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.

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.

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.

목 적: 초음파 세척기의 사용 시간에 따라서 안경렌즈 박막의 변화를 관찰하고자 한다. 방 법: 안경렌즈를 물이 담긴 초음파 세척기 안에 고정시킨 후 0시간, 0.5시간, 1시간, 1.5시간, 2시간을 초음파 세척기를 작동시킨 후 시간에 따라서 안경렌즈 코팅 박막의 변화를 관찰하였다. 안경렌즈 표면은 광 학현미경을 사용하여 관찰하였고, 접안렌즈의 배율은 10배이고 대물렌즈의 배율은 1배에서 4배까지 변하는 줌렌즈를 사용하였다. 안경렌즈의 광 투과율은 광 투과율 측정기를 사용하여 280~780 nm파장에서의 투과율을 측정하였으며, 안경렌즈 표면에서의 접촉각은 디지털 카메라와 스마트 앱을 이용하여 측정하였으며, 안경렌즈의 ITO 박막의 두께 변화는 RF 고주파 송수신 측정 장치를 이용하여 측정하였다. 결 과: 안경렌즈에 초음파 세척기를 30분 한 후에는 안경렌즈 표면이 아무런 변화가 없었고, 초음파 세 척기를 1시간 한 후에는 안경렌즈 표면이 국부적으로 흠집이 나타났으며, 이 후 초음파 세척기를 2시간 할 때까지 흠집이 점점 확대되는 것이 관찰되었다. 평균투과율은 처음 97.85%로 시작하여 초음파 세척기를 2 시간 한 후에는 96.97%로 감소하였다. 접촉각은 초음파 세척기를 30분 한 후 조금 감소된 것을 관찰하였다. ITO 박막의 두께는 초음파 세척기를 안경렌즈에 한 시간에 따라 변화가 없었다. 결 론: 안경렌즈에 초음파 세척기를 1시간 한 후부터는 국부적으로 안경렌즈 박막에 흠집이 생기고 시간 이 지남에 따라 점점 확대되는 것을 알 수 있었고, 안경렌즈 전체적으로는 초음파 세척기 30분 한 후부터 안 경렌즈 발수코팅막에 영향을 주는 것을 알 수 있다.

The principal hygienic problem caused by livestock industry is the odor exposed to farm workers. This study was performed to assess air cleaner efficiency for reducing odor through on-site evaluation. The concentration of ammonia and hydrogen sulfide, which are major odorous compounds generated from livestock building, were monitored by realtime direct recorder. The odor mixture was measured by air dilution method applying human noses of five panels. Their reduction efficiencies were represented by difference between initial concentration exhausted by non-treatment and concentration measured after treatment of respective control mechanism (water, germicide and plasma ion) of air cleaner. Mean levels of ammonia and hydrogen sulfide were 1.84 (SD:0.22) ppm and 76.83 (SD:1.37) ppb for non-treatment, 1.23 (SD:0.09) ppm and 59.07 (SD:2.68) ppb for wet scrubber (water), 1.08 (SD:0.03) ppm and 58.55 (SD:1.62) ppb for wet scrubber (germicide), and 0.96 (SD:0.03) ppm and 53.66 (SD:1.37) ppb for plasma ion, respectively. Mean dilution factors of odor mixture were 100 for non-treatment, 66.9 for wet scrubber (water), 144.2 for wet scrubber (germicide), and 66.94 for plasma ion, respectively. Based on the results obtained from on-site evaluation, ammonia and hydrogen sulfide showed the mean reduction efficiency of 40% and 25.7% compared with non-treatment process of air cleaner, respectively. In the case of odor mixture, the highest dilution factor was observed at wet scrubber (germicide) compared with other control mechanism of air cleaner.

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.

목적: 착용 중인 안경렌즈에 대한 세균 오염정도를 확인하고 동시에 국내 최초로 유통되고 있는 1회용 안경렌즈 클리너(Lens Cleaning WIPE, ZEISS, Germany)에 대한 미생물학적 오염의 세척 효과를 검증하고자 하였다. 방법: 만 19세에서 만 38세 사이의 대학생 29명을 대상으로 착용 중인 안경렌즈에서 1회용 안경렌즈 클리너(Lens Cleaning WIPE, ZEISS, Germany)를 이용한 세척 전, 후에 대하여 멸균된 면봉으로 오염 균을 채취하였고 Thioglycollate Medium 수용성 배지와 혈액한천배지 및 MacConkey 배지에 접종하여 배양한 후 집락 수를 계산하였다. 세균의 동정은 Phoenix ID(BD Diagnostics, Inc. Sparks, Maryland, USA) 자동기기로 하였다. 결과: 세척 전 사용 중인 안경렌즈에서는 그람양성 알균이 6종으로 Streptococcus sp., Staphylococcus aureus, Staphylococcus hominis, Staphylococcus haemolyticus, Staphylococcus epidermidis, Micrococcus luteus가 검출되었으며 그람양성 막대균으로는 Bacillus cereus로 1종이 검출되었다. 1회용 안경렌즈 클리너를 이용하여 세척한 후에는 대부분 제거되었으나 Staphylococcus hominis와 Micrococcus luteus에서는 집락 수의 감소만 나타났다. 결 론: 본 실험에서는 사용 중인 안경렌즈에서 기회감염성 세균류인 그람양성 알균 6종과 그람양성 막대균 1종이 오염되었음을 확인하였다. 외부로 노출되어 있는 우리의 눈은 면역력이 떨어지거나 상처 등을 입었을 때 쉽게 감염을 일으킬 수 있는 기회감염성 균들에 대한 대안이 요구되는 현실에서 1회용 안경렌즈 클리너(Lens Cleaning WIPE, ZEISS, Germany)의 활용은 매우 유용한 것으로 판단된다.

원자력이용시설에서 발생한 작은 크기의 금속 조각들을 효과적으로 제염하는 스마트 장치를 개발하였다. 이 장치는 자성연 마재를 포함한 영역의 자속밀도를 연속적으로 변화시키는 방법과 초음파를 이용하는 다중 제염장치이다. 한편, 제염 효율을 높이기 위해 제염 장치가 제염 대상 전체에 작용하도록 장치들의 구성을 수정하였다. 개발된 장치들의 최적 작동조건을 도 출하여 샘플로 선정한 소형의 금속방사성페기물에 대하여 자기장과 초음파제염을 각각 15분간 실시하였다. 그 결과 제염계 수의 범위는18~56으로 크게 향상되었으며 제염 후 모든 샘플은 백그라운드(BKG)값 이하로 확인되었다.

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.

This paper presented experimental results for photocatalytic air cleaner removal performance for malodorous compounds generated from rest room. Photocatalytic oxidation (PCO) efficiency was up to 80∼ 90% for NH₃ in chamber, 29.3% for H2S, 79.6% for CH3SH, 58.8% for DMDS individually. PCO efficiency for DMS(Dimethy Sulfide) and DMDS(Dimethyl Disulfide) were relatively lower than that of NH₃ and CH3SH, this results indicate that DMS and DMDS removal process were effected by by-products of photocatalytic oxidation and humidity. Ozone was relatively low (below 5ppb) under the test conditions through photocatalytic oxidation. It is necessary to test a reliability of the air cleaner for a longtime under the various indoor conditions. But, prototype photocatalytic air cleaner will promise useful air cleaner for indoor air quality applications.

Test methods of Korea Air Cleaning Association (KACA) and Association of Home Appliance Manufacturers (AHAM) for particle cleaning capacity performance of an indoor air cleaner were compared in terms of the conditions of the test particle generation, the range of particle measurement and the calculation methods for particle cleaning capacity, and types of the test particles. The performance test was conducted in a 30 m³ chamber with the same test specimen and the test particles of each test were generated until the number concentration of 0.3 ㎛ particles reached 2.2 × 108 #/m³. The performance test results showed that the cleaning capacity with the particles of higher surface area and volume density, regardless of the type of test particles, was higher than with those of lower and the capacity from calculation with 0.3～1 ㎛ particles was higher than with 0.3 ㎛ particles. Moreover, the cleaning capacity with the calculation of KACA method was lower than with that of AHAM method in spite of using the same test specimen.

Recently, it was under an obligation to install the VOCs recycling unit in the cleaners and the gas station to prevent from discharging VOCs emitted from the cleaners and the gas station. The objectives of this study was to investigate the VOCs recycling unit used thermoelectric module to recycle the organic solvent from the cleaners and after washing. The traditional way was the use of the VOCs recycling unit with the compressor. But the recycling unit has many weak points , noise, size, danger of fire, additional pollution and so on. In order to improve these weak points, it was developed the new VOCs recycling unit using the thermoelectric module through this study. The cooling block with 32 thermoelectric module was applied to cool the hot VOCs where comes to occur from the dryer in high temperature condition. Also a water-cooled equipment was used to remove the heat from the hot surface of thermoelectric module. The experimental results from new VOCs recycling unit shows that the maximum recovery rate of the unit was 83.2 % and the recycled VOCs' purity was 98 % or more. And the noise problem was solved by applying the thermoelectic module to the VOCs recycling unit.

The fluidized bed has been used generally for Industrial process such as chemical reaction process, separation process, incineration and etc. It is very efficient for such application because of equitable contact of each fluidized element with fluid passing through it and maximizing active contact area to adsorb and react from the fluid. This study had focus on application of fluidized bed for air purifier as household appliance and analyzed its performance in comparison to typical fixed media type. As a result, fluidized bed performed in this study had higher removal efficiency for acetaldehyde over two times within initial operation term and had lower pressure drop over 0.7mmAq than that of fixed media type.

A high efficiency roll-type electret polypropylene (PP) filter with an external electric field was developed and its particle collection efficiency and air cleaning capacity was investigated in a room when applied to an air cleaner having a fan. To enhance air cleaning performance of the cleaner, a wire-plate type ionizer was installed in front of the filter to enhance electric field to filter and one side of the filter was embossed by press of a pattern with a lot of circular projection. Performance test results showed that the newly developed electret PP filter with an ionizer becomes an appropriate filter to be applied to indoor air cleaner due to its low pressure drop and high air cleaning performance.

The performance of various air-cleaning devices and an assembled air cleaner has been evaluated for the removal of biological pollutants in indoor air. Bacteria, fungi, and viruses were sprayed in a test chamber, and air samples in the chamber were taken for analysis. Air-cleaning devices - UV lamp, ion generator, an UV LED and plasma electricity dust collector - were tested for their ability in the removal of microorganisms in the air. The UV lamp and the ion generator tested exhbited complete sterilization effect within 4hrs of operation. Other devices were less effective: The extent of removal by the UV LED and the plasma electricity dust collector after 6hrs of operation was about 20% to 82%, depending on the microorganisms tested. The performance of an assembled air cleaner was much superior to individual air-cleaning devices: the extent of removal being 97.6%, 99.1%, 98.7%, and 93.7% for Staphylococcus aureus (Gram(+) bacteria), Escherichia coli (Gram(-) bacteria), Aspergillus niger and Penicillium funiculosum (fungi), respectively, after 3hrs of operation. The removal of influenza virus was even more effective, with 99.9% of removal within 25min of operation. The results show that the air cleaner is effective for the removal of microbial and viral pathogens in the air.