본 연구는 지카바이러스, 메르스, coronavirus disease-19 (COVID-19) 등의 감염병 방역 및 의료현장에서 사용할 수 있는 의료용 공기정화호흡기(powered air purifying respirators, PAPR)의 항균성 보호복의 후드와 필터를 개발하였다. PAPR은 전동팬 본체 및 필터, 배터리팩, 후드로 구성되며 보호복의 후드 소재는 뛰어난 흡습성, 풍압, 외부충격을 견딜 수 있는 폴리프로필렌 슐폰레이스(spunlace) 부직포 직물(SFS)을 사용하였다. 사용자의 감염위험을 낮추기 위해 후드의 외피에는 피톤치드계 물질을 사용하여 99.9%의 안티-박테리얼(antibacterial) 효과를 얻었으며 내피에는 친수가공을 하여 흡수성을 25% 향상시켰다. 의료용 보호복 후드에 필요한 인공혈액 침투저항성, 건조미생물 침투저항성, 습식세균 침투저항성, 그리고 박테 리오파아지 침투저항성을 평가한 결과 2~6 단계의 합격평가를 받았다. 한편, 항균 처리된 슐폰레이스(spunlace filter, SF) 헤 파 필터(high efficiency particulate air, HEPA)의 성능을 평가한 결과 우수한 항균성, 분진제거율, 차압 효과를 확인하였다.

High concentrations of fine particles are increasingly being detected due to inflows from abroad and local emission sources in Korea. As most people spend about 90% of their time indoors, the use of indoor air cleaners has grown significantly as they are now thought to be essential items. In this study, the noise, power consumption, and clean air delivery rate (CADR) of commercial air cleaners were analyzed according to the structural shape of the air cleaners. Analyses were performed based on the experimental results of 249 cases for air cleaners certified by Korea Air Cleaning Association. The air cleaners with front inlet and upper outlet air flow direction, which currently account for the highest market share, were found to have the highest noise per CADR (dB(A)/(m3/min)). On the other hand, the air cleaners with the inlet and outlet air flow in the same horizontal direction were found to have lowest noise per CADR than other structures.

Subway trains with air cleaners have been newly deployed in the Seoul Metro system. The purpose of this study was to determine differences regarding in-cabin particulate matter with respect to concentrations less than 10 um (PM10) and 2.5 um (PM2.5) through the operation of air cleaners in subway trains. One subway train newly installed with in-cabin air cleaners on Seoul Metro Line number 2 was chosen monitoring in 2020. In-cabin air cleaners were turned-on at both front and back areas while those in the middle area were turned-off while the train was running. In-cabin PM10 and PM2.5 concentrations were measured in each area using a real-time aerosol monitor. Average in-cabin PM10 concentrations were statistically significantly lower (by 15%) in areas with air cleaners turned-on (43.8±12.1 μg/m3) compared to those areas where the air cleaners were turned-off (51.4±15.0 μg/m3). Average incabin PM2.5 concentrations were significantly lower (by 14%) in areas with air cleaners turned on (33.7±12.2 μg/m3) compared to those areas where air cleaners were turned-off (39.2± 14.4 μg/m3). In-cabin PM10 and PM2.5 concentrations ratios were similar regardless of area with air cleaners turned-on or turned-off. The in-cabin PM10 and PM2.5 concentrations were not associated with commute time. Use of air cleaners in subway trains effected reductions in in-cabin PM10 and PM2.5 concentrations.

This study was undertaken to investigate whether HEPA filter-equipped air purifiers can remove aerosolized virus, whether the removed virus can re-scatter through the filter, and how long the removed virus keeps its infectivity in the filter. For this investigation, six HEPA filter-equipped air purifiers produced by different companies were tested against PhiX174 and MS2 phages aerosolized by nebulizers. For viral detection from the air, LB agar plates covered with Escherichia coli hosts and an Andersen air sampler were used, and from the surface, the swab method was used. Both the aerosolized PhiX174 and MS2 viruses absorbed by the HEPA filters in the air purifiers were not detected from the air through filters or the surface of the outlet of the air purifiers. During the operation of the air purifiers at medium mode, the infectious viral concentration of these viruses in the HEPA filters decreased to 0%~12.3% as the time period passed. These results regarding infectious viral concentration differences were assumed to be due to the different wind speed and air volume among the six air purifiers. Based on observations over 5 days, the infectious viral concentration of the PhiX174 phage was 8,600 times lower when the air purifier was operated than when it was not operated. Overall, our results demonstrate that HEPA filter-equipped air purifiers can efficiently remove the two aerosolized viruses and the removed viruses in the HEPA filter could not re-spread and maintain their infectivity.

물 공급은 늘어나는 담수 수요와 다르게 줄어들고 있다. 담수의 수요를 충당하기 위해서 나노여과법은 가장 효율 적이고 경제적인 방법이라고 할 수 있다. 해수담수화를 위한 나노여과법의 일반적인 방법으로는 나노여과 멤브레인을 이용한 역삼투압 방식이다. 하지만 기존의 멤브레인들은 주요 특성인 안정성, 경제성, 그리고 살균 및 방오특성이 부족하다. 기존의 나노여과 멤브레인을 향상시키기 위해서 친수성과 방오성이 높은 흑연 산화물이 가장 향상성이 높으며 널리 연구되고 있는 재료이다. 멤브레인 변형은 다른 레이어에 적용될 수 있다. 얇은 막으로 이루어진 멤브레인은 다른 세 레이어로 구성되어 있 다, 표면의 폴리아미드 레이어, 기공 레이어, 그리고 전체적인 구조를 구성하는 지원 직물이다. 정삼투압 토한 에너지 효율적 인 해수담수화 방식이지만 효율이 생물 오염 때문에 떨어진다. 산화그래핀 결합은 향균 기능을 향상할 수 있으며 멤브레인 표면에 바이오필름 생성을 억제할 수 있다. 압력지연삼투는 해수에서 청정에너지를 발전시키는 최고의 방법 중 하나이다. 멤 브레인의 생물 오염은 합성 폴리머 멤브레인의 합성 레이어에 산화 그래핀을 합성하여 줄일 수 있다. 나노여과 멤브레인을 개량하는 여러 연구가 각자의 장단점을 가지고 이루어지고 있다. 이 보고서는 나노여과 멤브레인의 개량, 성질, 그리고 성능 에 대해 논의한다.

High concentrations of PM2.5 were generated in new apartments before moving in, and PM2.5 reduction efficiencies using air cleaners and ventilation systems were evaluated. The experimental results for different air cleaner capacities showed that the PM2.5 reduction efficiencies for 46.2 m2, 66 m2, and 105.6 m2 areas were 81.7%, 92.9%, and 92.5%, respectively. Thus, the larger the air cleaning application area, the higher the PM2.5 reduction efficiency. However, there was no difference in the efficiency of overcapacity air cleaners above a certain capacity. The efficiencies of air cleaners located at the living room center, interior wall, and edge were 81.7%, 79.2%, and 75.8%, respectively. There was, therefore, no significant difference in the PM2.5 reduction efficiencies of air cleaners in different locations. Furthermore, the PM2.5 reduction efficiencies at distances of 1 m, 2 m, and 3 m were 81.7%, 81.3%, and 81.7%, respectively. Therefore, there was also no significant difference in efficiency with distance. The PM2.5 concentration decreases rapidly during natural ventilation. Therefore, when the indoor PM2.5 is higher than the outdoor PM2.5, the air cleaner should be used after natural ventilation. The efficiency of PM2.5 reduction using an air supply-type ventilation system in apartments was 35%, which is not high. The simultaneous operation of the ventilation system and kitchen range hood was effective, showing a PM2.5 reduction efficiency of 69.1%. However, a water sprayer was not effective, showing a PM2.5 reduction efficiency of 24.3%. The results of this study suggest that PM2.5 reduction performance should be standardized by evaluating the efficiency of different ventilation systems. Effective usage and maintenance standards for ventilation systems need to be disseminated, and ventilation systems and air cleaners should be used effectively.

The planning acumen led by the crown prince stands out during the banquets that were held continually during the reign of Crown Prince Hyomyung around the late Joseon period from 1827 to 1929. If we examine the changes in banquet space during the period that Crown Prince Hyomyung ruled by proxy, the Jagyeongjeon(慈慶 殿) in Changgyeonggung Palace, which was built during the time of King Jeongjo was repaired after the in 1827 during the reign of the crown prince and appeared in its changed form in Muja Jinjakin 1828. It is believed that the Jagyeongjeonwas expanded and repaired during the reign of Crown Prince Hyomyung to conduct banquets for important guests. Jagyeongjeon which was repaired during the crown prince's reign, is a space where banquets were continuously held during the three years that he reigned, and we can see that it is an important space for royalty where the authority of King Sunjo, Queen Sunwon, and Crown Prince Hyomyung was reflected. Yeongyeongdan(演慶堂) was a structure built in 1828, which is after the period when the Jagyeongjeonwas changed in 1827, and it is a space that emerged during the reign of the crown prince. Hwanchwijeong(環翠亭), which was constructed during the time of King Seongjong was changed after 1827 during the reign of Crown Prince Hyomyung and appeared in its changed form in Muja Jinjakin 1828. Hwanchwijeongwas the place where the Crown Prince Hyomyung stayed and planned banquets and it was repaired along with Jagyeongjeonin 1827. During his reign, the political intent of the crown prince was reflected not in superficial political spaces but in spaces where banquets were held and accordingly the main spaces for banquets and their related royal palace locations were changed or newly established. You need to briefly explain what this and Muja Jinjak are. New information is not provided in this paragraph. You have already established why the crown prince renovated the banquets and its significance in the first two paragraphs. You could just add “Jagyeongjeon(慈慶殿), Yeongyeongdan(演慶堂), and Hwanchwijeong(環翠亭) in Changgyeonggung Palace during his reign were changed and renovated during the time when the royal banquets of the 19th century were getting established. It was spaces that reflected the royal family and royal authority” to the end of the second paragraph and it would convey your intended meaning.

Statistical analysis for the 703 air purifiers certified by Korea Air Cleaning Association from 2003 to 2019 was performed. Sixty-one percent of the products had an area coverage of 15 m2~30 m2 and the median value of the total products was 37.6 m2. The number of certified products by the top five manufacturers was 325, which corresponds to 46.2% of the total products. The median value of the clean air delivery rate (CADR) of the 703 products was 4.8 m3/min but the number of air purifiers over the value increased to 62.5%~66.3% since 2018. The odor removal ratio showed a median of 86.0% which was higher than the certification criteria but had large differences in efficacy in the five test compounds. Removal efficiencies of each compound in terms of the median and ratio to the average value showed acetate > formaldehyde > toluene > ammonia > acetaldehyde in descending order with large variances. The median noise level average value from five positions of air purifiers was 47.7 dB(A). However the medians of the top position and the front, where purified air was vented out, were relatively higher in 49.8 dB(A) and 48.2 dB(A), respectively. Noise level ratio to noise criteria had a median value of 96.4%, which showed that most of the noise levels were distributed near the criteria limit. The probability of the noise level at 100% of the criteria was calculated ton 0.232, which indicated excess noise levels.

sesses the finishing capabilities for application to high-precision machining. Because Ti-6AL-4V (Eli) is widely used in applications where it is exposed to the human body, the industrial grinding oil that is commonly used in the magnetic abrasive finishing process was replaced by vegetable oils; the processing performances of these different grinding oils were compared and verified. The characteristics of magnetic abrasive finishing were also investigated according to the temperature of the material. The experimental results show that olive oil yields a surface roughness improvement of 87%. Also, in terms of the roundness and the amount of material removal, the performance was excellent. This demonstrates the possibility of replacing the conventional industrial oil for grinding. Furthermore, when olive oil was used at different temperatures, the finishing characteristics at room temperature were the most excellent. SEM and EDX analyses of the machined components (before and after processing) showed that the material composition was not changed. Additionally, the magnetic abrasive tool composition was not found on the surface of the finished samples. In conclusion, the possibility of using vegetable oil as the grinding oil for high-precision machining of Ti-6Al-4V (Eli) bars via a magnetic abrasive finishing process at room temperature conditions was verified.

The use of air cleaners has become popular to quickly remove contaminants present in indoor air such as fine dust and fungi. However, fungal information is rarely available in the filters equipped in the air cleaners. This study was conducted in winter to examine fungal concentration and species in the air cleaner filters of ten residential houses located in Incheon, Seoul, Hwaseong, and Gimpo cities. Fungi were detected in nine out of eleven filters from the ten houses. The level of fungi in the filters ranged from 0 CFU/cm2 to 2,370 CFU/cm2. There were differences in the fungal concentration among the eleven filters. Filters from three houses revealed levels over 1,000 CFU/cm2. The operation time of air cleaners did not seem directly related to the level of fungal concentration. A total of 326 isolates were obtained and classified as six genera belonging to Alternaria, Aspergillus, Cladosporium, Fusarium, Penicillium, and Trichoderma. Among these six genera, 20 species including one Alternaria, one Aspergillus, three Cladosporium spp., two Fusarium spp., eleven Penicillium spp., and two Trichoderma were identified. There were species that cause allergic reaction, pneumoniae, mycosis, and plant disease. Three species were known species of mycotoxin producers. Aspergillus niger, Cladosporium cladosporioides, and Penicillium brevicompactum were the most frequently detected fungi both in the air and in the air cleaner filters. This is the first report of fungal communities present in the air cleaner filters of residential houses in Korea.

Fungus has been regulated as an air contaminant in indoor environments in Korea. To remove the contaminant, air purifiers have been used in houses. However, not much information on the status of fungal contamination in the indoor air of houses is available. The present study was carried out to investigate fungal concentration and species in the indoor air of houses using air purifiers in winter. The results of indoor air sampling of ten houses located in the cities of Incheon, Seoul, Hwaseong, and Gimpo showed that the level of fungi ranged from 9 CFU/ m3 to 782 CFU/m3. Eight out of ten houses showed a level of less than 165 CFU/m3 indicating that the fungal level is generally low. Only one house exceeded the Korean regulatory standard value of 500 CFU/m3. A total of 175 isolates were obtained and classified as three genera belonging to Aspergillus, Cladosporium, and Penicillium. Among these three genera, 15 species including four Aspergillus spp., two Cladosporium spp., and nine Penicillium spp. were identified. Regarding the detection rate of the 15 identified fungal species, A. niger was the most detected species and followed by Cladosporium cladosporioides. Three to six species were present in the individual house that was investigated. Overall, our results showed that the level of fungal concentration and species diversity are low in the indoor air of houses that use air purifiers in winter.

Many air purifiers have been developed and released with increasing PM. In generally, the performance of air purifiers has been evaluated in the environment chamber by relevant standards. However, as there is a lack of information about air cleaning performance of air purifier in the living area, consumers have difficulty with product selection. In this study, five air purifiers were tested in apartments with different structures. In order to examine the effect of air purifiers, we assumed 3 cases such as inflow of pollutants from outdoors by ventilation, smoking patterns of residents, and cooking methods (e.g., frying fish). The evaluation results showed that the efficiency of air purifier products D and B of the 3-stage configuration (pre-filter + HEPA filter + activity carbon) was the best in most experiments. In the case of the ionizer type E product, the efficiency was very low and, at times, had increased the particulate matter indoors. Considering the cost-performance ratio, it is most reasonable to use an air purifier comprising a pre-filter and a HEPA filter without an additional configuration.

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.

This study was carried out considering that activated carbon physically adsorbs radon. Among the air cleaners equipped with activated carbon filter, eight air cleaners sold in Korea were selected and the radon reduction rate experiment was conducted. The instrument used an ionization chamber type instrument with a sensitivity of 3 CPM. The experiment was carried out by excluding the natural rate of reduction of radon in order to accurately grasp the radon reduction rate of activated carbon filter. Of the eight air purifiers, only three showed a reduction rate of more than 30%, while the remaining five air purifiers showed a reduction rate of less than 20%. This does not seem to be much different from the natural reduction rate. In addition, since it is not adsorbed by radon alone due to the nature of activated carbon, it is expected that the reduction rate will be lower in a real life environment.

In this study, a system was developed that can evaluate the radon gas removal efficiency of air cleaner filters. The system has three acrylic chambers connected in series;: the 1st chamber, the filter chamber and the 2nd chamber. In the 1st chamber, a radon source and an air pump were installed to create an environment with a constant radon concentration. Radon concentration in the two chambers was continuously monitored by ionization chamber detectors(RD-200, FRD1600, FTLab, Korea) and, in the 2nd chamber, the radon concentration increase of air filtrated by each filter was inter-compared. HEPA filters and two honeycomb type filters were evaluated. Results of HEPA filter, GAC 1 and GAC 2 were 1142 Bq, 7016 Bq and 12053 Bq, respectively. HEPA filter showed a significantly lower capacity for radon removal than the GAC filters. Also, the GAC 2 filter showed a more than 70 % better result compared to GAC 1 due to the difference in filter materials. Therefore, this system can be used to evaluate the radon removal ability of air cleaner filters, by filter type and filter material.

During periods where a fine dust watch was announced, we measured particulate matter by the light scattering method and the gravimetric method in accordance with the application of an air cleaner in 3 homes. The first investigation showed a lower indoor particulate matter 2.5 (PM2.5) concentration distribution than normal when there was a fine dust warning. Also, it was found that the result of the second research was similar to the first research, and was the effect of an air cleaner. The result of a comparison of black carbon (BC) concentration in accordance with an air cleaner at one room showed a lower concentration distribution than normal, as in the first and the second research when there was a fine dust warning. PM2.5 risk reduction effect showed 9.09E-5 (light scattering method) ~ 9.37E-5 (Gravimetric method) and 1.71E-4 (Light scattering method) ~ 1.76E-4 (Gravimetric method). Therefore, it was found that when there was a fine dust watch without ventilation, if air cleaner with the proper capacity is used and the influx of outside air reduced, the harmful effects of the fine dust can be lessened.

Ventilation devices and room air cleaners can be used to remove indoor contaminants from indoor air. Generally, room air cleaners are rated according to clean air delivery rate (CADR). However, a similar metric for ventilation has not been used to be compared with CADR of room air cleaner. The CADRs and cost-effectiveness metrics (CADR/kw) of ventilation devices and room air cleaners were newly defined and theoretically compared for a child care center. The results indicate that the CADRs of room air cleaner were greater than that of ventilation. A higher collection efficiency for the particles guaranteed a higher CADR for ventilation. Ventilation filter had a performance that exceeds MERV11 should be used to effectively control the indoor particle concentration. The stand alone type air cleaner was found to have the best performance in the cost-effectiveness. The reason for this is that the effective air cleaning ratio of the stand alone type air cleaner is higher than that of the others and the power consumption of the stand alone type air cleaner is lowest.

We estimated decreasing rate of indoor air pollutants with are airborne bacteria, airborne fungi, formaldehyde, total volatile organic compounds, PM10, and PM2.5 in 10 children’s hospitals and 6 childbirth houses located in Seoul and Gyeonggi-do from November to December in 2012. Sectional period was respectively divided for operating and non-operating the air cleaners. There was a trend that concentration of surveyed pollutants in children’s hospitals and childbirth houses during operating period decreased among indoor air. We used Monte-Calro simulation to remove uncertainty and identify efficiency of eliminated pollutants such as surveyed pollutants by the air cleaners. Average efficiency of removal were 61.39 ± 21.42% for airborne bacteria, 71.77 ± 19.65% for airborne fungi, 73.37 ± 24.62% for formaldehyde, 71.20 ± 25.96% for total volatile organic compounds, 65.16 ± 23.80% for PM10, and 71.06 ± 23.97% for PM2.5.