and gel bonder. In the case of repair silk nail care techniques, which generated the most VOCs, the total amount of VOCs detected was about 1,118.8 ± 359.6 mg/capita. Of the VOCs, butane (862.2 ± 283.9 mg/capita), which is contained in glue dryer, represented the largest share. In the process of acrylic overlay nail care technique, ethyl methacrylate (EMA), which is the basic element of acrylic, and highly toxic methyl methacrylate (MMA) were detected at 396.6 ± 42.3 mg/capita and 141.8 ± 8.2 mg/capita, respectively. The per capita data is very useful in designing a ventilation system for environmental improvement of a nail shop and setting a health care policy for nail artists and customers.

With increasing interest, there have been studies on LiDAR(Light Detection And Ranging)-based DEM(Digital Elevation Model) to acquire three dimensional topographic information. For producing LiDAR DEM with better accuracy, Filtering process is crucial, where only surface reflected LiDAR points are left to construct DEM while non-surface reflected LiDAR points need to be removed from the raw LiDAR data. In particular, the changes of input values for filtering algorithm-constructing parameters are supposed to produce different products. Therefore, this study is aimed to contribute to better understanding the effects of the changes of the levels of GroundFilter Algrothm’s Mean parameter(GFmn) embedded in FUSION software on the accuracy of the LiDAR DEM products, using LiDAR data collected for Hwacheon, Yangju, Gyeongsan and Jangheung watershed experimental area. The effect of GFmn level changes on the products’ accuracy is estimated by measuring and comparing the residuals between the elevations at the same locations of a field and different GFmn level-produced LiDAR DEM sample points. In order to test whether there are any differences among the five GFmn levels; 1, 3, 5, 7 and 9, One-way ANOVA is conducted. In result of One-way ANOVA test, it is found that the change in GFmn level significantly affects the accuracy (F-value: 4.915, p<0.01). After finding significance of the GFmn level effect, Tukey HSD test is also conducted as a Post hoc test for grouping levels by the significant differences. In result, GFmn levels are divided into two subsets ( ‘7, 5, 9, 3’ vs. ‘1’). From the observation of the residuals of each individual level, it is possible to say that LiDAR DEM is generated most accurately when GFmn is given as 7. Through this study, the most desirable parameter value can be suggested to produce filtered LiDAR DEM data which can provide the most accurate elevation information.

This study investigated the emission characteristics of airborne particles and bacteria from six types of household vacuum cleaners in the closed chamber. A test cleaner without HEPA filter was examined focusing on the first one minute of initial operation, observing significant generation of airborne particles, and especially for particle size of 0.5 to 2.5 μm, the generation rate increased up to 68.5 × 103 particles/min. Concentrations of airborne particles and bacteria depends on the production year, the motor power, and the dust filter efficiency of the vacuum cleaner. The observed results should be taken into consideration in the design of the vacuum cleaner as well as how they are operated in indoor environment.

Recently SARS and bird flu has been infected widely in the world; we have to care about germs and virus in indoor air environment. Especially that transmission by means of transportation is a major infection route. In this study, a private car simulated with CFD for prediction of indoor airborne microbe transport. Simulation performed with real situation in car, four occupants with a infected driver and four stage air ventilation controled by HVAC system. Result show that CFD can be visualized microbe transport other occupants and who is more exposed to airborne microbe. also it make a prediction of microbe transport in car.

Since airborne fungi have been known to aggravate indoor air quality, studies on developing anti-fungal filters increase recently. In this study, silver (Ag) nanoparticle was selected as anti-fungal agent. HEPA filter was coated with silver nanoparticles which were generated via spark discharge system operating at atmospheric pressure and temperature. The anti-fungal effect of the Ag-filter was evaluated with the conventional culture assay. When the number of Ag nano particle per a fungal particle in the filter was 1.91X106, the fungicidal efficiency was higher than 99%. As another anti-fungal test, ATP bioluminiscence detection method was also carried out and the results were correlated with those of the culture assay.

Recently, airborne fungi as indoor air pollutant have attention due to its health related problems such as asthma, rhinitis, sinusitis, atopy, pneumonia, building syndrome and etc.. However, it is considered that current laws and policies in Korea are not efficient to deal with these problems. Our research investigated influential factors and species distribution on the basis of previous research related to airborne fungi issue conduced in Korea by applying meta analysis technique. We selected 15 articles containing variables affecting fungi population such as outdoor air characteristics, temperature, location, and ventilation to evaluate significant factors. It was confirmed that airborne fungi level has partial correlation to those factors despite of limited sample size. It is required that the consistent and systematic research effort should be extended to characterize health effect caused by these fungi as well as to control them efficiently.