• International Journal of Aeronautical and Space Sciences
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• 제8권2호
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• pp.54-66
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• 2007

Traffic and emergency monitoring systems are essential constituents of Intelligent Transportation System (ITS) technologies, but the lack of traffic monitoring has become a primary weakness in providing prompt emergency services. Demonstrated in numerous military applications, unmanned aerial vehicles (UAVs) have great potentials as a part of ITS infrastructure for providing quick and real-time aerial video images of large surface area to the ground. Despite of obvious advantages of UAVs for traffic monitoring and many other civil applications, it is rare to encounter success stories of UAVs in civil application including transportation. The objective of this paper is to report the outcomes of research supported by the state agency in US to investigate the feasibility of integrating UAVs into urban highway traffic monitoring as a part of ITS infrastructure. These include current technical and regulatory issues, and possible suggestions for a future UAV system in civil applications.

• 한국도로학회논문집
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• 제18권3호
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• pp.109-114
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• 2016

PURPOSES : The demand for extending national highways is increasing, but traffic monitoring is hindered because of resource limitations. Hence, this study classified highway segments into 5 types to improve the efficiency of short-term traffic count planning. METHODS : The traffic volume trends of 880 highway segments were classified through R-squared and linear regression analyses; the steadiness of traffic volume trends was evaluated through coefficient of variance (COV), and the normality of the data were determined through the Shapiro-Wilk W-test. RESULTS : Of the 880 segments, 574 segments had relatively low COV and were classified as type 1 segments, and 123 and 64 segments with increasing and decreasing traffic volume trends were classified as type 2 and type 3 segments, respectively; 80 segments that failed the normality test were classified as type 4, and the remaining 39 were classified as type 5 segments. CONCLUSIONS : A theoretical basis for biennial count planning was established. Biennial count is recommended for types 1~4 because their mean absolute percentage errors (MAPEs) are approximately 10%. For type 5 (MAPE =19.26%), the conventional annual count can be continued. The results of this analysis can reduce the traffic monitoring budget.

• Smart Structures and Systems
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• 제17권6호
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• pp.995-1015
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• 2016

In the design and condition assessment of bridges, it is usually necessary to take into consideration the extreme conditions which are not expected to occur within a short time period and thus require an extrapolation from observations of limited duration. Long-term structural health monitoring (SHM) provides a rich database to evaluate the extreme conditions. This paper focuses on the extrapolation of extreme traffic load effects on bridges using long-term monitoring data of structural strain. The suspension Tsing Ma Bridge (TMB), which carries both highway and railway traffic and is instrumented with a long-term SHM system, is taken as a testbed for the present study. Two popular extreme value extrapolation methods: the block maxima approach and the peaks-over-threshold approach, are employed to extrapolate the extreme stresses induced by highway traffic and railway traffic, respectively. Characteristic values of the extreme stresses with a return period of 120 years (the design life of the bridge) obtained by the two methods are compared. It is found that the extrapolated extreme stresses are robust to the extrapolation technique. It may owe to the richness and good quality of the long-term strain data acquired. These characteristic extremes are also compared with the design values and found to be much smaller than the design values, indicating conservative design values of traffic loading and a safe traffic-loading condition of the bridge. The results of this study can be used as a reference for the design and condition assessment of similar bridges carrying heavy traffic, analogous to the TMB.

• Structural Engineering and Mechanics
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• 제18권5호
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• pp.609-626
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• 2004

The Land Transport Authority of Singapore has a continuing program of highway bridge upgrading, to refurbish and strengthen bridges to allow for increasing vehicle traffic and increasing axle loads. One subject of this program has been a short span bridge taking a busy highway across a coastal inlet near a major port facility. Experiment-based structural assessments of the bridge were conducted before and after upgrading works including strengthening. Each assessment exercise comprised two separate components; a strain and acceleration monitoring exercise lasting approximately one month, and a full-scale dynamic test carried out in a single day. This paper reports the application of extreme value statistics to estimate bridge live loads using strain measurements.

• Asian Journal of Atmospheric Environment
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• 제6권2호
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• pp.96-103
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• 2012

Ambient particulate matter (PM) and particle-bound polycyclic aromatic hydrocarbon (PAH) concentrations were measured continuously for 70 days at a Korean elementary school located near a highway. The $PM_{10}$, $PM_{2.5}$, and $PM_1$ values were measured with a light-scattering, multi-channel, aerosol spectrometer (Grimm, Model 1.107). The number concentrations of the particles were measured using a scanning mobility particle sizer and counter (SMPS+C) which counted particles from 11.1 to 1083.3 nm classified in 44 channels. Particle-bound PAHs were measured with a direct reading, photoelectric aerosol sensor. The daily $NO_2$, $SO_2$, and CO concentrations were obtained from a national air-monitoring station located near the school. The average concentrations of $PM_{10}$, $PM_{2.5}$, and $PM_1$ were 75.3, 59.3, and $52.1{\mu}g/m^3$, respectively. The average number concentration of the ultrafine particles (UFPs) was $46,307/cm^3$, and the averaged particle-bound PAHs concentration was $17.9ng/cm^3$ during the study period. The ambient UFP variation was strongly associated with traffic intensity, particularly peak concentrations during the traffic rush hours. Particles <100 nm corresponded to traffic-related pollutants, including PAHs. Additional longterm monitoring of ambient UFPs and high-resolution traffic measurements should be carried out in future studies. In addition, transient variations in the ambient particle concentration should be taken into consideration in epidemiology studies in order to examine the short-term health effects of urban UFPs.

• 한국도로학회논문집
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• 제16권2호
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• pp.1-9
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• 2014

PURPOSES : This study aims to evaluate the performance of interlocking block pavement system for low speed highway. METHODS : Through on-site monitoring, environmental impact assessment of interlocking block pavement such as heat island reduction, traffic safety, noise pollution were evaluated as compared with asphalt pavement. Also the pavement condition and roughness were evaluated according to performance period. RESULTS : Surface temperature of interlocking block pavement was about 7 degree lower than asphalt pavement in midsummer. Compared to asphalt pavement, vehicle speed reduction effect of interlocking block pavement was about 2kph. For low speed driving, the noise pollution was measured at a similar level for both asphalt and interlocking block pavement. After 42month service period, the breakage of block was only 0.24% for the whole surveyed area. IRI of interlock block pavement was estimated within the range of 5~8m/km. CONCLUSIONS : Depending on the performance monitoring results such as heat island reduction, providing traffic safety and keeping a good pavement condition for a long service period, it assures that interlocking block pavement was applicable for low speed road.

• Journal of Korean Society for Atmospheric Environment
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• 제9권E호
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• pp.397-400
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• 1993

The possible air pollution problems in a proposed underground highway are discussed using carbon monoxide (CO) as an indicator. Carbon monoxide concentrations in the underground highway depend on several factors, including the size of tunnel, the number of automobiles, the CO emission rate, and the tunnel ventilation rate. Using the estimated values, CO concentrations in the underground highway can be predicted. Without proper ventilation system, CO concentration in the underground highway can be dangerous level. However, the cost of operating the mandatory mechanical ventilation system may be tremendouslyy high and may be technically unrealistic to implement. If the underground highway is constructed with proper ventilation system, a continuous air pollution monitoring system with alarming function must be installed to alert personnel of serious air pollution built up in the underground highway. Traffic must be restricted, whenever the inside air pollution levels exceed agreed values. Short distances between evacuation exits are necessary for emergency situations or malfunction of ventilation system.

• 한국소음진동공학회논문집
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• 제26권6_spc호
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• pp.729-735
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• 2016

According to the survey for working environment of the cashiers in highway tollbooths, workers replied that noise was the most harmful substances next to air pollutant in the tollbooth. Researches on the noise levels exposed to cashiers in the highway tollbooth scarcely have been performed. Therefore, the aim of this study was to acquire baseline data to prevent health impairments of the cashiers by evaluating noise level exposed to them. Noise dosimeters were used for monitoring workers' noise exposure level in the tollbooths at 8 different highway tollgates. The noise levels of tollbooths did not exceed noise exposure limit of the ministry of labor, 90 dB(A). The average TWA inside of the tollbooths was 55.4 dB(A) and the average TWA outside of tollbooths was 58.3 dB(A). The average TWA outside of tollbooths was slightly higher than that of inside of tollbooths. However, the significance probability(p-value) was 0.255 which means statistically not significant. The noise levels inside and outside of tollbooth were statistically significant to both mean traffic volume per day and traffic volume of passenger car.

• 한국도로학회논문집
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• 제20권1호
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• pp.127-135
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• 2018

PURPOSES : Traffic cameras have been installed to reduce traffic accidents. The effectiveness of traffic cameras has been proved by dozens of studies, but recently questions over its effectiveness have been raised by a series of studies. In this study, the effectiveness of traffic cameras was analyzed with a focus on different road environments. METHODS : The effectiveness of the traffic cameras was analyzed by extracting the occurence frequency before and after camera installation. The effect of reduction was analyzed comprehensively considering the installation position, monitoring direction, and surrounding environment of traffic cameras. RESULTS : The result of this study is as follows. First, the installation of cameras in an area with relatively low accidental traffic was more effective. Secondly, the effect of camera installation on car-to-pedestrian collisions was better than that of car-to-car collisions. Thirdly, accidents tended to occur more frequently when cameras were installed in front of the accident-prone owing to the negative spill-over effect. CONCLUSIONS : The result can be used to guide placement of traffic cameras. Moreover, the installation of cameras with consideration of the road environment is expected to contribute to a reduction in traffic fatalities.

• 한국측량학회지
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• 제30권1호
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• pp.11-19
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• 2012

기존의 교통정보 수집 인프라는 고속도로와 국도 위주로 구축되어 있어 그 주변지역의 좁은 도로에 대한 교통상황을 정확하게 알 수 없어 교통정보의 신뢰성이 떨어짐으로써 내비게이션 등의 교통정보를 이용하는 사용자들에게 신뢰도 높은 교통정보를 제공하기 어려운 실정이다. 따라서 본 연구에서는 광역의 모니터링이 가능한 비행선을 이용하여 항공영상을 수집하고, 그 수집된 데이터로부터 차량속도를 추출하는 방법을 제시하였으며, 추출된 차량속도의 정확도를 검증하기 위한 실험도 수행하였다. 본 연구에서 제시한 차량속도 추출 방법은 교통 모니터링의 수요 증대에 따른 새로운 접근의 교통정보를 추출하는데 이용이 가능하며, 항공영상을 이용한 차량 및 교통정보 추출 기술에 있어 새로운 연구 트렌드로 자리매김할 것으로 예상된다.