• Structural Engineering and Mechanics
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• v.74 no.4
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• pp.495-502
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• 2020

This study investigated the effects of prestressing force on the natural frequency of concrete beams considering changes in the self-weight of the beam. For this, a finite element formulation was derived to account for the increase in the stiffness of a beam-tendon system due to the axial force and deformation induced by prestressing of the tendon. The developed finite element formulation was validated with the data obtained in laboratory experiments. The experimental natural frequencies of the small prestressed concrete (PSC) beam specimens were consistent with those obtained using the proposed method. The first natural frequency increased almost linearly as the prestressing force increased. The proposed method was then applied to four actual PSC bridges typically employed in the field. Different from the laboratory specimens, the first natural frequencies of the actual PSC bridges barely changed or increased with increasing prestressing force. The results of an analytical parametric study showed that the increase in the natural frequency strongly depended on the magnitude of the prestressing force relative to the total weight of the structure. Thus, the variation in the natural frequencies of the actual PSC bridges with high total weight relative to the prestressing force was negligible due to the application of the prestressing force.

• The Journal of Korean Physical Therapy
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• v.11 no.2
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• pp.11-20
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• 1999

We can sec the case of hand injury patient in the industry field. Hand injury has more particularity than other injury cases. Because it is densely a lot of muscle, tendon, bone, vessels, and in progressing speedily to fibrosis, adhesion, stiffness than other joints. If it has baud injury, it is important to the physical therapy in early stage after operation. Otherwise, it is difficult to recover the function. Hand malfunction intimately has to do with the return to work and the grade of disability. There are many different hand injury cases but, we want to investigate several cases. : fracture. joint injury, tendon injury, and want to looking for treatment tine and method about these. So, we'll understand hand injury of industry disaster. and acknowledge of the importance of physical therapy in the early stage through these.

• Computers and Concrete
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• v.30 no.1
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• pp.75-83
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• 2022

This study introduced a post-tensioned precast concrete system that was developed and designed to improve the performance of joints by post-tensioning. Full-scaled specimens were tested to investigate flexural performances at the negative moment region, where the test variables were the presence of slabs, tendon types, and post-tensioned lengths. A specimen with slabs exhibited significantly higher stiffness and strength values than a specimen without slabs. Thus, it would be reasonable to consider the effects of a slab on the flexural strength for an economical design. A specimen with unbonded mono-tendons had slightly lower initial stiffness and flexural strength values than a specimen with bonded multi-tendons but showed greater flexural strength than the value specified in the design codes. The post-tensioned length was found to have no significant impact on the flexural behavior of the proposed post-tensioned precast concrete system. In addition, a finite element analysis was conducted on the proposed post-tensioned precast concrete system, and the tests and analysis results were compared in detail.

• Journal of the Korea Concrete Institute
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• v.17 no.4 s.88
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• pp.521-526
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• 2005

Prestressing tendons in a nuclear containment building dome are non-axisymmetrically arranged in most cases. However, simple axisymmetric modeling of the containment has been often employed in practice to estimate structural behavior for the axisymmetric loadings such as an internal pressure. In this case, the axisymmetric approximation is required for the actual tendon arrangements in the dome. Some procedures are proposed that can implement the actual 3-dimensional tendon stiffness and prestressing effect into the axisymmetric model. Prestressing tendons, which are arranged in 3 or 2-ways depending on a containment type, are converted into an equivalent layer to consider the stiffness contribution in meridional and hoop directions. In order to reflect the prestressing effect, equivalent load method and initial stress method are devised and the corresponding loads or stresses are derived in terms of the axisymmetric model. In a companion paper, the proposed schemes are applied into CANDU and KSNP(Korean Standard Nuclear Power Plant) type containments and are verified through some numerical examples comparing the analysis results with those of the actual 3-dimensional model.

• Structural Engineering and Mechanics
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• v.72 no.3
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• pp.355-366
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• 2019

Self-centering wall (SCW) is a resilient and sustainable structural system which incorporates unbonded posttensioning (PT) tendons to provide self-centering (SC) capacity along with supplementary dissipators to dissipate seismic energy. Hysteretic energy dissipators are usually placed at two sides of SCWs to facilitate ease of postearthquake examination and convenient replacement. To achieve a good prediction for the skeleton curve of the wall, this paper firstly developed an analytical investigation on lateral load responses of self-centering walls with distributed vertical dampers (VD-SCWs) using the concept of elastic theory. A simplified method for the calculation of limit state points is developed and validated by experimental results and can be used in the design of the system. Based on the analytical results, parametric analysis is conducted to investigate the influence of damper and tendon parameters on the performance of VD-SCWs. The results show that the proposed approach has a better prediction accuracy with less computational effects than the Perez method. As compared with previous experimental results, the proposed method achieves up to 60.1% additional accuracy at the effective linear limit (DLL) of SCWs. The base shear at point DLL is increased by 62.5% when the damper force is increased from 0kN to 80kN. The wall stiffness after point ELL is reduced by 69.5% when the tendon stiffness is reduced by 75.0%. The roof deformation at point LLP is reduced by 74.1% when the initial tendon stress is increased from $0.45f_{pu}$ to $0.65f_{pu}$.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.11
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• pp.1405-1411
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• 2012

Remote handling manipulators are widely used for performing hazardous tasks, and it is essential to ensure the reliable performance of such systems. Toward this end, tendon-driven mechanisms are adopted in such systems to reduce the weight of the distal parts of the manipulator while maintaining the handling performance. In this study, several approaches for the design of a gripper system for a tendon-driven remote handling system are introduced. Basically, this gripper has an underactuated spring mechanism that is combined with a slave manipulator triggered by a master operator. Based on the requirements under the specified tendon-driven mechanism, the connecting position of the spring system on the gripper mechanism and kinematic influence coefficient (KIC) analysis are performed. As a result, a suitable combination of components for the proper design of the target system is presented and verified.

• Clinics in Shoulder and Elbow
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• v.17 no.3
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• pp.107-113
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• 2014

Background: Sonoelastography (SE) is a new technique that can assess differences in tissue stiffness, the purpose of this study was to evaluate the ability of SE to assess the long head of biceps tendon alteration. Methods: Forty shoulders of 36 consecutively registered patients with clinical symptoms and conventional ultrasonography findings of biceps tendinitis or tendinosis, and 40 asymptomatic shoulders of 20 healthy volunteers were assessed with SE. Transverse and longitudinal images of long head of biceps tendon were obtained using SE. SE images were performed by one orthopedic surgeon and evaluated by two orthopedic surgeons using an experimentally proven color grading system. Results: The transverse images of SE showed a sensitivity of 87.5%, a specificity of 95.0% and a accuracy of 91.3%, the longitudinal images of SE showed a sensitivity of 92.5%, a specificity of 90.0% and a accuracy of 91.3%. Inter-observer reliability of SE was in 'almost perfect agreement' with a weighted kappa coefficient of 0.83. Conclusions: SE is valuable in the detection of the intratendinous and peritendinous alterations of biceps tendon, and has excellent accuracy and excellent correlation with conventional ultrasound findings.

• Journal of the Korea institute for structural maintenance and inspection
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• v.7 no.2
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• pp.247-261
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• 2003

The technique of posttensioning has been used successfully to improve the performance of existing concrete structures. However, very few applications of this technique can be found in steel structures. Posttensioning by means of high strength cable or bar can be used to effectively increase the working load capacity of Truss Bridges. The benefits of posttensioning trusses can be achieved in strengthening of existing structures as well as in the design of new structures. In this paper, the elastic behavior of posttensioned trusses with straight and draped tendon profiles is examined. For the analysis of posttensioned trusses in the elastic range of behavior, two methods are presented, namely, the flexibility method and the mixed-method, i.e., a combination of the stiffness and flexibility methods. Using the presented methods, the effects of design variables such as the tendon profile, truss type, prestress force, and tendon eccentricity on the working load and deflection of trusses are studied. The results show that the allowable load of truss increases proportionally with increase in prestress force and eccentricity. Posttesioning enlarges the elastic range, increases redundancy, and reduces deflection and member stresses. Thus, the remaining life of a truss bridge can be increased relatively inexpensively.

• The Journal of Churna Manual Medicine for Spine and Nerves
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• v.1 no.2
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• pp.81-92
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• 2006

Objectives: To review recent findings from physiologic research about the nature of proprioceptive spinal reflex, proposed explanation for mechanisms of musculoskeletal problems associated with propriceptive dysfunction and techniques controlling this problem. Methods: MEDLINE databases were searched using various combinatins of the keywords proprioception, spinal reflex, somata-somatic reflex, spinal manipulation, muscle spindle, Golgi-tendon organ, along with searching the related articles and textbooks. Results and Conclusion: Proprioceptors(muscle spindle, Golgi-tendon organs) monitor the position of joints, tension in tendons and ligaments, and the state of muscular contraction. Disturbed activity of proprioceptive spinal reflex can cause chronic state of increased muscle stiffness, pain, deficiencies both in muscle coordination and propioception, and so on. All kinds of techniques that control proprioceptive primary afferent neurons can affect the motor control system and evoke changes in the neuromuscular system.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.758-761
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• 2004

Prestressing tendons of the nuclear containment building dome are arranged in a non-axisymmetric manner. However, simple axisymmetric modeling of the containment building is often employed to estimate the structural behavior for, e.g. the ultimate pressure, which requires the axisymmetric approximation of the actual tendon arrangements of the dome. A procedure is proposed that can devise the actual 3-dimensional tendon stiffness and prestressing effect into the axisymmetric model. A numerical example of the CANDU type is presented to verify the procedure and to estimate the amount of approximation.