본 연구는 공기 중 음이온이 미세먼지(PM10, PM2.5) 정화에 미치는 영향을 파악하고, 식물이 공기 중 음이온 발생과 미세먼지 정화에 미치는 영향을 평가하기 위하여 음이온 발생요인별 음이온 발생량을 측정하고, 각 요인별, 식물 용적별 미세먼지 저감 모형을 구축하여 비교하였다. 음이온 발생요인별 특성은 Type N.I(Negative ion generator; 204,133.33ea/㎤) > Type P₃₀(Plant Vol. 30%; 362.55ea/㎤) > Type C(Control; 46.22ea/㎤)의 순으로 음이온 발생량 을 살펴보면 무처리구에 비하여 음이온 발생기 처리구에서 약 4,417배, 식물 배치구에서 약 8배 많았다. 이에 따른 음이온 발생원별 미세먼지 저감 특성은 PM10에서 Type NI가 Type C에 비하여 정화효율이 2.52배, Type P30이 1.46배 높았으며, PM2.5의 경우, Type NI가 Type C에 비하여 정화효율이 2.26배, Type P30이 1.31배 높은 것으로 분석되었다. 식물의 용적별 미세먼지 정화 효율은 Type P₂₀(84.60분) > Type P₃₀(106.50분) = Type P₂₅(115.50분) = Type P₁₅(117.60분) > Type P₅(125.25분) = Type P₁₀(129.75분)의 순이었으며, 초미세먼지의 경우 Type P₂₀ (104.00분) > Type P₃₀(133.20분) = Type P₂₅(144.00분) = Type P₁₅(147.60분) > Type P₅(161.25분) = Type P₁₀ (168.00분)의 순이었다. 이렇게 음이온의 미세먼지 정화 능력과 식물의 미세먼지 정화능력을 정량적으로 분석하였으며, 향후 미세먼지 정화를 고려한 녹지계획 및 식물식재에 고려해야할 사항을 제안하였다.

Although airborne wear particles (AWPs) generated from wheel-rail contacts are the major source of particulate matter (PM) in subway systems, studies on reducing the generation of such particles in order to enhance air quality are extremely rare. Therefore, this study investigated the effect of applying water-lubricant (applying tap water) on improving air quality by reducing the mass concentration (MC) of AWPs from wheel-rail contacts at a train velocity of 73 km/h using a twin-disk rig. An optical particle sizer was used to measure the MC of particles with the diameter range of 0.3 μm~10 μm. The results showed that the generation trends regarding PM1, PM2.5, and PM10 were different for dry and water-lubricated conditions: all three PMs showed an increasing-decreasing trend with slip rate under dry conditions; however, they were almost constant with slip rate under water-lubricated conditions. The particle size distributions were also different for dry and water-lubricated conditions: the peak occurred in multi-modal with the largest peak at approximately 6 μm in diameter under dry conditions; whereas, the peak occurred in bi-modal with the largest peak at approximately 0.9 μm in diameter under water-lubricated conditions. In addition, MCs were mostly smaller under water-lubricated conditions than dry conditions except at approximately 0.9 μm in diameter. Applying water significantly decreased PM1~2.5 and PM2.5~10 by more than 95%. This caused a decrease in PM2.5 and PM10 by 48.1% and 78.5%, respectively. On the other hand, applying water increased PM0.3~1 (i.e., PM1) by 52.8%, possibly owing to the effect of water vapor and mineral crystals from tap water. Overall, these findings indicate that water-lubrication can improve air quality in subway systems by reducing the MC of APWs generated from wheel-rail contacts. This study may provide a reference for future studies seeking to improve air quality in subway systems by reducing AWPs generated from wheel-rail contacts by applying lubricants.

Indoor air quality management is essential for a healthy life. However, it is difficult to perceive, detect, and monitor the level of indoor air pollution and this means that it is possible to be exposed to more pollution indoors than outdoors. In this study, in order to derive effective indoor air quality management measures, public perceptions and behavioral characteristics regarding indoor particulate matter and air quality management methods were investigated through a survey of 1,000 people. Based on the survey, it was found that most of the respondents had a negative perception of the indoor air quality of their residence, and natural ventilation was the most used method for indoor air quality management. Although the frequency of use of air quality management devices such as air purifiers and mechanical ventilation systems was relatively low, their effect regarding air quality management was positively perceived. In particular, the results of survey indicated that respondents of families which included members with fragile health engaged in more active behavior regarding in indoor air quality management than those respondents whose family members had no health issues and that the former have used air quality management devices more frequently. Therefore, it is necessary to develop proper guidelines to encourage more people to actively participate in improving indoor air quality.

In this paper, a survey on students’ perceptions of air pollution, particulate matter (PM) and indoor air quality (IAQ) in school classrooms was analyzed. A total of 174 students participated in the survey, where 127 and 47 participants were elementary school students and middle school students, respectively. The elementary school was located in a rural area of Korea, whereas the middle school was located in an urban area. The questionnaire of the survey was mainly composed of three parts: (1) students’ perceptions of air pollution, (2) students’ perceptions of IAQ in the classroom, and (3) students’ perceptions of how to improve IAQ in the classroom. Based on our study, the responses of the students for the given questionnaire showed an opposite tendency. The students in the rural area tended to have positive perceptions regarding IAQ in the classroom as well as air pollution, whereas the students in the urban area revealed negative perceptions for the same items. Our survey results can be used by school officials in order to maintain and improve IAQ in school classrooms based on the perceptions of the students.

In this paper, we conducted a survey to reveal the general perception of parents toward outdoor air quality, particulate matter (PM), and indoor air quality (IAQ) at schools where their children attend. A total of 1,030 parents participated in this survey, where the age of their children ranged between 7 years to over 19 years of age. Each participant was either a member of a non-governmental organization (NGO) with a keen interest in air quality or an ordinary public panel member with less interest. The result of the survey indicated that the participants had a negative perception of air quality, and parents believed that the outdoor and indoor air is extremely polluted. The participants pointed out that they believe that the main reason for the pollution is due to particulate matter (PM) and school classrooms are the location where their children are exposed to PM the most. Based on our study, the majority of the participants prefer a mechanical ventilation system to reduce indoor air pollutants in schools. Our study should be referred to by school officials in order to maintain IAQ and as a way of addressing the concerns of parents who want to protect their children’s health.

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 goal of this study was to measure the indoor and outdoor fine and ultrafine particulate matter concentrations (PM10, PM1.0) of some houses in Yeosu and in S university in Asan from March to September 2018. PM10 concentration in indoor air in Yeosu area was 18.25 μg/m3, while for outdoor air it was 14.53 μg/m3. PM1.0 concentration in indoor air in the Asan area was 1.70 μg/m3, while for outdoor air it was 1.76 μg/m3, showing a similar trend. Heavy metal concentrations in the Yeosu region were the highest, at Mn 2.81 μg/m3, Cr 1.30 μg/ m3, and Ni 1.11 μg/m3 indoors. Outside, similar concentrations were found, at Cr 3.44 μg/m3, Mn, 2.60 μg/m3, and Ni 1.71 μg/m3. Our analysis of indoor and outdoor PM concentrations in the Asan region, which was carried out using the MOUDI (Micro-orifice Uniform Deposit Impactor) technique, found that PM concentration is related to each particle size concentration, as the concentration of 18 μm and 18-10 μm inside tends to increase by 3.2- 1.8 μm and 0.56-0.32 μm.

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.

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.

This study tried to survey air quality inside and outside the schools where are located in about 5km of industrial complex targeting aldehyde, PM10, PM2.5. Also, the aim was also to examine both a change in indoor air after 3 years and within 3 years of addition and improvement, and a change according to season. It collected specimens at totally 20 places. Aldehyde was analyzed through HPLC. PM10 and PM2.5 were measured by using Met One 831. Formaldehyde and Acetaldehyde were detected with 42.1 μg/m3 and 5.7 μg/m3 at the school where is located inside 5km of the industrial complex, and were detected with 55.0 μg/m3 and 6.8 μg/m3 at the school where is located outside 5 km. This could be confirmed to have been detected more highly in the indoor air than the outdoor air regardless of the distance from the industrial complex. Most substances were indicated to be higher by about 150% in the indoor air within 3 years than the indoor air following 3 years of addition and improvement. However, PM10 and PM2.5 were measured with 32.6 μg/m3 and 14.9 μg/m3 after 3 years and were gauged with 22.4 μg/m3 and 14.2 μg/m3 within 3 years. Seeing a seasonal change, Formaldehyde and Propionaldehyde were detected with 5.5 μg/m3 and 1.0 μg/m3 in spring, 7.7 μg/m3 and 1.6 μg/m3 in summer, and 8.3 μg/m3 and 1.9 μg/m3 in autumn. This could be confirmed the tendency of growing according to season.

The current interest in atmospheric particulate matter (PM) is mainly due to its effect on human health.Exposure to outdoor PM is associated with a wide range of adverse health effects. Indoor air contains a complexmixture of bioaerosols such as bacteria, fungi and allergens. Children are known to be more susceptible tothe exposures of PM and bioaerosols which are represented by airborne bacteria, fungi, and allergens. Thisstudy is to assess concentrations of the atmospheric PM and bioaerosols indoors and outdoors at 15 daycarecenters for children located in Seoul. Particles were measured indoors and outdoors with automatic particlemonitoring using beta radiation absorption. Airborne bacteria and fungi were sampled by Anderson sampler.Analysis shows that average indoor PM10 was 95.7µg/m³ (SD 26.6µg/m³) and average level of airbornebacteria and fungi were 575.0CFU/m³ (SD 431.6CFU/m³) and 77.9CFU/m³ (SD 45.6CFU/m³), respectively.Finally, efficient ventilation and effective air cleaning strategies are necessary to reduce indoor concentrationsof particles and bioaerosols.

본 연구는 강원도 소재 동해항만에서 발생하는 미세먼지 관리를 위한 환경비용편익을 산출하는 것이다. 항구 인근에 부유하는 미세먼지의 농도는 매우 높은 편이며, 지점에 따라 국가 기준인 100μg/m3 이상으로 관측되는 곳도 있다. 시험대상 항구는 주로 석회석과 석탄을 취급함으로써 미세입자상 물질이 하역시 다량 발생한다. 연구결과 PM10을 기준으로 년간 12톤의 미세먼지가 하역작업 시 발생하는 것으로 밝혀졌다. 덧붙여서 원료물질을 비롯한 다양한 화물을 운송하는 대형차량 및 중장비는 디젤 검댕이를 발생하고, 도로먼지의 비산을 유발한다. 지방정부는 해마다 20억원 이상의 비용을 투자하여 대기중 미세먼지를 제거하고 있다. 편익대비 비용을 산출한 결과 그 효과는 최소 240%에서 최대 720%까지 얻을 수 있는 것으로 나타났다.

Micro bubbles are widely used in many cases such as agriculture, fishery, skin care, prevention of water pollution. A high pressure compressor which is one of part of a micro bubble generating system is needed to generate these micro bubbles. The purpose of this research is the development of a high pressure compressor which is achieve following conditions; discharge flow 0.6ℓ/min, maximum air flow 2ℓ/min, discharge pressure 5bar. To achieve these conditions, we optimized the geometry of cylinder and piston, clearance volume, compression ratio, power of operating motor experimentally. Moreover, we minimized the compressor which is the biggest part of a micro bubble generating system so that we could minimized the size of entire system.

The present study concerns a measurement of porosity at the nano-fibre interface in concrete. Concrete cast with a centrally located nano-fibre (Ø0.39 × 15.0 mm) was segmented for microscopic observation at a bascattered electron (BSE) image. As a result, it was found that the pores generated in the vicinity of the nano-fibre ranged from 5.40 to 11.45%, equivalent to 0.51 - 1.08% of air void in a bulk concrete.