• International conference on construction engineering and project management
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• 2022.06a
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• pp.871-876
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• 2022

In the construction industry, fatal accidents related to scaffolds frequently occur. To prevent such accidents, scaffolds should be carefully monitored for their safety status. However, manual observation of scaffolds is time-consuming and labor-intensive. This paper proposes a method that automatically analyzes the installation status of scaffold joints based on images acquired from a Unmanned Aerial Vehicle (UAV). Using a deep learning-based object detection algorithm (YOLOv5), scaffold joints and joint components are detected. Based on the detection result, a two-stage rule-based classifier is used to analyze the joint installation status. Experimental results show that joints can be classified as safe or unsafe with 98.2 % and 85.7 % F1-scores, respectively. These results indicate that the proposed method can effectively analyze the joint installation status in UAV-acquired scaffold images.

• Biomaterials and Biomechanics in Bioengineering
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• v.2 no.3
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• pp.159-172
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• 2015

Treatment of polymicrobial infected musculoskeletal defects continues to be a challenge in orthopaedics. This research investigated single and dual-delivery of two antibiotics, vancomycin and amikacin, targeting different classes of microorganism from a biodegradable calcium sulfate-chitosan-nHA microsphere composite scaffold. The addition of chitosan-nHA was included to provide additional structure for cellular attachment and as a secondary drug-loading device. All scaffolds exhibited an initial burst of antibiotics, but groups containing chitosan reduced the burst for amikacin at 1hr by 50%, and vancomycin by 14-25% over the first 2 days. Extended elution was present in groups containing chitosan; amikacin was above MIC ($2-4{\mu}g/mL$, Pseudomonas aeruginosa) for 7-42 days and vancomycin was above MIC ($0.5-1{\mu}g/mL$ Staphylococcus aureus) for 42 days. The antibiotic activity of the eluates was tested against S. aureus and P. aeruginosa. The elution from the dual-loaded scaffold was most effective against S. aureus (bacteriostatic 34 days and bactericidal 27 days), compared to vancomycin-loaded scaffolds (bacteriostatic and bactericidal 14 days). The dual- and amikacin-loaded scaffolds were effective against P. aeruginosa, but eluates exhibited very short antibacterial properties; only 24 hours bacteriostatic and 1-5 hours bactericidal activity. For all groups, vancomycin recovery was near 100% whereas the amikacin recovery was 41%. In conclusion, in the presence of chitosan-nHA microspheres, the dual-antibiotic loaded scaffold was able to sustain an extended vancomycin elution longer than individually loaded scaffolds. The composite scaffold shows promise as a dual-drug delivery system for infected orthopaedic wounds and overcomes some deficits of other dual-delivery systems by extending the antibiotic release.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2019.11a
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• pp.189-190
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• 2019

Designers and builders are omitting structural design and relying on workers' experience, due to the lack of awareness of the importance of scaffolding in domestic construction sites, and there is a high probability of collapsing accidents such as inappropriate wall joint installation and non-compliance with work procedures. Therefore, risk factors were analyzed in detail and major risk factors were derived from opinions of site managers and scaffolding experts in this study.

• Structural Engineering and Mechanics
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• v.10 no.1
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• pp.53-66
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• 2000

This paper proposes a simple numerical model for use in a finite analysis (FEA) of scaffold-shoring systems. The structural model consists of a single set of multiple-story scaffolds with constraints in the out-of-plane direction at every connection joint between stories. Although this model has only two dimensions (termed the 2-D model), it is derived from the analysis of a complete scaffold-shoring system and represents the structural behavior of a complete three-dimensional system. Experimental testing of scaffolds up to three stories in height conducted in the laboratory, along with an outdoor test of a five-story scaffold system, were used to validate the 2-D model. Both failure modes and critical loads were compared. In the comparison of failure modes, the computational results agree very well with the test results. However, in the comparison of critical loads, computational results were consistently somewhat greater than test results. The decreasing trends of critical loads with number of stories in both the test and simulation results were similar. After investigations to explain the differences between the computationally and experimentally determined critical loads, it was recommended that the 2-D model be used as the numerical model in subsequent analysis. In addition, the computational critical loads were calibrated and revised in accordance with the experimental critical loads, and the revised critical loads were then used as load-carrying capacities for scaffold-shoring systems for any number of stories. Finally, a simple procedure is suggested for determining load-carrying capacities of scaffold-shoring systems of heights other than those considered in this study.

• Archives of Plastic Surgery
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• v.41 no.3
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• pp.231-240
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• 2014

Cartilage has a limited regenerative capacity. Faced with the clinical challenge of reconstruction of cartilage defects, the field of cartilage engineering has evolved. This article reviews current concepts and strategies in cartilage engineering with an emphasis on the application of nanotechnology in the production of biomimetic cartilage regenerative scaffolds. The structural architecture and composition of the cartilage extracellular matrix and the evolution of tissue engineering concepts and scaffold technology over the last two decades are outlined. Current advances in biomimetic techniques to produce nanoscaled fibrous scaffolds, together with innovative methods to improve scaffold biofunctionality with bioactive cues are highlighted. To date, the majority of research into cartilage regeneration has been focused on articular cartilage due to the high prevalence of large joint osteoarthritis in an increasingly aging population. Nevertheless, the principles and advances are applicable to cartilage engineering for plastic and reconstructive surgery.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1409-1410
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• 2008

Layer manufacturing technology has been recently spotlighted as a promising candidate to fabricate porous scaffolds for tissue engineering, because it can provide three dimensional interconnectivity and different pore structures and on-demand scaffold design. This study aims to fabricate HA/PCL composite scaffolds for bone tissue engineering by a layer manufacturing technology, paste extruding deposition, and to characterize in vitro and in vivo biocompatibilities of the scaffolds. This study discusses the mechnical properties, proliferation and differentiation of osteogenic cells, and tissue in-growth and bone regeneration behavior using animal models.

• BMB Reports
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• v.46 no.6
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• pp.328-333
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• 2013

Many bioactive molecules like recombinant human bone morphogenetic protein 2 (rhBMP-2) have been developed for mineralized bone grafts, for which proper scaffolds are necessary to successfully apply the bioactive molecules. In this study, we tested the osteogenic efficacy of rhBMP-2 produced in-house in combination with gelatin sponge as the scaffold carrier in a rabbit radial defect model. The efficacy of the rhBMP-2 was determined by alkaline phosphatase activity assay of C2C12 cells. Two groups of ten rabbits each were treated with rhBMP-2/gelatin sponge, or gelatin sponge only. At 4 weeks, rhBMP-2/gelatin sponge grafts showed more bone regeneration than gelatin sponge grafts, as determined by X-ray radiography, micro-computed tomography, and histological analyses. At 8 weeks, rhBMP-2/gelatin sponge grafts exerted much stronger osteogenic effects. The study demonstrates the improved osteogenic efficacy of the rhBMP-2/gelatin sponge grafts in a rabbit radial bone defect model acting as a bone-inductive material.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.9
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• pp.121-126
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• 2019

Despite the trend of decreasing accidents, falling accidents in the construction industry have not decreased and are even rising. Most major accidents are falling accidents caused by hanging scaffolding and are mostly serious. We conducted a review of the literature, institutions, and regulations, which showed that domestic standards are not unified because they are drawn up by referring to overseas standards for hanging scaffolding. New regulations or standards should be established, which should reflect the safety plans for equipment, work advance plans, education, and management. If facility improvement plan for Hanging Scaffolding and implementation of revision of the current work use, regulations and guides are implemented, it will be recognized in advance of the causes of the accident statistics and the classification system and will be the basis for the implementation of joint efforts by workers, managers, supervisors and owners to reduce accidents.