• Smart Structures and Systems
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• v.17 no.6
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• pp.917-933
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• 2016

In a prestressed concrete bridge, the magnitude of the prestress force (PF) decreases with time. This unexpected loss can cause failure of a bridge which makes prestress force identification (PFI) critical to evaluate bridge safety. However, it has been difficult to identify the PF non-destructively. Although some research has shown the feasibility of vibration based methods in PFI, the requirement of having a determinate exciting force in these methods hinders applications onto in-service bridges. Ideally, it will be efficient if the normal traffic could be treated as an excitation, but the load caused by vehicles is difficult to measure. Hence it prompts the need to investigate whether PF and moving load could be identified together. This paper presents a synergic identification method to determine PF and moving load applied on a simply supported prestressed concrete beam via the dynamic responses caused by this unknown moving load. This method consists of three parts: (i) the PF is transformed into an external pseudo-load localized in each beam element via virtual distortion method (VDM); (ii) then these pseudo-loads are identified simultaneously with the moving load via Duhamel Integral; (iii) the time consuming problem during the inversion of Duhamel Integral is overcome by the load-shape function (LSF). The method is examined against different cases of PFs, vehicle speeds and noise levels by means of simulations. Results show that this method attains a good degree of accuracy and efficiency, as well as robustness to noise.

• Computers and Concrete
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• v.20 no.5
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• pp.617-625
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• 2017

Prestress force identification (PFI) is crucial to maintain the safety of prestressed concrete bridges. A synergic identification method has been proposed recently by the authors that can determine the prestress force (PF) and the excitation force simultaneously in prestressed concrete beams with good accuracy. In this paper, the ability of this method in the application with prestressed concrete box-girder bridges is demonstrated. A reasonable assumption is made to capture the similarity of the dynamic behavior of the prestressed concrete box-girder bridge and a beam under a certain loading scenario, and the feasibility of this method for application in a prestressed box-girder bridge is affirmed. A comprehensive laboratory test program is conducted, and the effects of PF, excitation, measuring time and uncertainties are studied. Results show that the proposed method can predict the PF and the excitation force in a prestressed concrete box-girder accurately and has a great robustness against uncertainties.

• Journal of Periodontal and Implant Science
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• v.46 no.4
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• pp.244-253
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• 2016

Purpose: The aim of this study was to characterize the healing in the grafted calvarial defects of rats after adjunctive hyperbaric oxygen therapy. Methods: Twenty-eight male Sprague-Dawley rats (body weight, 250-300 g) were randomly divided into two treatment groups: with hyperbaric oxygen therapy (HBO; n=14) and without HBO (NHBO; n=14). Each group was further subdivided according to the bone substitute applied: biphasic calcium phosphate (BCP; n=7) and surface-modified BCP (mBCP; n=7). The mBCP comprised BCP coated with Escherichia-coli-derived recombinant human bone morphogenetic protein-2 (ErhBMP-2) and epigallocatechin-3-gallate (EGCG). Two symmetrical circular defects (6-mm diameter) were created in the right and left parietal bones of each animal. One defect was assigned as a control defect and received no bone substitute, while the other defect was filled with either BCP or mBCP. The animals were allowed to heal for 4 weeks, during which those in the HBO group underwent 5 sessions of HBO. At 4 weeks, the animals were sacrificed, and the defects were harvested for histologic and histomorphometric analysis. Results: Well-maintained space was found in the grafted groups. Woven bone connected to and away from the defect margin was formed. More angiogenesis was found with HBO and EGCG/BMP-2 (P<0.05). None of the defects achieved complete defect closure. Increased new bone formation with HBO or EGCG/BMP-2 was evident in histologic evaluation, but it did not reach statistical significance in histometric analysis. A synergic effect between HBO and EGCG/BMP-2 was not found. Conclusions: Within the limitations of this study, the present findings indicate that adjunctive HBO and EGCG/BMP-2 could be beneficial for new bone formation in rat calvarial defects.

• The Korea Journal of Herbology
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• v.26 no.3
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• pp.37-45
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• 2011

Objectives : This study focused on Schisandrae Fructus (SF) and Perilae Folium (PF), traditional medicine herbs and health functional food in Korea, Japan and China. We investigated various pharmacological activities that include a potential source of free radical scavenging, anti-viral, anti-microbial, anti-allergy and anti-inflammatory activities. Methods : We conducted an investigation of total contents of phenolic and flavonoid compounds in these single herbal extraction with/without combined to mixture. We also measured antioxidant activities such as DPPH free radical scavenging, SOD-like scavenging, nitrite scavenging and hydroxyl radical scavenging activities, xanthine oxidase inhibition, linoleic acid peroxidation inhibition, and reducing power. Results : As the results, contents of total phenoilc compounds and flavonoids were higher in those of PF than those of SF. Those of SF+PF mixture showed the synergy effects compared with those of SF and PF single extractions. Activities of DPPH free radical and SOD-like scavenging in 1 mg/mL concentration increased in dose dependent manners. That of SF increased compared with that of PF. That of SF and PF mixture also increased compared with that of BHA as a positive control. The other antioxident activities also showed similar to patten of activity of DPPH free radical scavenging. When combined to SF and PF extractions, there was showed synergic effect compared with those of BHA, excepted activities of xanthine oxidase inhibition and reducing power. Taken together, SF and PF have high phenolic and flavonoid compounds content furthermore, antioxidant activities in SF and PF mixture showed more synergy effect compared with those of BHA. Conclusions : Therefore, these findings suggest that SF and PF mixture may offer functional materials potential for development of functional beverage. But further studies are needed for the identification of the active compounds.