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        검색결과 82

        1.
        2024.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study aimed to assess the global and domestic efforts regarding the reduction of environmental-impact-factor emissions in the production and construction processes of concrete pavements. By utilizing internationally commercialized programs, this study sought to calculate the environmental impact factors generated by specific domestic concrete-pavement projects and identify areas for improvement. This study evaluated the global and domestic efforts of environmental impact reduction by focusing on the production and construction of concrete pavements. This study calculated the environmental impact factors for five cases using internationally commercialized software. The analysis revealed that, during the production and construction of concrete pavements, Portland cement production is a dominant cause of global warming, smog, acidification, and non-carcinogenic factors, whereas aggregate production is a dominant cause of ozone depletion, eutrophication, carcinogenicity, respiratory issues, environmental toxicity, and fossil-fuel depletion. This study analyzed the environmental impact factors of material mix and process during concrete pavement production and construction using foreign life-cycle inventory (LCI) databases. The environmental impact of each input material was identified. In the future, if an LCI and life-cycle impact assessment (LCIA) database for domestic road pavement materials is established and analyzed based on the conditions presented in this study, it is expected to lay the foundation for the development of environmentally friendly materials.
        4,300원
        2.
        2024.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study aimed to assess the current global efforts to reduce greenhouse gas emissions and understand the domestic scenario, particularly focusing on pavement-marking works during road-construction projects. Using internationally commercialized programs, this study aimed to calculate carbon emissions from these projects, identify areas that require further action or improvement, and propose strategies to address them. This study assessed the current global efforts to reduce greenhouse gas emissions and understand the domestic scenario, particularly focusing on pavement-marking works during road-construction projects. Using internationally commercialized programs, this study aimed to calculate carbon emissions from these projects, identify areas that require further action or improvement, and propose strategies to address them. Carbon dioxide emissions from pavement-marking projects were estimated. For a 5,746 m2 construction project, a total of 96.637 was emitted; for a 5,032 m2 project with four types of markings, 89.840 was emitted. A project involving five types of markings, traffic controls, and safety measures resulted in 6.662 emissions. On average, 16.8 was emitted per 1 m2, with 17.8 for the four types and 9.3 for the five types of markings. This study is significant because it calculated the carbon dioxide emissions from domestic pavement-marking works. The use of unit price data is convenient, and for more accurate calculations, expanding environmental product declaration (EPD) certified items and accelerating the establishment of a domestic life-cycle inventory (LCI) are recommended.
        4,200원
        3.
        2024.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study determined the minimum size of a representative molecular structure for use in future dynamic analyses of asphalt binders. The minimum representative size, considering factors such as aging, additive types, and temperature variations, was established using density and radial distribution functions. This approach ensures that the structure reflects temperature-dependent property changes, which are critical characteristics of asphalt binders. In this study, the structure of asphalt-binder molecules was generated using the composition proposed by Li and Greenfield (2014) for AAA1. To assess the appropriateness of the molecular structure size, we generated additional structures, X2 and X3, maintaining the same composition as X1, but with two and three times the number of molecules, respectively, as suggested by Li and Greenfield (2014). Silica and lignin were considered as additives, and the aging conditions examined included unaged, short-term aging, and long-term aging. In addition, 11 temperature conditions were investigated. The density and radial distribution functions were plotted and analyzed. The variables influencing the density and radial distribution functions were set as the aging degree of the asphalt binder (unaged, short-term aging, long-term aging), 11 temperature conditions ranging from 233 to 433 K in 20 K intervals, structure size (X1, X2, and X3), and the presence of additives (no additives, silica, and lignin). For density, clear differences were observed based on the degree of aging, temperature conditions, and presence of additives, whereas the structure size did not significantly affect the density. In terms of radial distribution functions, the X1 structure reflected differences based on the degree of aging and the presence of additives but was limited in exhibiting temperature-dependent variations. In contrast, the X3 structure effectively captured temperature-dependent trends, indicating that the size of the molecular structure is crucial when evaluating energy calculations or physical tensile strength, necessitating careful assessment.
        4,000원
        4.
        2024.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This paper explores a convergent approach that combines advanced informatics and computational science to develop road-paving materials. It also analyzes research trends that apply artificial-intelligence technologies to propose research directions for developing new materials and optimizing them for road pavements. This paper reviews various research trends in material design and development, including studies on materials and substances, quantitative structure–activity/property relationship (QSAR/QSPR) research, molecular data, and descriptors, and their applications in the fields of biomedicine, composite materials, and road-construction materials. Data representation is crucial for applying deep learning to construction-material data. Moreover, selecting significant variables for training is important, and the importance of these variables can be evaluated using Pearson’s correlation coefficients or ensemble techniques. In selecting training data and applying appropriate prediction models, the author intends to conduct future research on property prediction and apply string-based representations and generative adversarial networks (GANs). The convergence of artificial intelligence and computational science has enabled transformative changes in the field of material development, contributing significantly to enhancing the performance of road-paving materials. The future impacts of discovering new materials and optimizing research outcomes are highly anticipated.
        4,200원
        5.
        2024.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        PURPOSES : This study aimed to develop a quantitative structure property relationships (QSPR) model to predict the density from the molecular structure information of the asphalt binder AAA1, a non-full connected structure mixed with a total of 12 molecules. METHODS : The partial least squares regression (PLSR) model, which models the relationship between predictions and responses and the structure of these variables, was applied to predict the density of a binder with molecule descriptors. The PLSR model could also analyze data with collinear, noisy, and multiple dimensional independent variables. The density and additive-free AAA1 binder’s molecule systems generated by an asphalt binder’s molecules-related study were used to fit the PLSR model with the molecular descriptors produced using alvaDesc software. In addition to developing the relationship, a systematic feature selection framework (i.e., the V-WSP- and PLSR-modelbased genetic algorithm (GA)) was applied to explore sets of predictors which contributed to predicting the physical property. RESULTS : The PLSR model accurately predicted the density for the AAA1 binder’s molecules using the condition of the temperature and aging level (R2 was 0.9537, RMSE was 0.00424, and MAP was 0.00323 for the test data) and provided a set of features which correlated well to the property. CONCLUSIONS : Through the establishment of the physical property prediction model, it was possible to evaluate the physical properties of construction materials without limited experiments or simulations, and it could be used to comprehensively design the modified material composition.
        4,000원
        6.
        2024.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        PURPOSES : As evaluation methods for road paving materials become increasingly complex, there is a need for a method that combines computational science and informatics for new material development. This study aimed to develop a rational methodology for applying molecular dynamics and AI-based material development techniques to the development of additives for asphalt mixtures. METHODS : This study reviewed relevant literature to analyze various molecular models, evaluation methods, and metrics for asphalt binders. It examined the molecular structures and conditions required for calculations using molecular dynamics and evaluated methods for assessing the interactions between additives and asphalt binders, as well as properties such as the density, viscosity, and glass transition temperature. Key evaluation indicators included the concept and application of interaction energy, work of adhesion, cohesive energy density, solubility parameters, radial distribution function, energy barriers, elastic modulus, viscosity, and stress-strain curves. RESULTS : The study identified key factors and conditions for effectively evaluating the physical properties of asphalt binders and additives. It proposed selective application methods and ranges for the layer structure, temperature conditions, and evaluation metrics, considering the actual conditions in which asphalt binders were used. Additional elements and conditions considered in the literature may be further explored, considering the computational demands. CONCLUSIONS : This study devised a methodology for evaluating the physical properties of asphalt binders considering temperature and aging. It reviewed and selected useful indicators for assessing the interaction between asphalt binders, additives, and modified asphalt binders and aggregates under various environmental conditions. By applying the proposed methods and linking the results with informatics, the interaction between asphalt binders and additives could be efficiently evaluated, serving as a reliable method for new material development.
        4,600원
        7.
        2024.01 KCI 등재 구독 인증기관 무료, 개인회원 유료
        해외 위험지역에서 다양한 위난상황으로부터 재외국민을 보호하고 본 국으로 안전한 귀환을 위해 외교·국방·정보 역량을 동원하여 수행되는 활 동이 비전투원후송작전(NEO)이다. 미국과 한국이 수행했던 NEO 사례분 석을 바탕으로 도출된 NEO의 성공적인 수행을 위한 요인과 시사점은 다 음과 같다. 첫째, NEO 계획의 핵심요소는 변화하는 작전환경에 대한 상 황인식과 대비태세이다. 둘째, 후송작전의 기본원칙인 정확성, 보안, 속 도를 기반으로 하여 적대세력의 접근경로와 공격유형을 파악하고, 급변 하는 위협환경에 대응할 수 있는 신속대응군과 후송부대를 투입해야한 다. 셋째, NEO 계획, 경보발령, 집결·재배치, 후송·귀환 과정에서 국무부 /외교부, 국방부, 재외공관, NEO 수행부대 간의 효과적인 협력과 조정 업무가 이루어져야한다. 넷째, 국방부와 정보기관은 현지 임무수행단에 게 작전지역 평가, 위협평가, 적대세력의 위협방책 식별, 대응책 등의 정보를 제공해야한다. 다섯째, 내란과 분쟁지역에서 NEO는 시·공간 제 한사항이 많은 원거리 해외지역에서 작전이기 때문에 동맹국·우방국과의 긴밀한 군사협력 및 연합작전도 필수적이다.
        7,000원
        8.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        PURPOSES : In this study, the resources and energy consumed to produce hot mix asphalt mixtures and hot mix reclaimed asphalt mixtures in asphalt concrete plants were estimated and the emissions from the detailed processes of the production process were evaluated based on TRACI(the tool for the reduction and assessment of chemical and other environmental impacts). METHODS : To estimate the energy consumption of the aggregate drying process, which consumes a significant amount of energy in the production process, an energy consumption calculation model based on the thermal equilibrium equation was used, and the energy consumed for material transportation, storage, and operation of other facilities was cited from the literature. RESULTS : For the system boundary conditions established and the inventory considered, the emissions to produce one ton of hot mix reclaimed asphalt mix are greater than the emissions to produce one ton of hot mix asphalt mix for a number of key impact categories. The process of producing hot mix reclaimed asphalt mixtures was evaluated to consume more resources and energy in the production of recycled aggregates and heating for drying than in the production of hot mix asphalt mixtures, but less resources and energy in the production of binders and natural virgin aggregates and the heating to heat these materials. CONCLUSIONS : The results of the emissions assessment using the life cycle inventory for the production of hot mix asphalt mixtures were generally similar to the results understood in the field and in much of the literatures, confirming the reliability of the methodology. However, in order to evaluate the dominance of specific processes or mixtures, it is believed that the construction of a wide range of inventory databases after inventory redesign is necessary for a specific and rigorous assessment.
        4,000원
        9.
        2023.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        PURPOSES : In this study, energy-consuming processes in asphalt plants were evaluated, and the drying and mixing processes were characterized using a thermal equilibrium equation-based model to quantitatively estimate the amount of energy consumed during the production of mixtures in asphalt concrete plants. METHODS : An energy consumption model based on the thermal equilibrium equation was used to estimate the energy consumption of the aggregate drying process that consumes the maximum energy; the energy consumed for material transportation, storage, and operation of other facilities was cited from the literature. The results were compared with the actual results obtained for recycled hot asphalt mixtures and recycled warm mix asphalt mixtures, and a sensitivity analysis was performed by varying the conditions. RESULTS : An analysis of the main processes required to produce asphalt mixtures showed that the water content had the largest impact on energy consumption (approximately 80%). This quantitatively supports the opinion of field practitioners that maximum energy is consumed during aggregate drying. Although some discrepancies were observed, the results were found to be reasonable and within the range of typical measurements. CONCLUSIONS : The thermal energy consumption estimation model provides consistent results that reflect the characteristics of the mixture and can be used to derive the thermal energy consumption rates for individual materials, such as aggregates and binders. This can be used to identify the priorities for process optimization within a plant.
        4,000원
        10.
        2023.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        PURPOSES : This study aims to determine whether machine learning techniques based on the results of chemical analysis experiments can be rationally applied to evaluate the aging of various asphalt binders used throughout the country. METHODS : We conducted chemical experiments such as FT-IR, H-NMR, C- NMR, and GPC for the three-stage aging levels of eight types of asphalt binders used in the country and utilized two artificial neural network models to determine valid chemical experimentation and conditions for the use of neural modeling through predictions. RESULTS : The M-prop model, which combined the findings from each neural network model into a single artificial neural network model, demonstrated superior predictive performance compared with the M-base model, which assessed aging using two cluster layers. In addition, the minimum amount of data required to achieve 100% predictive accuracy for the target asphalt binders, regardless of the artificial neural network model, was 18, and the amount of training data decreased to less than 50%. CONCLUSIONS : The predictive accuracy of the aging of asphalt binders was significantly enhanced when GPC data was used, indicating that GPC should be prioritized in evaluating the aging of asphalt binders.
        4,000원
        13.
        2023.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        PURPOSES : In this study, we aimed to evaluate the transition temperature (Tt) of asphalt binders using molecular dynamics simulations, which can provide a more accurate assessment of the mechanical properties of a material at the molecular level and can be applied to material development and design. METHODS : Unlike conventional macro- or meso-level simulations, we utilized MD simulations to evaluate the Tg of asphalt binders based on material composition and aging degree as input variables. In this analysis, 11 temperatures ranging from 434 K to 233 K at 20 K intervals were utilized, and the bulk volume and density were calculated through MD simulations. RESULTS : The MD simulation successfully predicted the Tg of the asphalt binder, and the molecular-level properties and interactions determined in this study can be applied not only to material development but also to the determination of constitutive equations or contact models used in continuum mechanics or discrete element methods. The calculated Tg was slightly different depending on the aging of the asphalt binder; however, it was found to accurately reflect the transitional characteristics. CONCLUSIONS : This study demonstrated the potential of MD simulations as valuable tools for material development and design in the construction industry. The results indicate that the use of MD simulations can lead to more accurate and efficient material development and design by providing a more detailed understanding of material properties and interactions at the molecular level.
        4,000원
        14.
        2022.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        PURPOSES : In this study, emissions from asphalt mixture production and construction processes are calculated and used to estimate the emission from each asphalt pavement layer. The calculated emissions for the processes are used as fundamental data to estimate the total emission from the entire life cycle of pavement engineering in South Korea. METHODS : A design proposal and the Korean standard, which provide quantitative information for activities, were used to estimate the amount of construction materials and energy consumption. Subsequently, the LCI DB from NAPA and the LCIA DB from EPA were utilized in conjunction with the estimated quantity to assess the effect of the emissions to determine their environmental impact categories. RESULTS : Calculation results show that 5.84 million ton of CO2eq is discharged from production and construction processes, whereas 3.24 million ton of CO2eq is discharged from operation processes in the pavement engineering sector. The total GHG emission, i.e., 9.08 million ton of CO2eq, is approximately 1.25% of the national GHG emission in 2018. The asphalt mixture production process results in the highest GHG emission in the life cycle of asphalt pavements. CONCLUSIONS : An LCI DB that accounts for the industrial characteristics of South Korea must be established to provide more reliable emission data to be used for national GHG reduction plans, including those for the pavement engineering sector.
        4,000원
        17.
        2021.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        PURPOSES : The cooling characteristics of the asphalt mixture in a moving dump truck were analyzed using a numerical simulation method. The cooling characteristic can be used to determine the optimum transport path for minimizing the temperature drop of the asphalt mixture. METHODS : In this research, a coupled analysis of the discrete element method (DEM) with computational fluid dynamics (CFD) was applied for cooling characteristic analysis of asphalt mixtures in transit. Two different transit speeds, 30 km/h and 60 km/h, were considered to evaluate the effect of speed on the temperature drop of the asphalt mixture. Velocity, pressure, and temperature contours were plotted and temperature variations were compared. RESULTS : Most of the temperature drops in the asphalt mixture were observed in the middle of the dump box in the longitudinal direction. It was confirmed that a faster speed causes a greater temperature drop for the same travel time and a slower speed causes the more temperature to reach the same travel distance as expected. CONCLUSIONS : It is concluded that the coupled analysis method can be used to quantitatively evaluate the effect of vehicle speed on temperature drop in asphalt mixtures. In addition, the method can be used to determine the optimum travel path considering environmental conditions and traffic congestion.
        4,000원
        18.
        2020.12 구독 인증기관 무료, 개인회원 유료
        3,000원
        19.
        2020.09 구독 인증기관·개인회원 무료
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