• Smart Structures and Systems
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• v.31 no.6
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• pp.561-571
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• 2023

Ensuring the safety of a structure necessitates that repairs are carried out based on accurate inspections and records of damage information. Traditional methods of recording damage rely on individual paper-based documents, making it challenging for inspectors to accurately record damage locations and track chronological changes. Recent research has suggested the adoption of building information modeling (BIM) to record detailed damage information; however, localizing damages on a BIM model can be time-consuming. To overcome this limitation, this study proposes a method to automatically localize damages on a BIM model in real-time, utilizing consecutive images and measurements from an inertial measurement unit in close proximity to damages. The proposed method employs a visual-inertial odometry algorithm to estimate the camera pose, detect damages, and compute the damage location in the coordinate of a prebuilt BIM model. The feasibility and effectiveness of the proposed method were validated through an experiment conducted on a campus building. Results revealed that the proposed method successfully localized damages on the BIM model in real-time, with a root mean square error of 6.6 cm.

• Advances in concrete construction
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• v.6 no.2
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• pp.177-197
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• 2018

This paper presents a case study about the damages on the structural elements of a cast in place reinforced concrete (RC) building after a big fire which was able to be controlled after six hours. The fire broke off at the $2^{nd}$ basement floor of the building, which has five basements, one ground, and two normal floors. As a result of intensely stocked ignitable materials, it spread out to the all of the upstairs. In visual inspection, most of the typical fire damages were observed (such as spalling, net-like cracks, crumbled plasters, bared or visible reinforcement). Also, failures of the $2^{nd}$ basement columns were encountered. It has been concluded that the severity failures of the columns at the $2^{nd}$ basement caused utterly deformation of the building, which is responsible for the massive damages on the beam-column connections. All of the observed damages were categorized related to the types and presented separated regarding the floors. Besides to the visual inspection, the numerical analysis was run to verify the observed damaged on the building for columns, beams, and the connection regions. It is concluded from the study that several parameters such as duration of the fire, level of the temperature influence on the damages to the RC building. Also, it is highlighted by the study that if the damaged building is considered on the overall structural system, it is not able to satisfy the minimum service requirements neither gravity loads nor earthquake conditions.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.42 no.1
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• pp.56-60
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• 1997

In order to investigate the relationships between the responses of four crops (rice, soybeans, potatoes, and red pepper) to acid rain, the simulated acid rain(SAR) of pH 1.8, 2.3, and 2.8 and normal rain of pH 6.0 were applied from 30 days after emergence to harvest at the two-week interval for rice, soybeans and red pepper and at a week interval for potatoes. SAR of pH 1.8 and 2.3 caused brown spots in the leaves of rice, soybeans, and red pepper and the damages were severer as the pH of SAR lowered, while no visual damages were observed in potatoes. The SARs did not affect chlorophyll content of rice and potatoes, while chlorophyll content of soybeans and red pepper decreased as the pH of SAR lowered. Photosynthetic activity was not significantly different among the pHs of SAR in rice, while decreased as pHs of SAR lowered from pH 2.8 to 1.8 in soybeans, potatoes, and red pepper. Yield of rice, soybeans, and potatoes was not affected by the pHs of SAR, but in red pepper the length, diameter, and weight of a fruit, the number of fruits per plant, and total matured fruit yield decreased as the pHs of SAR lowered. In rice and potatoes visual damages caused by SAR did not correlated with other observed traits. However, visual damages were negatively correlated with chlorophyll content and photosynthetic activity of soybeans and photosynthetic activity and yield of red pepper.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.6A
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• pp.873-880
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• 2008

When checking the state of deterioration or damage structures, regular visual inspection has very important role. At this point, a visual inspection is performed mainly by sketch or photography with a camera of inspectors. If that happens, it takes a lot of effort and time to inspect appearance damages. The purpose of this study is to develop the automatic recognition system for a more efficient and effective inspection of appearance damages. In the process, the image processing technology and the data management & analysis system for damage recognition are mainly developed and applied. This automatic recognition system enables inspectors or clients to obtain correct data that can recognize a damage, such as, crack, water leakage, efflorescence, delamination (peeling), spalling, etc. In addition, this study takes aim at the effect of secure safety, functional maintenance and extension of design lifetime according to build up continuous and systematic data management system.

• Smart Structures and Systems
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• v.31 no.6
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• pp.573-583
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• 2023

Although unmanned aerial vehicles have been used to overcome the limited accessibility of human-based visual inspection, unresolved issues still remain. Onsite inspectors face difficulty finding previously detected damage locations and tracking their status onsite. For example, an inspector still marks the damage location on a target structure with chalk or drawings while comparing the current status of existing damages to their previous status, as documented onsite. In this study, an augmented-reality-based structural inspection system with onsite damage information marking was developed to enhance the convenience of inspectors. The developed system detects structural damage, creates a holographic marker with damage information on the actual physical damage, and displays the marker onsite via an augmented reality headset. Because inspectors can view a marker with damage information in real time on the display, they can easily identify where the previous damage has occurred and whether the size of the damage is increasing. The performance of the developed system was validated through a field test, demonstrating that the system can enhance convenience by accelerating the inspector's essential tasks such as detecting damages, measuring their size, manually recording their information, and locating previous damages.

• Structural Engineering and Mechanics
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• v.52 no.2
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• pp.307-322
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• 2014

A two-step procedure to detect and quantify damages in structures from changes in curvature mode shapes is presented here. In the first step the maximum difference in curvature mode shapes of the undamaged and damaged structure are used for visual identification of the damaged internal-substructure. In the next step, the identified substructures are searched using unified particle swarm optimization technique for exact identification of damage location and amount. Efficiency of the developed procedure is demonstrated using beam like structures. This methodology may be extended for identifying damages in general frame structures.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2001.10a
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• pp.101-108
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• 2001

In the previous study, an improved QRD (QR Decomposition)-ILS(Iterative Least-Squares) method is proposed to estimate the structural parameters at the element level using response data alone without using any information of excitation measurements for the assessment of local damages and deterioration in complex and large structural systems. But for a complex and large structural system, where response measurement at every dynamic degree of freedom(DDOF) is not possible, the absence of some observation points of responses and its effect on the proposed SI method must be studied In the paper, a QRD-ILS technique that utilizes the known intact stiffness information estimated based on the visual inspection, field measurements and/or NDT tests is proposed to identify local damages of fracture critical members using measured responses only at limited DDOFs. A numerical example is used to illustrate the application of this technique. The results indicate that the proposed SI technique is very simple but efficient, since no input information are required with only limited observations.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2017.11a
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• pp.65-66
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• 2017

Early-frost damages easily take place in smaller and thinner walls and slabs. In case of slabs, it is difficult to visually determine the depth of early-frost damage. As such, the current study aims to determine the depth of early-frost damage caused to concrete structures due to bad curing in the winter. As a result, the study found that the depth of early-frost damages increased from the top as the atmospheric temperature on the concrete surface decreased. The changes in the color allowed the observer to easily identify the depth of early-frost damage with the naked eye. In particular, the color difference between potentially damaged parts and undamaged parts were the greatest around thirty minutes of drying after wetting.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.840-845
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• 2008

To develop our original technology of concrete slab track, being widely accepted for new track, prefabricated concrete slab track, or precast concrete slab track has been developed. They have two different types according to slab shape and its dimensions, connection of slabs and connecting structure onto substructure. After the system design and successful performance evaluation in the laboratory, the trial installation on revenue line has been carried out. This paper is presenting the result of the trial installation and the performance tests in field. The performance tests have been performed as visual inspection for cracks and damages, measurement of track alignment and elastic behavior of track under passing trains. The performance test results during last 2 years have shown that no remarkable damages and settlements were found, and track alignment and elastic track behavior both exhibits good status.

• Journal of Advanced Information Technology and Convergence
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• v.8 no.2
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• pp.89-99
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• 2018

Due to global warming, various natural disasters such as floods and droughts are increasing. If we can detect the possibility of natural disasters in advance, we can prevent massive damages caused by natural disasters. Recent advances in visual sensor technologies have enabled remote monitoring of a variety of natural environments, including lakes, rivers, and shores. In this paper, we propose a method to segment an image obtained from video sensor networks into regions in order to monitor the environment effectively. In the proposed method, we first partition the image into superpixels and model the connections between superpixels as a graph. Then, initial seeds for each region are set by using the prior information, and the initial seeds are expanded to form regions using agglomerative clustering. Experimental results show that the proposed method extracts the regions from natural environment images easily and accurately.