간행물
한국도로학회논문집 KCI 등재 International journal of highway engineering
- 발행기관 한국도로학회
- 자료유형 학술지
- 간기 격월간
- ISSN 1738-7159 (Print)2287-3678 (Online)
- 수록기간 1999 ~ 2024
- 주제분류 공학 > 토목공학 공학 분류의 다른 간행물
- 십진분류KDC 534DDC 625
권호리스트/논문검색
제22권 제5호 (2020년 10월) 11건
1.
2020.10
구독 인증기관 무료, 개인회원 유료
PURPOSES : NOx is a particle matter precursor that is harmful to humans. Various methods of removing NOx from the air have been developed. TiO2 and activated carbon are particularly useful materials for removing NOx, and the method is known as particulate matter precursor reduction. The removal of NOx using TiO2 requires sunlight for the photocatalytic reaction, whereas activated carbon absorbs NOx particles into its pores after contact with the atmosphere. The purpose of this study is to evaluate the NOx removal efficiency of TiO2 and activated carbon applied to concrete surfaces using the penetration method.
METHODS : Surface penetration agents, such as silane-siloxane and silicate, were used. Photocatalyst TiO2 and adsorbent activated carbons were selected as the materials for NOx removal. TiO2 used in this study was formed by crystal structures of anatase and rutile, and plant-type and coal-type materials were used for the activated carbon. Each surface penetration agent was mixed with each particulate matter sealer at a concentration ratio of 8:2, and the mixtures were sprayed onto the surface. The NOx removal efficiency was evaluated using NOx removal efficiency equipment fabricated in compliance with the ISO 22197-1 standard.
RESULTS : Anatase TiO2 showed a maximum NOx removal efficiency of 48% when 500 g/m² was applied. However, 500 g/m² of rutile TiO2 showed a NOx removal efficiency of up to 10%. When 700 g/m² of coal-based activated carbon and plant-based activated carbon was used, NOx removal efficiencies of up to 11% and 14%, respectively, were obtained.
CONCLUSIONS : Rutile TiO2, a coal-based activated carbon, and plant-based activated carbon have lower NOx removal efficiencies than anatase TiO2. A lower amount of anatase TiO2 (500 g/m²), compared to the other spraying volumes, yielded the most significant NOx removal efficiency under optimal conditions. Therefore, it is recommended that 500 g/m² of anatase TiO2 should be sprayed onto concrete structures to improve the economic and long-term performance of these structures.
4,200원
2.
2020.10
구독 인증기관 무료, 개인회원 유료
PURPOSES : In this study, the wetting band depths of road slopes estimated using numerical analyses and one-dimensional empirical equations were evaluated.
METHODS : The one-dimensional empirical equations used in this study to estimate the wetting band depth were the Pradel and Raad equation, based on modifying the Green and Ampt equation, Lumb's equation, and Sun equation. The numerical analysis of a finite load slope model was carried out using the Seep/w program (2D). In particular, the effect of the initial suction, which indicated the effect of the antecedent rainfall based on the soil–water characteristic curve, was examined as one condition. The results of the wetting band depths obtained using the empirical equations were evaluated and compared with those of the numerical analysis.
RESULTS : The wetting band depths obtained using one-dimensional empirical equations were greater than those from the analytical results. In the case of empirical equations, the estimated results obtained for the wetting band depth might be misleading because it has the limitation of being expressed using a one-dimensional equation with an error, owing to several assumptions for the water infiltration phenomenon. It was also found that the accuracy of the wetting band depth was closely related to the results of the soil–water characteristic curve.
CONCLUSIONS : Because the wetting band depths obtained using the empirical equation may lead to overestimation, the slope stability could be evaluated as low; however, there was an advantage in terms of inducing conservative design of the road slope. In addition, it was confirmed that the estimated value of the wetting band depth obtained using the Pradel and Raad equation varied with the suction and volumetric function ratios, and further attention should be paid to these two variables.
4,200원
3.
2020.10
구독 인증기관 무료, 개인회원 유료
PURPOSES : A pilot experimental study on the formation of fine particulate matter through photochemical reactions using precursor gas species (volatile organic compounds (VOCs), NH3, SO2, and NOx) was conducted to evaluate the large-scale environment chamber for investigating the pathway of aerosol formation and the subsequent assessment techniques used for reducing fine particulate matter. Two small-scale environment chambers (one experimental group and one control group), each with a width, depth, and height of 3 m, 2 m, and 2.3 m, respectively, were constructed using ethylene tetrafluoroethylene (ETFE) films.
METHODS : The initial conditions of the fine particles and precursor gases (NOx and VOCs) for the small-scale environment chamber were set up by injecting diesel vehicle exhaust. NH3 and H2O2 were added to the small-scale environment chamber for the photochemical reaction to form organic and inorganic aerosols. The gas phase of the VOCs and the chemical compositions of aerosols were investigated using a proton transfer reaction time-of-flight mass spectrometer and the aerodyne high-resolution time-of-flight aerosol mass spectrometer at 1 and 10 s time resolutions, respectively. Gas phases of NO and NO2 were measured using Serinus 40 NOx at a 20 s time resolution.
RESULTS : The small-scale environment chambers built using ETFE films were proved to supply sufficient natural sunlight for the photochemical reaction in the environment chambers at an average of approximately 89% natural sunlight transmission at 300–1000 nm. When the intermediates of NH3 and H2O2 for the atmospheric chemical reaction were injected for the initial condition of the small-scale environment chamber, nitrate and ammonium in the experimental group increased to 4747% and 1837%, respectively, compared to the initial concentrations (5.4 μg/m3 of nitrate and 5.2 μg/m3 of ammonium), indicating the formation of secondary inorganic aerosols of ammonium nitrate (NH4NO3). This implies that it is necessary to inject intermediates (NH3 and H2O2) for the formation of fine particulate matter when simulating the atmospheric photochemical reaction for assessing the environment chamber. CONCLUSIONS : This study has shown that small-scale environment chambers can simulate the atmospheric photochemical reaction for the reduction of fine particulate matter and the formation of the aerosol pathway. The results of this study can be applied to prevent time and economic losses that may be incurred in a full-scale environment chamber.
4,200원
4.
2020.10
구독 인증기관 무료, 개인회원 유료
PURPOSES : In this study, the characteristics of fine particulate matter (PM2.5) concentrations under different weather conditions of different types of bus stops, such as enclosed-type and open-type bus stops, were analyzed using statistical methods.
METHODS : Data was collected inside and outside an enclosed bus stop on sunny and rainy days to compare and analyze the characteristics of fine particulate matter concentration in the target bus stop. The probability distributions were estimated for each data point using the Anderson–Darling test. Based on the estimated probability distributions, probability density functions were computed, and the values were used to estimate and compare probability for each air quality index inside and outside the bus stop under different weather conditions RESULTS : For the results of descriptive statistics, the average concentrations of fine particulate matter inside and outside the bus stop were 42.296 and 35.482 μg/m3 on a sunny day and 40.831 and 39.321 μg/m3 on a rainy day, respectively. Results of the statistical method, obtained using the Anderson-Darling test, indicate that the probability of the air quality index inside the bus stop reaching high concentrations on a sunny day was "high" or "very high," compared to that outside the bus stop. However, on rainy days, the differences in fine particulate matter concentrations inside and outside the bus stops were difficult to identify based on statistical evidence. CONCLUSIONS : It was found that the open-type bus stop had an advantage of preventing fine particulate matter effects on sunny days, compared to the enclosed-type bus stops. Furthermore, there were slight differences in fine particulate matter concentrations inside and outside the bus stop on a rainy day because of atmospheric flow and stormwater.
4,000원
5.
2020.10
구독 인증기관 무료, 개인회원 유료
PURPOSES : This paper presents the experimental results of tests conducted on concrete produced with air-cooled (AS) and water-cooled (WS) ground blast-furnace slag exposed to multi-deterioration environments of carbonation and scaling.
METHODS : Carbonated and uncarbonated concrete specimens were regularly monitored according to the ASTM C 672 standard to evaluate the durability of concrete exposed to both scaling and combined carbonation and scaling conditions. Additionally, mechanical properties, such as compressive strength, flexural strength, and surface electric resistivity, were analyzed. RESULTS : It was found that concrete specimens produced with AS and WS had a beneficial effect on the mechanical properties because of the latent hydraulic properties of the AS and WS mineral admixtures. Moreover, carbonated concrete showed good scaling resistance in comparison to uncarbonated concrete, particularly for concrete produced with AS and WS. CONCLUSIONS : The improved scaling resistance of carbonated concrete showed that AS is a suitable option for binders used in cement concrete pavements subjected to combined carbonation and scaling.
4,000원
6.
2020.10
구독 인증기관 무료, 개인회원 유료
PURPOSES : The aim of this study is to determine the maintenance costs for a reasonable preliminary feasibility study, feasibility study, or evaluation
METHODS : This study was based on government budget execution and budget execution data for expressways, national highways, cable-supported bridges and long-tunnels. For the expressway, data obtained from the Korea Expressway Corporation were used. For the national highway, data was obtained from the Ministry of Land, Infrastructure and Transport. Similarly, data collected from expressway maintenance costs and the Korea Infrastructure Safety and Technology Corporation were used for long tunnels and cable-supported bridges, respectively. The items for highway maintenance cost were reclassified more rationally to facilitate the calculation of the maintenance costs. The replacement cycle for each item was also calculated based on the budget expenditure data.
RESULTS : The results of this study showed the standard maintenance cost model for expressways, national highways, cable-supported bridges, and long-tunnels. In other words, a basis for predicting reasonable maintenance costs was prepared for a feasibility study. CONCLUSIONS : The reliability of the maintenance cost results was improved and it was more consistent with actual costs compared to the results of previous studies. It can be used as a basis for estimating the maintenance cost of a preliminary feasibility study and feasibility evaluation in the future.
4,300원
7.
2020.10
구독 인증기관 무료, 개인회원 유료
PURPOSES : In this experimental study, the resistance of blended cement concrete containing air-cooled slag (AS) and water-cooled slag (WS) to freeze–thaw action was investigated. For comparison, the durable performance of ordinary Portland cement (OPC) concrete exposed to a similar damage environment was also evaluated.
METHODS : Based on the ASTM C 666 standard, the relative dynamic modulus of elasticity, mass ratio, surface electric resistivity, and compressive strength of blended cement concrete specimens were periodically measured and compared with those of OPC concrete to evaluate the durability of concrete exposed to the freezing-thawing environment. In addition, microstructural characteristics of deteriorated concrete parts were evaluated using scanning electron microscopy (SEM) and energy dispersive spectroscopy techniques to detect products formed by freeze–thaw action.
RESULTS : It was found that the resistance of blended cement concrete containing AS and WS to freeze–thaw action was significantly better than that of OPC concrete. Furthermore, the SEM results revealed the frost damage of OPC concrete, owing to the formation of thaumasite. CONCLUSIONS : The application of AS in concrete can effectively improve the durability of concrete, particularly in freeze–thaw environments.
4,000원
8.
2020.10
구독 인증기관 무료, 개인회원 유료
PURPOSES : In this study, the flatness of a sidewalk surface was evaluated by measuring the vibration acceleration experienced by wheelchair users passing the sidewalk using a walking measure. The objective of this study is to derive a linear equation for converting the vibration acceleration of a sidewalk surface measured using a walking measure into vibration acceleration of a wheelchair.
METHODS : To this end, field measurements were obtained. Twenty sites with different sidewalk surface materials were selected to measure the vibration accelerations of the walking measure and wheelchair. A regression analysis was conducted with the measured root mean square value of the vibration acceleration, and a linear equation expressing the walking measure and wheelchair vibration acceleration was derived.
RESULTS : The regression analysis was conducted by inputting the vibration acceleration of the wheelchair into the Y-axis and that of the walking measure into the X-axis. Thus, a linear equation between the walking measure and wheelchair acceleration could be derived. Further, linear equations could be derived and applied based on the situation using various standard walking measures and wheelchairs. These equations could be used to convert the vibration acceleration of the walking measure into that of the wheelchair. Substituting the converted vibration acceleration into the comfort level specified in ISO 2631-1 was expected to indicate the flatness of the sidewalk.
CONCLUSIONS : This study confirmed that a linear equation for the two vibration accelerations could be derived by measuring the vibration accelerations of the walking measure and wheelchairs of 20 different sites. The vibration acceleration measured using the walking measure could be converted into that of the wheelchair using this linear equation. In addition, the flatness of the sidewalk could be evaluated by measuring the vibration acceleration of the walking measure using this linear equation.
4,000원
9.
2020.10
구독 인증기관 무료, 개인회원 유료
Relationship Between Pavement Marking Types and Visibility Distance Under Adverse Weather Conditions
PURPOSES : In this study, the relationship between the types of road pavement markings and the visibility distance under adverse weather conditions was evaluated.
METHODS : Rainy and foggy conditions at the weather proving ground were replicated in this study. The researchers recorded the visibility distance corresponding to each experiment scenario comprising the weather conditions and pavement marking types.
RESULTS : Visibility distances under adverse weather conditions decreased more than those of normal weather conditions. Under rainy conditions, the average visibility distance across all pavement markings decreased by 33%. However, the average visibility distance across all pavement markings foggy conditions decreased by 46.8%. Based on the test results of the visibility distance, the speed reduction rates corresponding to the adverse and normal weather conditions, i.e., 24% and 36% speed reduction under rainy and foggy conditions, respectively, were established.
CONCLUSIONS : This study validated the reduction in the visibility distance affected by weather conditions by applying actual road scale weather proving ground. In addition, speed reduction was recommended for safe driving under adverse weather conditions.
4,000원
10.
2020.10
구독 인증기관 무료, 개인회원 유료
PURPOSES : Despite the availability of larger traffic data and more advanced data collection methods, the problem of missing data is yet to be solved. Imputing missing data to ensure data quality and reliability of statistics has always been challenging. Missing data are imputed via several existing methods, such as autoregressive integrated moving average, exponential smoothing, and interpolation. However, these methods are complicated and results in significant errors.
METHODS : A deep-learning method was applied in this study to impute traffic volume data of the South Korean national highway. Traffic data were trained using the long short-term memory method, which is a suitable deep-learning method for time series analysis.
RESULTS : Three cases were proposed to estimate the traffic volume. In the first case, which represented the general conditions, the mean absolute percentage error (MAPE) was 12.7%. The second estimation case, which was based on the opposite traffic flow, exhibited a MAPE of 17%~18%. The third case, which was estimated using adjacent-section data, had a MAPE of 18.2%. CONCLUSIONS : Deep learning may be a suitable alternative data imputation method based on the limited site and data. However, its application depends on the specific situation. Furthermore, deep-learning models can be improved using an ensemble method, batch-size, or through model-structure optimization.
4,000원
11.
2020.10
구독 인증기관 무료, 개인회원 유료
PURPOSES : In this study, the causality between smart parking user services and its satisfaction level was analyzed statistically, and a smart parking priority decision model was established in terms of the user side.
METHODS :The results of the Daegu Metropolitan City survey for the parking state, parking fee, transfer, convenience of use, facilities, and safety that could influence smart parking user satisfaction were used. A structural equation model in SPSS 26 and AMOS 26 programs that facilitates hypothesis testing and importance factor analysis between observed and latent variables was used.
RESULTS : The results demonstrated that the importance factor loading on smart parking user services was in the following order: convenience of use (0.996), parking facilities (0.814), safety (0.803), parking information (0.706), transfer (0.618), and parking fee (0.426). Among them, the parking fee was not quite influential in decision making.
CONCLUSIONS : The most influential user service on smart parking information systems was the convenience of use, in which congestion in parking lots and parking time were the most influential variables. The most influential variables were in the following order: in parking facilities, the route design of vehicle flow and size of the parking garage; in safety, the entrance location and the level of wear; in the parking state, the availability of parking space and parking fees; and finally in transfer, the convenience of transfer to other modes and the number of transfer parking lots.
4,000원
