• Journal of Korean Society of Steel Construction
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• v.23 no.2
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• pp.159-167
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• 2011

Steel structure construction is currently increasing on account of the many merits of steel structures. Due to numerous environmental factors, many cracks and extensive corrosion occur in steel structures, which cause the deterioration of the performance and life cycle of such structures. Maintenance of steel structures is thus strongly demanded, for safety control. The inspection methods that are currently being used, however, are very limited and can detect only local defects in steel structures. They also take much time to use and incur high maintenance costs. Moreover, such methods cannot be applied to huge steel structures, which men find unapproachable. They also require much time due to the need for periodic checks, and may lead to cost loss. Therefore, the development of a monitoring system that can detect defects in whole structures and can reduce the repair and strengthening costs at an early stage is very much needed. In this study, the generation and propagation of cracks were monitored via the electric-potential-drop method (EPDM).

• Smart Structures and Systems
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• v.33 no.6
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• pp.399-414
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• 2024

This study discusses the long-term deformation monitoring and shape sensing of bridge girder surfaces with an automated extraction scheme for point clouds in the Region Of Interest (ROI), invariant to the position of a Light Detection And Ranging system (LiDAR). Advanced smart construction necessitates continuous monitoring of the deformation and shape of bridge girders during the construction phase. An automated scheme is proposed for reconstructing geometric model of ROI in the presence of noisy non-stationary background. The proposed scheme involves (i) denoising irrelevant background point clouds using dimensions from the design model, (ii) extracting the outer boundaries of the bridge girder by transforming and processing the point cloud data in a two-dimensional image space, (iii) extracting topology of pre-defined targets using the modified Otsu method, (iv) registering the point clouds to a common reference frame or design coordinate using extracted predefined targets placed outside ROI, and (v) defining the bounding box in the point clouds using corresponding dimensional information of the bridge girder and abutments from the design model. The surface-fitted reconstructed geometric model in the ROI is superposed consistently over a long period to monitor bridge shape and derive deflection during the construction phase, which is highly correlated. The proposed scheme of combining 2D-3D with the design model overcomes the sensitivity of 3D point cloud registration to initial match, which often leads to a local extremum.

• International conference on construction engineering and project management
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• 2022.06a
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• pp.361-369
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• 2022

Unsafe actions and behaviors of workers cause most accidents at construction sites. Nowadays, occupational safety is a top priority at construction sites. However, this problem often requires money and effort from investors or construction owners. Therefore, decreasing the accidents rates of workers and saving monitoring costs for contractors is necessary at construction sites. This study proposes an unsafe behavior detection method based on a skeleton model to classify three common unsafe behaviors on the scaffold: climbing, jumping, and running. First, the OpenPose method is used to obtain the workers' key points. Second, all skeleton datasets are aggregated from the temporary size. Third, the key point dataset becomes the input of the action classification model. The method is effective, with an accuracy rate of 89.6% precision and 90.5% recall of unsafe actions correctly detected in the experiment.

• The Journal of Engineering Geology
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• v.21 no.4
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• pp.305-312
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• 2011

Because groundwater recharge shows spatial-temporal variability due to climatic conditions, it is necessary to investigate land use and hydrogeological heterogeneity, and estimate the spatial variability in the daily recharge rate based on an integrated surface-groundwater model. The integrated SWAT-MODFLOW model was applied to compute physically based daily groundwater recharge in the Jincheon region. The temporal variations in estimated recharge were calibrated using the observed groundwater head at several National Groundwater Monitoring Stations and at automatic groundwater-monitoring sites constructed during the Basic Groundwater Investigation Project (2009-2010). For the whole Mihocheon watershed, including the Jincheon region, the average groundwater recharge rate is estimated to be 20.8% of the total rainfall amount, which is in good agreement with the analytically estimated recharge rate. The proposed methodology will be a useful tool in the management of groundwater in Korea.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.10a
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• pp.56-65
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• 2006

As portions(28m) of the designed tunnel was crossing the abandoned tunnel, methods for safe construction were demanded. The level of the abandoned tunnel and the designed tunnel was almost same and each tunnel was crossing at an angle of about 40 degrees. Therefore the abandoned tunnel would adversely affect the stability of the designed tunnel. Some sections of the abandoned tunnel passes through the designed tunnel wall were fully filled with tunneling spoil and cement milk grouting to increase tunnelling stability. By checking physical properties of grouting cores drilled at the cross section of the designed tunnel and the abandoned tunnel, the quality of material filled in the abandoned tunnel was confirmed. Also the stability of the designed tunnel was checked by the monitoring during excavation of the tunnel.

• Journal of the Korea Institute of Building Construction
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• v.9 no.1
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• pp.95-101
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• 2009

Although the concept of RTLS is very unfamiliar to construction industry, recently it is popular in other industry, such as logistics, ship building, mobile telecommunication based on state-of-the-art information technology. Effective resource management using cutting-edge information technology makes it possible to succeed a project with saving the time and cost. And effective information management in construction project can be achieved by the new technologies such as RFID, WEB-based internet, DB technology, real-time monitoring technology, etc. This paper suggest the characteristics and applicability of the international standard electric waves to be used for the real-time locating system (RTLS) on the viewpoint of transmission loss in construction field to monitor and manage resources of construction project effectively The two types of electric waves based on the international standard is to be suggested after surveying the as-is technology in the related industries and then is analyzed to find out the characteristics of those by the concept of the electric wave transition loss in the several construction situations. Two main electric waves, the 2.4GHz and the 433MHz technologies as the international standard is researched on the applicability to the indoor environment of construction site.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2010.10a
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• pp.554-555
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• 2010

• 한국도로학회:학술대회논문집
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• 2004.10a
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• pp.331-338
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• 2004

• Proceedings of the Korean Society for Rock Mechanics Conference
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• 2008.03a
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• pp.185-201
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• 2008

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.10a
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• pp.790-791
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• 2012