• Structural Engineering and Mechanics
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• v.77 no.2
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• pp.179-196
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• 2021

Experimental investigations on the seismic behaviors of the PVC-FRP Confined Reinforced Concrete (PFCRC) columns under low cyclic loading are carried out and two variable parameters including CFRP strips spacing and axial compression ratio are considered. The PFCRC column finally fails by bending and is characterized by the crushing of concrete and yielding of the longitudinal reinforcement, and the column with a high axial compression ratio is also accompanied by the cracking of the PVC tube and the fracture of CFRP strips. The hysteretic curves and skeleton curves of the columns are obtained from the experimental data. With the increase of axial compression ratio, the stiffness degradation rate accelerates and the ductility decreases. With the decrease of CFRP strips spacing, the unloading sections of the skeleton curves become steep and the ductility reduces significantly. On the basis of fiber model method, a numerical analysis approach for predicting the skeleton curves of the PFCRC columns is developed. Additionally, a simplified skeleton curve including the elastic stage, strengthening stage and unloading stage is suggested depending on the geometric drawing method. Moreover, the loading and unloading rules of the PFCRC columns are revealed by analyzing the features of the skeleton curves. The quantitative expressions that are used to predict the unloading stiffness of the specimens in each stage are proposed. Eventually, an analytical model for the PFCRC columns under low cyclic loading is established and it agrees well with test data.

• Journal of the Korean Recycled Construction Resources Institute
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• v.10 no.4
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• pp.402-410
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• 2022

The present study introduces a calibration method of the CSC model implemented in the LS-DYNA program for considering the material properties of ultra-high performance concrete(UHPC). Based on previous experimental studies, various parameters, which constitute three shear failure surfaces, pressure-volumetric strain curve, fracture energy, dynamic increase factor(DIF), and so on, are modified. Then, the proposed calibration method is verified by comparing the numerical result with the experimental data through the single element analysis. In addition, based on the established finite element models, the applicability of the calibrated CSC model is examined for UHPC structures subjected to impact and blast loadings.

• Physical Therapy Korea
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• v.29 no.1
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• pp.48-53
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• 2022

Background: The gastrocnemius tightness can easily occur. Gastrocnemius tightness results in gait disturbance. Thus, various interventions have been used to release a tight gastrocnemius muscle and improve gait performance. Moreover, focal muscle vibration (FMV) has recently been extensively researched in terms of tight muscle release and muscle performance. However, no study has investigated the effects of FMV application on medial gastrocnemius architectural changes. Objects: In this study, we aimed to investigate the effects of FMV on medial gastrocnemius architecture in persons with limited ankle dorsiflexion. Methods: Thirty one persons with <10° of passive ankle dorsiflexion participated in this study. We excluded persons with acute ankle injury within six months prior to study onset, a history of ankle fracture, leg length discrepancy greater than 2 cm, no history of neurological dysfunction, or trauma affecting the lower limb. The specifications of the FMV motor were as follows: a fixed frequency (fast wave: 150 Hz) and low amplitude (0.3-0.5 mm peak to peak) of vibration; the motor was used to release the medial gastrocnemius for 15 minutes. Each participant completed three trials for 10 days; a 30-second rest period was provided between each trial. Medial gastrocnemius architectural parameters [muscle thickness (MT), fiber bundle length (FBL), and pennation angle (PA)] were measured via ultrasonography. Results: MT significantly decreased after FMV application (p < 0.05). FBL significantly increased from its baseline value after FMV application (p < 0.05). PA significantly decreased from its baseline value after FMV application (p < 0.05). Conclusion: FMV application may be advantageous in reducing medial gastrocnemius excitability following a decrease in the amount of contractile tissue. Furthermore, FMV application can be used as a stretching method to alter medial gastrocnemius architecture.

• Clinics in Shoulder and Elbow
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• v.24 no.3
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• pp.125-134
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• 2021

Background: To evaluate clinical and radiological outcomes of bony increased offset-reverse total shoulder arthroplasty (BIO-RSA) in the Asian population at mid-term follow-up. Methods: From June 2012 to August 2017 at a single center, 43 patients underwent BIO-RSA, and 38 patients with minimum 2 years follow-up were enrolled. We evaluated the clinical and radiological outcomes, and complications at the last follow-up. In addition, we divided these patients into notching and no-notching groups and compared the demographics, preoperative, and postoperative characteristics of patients. Results: Visual analogue scale, American Shoulder and Elbow Surgeons, University of California-Los Angeles Shoulder Scale, and Simple Shoulder Test scores improved significantly from preoperative (5.00, 3.93, 1.72, 3.94) to postoperative (1.72, 78.91, 28.34, 7.66) (p<0.05) outcomes. All range of motion except internal rotation improved significantly at the final follow-up (p<0.05), and the bone graft was well-incorporated with the native glenoid in all patients (100%). However, scapular notching was observed in 20 of 38 patients (53%). In the comparison between notching and no-notching groups (18 vs. 20 patients), there were no significant differences in demographics, radiological parameters, and clinical outcomes except acromion-greater tuberosity (AT) distance (p=0.003). Intraoperative complications included three metaphyseal fractures and one inferior screw malposition. Postoperative complications included ectopic ossification, scapular neck stress fracture, humeral stem relaxation, and late infection in one case each. Conclusions: BIO-RSA showed improved clinical outcomes at mid-term follow-up in Asian population. However, we observed higher scapular notching compared to the previous studies. In addition, adequate glenoid lateralization with appropriate humeral lengthening (AT distance) might reduce scapular notching.

• Composites Research
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• v.20 no.5
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• pp.56-63
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• 2007

An approach using complex potentials is presented for analysis of composite plate with an elliptical hole or a rectilinear crack. Composite structure is susceptible to encounter impact damages, which lead to considerable decrease in its residual strength. Such impact damages could be modeled as an equivalent elliptical hole or notch-like crack. Even though finite element method is widely used to analyze stresses or fracture mechanics parameters around such damage, it is tedious to make successive FE-modeling for damage tolerance assessment under fatigue loadings. In this point of view, the solutions based on complex potentials are very simple and easy to use. The computed results are also compared and discussed with those from FEA.

• Restorative Dentistry and Endodontics
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• v.46 no.3
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• pp.42.1-42.15
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• 2021

Objectives: This study aimed to analyze the main features of the 25 most-cited articles in minimally invasive access cavities. Materials and Methods: An electronic search was conducted on the Clarivate Analytics' Web of Science 'All Databases' to identify the most-cited articles related to this topic. Citation counts were cross-matched with data from Elsevier's Scopus and Google Scholar. Information about authors, contributing institutions and countries, year and journal of publication, study design and topic, access cavity, and keywords were analyzed. Results: The top 25 most-cited articles received a total of 572 (Web of Science), 1,160 (Google Scholar) and 631 (Scopus) citations. It was observed a positive significant association between the number of citations and age of publication (r = 0.6907, p < 0.0001); however, there was no significant association regarding citation density and age of publication (r = -0.2631, p = 0.2038). The Journal of Endodontics made the highest contribution (n = 15, 60%). The United States had the largest number of publications (n = 7) followed by Brazil (n = 4), with the most contributions from the University of Tennessee and Grande Rio University (n = 3), respectively. The highest number of most-cited articles were ex vivo studies (n = 16), and 'fracture resistance' was the major topic studied (n = 10). Conclusions: This study revealed a growing interest for researchers in the field of minimally invasive access cavities. Future trends are focused on the expansion of collaborative networks and the conduction of laboratory studies on under-investigated parameters.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.6D
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• pp.895-904
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• 2008

CWR (Continuous Welded Rail) may be broken when a temperature drop below the neutral temperature changes in axial force, causing tensile fracture and rail gap, in winter. Rail-breaks may lead to the damage of the rail and wheel by dynamic load, and the reduction of running safety if not detected before the passage of a train. In this study, the track and train coupled model with open gap for dynamic interaction analysis, is proposed. Linear track and train systems is coupled by the nonlinear Herzian contact spring and the complete system matrices of total track-train system is constructed. And the interaction phenomenon considering open gap, was defined by assigning the irregularity functions between the two sides of a gap. Time history analysis, which have an iteration scheme such as $Newmark-{\beta}$ method based on Modified Newton-Raphson methods, was performed to solve the nonlinear equation. Finally, numerical studies are performed to assess the effect of various parameters of system, apply to various speeds, open gap size and the support stiffness of rail.

• Archives of Craniofacial Surgery
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• v.24 no.6
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• pp.273-277
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• 2023

Background: The clinical characteristics of pediatric nasal fractures can vary depending on the child's age, social activities, and environment. Therefore, this study aimed to analyze these characteristics in different age groups. Methods: We retrospectively reviewed of a series of patients aged under 12 years who received treatment between 2013 and 2021. The initial study design involved dividing the patients into four age groups, corresponding to different developmental ages, but there were no cases in infants aged 0 to 1 year. Therefore, the patients were divided into three groups: group I, between 2 and 5; group II, between 6 and 9; and group III, between 10 and 12 years of age. The following parameters were evaluated: sex, age, etiology, fracture type and severity, and the incidence of septal injuries. Results: In total, 98 patients were included in this study. In group III, the ratio of boys to girls was 3.88:1, exceeding the overall ratio of 1.97:1. The most common cause varied with age: slipping down in group I, bumping accidents in group II, and sports accidents in group III. Concomitant septal injuries were present in 4.17% of patients in group I, 5.71% of patients in group II, and 28.21% of patients in group III. Conclusion: Increasing age was accompanied by a greater tendency for male predominance and a higher prevalence of sports-related causes and septal injuries. Violence was infrequent but started to become a contributing factor during school age. These varying environmental factors across age groups can offer valuable insights into the epidemiology and clinical characteristics of pediatric nasal bone fractures.

• Journal of the Korea institute for structural maintenance and inspection
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• v.11 no.1
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• pp.181-192
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• 2007

The purpose of this study is to analyse and compare experimentally flexural behavior of RC beams strengthened with CFRP plates by different methods, and finally suggest the evaluation equations of flexural capacity of RC beams with the aim of application of prestressed CFRP strengthening. The experimental parameters are compressive strength, reinforcement ratio, prestressing level and strengthening methods. The non-prestressed specimens failed on account of separation of the plates from the beams due to premature de-bonding, while most of the prestressed specimens failed due to CFRP plate fracture. The evaluation equations of flexural capacity of RC beams is suggested and these equations have a good reliability in predicting flexural strength of RC beams.

• Imaging Science in Dentistry
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• v.54 no.3
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• pp.232-239
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• 2024

Purpose: The use of artificial intelligence (AI) and deep learning algorithms in dentistry, especially for processing radiographic images, has markedly increased. However, detailed information remains limited regarding the accuracy of these algorithms in detecting mandibular fractures. Materials and Methods: This meta-analysis was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Specific keywords were generated regarding the accuracy of AI algorithms in detecting mandibular fractures on radiographic images. Then, the PubMed/Medline, Scopus, Embase, and Web of Science databases were searched. The Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2) tool was employed to evaluate potential bias in the selected studies. A pooled analysis of the relevant parameters was conducted using STATA version 17 (StataCorp, College Station, TX, USA), utilizing the metandi command. Results: Of the 49 studies reviewed, 5 met the inclusion criteria. All of the selected studies utilized convolutional neural network algorithms, albeit with varying backbone structures, and all evaluated panoramic radiography images. The pooled analysis yielded a sensitivity of 0.971 (95% confidence interval [CI]: 0.881-0.949), a specificity of 0.813 (95% CI: 0.797-0.824), and a diagnostic odds ratio of 7.109 (95% CI: 5.27-8.913). Conclusion: This review suggests that deep learning algorithms show potential for detecting mandibular fractures on panoramic radiography images. However, their effectiveness is currently limited by the small size and narrow scope of available datasets. Further research with larger and more diverse datasets is crucial to verify the accuracy of these tools in in practical dental settings.