• Advances in nano research
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• v.10 no.2
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• pp.129-138
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• 2021

In present article, utilizing the Love shell theory with volume fraction laws for the cylindrical shells vibrations provides a governing equation for the distribution of material composition of material. Isotopic materials are the constituents of these rings. The position of a ring support has been taken along the radial direction. The Rayleigh-Ritz method with three different fraction laws gives birth to the shell frequency equation. Moreover, the effect of height- and length-to-radius ratio and angular speed is investigated. The results are depicted for circumferential wave number, length- and height-radius ratios with three laws. It is found that the backward and forward frequencies of exponential fraction law are sandwich between polynomial and trigonometric laws. It is examined that the backward and forward frequencies increase and decrease on increasing the ratio of height- and length-to-radius ratio. As the position of ring is enhanced for clamped simply supported and simply supported-simply supported boundary conditions, the frequencies go up. At mid-point, all the frequencies are higher and after that the frequencies decreases. The frequencies are same at initial and final stage and rust itself a bell shape. The shell is stabilized by ring supports to increase the stiffness and strength. Comparison is made for non-rotating and rotating cylindrical shell for the efficiency of the model. The results generated by computer software MATLAB.

• Journal of the Korea Institute of Building Construction
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• v.21 no.6
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• pp.617-627
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• 2021

In this study, a numerical analysis using a three-dimensional numerical simulation was performed to assess the applicability of foundation reinforcing method using load transfer apparatus which can be used in the remodeling of deteriorated structures. The numerical model was validated through comparison with the real scale experimental results, and then a parametric study was performed to investigate the effect of friction coefficient of load transfer apparatus and axial stiffness of pile on the performance of foundation reinforcing method. It was confirmed that the foundation reinforcing method considered in this study can efficiently control the load applied to an existing foundation.

• Steel and Composite Structures
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• v.43 no.3
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• pp.403-417
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• 2022

Recently, there has been an increasing demand for buildings that allow rapid assembly of construction elements, have ample open space areas and are flexible in their final intended use. Accordingly, researchers have developed new competitive structures in terms of cost and efficiency, such as cold-formed steel and timber composite floors, to satisfy these requirements. Cold-formed steel and timber composite floors are light floors with relatively high stiffness, which allow for longer spans. As a result, they inherently have lower fundamental natural frequency and lower damping. Therefore, they are likely to undergo unwanted vibrations under the action of human activities such as walking. It is also quite expensive and complex to implement vibration control measures on problematic floors. In this study, a finite element model of a composite floor reported in the literature was developed and validated against four-point bending test results. The validated FE model was then utilised to examine the vibration behaviour of the investigated composite floor. Predictions obtained from the numerical model were compared against predictions from analytical formulas reported in the literature. Finally, the influence of various parameters on the vibration behaviour of the composite floor was studied and discussed.

• Smart Structures and Systems
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• v.30 no.2
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• pp.183-193
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• 2022

Structural health monitoring and structural vibration control are multidisciplinary and frontier research directions of civil engineering. As intelligent materials that integrate sensing and actuation capabilities, shape memory alloys (SMAs) exhibit multiple excellent characteristics, such as shape memory effect, superelasticity, corrosion resistance, fatigue resistance, and high energy density. Moreover, SMAs possess excellent resistance sensing properties and large deformation ability. Superfine NiTi SMA wires have potential applications in structural health monitoring and micro-drive system. In this study, the mechanical properties and electrical resistance sensing characteristics of superfine NiTi SMA wires were experimentally investigated. The mechanical parameters such as residual strain, hysteretic energy, secant stiffness, and equivalent damping ratio were analyzed at different training strain amplitudes and numbers of loading-unloading cycles. The results demonstrate that the detwinning process shortened with increasing training amplitude, while austenitic mechanical properties were not affected. In addition, superfine SMA wires showed good strain-resistance linear correlation, and the loading rate had little effect on their mechanical properties and electrical resistance sensing characteristics. This study aims to provide an experimental basis for the application of superfine SMA wires in engineering.

• Physical Therapy Rehabilitation Science
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• v.11 no.3
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• pp.321-328
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• 2022

Objective: The purpose of this study was to investigate the effect of neck stabilization exercise combined with vibroacoustic sound on patients with chronic neck pain and tension-type headache. Design: Two group pre test - post test design. Methods: 36 patients participated. Headache impact test-6(HIT-6), numerical rating scale(NRS) and muscle characteristics were measured at pre-post test. Participants divided into vibroacoustic sound group(VSG, n=18), control group(CG, n=18). VSG performed neck stabilization exercise and vibroacoustic sound stimulation. CG performed neck stabilization exercise. Both groups participated 3 times a week for a total of 4 weeks. Results: NRS showed a significant difference before and after intervention in both groups (p<0.05). HIT-6 showed a significant difference before and after intervention in the VSG group (p<0.05). Muscle tone showed a significant difference before and after intervention in the experimental group (p<0.05). There was no significant difference in muscle stiffness and muscle elasticity before and after the intervention in both groups (p>0.05). Conclusions: Based on the results of the study, it is thought that sonic vibroacoustic sound can be established as an effective treatment tool through a study applied to various diseases and symptoms.

• Steel and Composite Structures
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• v.48 no.5
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• pp.565-582
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• 2023

The present research reports the application of engineered cementitious composites (ECC) as an alternative to conventional concrete to improve the seismic behavior of short columns. Experimental and finite element investigation was conducted by testing five reinforced engineered cementitious composite (RECC) concrete columns (half-scale specimens) and one control reinforced concrete (RC) specimen for different shear-span and transverse reinforcement ratios under cyclic lateral loads. RECC specimens with higher shear-span and transverse reinforcement ratios demonstrated a significant effect on the column lateral load behavior by improving ductility (>5), energy dissipation capacity (1.2 to 4.1 times RC specimen), gradual strength degradation (ultimate drift >3.4%), and altering the failure mode. The self-confinement effect of ECC fibers maintained the integrity in the post-peak region and reserved the transmission of stress through fibers without noticeable degradation in strength. Finite element modeling of RECC specimens under monotonic incremental loads was carried out by adopting simplified constitutive material models. It was apprehended that the model simulated the global response (strength and stiffness) and damage crack patterns reasonably well.

• Structural Engineering and Mechanics
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• v.88 no.5
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• pp.501-519
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• 2023

This paper introduces a new hybrid structural connection joint that combines shear walls with section steel beams, fundamentally resolving the construction complexity issue of requiring pre-embedded connectors in the connection between shear walls and steel beams. Initially, a quasi-static loading scheme with load-deformation dual control was employed to conduct low-cycle repeated loading experiments on five new connection joints. Data was acquired using displacement and strain gauges to compare the energy dissipation coefficients of each specimen. The destruction process of the new connection joints was meticulously observed and recorded, delineating it into three stages. Hysteresis curves and skeleton curves of the joint specimens were plotted based on experimental results, summarizing the energy dissipation performance of the joints. It's noteworthy that the addition of shear walls led to an approximate 17% increase in the energy dissipation coefficient. The energy dissipation coefficients of dog-bone-shaped connection joints with shear walls and cover plates reached 2.043 and 2.059, respectively, exhibiting the most comprehensive hysteresis curves. Additionally, the impact of laminated steel plates covering composite concrete floors on the stiffness of semi-rigid joint ends under excessive stretching should not be disregarded. A comparison with finite element analysis results yielded an error of merely 2.2%, offering substantial evidence for the wide-ranging application prospects of this innovative joint in seismic performance.

• Structural Engineering and Mechanics
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• v.88 no.4
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• pp.379-387
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• 2023

Wind and earthquake loads may cause strong vibrations in large-span cable-stayed bridges, leading to the inability of the bridge to operate normally. An improved Pounding Tuned Mass Damper (PTMD) system was designed to improve the safety of the large-span cable-stayed bridge. The vibration control effect of the improved PTMD system on the large-span cablestayed bridge under the combined action of earthquake-wind-traffic was studied. Furthermore, the impact of different parameters on the vibration suppression performance of the improved PTMD system was analyzed. The numerical results indicate that the PTMD system is very effective in suppressing the displacements of the bridge caused by both the traffic-wind coupling and traffic-earthquake coupling. Moreover, the number, mass ratio, pounding stiffness, and gap values have a significant influence on the vibration suppression performance of the improved PTMD system. When the number of PTMD is increased from 3 to 9, the vibration reduction ratio of the vertical displacement is increased from 25.39% to 48.05%. As the mass ratio changes from 0.5% to 2%, the vibration reduction ratio increases significantly from 22.23% to 53.30%.

• Wind and Structures
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• v.10 no.4
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• pp.301-314
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• 2007

The lever-type active multiple tuned mass dampers (LT-AMTMD), consisting of several lever-type active tuned mass dampers (LT-ATMD), is proposed in this paper to attenuate the vibrations of long-span bridges under the excitation directly acting on the structure, rather than through the base. With resorting to the derived analytical-expressions for the dynamic magnification factors of the LT-AMTMD structure system, the performance assessment then is conducted on the LT-AMTMD with the identical stiffness and damping coefficient but unequal mass. Numerical results indicate that the LT-AMTMD with the actuator set at the mass block can provide better effectiveness in reducing the vibrations of long-span bridges compared to the LT-AMTMD with the actuator set at other locations. An appealing feature of the LT-AMTMD with the actuator set at the mass block is that the static stretching of the spring may be freely adjusted in accordance with the practical requirements through changing the location of the support within the viable range while maintaining the same performance (including the same stroke displacement). Likewise, it is shown that the LT-AMTMD with the actuator set at the mass block can further ameliorate the performance of the lever-type multiple tuned mass dampers (LT-MTMD) and has higher effectiveness than a single lever-type active tuned mass damper (LT-ATMD). Therefore, the LT-AMTMD with the actuator set at the mass block may be a better means of suppressing the vibrations of long-span bridges with the consequence of not requiring the large static stretching of the spring and possessing a desirable robustness.

• The Journal of Pediatrics of Korean Medicine
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• v.29 no.4
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• pp.67-76
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• 2015

Objectives The purpose of this review is to investigate the domestic and foreign studies of pediatric Chuna treatment and propose the directions of future studies and clinical applications. Methods We searched for the study at RISS, KISS, DBPIA, Pubmed, CNKI by keywords, '추나', 'Osteopathic', 'Chiropractic', 'Manipulation', '推拿', '導引', '按摩', After 2010. Results 1. Selected 3 domestic studies were categorized as 1 survey study and 2 case reports. Selected 41 foreign studies from Pubmed were categorized as 15 systemic reviews, 8 survey studies, 12 case reports and 6 control studies. Selected 82 foreign studies from CNKI were categorized as 10 systemic reviews, 22 case reports and 50 control studies. 2. 2 clinical domestic studies researched on idiopathic Scoliosis. The foreign clinical studies from Pubmed are 18 cases, and those studies were categorized into Premature baby care (3), Infant colic (2), ADHD (2), Congenital talipes equinovarus (1), Somatic dysfuntion (1), Nonsynostotic occipital plagiocephaly (1), Conversion disorder (1), Lower back pain (1), Chronic bilateral dorsal foot pain and stiffness (1), plantar fasciitis (1), Migraine headaches (1), Cyclic vomiting syndrome (1), Acute otitis media (1) and Cerebral palsy (1). The other 72 foreign clinical studies were from CNKI, and they studied 39 different diseases. Systematically, they studied about digestive diseases (25), respiratory diseases (20), fever (6), musculoskeletal diseases (5), nervous system diseases (5), dermatology diseases (2) and other disease states. The Chuna treatment was used in variety of studies. 3. 2 clinical domestic studies adopted techniques of Osteopathy Chuna. The foreign clinical studies from Pubmed adopted techniques of Osteopathic manipulation (10) and Chiropractic manipulation (8). The other foreign clinical studies from CNKI adopted techniques of Acupressure (69), Abdominal manipulation (23), Spinal manipulation (21), Thoracic manipulation (11), Traction manipulation (2), Muscular manipulation (2), Squeezing Sha manipulation (1), Spine correction (1), Joint manipulation (1) and Fascia manipulation (1). Conclusions In addition to musculoskeletal disorders, variety of pediatric diseases could be treated with Chuna treatment instead of acupuncture.