PURPOSES : This study predicts the concentration of suspended road dust (PM10) by analyzing meteorological, traffic, and atmospheric environmental data acquired at various angles, and attains a comprehensive understanding of the influencing factors of suspended road dust. METHODS : Experimental field methods were applied and statistical analyses were conducted. Field experiments were conducted using a vehicle-based measurement of suspended dust (PM10) to measure its concentration at the measurement site while maintaining a constant driving vehicular speed. Statistical analysis demonstrated the effects of the concentration of suspended dust on changes in meteorological and environmental factors and lanes per traffic volume at the time of measurement. Finally, a multiple linear regression model was applied to identify the factors which affected the generation of suspended dust. RESULTS : The analysis of suspended road dust concentrations according to the lanes per traffic volume and environmental factors showed that suspended dust concentrations increased at increasing driving speeds. In addition, the background concentration at the monitoring station was higher at high-wind speeds (>3.0 m/s) than at low-wind speeds (<1.6 m/s), but the suspended dust concentrations were higher at low-wind speeds. During the temperature inversion period from evening to morning, the suspended effects of traffic and meteorological factors were greater than the background concentration at the station. Multiple linear regression analysis showed that excluding yellow-dust days, which are known to affect atmospheric pollution levels, the accuracy of the model improved and resulted in increases in background PM10, vapor pressure, sea-level pressure, visibility, after-rainfall time, and in decreases in insolation and precipitation during low-wind speed conditions. CONCLUSIONS : At low-wind speeds, 5 days after rain, and when the relative humidity was higher than 72%, suspended dust was found to be higher than atmospheric PM10 concentration and may increase at increasing driving speeds and section lane traffic volumes. However, the volume of measured data in this study is limited to determining the patterns of suspended dust, as the silt loading of the operational road or the effects of prominent variables were not considered in this study. However, we identified prominent factors related to road-suspended dust for real-time road-dust predictions.

PURPOSES : This study describes the experimental findings on the mechanical properties of calcium aluminate cement (CAC)-based repair mortars with or without natural cellulose fiber (NCF). Additionally, the effect of adding NCF to the reduction of fugitive dust in the CAC powder was examined. METHODS : To produce mortar, four different levels of NCF (0.0.5, 1.0, and 2.0% by binder weight) were adopted, and the water-binder ratio was fixed at 0.485. The flow, strength characteristics, absorption, and surface electrical resistivity of the mortars were measured at predetermined periods. Additionally, SEM observations were performed to examine the microstructural changes and hydrates formed on the 28 day-mortar samples. RESULTS : The addition of NCF led to a decrease in fugitive dust. Regarding the mechanical properties of the mortars, that with 0.5% NCF exhibited a better performance in terms of strength development and surface electric resistivity compared to those of other mortars. However, the addition of NCF was less effective in the enhancement of the absorption of mortars. Further, we discovered that the microstructures of the mortars with additional NCF were comparatively dense compared to those without NCF. CONCLUSIONS : The appropriate addition of NCF can enhance the performance of CAC-based repair materials. However, further studies on the durability of CAC with the addition of NCF are needed to determine the optimal mixture.

PURPOSES : The objective of this study was to evaluate the effectiveness of dust removal by dust removal vehicles by the measuring dust load and PM10 concentrations on the sidewalks of block pavements. METHODS : Field experiments were conducted to determine a dust removal method suitable for the sidewalk conditions, as identified through a literature review. Data collection was followed by the evaluation of the sidewalk dust load with removal vehicles and analysis of the PM10 content within a service road. Moreover, an economic analysis was conducted based on the social costs of dust reduction. RESULTS : When cleaning a sidewalk block by spraying water, the contaminants in small gaps in the block pavement could be reduced, providing a potential solution to void clogging. The dust on the surface of the sidewalk was suspended from a paved road with a high level of traffic volume. Using sidewalk dust removal vehicles with sweeping, spraying water, and inhalation reduced the dust load and PM10 contents by more than 2 and 0.07g/m2, respectively. CONCLUSIONS : According to the economic analysis of the development of dust removal vehicles for sidewalks, the cost-benefit analysis method shows an input effect of 0.4, but if the reduction amount of fine particles such as PM2.5, further experiments are necessary to address the atmospheric fine dust concentrations resulting from cleaning sidewalk block pavements.

PURPOSES : The objective of this study is to evaluate the effectiveness of spraying dust suppressants in relation to the condition of road pavement in South Korea and to develop an optimal management method by continuously measuring re-suspended dust concentrations using a vehicle-based measurement. METHODS : Indoor experiments were conducted to select suppressants suitable for local conditions to reduce reducing road dust, which were identified through literature review. Data collection followed the evaluation method by selecting a section sprayed with dust suppressants and a non-sprayed section within the service road. RESULTS : The BPT experiment is designed to ensure the skid resistance of the road when dust suppressants are sprayed on the road. The Environmental toxic tests for PM10, HCHO, and TVOC all met the daily indoor air quality standards recommended in Korea for determining stability. Comparison of PM10 contents before and after spraying of the test road with dust suppressants and the non-sprayed section, it was confirmed that the dust suspended by the external environment may be reduced, but the amount of dust remaining on the road may increase. After 4 hours, when the water had evaporated, the dust suppressants remained effective and lasted for two-days. CONCLUSIONS : The concentration of fine dust in South Korea varies with the average duration of highly concentrated fine dust being 26.5 h nationwide, 20.5 h in the Seoul metropolitan area, and 25.1 h in Gyeonggi-province, suggesting a duration of one to two days. Thus, the fine dust problem can be solved by using dust suppressants.

국내 농업 분야 비산먼지의 배출계수와 활동도 자료는 국내의 환경조건(풍속, 습도 등)과 농업 의 특성을 반영하지 않고 미국의 인벤토리 체계를 그대로 적용해 왔다. 이 연구에서는, 활동 자료 중 하나 인 시간 해상도는 풍속 및 건기일수 적용을 통해 월별 배분계수를 도출하여 지역별로 시간 해상도를 향상 시켰고, 공간 해상도는 시·군·구에서 동과 리로 세분화하여 지역별로 공간 해상도를 향상시켰다. 이 연구를 통해, 지금 존재하는 농업분야의 비산먼지의 배출량, 활동도 자료의 개선에 중요한 자료로 활 용될 수 있을 것으로 판단된다.

PURPOSES : The purpose of this study is to measure and analyze the fugitive dust generated by each process through field tests to develop a technology to reduce fugitive dust generated during excavation-restoration work on road pavements. METHODS : The testbed was constructed based on a typical excavation-restoration construction section and comprised five sections for reproducibility and repeated measurements. The excavation-restoration work was divided into pavement cutting, pavement crushing, pavement removal, excavation, and restoration processes and fugitive dust generated by each process was measured. Fugitive dust (TSP, PM10, PM2.5, and PM1) was measured using a GRIMM particle spectrometer, which applies the principle of a light scattering spectrometer and can be measured in real-time. RESULTS : Analyses of the average mass concentration of PM10 generated by the excavation-restoration process are as follows: 1286.3 μg/m³ from pavement cutting, 246.8 μg/m³ from pavement crushing, 697.0 μg/m³ from pavement removal, 747.9 μg/m³ from excavation process, and 350.6 μg/m³ from the restoration process. In addition, the average particle size distribution of the excavationrestoration construction was in the order of PM10~PM2.5 (67 %), PM1 or less (24 %), and PM2.5~PM1 (9 %). The pavement cutting process is characterized by the emission of high concentrations of fugitive dust over a short time, compared to other processes. The pavement crushing process has the characteristic of steadily generating fugitive dust for a long period, although the emission concentration is small. CONCLUSIONS : In this study, it was found that the concentration and characteristics of fugitive dust generated during road pavement excavation-restoration works vary by process and the reduction technology for each process should be developed accordingly.

PURPOSES : The purpose of this fundamental study is to estimate the concentration of resuspended road dust in urban areas. This involves examining and measuring the factors that affect the dust concentration and measuring these factors and the concentration directly and indirectly by analyzing the factor-effect relationship of the dust in actual operation. METHODS : From the literature review, the factors that influence resuspended road dust, including traffic, environment, and weather data of roads and their relationship analysis were obtained to determine the effects of each element on resuspended road dust. The data characteristics and the quantitative changes in the factors when a high concentration of resuspended road dust is generated are analyzed for each condition. The concentrations of the resuspended dust are presented from the perspective of each factor. RESULTS : When the vehicle speed increased from 60 to 80 km/h, the measured resuspended dust concentration increased by 8㎍/m3 on the average. When the traffic was grouped, the resuspended concentration at 1200-1400 veh/h was 15.84㎍/m3 higher than that of 500-800 veh/h. A high concentration of 60㎍/m3 or more was generated in the SCL high and middle sections, and a high concentration of 10㎍/m3 or more was generated in the SCL low section. Eight cases were observed in the SCL high and middle section at an intense atmospheric wind speed of 3 m/s or more than the SCL level of zero cases. A high concentration of 89.8㎍/m3 resuspended dust was observed after 31 h of rainfall, and the dust concentration gradually decreased by over 50 h. Hence, the passing time after the rainfall, SCL and wind speed, traffic and vehicle speed, and air background (observation) concentration, all have a direct effect on the resuspended dust concentration. Atmospheric temperature and relative humidity have a significant effect on atmospheric dust concentration. CONCLUSIONS : The quantitative indicators of the factors using an estimation model of resuspended road dust in urban areas can be obtained if the conditions for high concentrations of resuspended dust are established using the quantitative relationship of the resuspended road dust factors presented in this study.

Conventional rotary sawing machine for cutting lumber generates severe amount of dust scattering to the environment. In this research, the design improvement of the rotary sawing machine is achieved to significantly reduce the dust scattering by the design process utilizing computational fluid dynamics (CFD) analysis. Several design candidates for the design improvement of the rotary saw system were proposed and modeled, and CFD analyses were performed to choose the best design in viewpoint of the least dust scattering. CFD analysis proved to be very useful to predict the characteristics of the air flow inside the saw system. The movement of dust particles with the air flow during the sawing process was analyzed for various design features of the saw system. The most efficient design to minimize the amount of dust particles ejected from the saw system was chosen based on the CFD analysis results. Then, the prototype of the best candidate of the improved rotary saw machine was built and the amount of dust particles were measured to verify its performance.

대기 공기질에 대한 국민적 관심이 높아짐에 따라 포장도로나 비포장도로에서 차량의 주행에 의해 발 생하는 도로 재비산 먼지를 줄이기 위한 노력이 이루어지고 있으며, 이에 따라 도로 재비산 먼지의 농도 와 특성을 조사 및 관측하는 연구가 진행되고 있다. 도로 상에 분포되어 있는 미세먼지는 각종 차량의 주 행에 의해 재비산되어 대기 중의 미세먼지 농도를 증가시킬 수 있으므로, 재비산 먼지의 농도를 실시간으 로 측정하여 도로의 정비와 청소의 근거 자료로 활용하고 있다. 따라서 도로 재비산 먼지를 효과적으로 측정하는 것은 매우 중요하다. 도로 재비산 먼지의 측정 효율에 영향을 주는 요소로는 측정차량의 속도, 샘플링 유량, 그리고 측정을 위한 샘플링 입구의 위치 등이 있다. 본 연구에서는 도로 상황에 따른 측정차 량의 다양한 속도를 고려하여 도로 재비산 먼지가 효과적으로 흡인되도록 하는 샘플링 입구의 위치 선정 에 관한 수치해석 연구를 진행하였다. CFD 해석을 위한 상용 코드인 FLUENT를 사용하였고, 도로 재비산 먼지의 측정에 실제 사용되고 있는 측정차량을 모사하여 측정차량 주위의 공기 유동을 해석하였다. 차량의 주행 속도를 고려하여 차량 전면 부로부터 일정한 속도의 기류가 불어오는 것으로 가정하였다. 또한, moving boundary 조건의 설정을 통 해 차량의 주행에 따른 바퀴의 회전과 도로면의 차량에 대한 상대적 이동을 구현하였다. 회전하는 바퀴 주변의 압력계수를 시뮬레이션을 통해 예측하여 이를 기존 문헌의 실험 결과와 비교함으로써 본 연구에서 채택한 시뮬레이션 방법의 정확성을 검증하였다. FLUENT에 내장되어 있는 DPM(Discrete Phase Models) 코드를 사용하여 도로 재비산 먼지의 이동 경로를 예측하였다. 측정차량의 주행에 따른 바퀴와 도로면의 마찰에 의해서 도로상의 먼지 또는 타이어 마모 먼지가 비산되는 것으로 가정하였고, 차량의 바 퀴와 도로면의 마찰부에서부터 입자가 어떠한 경로로 공기 중에서 이동하는 지 파악하였다. 도로 재비산 먼지의 이동 경로 해석 결과로부터 도로 재비산 먼지가 가장 많이 지나가는 위치를 파악하 고, 이를 토대로 하여 도로 재비산 먼지를 효과적으로 측정하기 위한 샘플링 입구의 위치를 제안하였다. 추후에 실험을 진행하여 제안된 샘플링 위치가 적절한 지 여부에 대해 시뮬레이션 결과와 비교하여 보완 할 예정이다.

대기오염의 심각성이 대두되면서 포장도로 혹은 비포장도로에서 발생되는 재비산 먼지의 농도 측정값 은 도로의 정비 및 청소의 근거 자료로 사용되며 대기의 공기질을 향상시키기 위한 개선책을 마련하는데 중요한 자료로 활용된다. 도로에서 재비산되는 먼지의 농도 측정은 도로 조건에 따라 변하는 측정차량의 속도, 측정 샘플링 입구의 위치, 샘플링 유량 등 다양한 변수의 영향을 받는다. 본 연구에서는, 도로 상황 에 따라 변하는 측정차량의 속도에 관계없이 효과적인 샘플링이 될 수 있도록 하는 등속흡인장치의 평가 를 수치해석 방법으로 진행하였다. 본 연구에서 사용된 등속흡인장치의 입구는 도로 재비산 먼지를 흡입하기 위한 샘플링 라인과 연결되 어 있고, 측정차량의 속도에 따라 등속흡인장치로 유입되는 공기의 유량이 변하게 된다. 등속흡인장치 내 로 유입된 공기는 2단으로 분리되어 등속흡인장치를 빠져나간다. 즉, 도로 재비산 먼지의 농도를 측정하 기 위해 3 L/min의 유량은 등속흡인장치의 가운데에 위치한 중심관을 통해 에어로졸 측정 장비로 유입되 고, 나머지 유량은 후단의 관을 통해 등속흡인장치를 빠져나게 된다. 이 때, 등속흡인 조건을 만족하기 위 해 중심관의 입구 위치가 측정차량의 속도, 즉 총 샘플링되는 유량의 변화에 맞추어 이동하게 된다. 유동의 높은 레이놀즈 수와 등속흡인장치의 형상을 고려하고 standard κ-ε turbulence model을 이 용하여 등속흡인장치 내에서의 유동의 특성을 해석하였다. 이후 유동해석 결과를 바탕으로 하여 입자의 거동을 해석하였다. 유동 해석과 입자 거동 해석을 통해 분석한 결과, 측정차량의 속도 변화에 따라 중심 관의 위치가 선형적으로 변하며 측정차량의 속도가 20km/h부터 35km/h까지 변할 때 등속흡인장치 내에 서 등속 흡인이 가능한 것으로 평가되었다.