• Journal of Korean Society on Water Environment
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• v.36 no.5
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• pp.405-422
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• 2020

Land use change by urbanization has significantly affected the hydrological process including the runoff characteristics. Due to this situation, it has been becoming more complicated to manage non-point source pollutions caused by rainfall. In order to effectively control non-point sources, it is necessary to identify the reduction efficiency of the various management method based on land use characteristics. Thus, the purpose of this study is to analyze the reduction efficiency of non-point source pollution management practices targeting three different watersheds with the different land use characteristics using the Soil and Water Assessment Tool (SWAT). To do this, the vulnerable subwatersheds to non-point source pollution occurrence within each watershed were selected based on the streamflow and water quality simulation results. Then, considering the land use, low impact development (LID) or best management practices (BMPs) were applied to the selected subwatersheds and the efficiency of each management was analyzed. As a result of analysis of the non-point source pollution reduction efficiency, when LID was applied to urban areas, the average reduction efficiencies of SS, NO₃-N, and TP were 5.92%, 4.62%, and 10.35%, respectively. When BMPs were applied to rural areas, the average reduction efficiencies of SS, TN and TP were 35.45%, 4.37%, and 10.16%, respectively. The results of this study can be used as a reference for determining appropriate management methods for non-point source pollution in urban, rural, and complex watersheds.

• Computers and Concrete
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• v.24 no.6
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• pp.541-553
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• 2019

Alkali-silica reaction (ASR) in concrete can induce degradation in its mechanical properties, leading to compromised serviceability and even loss in load capacity of concrete structures. Compared to other properties, ASR often affects the modulus of elasticity more significantly. Several empirical models have thus been established to estimate elastic modulus reduction based on the ASR expansion only for condition assessment and capacity evaluation of the distressed structures. However, it has been observed from experimental studies in the literature that for any given level of ASR expansion, there are significant variations on the measured modulus of elasticity. In fact, many other factors, such as cement content, reactive aggregate type, exposure condition, additional alkali and concrete strength, have been commonly known in contribution to changes of concrete elastic modulus due to ASR. In this study, an artificial intelligent model using artificial neural network (ANN) is proposed for the first time to provide an innovative approach for evaluation of the elastic modulus of ASR-affected concrete, which is able to take into account contribution of several influence factors. By intelligently fusing multiple information, the proposed ANN model can provide an accurate estimation of the modulus of elasticity, which shows a significant improvement from empirical based models used in current practice. The results also indicate that expansion due to ASR is not the only factor contributing to the stiffness change, and various factors have to be included during the evaluation.

• Journal of the Korean Recycled Construction Resources Institute
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• v.7 no.4
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• pp.316-322
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• 2019

A probabilistic approach considering uncertainties was employed to investigate the effects on the material characteristics and strength of nuclear bio-logical shield concrete walls, when exposed to long-term radiation during the entire service life. Time-dependent compressive and tensile strengths were estimated by conducting the neutron fluence analysis. For the contaminated concrete, individual compressive and tensile failure probabilities can be possibly evaluated by not only establishing limit-state function withthe predefined critical values but also performing Monte Carlo Simulation. Nuclear power plant types similar to the Kori Unit 1, which was shut off permanently in 2017 after the 40-year operation, were herein selected for an illustrative purpose. Consequently, the probability-based performance assessment and prediction of contaminated concrete walls were well demonstrated.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.41 no.5
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• pp.591-599
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• 2021

Rail transit agencies in Korea have been struggling to set up a performance-based rail facility maintenance plan because there are no formal definition and decision criteria for aging infrastructure. This study investigates the definition of aging infrastructure through extensive literature review and identifies benchmarking criteria through comparison with rail transit facility management systems in Korea and United States. As results, an aging infrastructure should be defined considering both service age and performance level of a facility. The priority of repair/replacement should be also determined with reasonable criteria based on relationship between service age and performance level. To determine the definition and decision criteria, a practicable classification system for aging rail transit needs to be established in accordance with classification system for performance assessment. Furthermore, a comprehensive database needs to be built including useful life, performance level, and maintenance cost of each component of rail transit. It will allow establishing an efficient budget execution plan for aging infrastructure.

• Computers and Concrete
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• v.33 no.4
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• pp.341-348
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• 2024

Ultra-high-performance concrete (UHPC) has received remarkable attentions in civil infrastructure due to its unique mechanical characteristics and durability. UHPC gains increasingly dominant in essential structural elements, while its unique properties pose challenges for traditional inspection methods, as damage may not always manifest visibly on the surface. As such, the need for robust inspection techniques for detecting cracks in UHPC members has become imperative as traditional methods often fall short in providing comprehensive and timely evaluations. In the era of artificial intelligence, computer vision has gained considerable interest as a powerful tool to enhance infrastructure condition assessment with image and video data collected from sensors, cameras, and unmanned aerial vehicles. This paper presents a computer vision-based approach employing deep learning to detect cracks in UHPC beams, with the aim of addressing the inherent limitations of traditional inspection methods. This work leverages computer vision to discern intricate patterns and anomalies. Particularly, a convolutional neural network architecture employing transfer learning is adopted to identify the presence of cracks in the beams. The proposed approach is evaluated with image data collected from full-scale experiments conducted on UHPC beams subjected to flexural and shear loadings. The results of this study indicate the applicability of computer vision and deep learning as intelligent methods to detect major and minor cracks and recognize various damage mechanisms in UHPC members with better efficiency compared to conventional monitoring methods. Findings from this work pave the way for the development of autonomous infrastructure health monitoring and condition assessment, ensuring early detection in response to evolving structural challenges. By leveraging computer vision, this paper contributes to usher in a new era of effectiveness in autonomous crack detection, enhancing the resilience and sustainability of UHPC civil infrastructure.

• Current Research on Agriculture and Life Sciences
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• v.27
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• pp.59-67
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• 2009

The purpose of this study is to propose the methodology for introducing green infrastructure that can improve the health of citizens by promoting walkability. The methodology is composed of the following three phases: classification of the types of green spaces, selection of core green spaces with two separate analyses, and introduction of the framework of green infrastructure to promote walkability. In the first phase, the classification of the types of green spaces was carried out in order to understand existing distribution pattern of green spaces in study site. In the second phase, walkable blocks were selected by such methods as walkability value. Through these two analyses, all the blocks were divided into three groups according to the ranking figured up the second analyses' results. The blocks in the first group, the group involved in the top 30% and having the greatest ranking, were defined as walkable blocks. In the last phase, a basic frame of the green infrastructure in study site was introduced by connecting the walkable blocks with using other blocks and the green spaces over 1ha. In case study, 28 important green spaces and 35 walkable blocks were selected through the two analysis process. Then, the basic framework of green infrastructure based on the selected 28 important green spaces and 35 walkable blocks was introduced. The methodology applied to this study can be used to get the best selections of the proper green infrastructure in accordance with the purpose of the ecological and recreational local development. In particular, this study will suggest a specific analysis model to use for the ecological and walkable urban planning with green spaces existing in the city.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.1
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• pp.103-109
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• 2016

The information security industry is technology-intensive, high value-added industries. South Korea's response has excellent ICT skills and experience and skills in a variety of cyber attacks, has become a benchmark in the world. However, the small size of the domestic information security company, supporting infrastructure is lacking. Domestic information security industry is the primary condition to activate the export. For the export of high value-added enterprise information security products and services, it is necessary the establishment of the domestic IT information security infrastructure of the industrial promotion is based overseas. Come to analyze the domestic information security industry, capital of this small, market reclamation of overseas expansion, information, manpower shortage was a problem. This fact, combined losses caused by cost-free period AS. Therefore, the study on information security in the infrastructure industry overseas bases is necessary. How to select and analyze the causes of infrastructure in selected overseas offices. By utilizing the infrastructure of overseas bases, can raise the added value of the products and services of the Information Security company, we can enable the export of small and medium Information Security company from overseas offices.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.29 no.4
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• pp.327-334
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• 2016

This study proposed a framework for an infrastructure asset management manual which can be adjusted by different ordering authorities to develop their own manuals. For this, The necessity of asset management manual was examined through analysis of the current status and insufficiencies and limitations in the asset management manuals of the domestic government and ordering authorities. Second, the systems and characteristics of infrastructure asset management manuals in developed countries such as Australia, the United Kingdom and the United States were examined and compared. Finally, based on the domestic infrastructure asset management characteristics and foreign infrastructure asset management manuals, a framework for an infrastructure asset management manual that can be utilized by the ordering authorities was proposed considering generality of asset management manual, asset management maturity of ordering authorities, serviceability of manual, and cyclic processes of asset management.

• International Journal of Computer Science & Network Security
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• v.21 no.3
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• pp.198-205
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• 2021

For twenty years, in the EU there has been a trend of a lack of maritime infrastructure and a redundance of the road one, which has a negative impact on the economy. The intermodal transport market structure in the EU has not changed over the past ten years. The stability of transport systems due to the lack of changes in the transport market remains under threat, affecting supply chains and networks through the optimization of warehousing and transportation costs. The research methodology is based on a quantitative assessment of cause-and-effect relations between economic growth and transport and logistics in the EU. A statistical analysis of security indicators, intermodal and modal transport, international trade in goods within the EU and in the world trade in goods, the dynamics of GDP of the EU countries, the level of openness of the EU economy, investment and maintenance costs of different modes of transport and infrastructure has been carried out. The results show that in 2000- 2010 there were positive changes in the transport and logistics infrastructure of the EU, which had a positive effect on trade, openness of the economy of the EU, GDP growth. However, at that time, negative effects of environmental impact and the load on road and rail transport were accumulating. Investment in different modes of transport is limited, and technical maintenance and infrastructure maintenance costs form a significant part of GDP of the EU. A slowdown in economic growth leads to budget constraints and infrastructure financing gap. As a result, the freight and passenger intermodal and modal transport market structure remains virtually unchanged. The load on rail and road transport remains stable, despite the reduced level of transport hazards. Transport productivity has declined over the past ten years. Herewith, the intensification of trade and the openness of the EU economies require constant modernization and innovative renewal. The EU policy in this direction remains normative, uncontrolled, which is reflected in investment differences within the EU and maintenance costs.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.2
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• pp.677-685
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• 2014

Despite the significant benefits of BIM (Building Information Modeling), it is not being vitalized for the facilities that are designed based on the horizontal and vertical alignments because of the lack of flexibility in manipulating surface models generated based on alignments. Alignment-based design produces a surface model in one piece through the definition of the typical cross-section along the alignment. Therefore, linking these alignment-based 3D surface models, that are not modularized and difficult to partition, to the required attribute information is very difficult This paper presents design of a flexible BIM technology suitable for the alignment-based civil infrastructure by providing the partitioning functionality for surface models, the contents library for cross-sectional design components, and the attribute information along with the critical functionalities needed for the design, construction and maintenance of alignment-based civil infrastructure.