• Journal of Korea Planning Association
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• v.53 no.7
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• pp.39-48
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• 2018

The purpose of this study is to verify the stable flight conditions of drones within a limited urban area by using the ICAO(International Civil Aviation Organization) reich model which is using to evaluate civil aircraft stability. The results of the study are summarized as follows. First, in order for the drones flying stably, the horizontal safety separation distance between a drone and another should be at least 1,852M. Second, assuming that no obstacles within 1,852M of horizontal space, two drones can be fly into upper and lower spaces. However there are obstacles such as buildings, it is impossible to secure a 1,852M distance between drones. Third, sensitivity analysis point out that the separation interval($s_x$) of drone aviation has the greatest influence on the TLS(Target Level of Safety). If future research is conducted to lower the numerical values, the safety distance between a drone and another drone will be drastically reduced, allowing more detailed urban space division, and will be presented as a scientific numerical value for establishing a dedicated path for the drones.

• International conference on construction engineering and project management
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• 2024.07a
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• pp.769-774
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• 2024

The availability of PMT(Project Management Tool) in the market has been increasing rapidly in recent years and Significant advancements have been made for project managers to use for planning, monitoring, and control. Recently, studies applying the Reinforcement-Learning Based Construction Schedule Simulation algorithm for construction project process planning/management are increasing. When reinforcement learning is applied, the agent recognizes the current state and learns to select the action that maximizes the reward among selectable actions. However, if the action of global optimal points is not selected in simulation selection, the local optimal resource may receive continuous compensation (+), which may result in failure to reach the global optimal point. In addition, there is a limitation that the optimization time can be long as numerous iterations are required to reach the global optimal point. Therefore, this study presented a method to improve optimization performance by increasing the probability that a resource with high productivity and low unit cost is selected, preventing local optimization, and reducing the number of iterations required to reach the global optimal point. In the performance evaluation process, we demonstrated that this method leads to closer approximation to the optimal value with fewer iterations.

• Structural Engineering and Mechanics
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• v.50 no.4
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• pp.541-561
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• 2014

This paper approaches the issue of seismic vulnerability assessment strategies for facade walls of traditional masonry buildings through the development of a methodology and its subsequent application to over 600 building facades from the old building stock of the historic city centre of Coimbra. Using the post-earthquake damage assessment of masonry buildings in L'Aquila, Italy, an analytical function was developed and calibrated to estimate the mean damage grade for masonry facade walls. Having defined the vulnerability function for facade walls, damage scenarios were calculated and subsequently used in the development of an emergency planning tool and in the elaboration of an access route proposal for the case study of the historic city centre of Coimbra. Finally, the methodology was pre-validated through the comparison of a set of results obtained from its application and also resourcing to a widely accepted mechanical method on the description of the out-of-plane behaviour of facade walls.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.37 no.5
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• pp.315-322
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• 2019

DSM (Digital Surface Model) is a digital representation of ground surface topography or terrain that is widely used for hydrology, slope analysis, and urban planning. Aerial photogrammetry and LiDAR (Light Detection And Ranging) are main technology for urban DSM generation but high-resolution satellite imagery is the only ingredient for remote inaccessible areas. Traditional automated DSM generation method is based on correlation-based methods but recent study shows that a modern pixelwise image matching method, SGM (Semi-Global Matching) can be an alternative. Therefore this study investigated the application of SGM for Kompsat satellite data of KARI (Korea Aerospace Research Institute). Firstly, the sensor modeling was carried out for precise ground-to-image computation, followed by the epipolar image resampling for efficient stereo processing. Secondly, SGM was applied using different parameterizations. The generated DSM was evaluated with a reference DSM generated by the first pulse returns of the LIDAR reference dataset.

• International conference on construction engineering and project management
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• 2022.06a
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• pp.678-685
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• 2022

Prefabrication is a construction technique that is increasingly being applied to different building components due to its many benefits, including higher quality and lower waste. Despite these advantages, there are challenges in execution of these components on projects, due to transportation logistics, skilled labor requirements, and project management techniques. This paper investigates the current landscape of prefabricated pipe spools and potential solutions for minimizing these challenges. The scope of this research includes a proposed workflow, to standardize implementation of these components. Semi-structured interviews were conducted with industry professionals to assess current industry practices and the validity of the proposed workflow. Findings of this paper indicate that greater integration between design, fabrication and transportation is required to minimize inefficiencies when implementing prefabricated pipe spools on projects.

• International conference on construction engineering and project management
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• 2020.12a
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• pp.371-380
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• 2020

With the 4th industrial revolution, many advanced information technologies are being applied to the area of construction engineering and project management. These applications are usually focusing on design, construction and operation stage and are producing many meaningful fruits. Even though these studies are very important for the development of the construction industry, this study insists that the other stage perspective such as construction business also should be emphasized. Because business phase has significant impacts on the success of a construction project as well as design, construction and operation phase. So, this study reviewed the intelligent-approach papers in planning and marketing, estimation and bid, contract and claim, and project financing fields. This study provides some insights such as values, difficulties, limitations and future directions of business intelligence application.

• International conference on construction engineering and project management
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• 2024.07a
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• pp.672-679
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• 2024

This study introduces a novel system for the 4D simulation of Building Information Modeling (BIM) objects in mixed reality (MR) environments, addressing challenges of file format compatibility and data management. By developing a system that effectively partitions and manages BIM data, specifically utilizing the OBJ format, the study enables precise simulation of construction project changes over time. This advancement enhances visualization and decision-making in construction project planning and execution. The study highlights the integration of BIM and MR technologies, facilitating enhanced project management and operational workflows. Future work will focus on expanding compatibility with various BIM data formats and MR devices, and integrating AI-based data analysis for more accurate and efficient construction simulations.

• Computers and Concrete
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• v.6 no.4
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• pp.305-318
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• 2009

Fiber Reinforced Polymer (FRP) is widely used for retrofitting concrete structures for various purposes. Especially, for the retrofitting of concrete structures subjected to blast loads, FRP is proven to be a very effective retrofitting material. However, a systematic design procedure to implement FRP for concrete structure retrofitting against blast loads does not exist currently. In addition, in case of concrete structures with inarticulate geometrical boundary conditions such as arch structures, an effective analysis technique is needed to obtain reliable results based on minimal analytical assumptions. Therefore, in this study, a systematic and efficient blast analysis procedure for FRP retrofitting design of concrete arch structure is suggested. The procedure is composed of three sequential parts of preliminary analysis, breach and debris analysis, and retrofit-material analysis. Based on the suggested procedure, blast analyses are carried out by using explicit code, LS-DYNA. The study results are discussed in detail.

• Geomechanics and Engineering
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• v.21 no.3
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• pp.301-313
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• 2020

In the process of mining closely spaced coal seams, the problem of roadway arrangement in lower coal seams has long been a concern. By means of mechanical model calculation and numerical simulation postprocessing, the distribution of the stress deviator below the floor of a goaf and the evolution of the stress deviator in the vertical and horizontal directions are studied under the influence of horizontal stress. The results of this theoretical study and numerical simulation show that the stress deviator decreases exponentially with increasing depth from the floor below the coal side. With the increase in the horizontal stress coefficient λ, the stress deviator concentration area shifts. The stress deviator is concentrated within 10 m below the goaf and 15 m laterally from the coal side; thus, the magnitude of the surrounding rock stress deviator should be considered when planning the construction of a roadway in this area.

• Advances in concrete construction
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• v.11 no.2
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• pp.89-98
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• 2021

Investigations on the dynamic behavior of concrete members, incorporating steel fibers with different aspect ratios, are limited so far and do not covered comprehensively in prior studies. Present endeavor is devoted to examine the dynamic response of the steel fibrous concrete beams and slabs under the influence of impact loading. These members were reinforced with steel fibers in different length of 25 mm and 50 mm. Four concrete mixes were designed and used based on the proportion of long and short fibers. Twenty-four slabs and beams were fabricated with respect to the concrete mix and these specimens were tested in impact load experiment. Testing observations revealed that the maximum dynamic deflection or ductility of the member can be achieved with increasing the fiber length. Structural behavior of the tested structures was predicted using nonlinear finite element analysis with specific material constitutive relationships. Eight nodes plate elements have been considered in the present dynamic analysis. Dynamic fracture energy of the members was calculated and agreement ratio, of more than 70%, was noticed between the experimental and analysis outcomes.