• Steel and Composite Structures
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• v.23 no.4
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• pp.385-397
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• 2017

Currently, CFRP (Carbon Fiber Reinforced Polymer) plate bonding is used quite extensively as a strengthening method. In this technique, a composite CFRP plate or sheet of relatively small thickness is bonded with an adhesion material to steel or concrete structure in order to improve its structural behavior and strength. The sheets or plates do not require much space and give a composite action between the adherents. In this study, the rotation capacity of CFRP-strengthened cold-formed steel (CFS) beams has been evaluated through numerical investigation. Studies on different structural levels have been performed. At the beam level, C-section has been adopted with different values of profile thickness, web height, and flange width. At the connection level, a web bolted moment resistant type of connection using through plate has been adopted. In web-bolted connections without CFRP strengthening, premature web buckling results in early loss of strength. Hence, CFRP sheets and plates with different mechanical properties and geometric configurations have been examined to delay web and flange buckling and to produce relatively high moment strength and rotation capacity. The numerical results reveal that CFRP strengthening may increase strength, initial stiffness, and rotation capacity when compared with the case without strengthening.

• The Journal of Korean Physical Therapy
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• v.33 no.6
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• pp.297-303
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• 2021

Purpose: The mass of facial muscles can be increased through exercise, as is also the case for muscles in the extremities. This systematic review was conducted to investigate the effect of facial exercises on facial muscle strengthening and facial rejuvenation, focusing on recent studies. Methods: A literature search was performed using the PubMed, ScienceDirect, and Web of Science databases. The quality of the trials was evaluated according to the PEDro scale. In total, 11 studies were included in this review: four studies on facial exercise for facial rejuvenation and seven studies on strengthening the muscles of the face. Results: Facial exercises for facial rejuvenation increased the mechanical properties and elasticity of the skin of the face and neck, the thickness and cross-sectional area of the facial muscles, and the fullness of the upper and lower cheeks. Conclusion: A study aimed at strengthening facial muscles showed improvements in labial closure strength and tongue elevation strength. Despite the positive results for facial rejuvenation and muscle strengthening, the level of evidence was low. Therefore, in future research, it will be necessary to investigate the effects of facial exercise in a thoroughly controlled experiment with a sufficient sample size to increase the level of evidence.

• Structural Engineering and Mechanics
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• v.15 no.4
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• pp.437-449
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• 2003

The aim of this study is to develop an analytical model of a beam with open cracks and external strengthening which is able to predict its modal scheme components (natural frequencies and mode shapes). The model is valid as far as the excitation level is low enough not to activate non linear effects. The application field of the model are either the prediction of the efficiency of the reinforcement or the non destructive assessment of the structural properties. The degrees of freedom associated to the fault lips must be taken into account in order to introduce the effect of the external strengthening. In a first step, an analytical formulation of a beam with thin notches is proposed according to the references. The model is then extended to incorporate the strengthening consisting in a longitudinal stiffness applied in the vicinity of the cracks. In a second step, the analytical results are compared with these obtained from a finite element simulation.

• Journal of Technology Innovation
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• v.15 no.1
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• pp.145-173
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• 2007

Using patent and firm-level panel data for 1982-2001, this study investigates spillover effects of patents and the strengthening of intellectual property rights on Productivity and Innovation. As well as we consider the effect of intra-industry spillovers, we extend the effect to inter-industry spillovers which implies the effects of IT industries on non-IT industries. The empirical results are summarized as follows. First, allowing for firm-level variables, market competition and technological spillovers, the strengthening of intellectual property rights does not play a significant role on innovative activities. Second, while innovative activities of domestic firms affect significantly firms' innovative activities, those of foreign firms do not. Third, innovative activities of IT industries as inter-industry spillovers play a significant role on innovative activities and labor productivities of domestic firms.

• Advances in concrete construction
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• v.10 no.1
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• pp.35-48
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• 2020

This paper deals with a comparative study among three different rehabilitation techniques, namely, (i) carbon fibre reinforced polymer (CFRP), (ii) glass fibre reinforced polymer (GFRP) and (iii) ferrocement on the flexural strengthening of reinforced cement concrete (RCC) beams. As these different techniques have to be compared on a level playing field, tensile coupon tests have been carried out initially for GFRP, CFRP and ferrocement and the number of layers required in each of these composites in terms of the tensile strength. It was found that for the selected constituents of the composites, one layer of CFRP was equivalent to three layers of GFRP and five layers of wiremesh reinforcement in ferrocement. Rehabilitation of RCC beams using these equivalent laminates shows that all the three composites performed in a similar way and are comparable. The parameters selected in this study were (i) the strengthening material and (ii) the level of pre-distress induced to the beams prior to the rehabilitation. It was noticed that, as the levels of pre-distress decreases, the percentage attainment of flexural capacity and flexural stiffness of the rehabilitated beams increases for all the three selected composites used for rehabilitation. Load-deflection behavior, failure modes, energy absorption capacity, displacement ductility and curvature ductility were compared among these composites and at different distress levels for each composite. The results indicate that ferrocement showed a better performance in terms of ductility than other FRPs, and between the FRPs, GFRP exhibited a better ductility than the CFRP counterpart.

• Steel and Composite Structures
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• v.25 no.2
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• pp.231-244
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• 2017

This paper presents the structural identification of an arch dam model for the damaged, repaired and strengthened conditions under different water levels. For this aim, an arch dam-reservoir-foundation model has been constructed. Ambient vibration tests have been performed on the damaged, repaired and strengthened dam models for the empty reservoir (0 cm), 10 cm, 20 cm, 30 cm, 40 cm, 50 cm and full reservoir (60 cm) water levels to illustrate the effects of water levels on the dynamics characteristics. Enhanced Frequency Domain Decomposition Method in the frequency domain has been used to extract the dynamic characteristics. The dynamic characteristics obtained from the damaged, repaired and strengthened dam models show that the natural frequencies and damping ratios are considerably affected from the varying water level. The maximum differences between the frequencies for the empty and full reservoir are obtained as 16%, 33%, and 25% for damaged, repaired and strengthened model respectively. Mode shapes obtained from the all models are not affected by the increasing water level. Also, after the repairing and strengthening implementations, the natural frequencies of the arch dam model increase significantly. After strengthening, between 46-92% and 43-62% recovery in the frequencies are calculated for empty and full reservoir respectively. Apparently, after strengthening implementation, the mode shapes obtained are more acceptable and distinctive compared to those for the damaged model.

• The Journal of Korean Physical Therapy
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• v.31 no.1
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• pp.7-12
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• 2019

Purpose: This study examined the effects of stretching and strengthening exercises on the pain, pelvic tilt (PT), functional disability, and balance of patients with chronic lower back pain (CLBP). Methods: A total of 42 patients with CLBP were randomly divided randomly into either experimental group I (EG I, n=21), who received stretching exercise, or experimental group II (EG II, n=21), who received strengthening exercise. Both interventions were applied three times a week for eight weeks. Assessments were made with a visual analogue scale (VAS), PT, Oswestry disability index (ODI), and Berg's balance scale (BBS) before and after the eight weeks intervention period. A paired t-test was conducted to compare the within-group changes before and after the intervention. An independent t-test was used compare the between-group difference. The statistical significance level was set to ${\alpha}=0.05$ for all variables. Results: The EG I and II showed significant within-group changes in the VAS, PT, ODI, and BBS (p<0.05). The changes in VAS, PT, ODI, and BBS were similar regardless of the exercise form. Conclusion: In this study, the application of stretching and strengthening exercise for subjects who complain of CLBP was effective in changing the level of pain, PT, functional disability, and balance.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.1
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• pp.117-124
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• 2010

Different to other social infrastructures, bridge elements or bridges can be damaged or collapsed and this may cause death toll and severe social and economical damage, bridges should be managed to maintain a safety level. Diverse strengthening methods is developed to improve a deteriorated bridge performance up to original design level. But rational decision-making process and methodologies to select a optimum strengthening method are absence yet in Korea. This paper therefore derived items and proposed methodologies for quantity estimate considering uncertainty to select a optimum strengthening method among conceptually designed alternatives. And also, to demonstrate the applicability and verification of the proposed approach, it was applied to select the optimum strengthening method for the deteriorated T-shape concrete girder bridge. The model and the procedure can greatly contribute to the uncertainty-oriented alternative selection.

• Computers and Concrete
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• v.31 no.4
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• pp.349-358
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• 2023

This paper describes an in-depth analysis on flexural strength of a girder-deck system experiencing a strand debonding damage with various strengthening systems, based on finite element software ABAQUS. A detailed finite element analysis (FEA) model was developed and verified against the relevant experimental data performed by other researchers. The proposed analytical model showed a good agreement with experimental data. Based on the verified FE model, over a hundred girder-deck systems were investigated with the consideration of following variables: 1) debonding level, 2) span-to-depth ratio (L/d), 3) strengthening type, 4) strengthening material thickness. Based on the data above, a new detailed analytical model was developed and proposed for estimating residual flexural strength of the strand-debonding damaged girder-deck system with strengthening systems. It was demonstrated that both finite element model and analysis model could be used to predict flexural behaviors for debonding damaged prestressed girder-deck systems. Since the strands are debonding from surrounding concrete over a certain zone over the length of the beam, the increase of strain in strands can be linked with a ratio ψ, which is L_p/c. The analytical model was proposed and developed regarding the ratio ψ. By conducting procedure of calculating ψ, the ψ value varies from 9.3 to 70.1. Multiple nonlinear regression analysis was performed in Software IBM SPSS Statistics 27.0.1 to derive equation of ψ. ψ equation was curved to be an exponential function, and the independent variable (X) is a linear function in terms of three variables of debonding level (λ), span length (L), and amount of strengthening material (A_s). The coefficient of determinate (R²) for curve fitting in nonlinear regression analysis is 0.8768. The developed analytical model was compared to the ultimate capacities computed by FEA model.

• Physical Therapy Korea
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• v.22 no.1
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• pp.58-68
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• 2015

This study aimed to determine the effect of lower trapezius muscle strengthening exercises on pain, neck disability index (NDI), cervical range of motion (ROM), and lower trapezius muscle strength in patients with unilateral neck pain. Following baseline measurements, the subjects (N=40) with unilateral neck pain were randomized into one of two 5 weeks exercise intervention groups: a experimental group (EG, $n_1=20$) that received strength training of the lower trapezius muscles or a control group (CG, $n_2=20$) that received routine physical therapy program. Each group participated in the intervention for 30 minutes, 3 times a week, for 5 weeks. All participants performed 2 repetitions of each intervention per day. The numeric pain rating scale for pain, NDI, ROM, and lower trapezius strength were recorded both pre- and post-intervention for both groups. Paired t-tests were used to determine significant changes post-intervention compared with pre-intervention and independent t-tests were used to analyze differences in the dependent variables between the 2 groups. After the 5-weeks intervention, both groups experienced significantly decreased pain and disability level (p<.05) and significantly increased cervical flexion, extension, lateral flexion, and rotation ROM (p<.05). The EG that received strength training of the lower trapezius muscles showed greater improvements in pain and functional disability level, cervical rotation, and lower trapezius strength than the CG (p<.05). These results suggest that a lower trapezius strengthening exercises reduce neck pain and neck disability level and enhance cervical ROM and lower trapezius strength level in patients with unilateral neck pain.