• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.1A
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• pp.61-69
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• 2010

Unbonded precast concrete piers have better seismic performances than conventional reinforced concrete piers. In this research, seismic performances of unbonded precast prestressed concrete piers are analyzed using OpenSEES. Main parameters of analysis are concrete strength, jacking force ratio, ratio of tendon, and size of precast segment. In results, as the ratio of tendon and jacking force ratio increase, the flexural strength increases at softening state and ultimate state. Concrete strength and size of precast segment are negligible. But initial jacking force ratio leads to early yielding of prestressing tendon. Since compressive strain in core concrete is much less than ultimate strain, it can be expected that the amount of transverse steel reinforcement is to be reduced in comparison with conventional reinforced concrete column.

• 대한관절경학회:학술대회논문집
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• 2006.11a
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• pp.3-8
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• 2006

• Magazine of the Korea Concrete Institute
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• v.9 no.4
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• pp.167-176
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• 1997

The current study is a part of series of research about the evaluation method of the unbonded tendon stress in prestressed concrete member at flexural failure. As the first part. previous design equations were examined in oder to find whether any modifications may be needed. A total of 167 experimental results tested for more than 40 years were gathered to build D/B and then previous proposed and codified equations were evaluated with the experimental relsults. The ACI Code equation and Naaman, Harajli, and Chakrabarti's equations were chosen for the purpose of examination. Then, the followings were obtained from the analytical examination. It is desirable to compute the tendon stress with the member analysis method instead of the sectional analysis method which has been used in the current ACI Code. The tendon stress may also be influenced significantly by the amount of ordinary bonded reinforcements and the loading types. And the current ACI Code overestimated the effect of span/depth ratio. As results, it was concluded that the revision of the ACi Code equation should be considered positively. Then, a new design has to be proposed with the reasonable and comprehensive investigation about influential factors on the tendon stress variation.

• Journal of the Korea institute for structural maintenance and inspection
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• v.28 no.2
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• pp.53-60
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• 2024

Prestressed concrete (PSC) bridges are vulnerable to corrosion and fracture of tendons, and in particular, structures using the internal post-tensioned with grouted system have difficulties in maintenance due to limitations of inspection. In this study, the actual behavior of PSC I girder bridge was analyzed according to tendon damage. The target PSC I girder bridge, an decommissioned highway bridge of upper and lower bridges, had the service period of 33 years and 20 years, respectively. Deflection and concrete strain were measured according to the location of damaged tendon and loading method. Regardless of the age of the bridge, its structural performance decreased when the damaged tendon was closer to the center of the girder. The change in behavior increased as the truck load approached to the girder where the tendon cut. If the load was applied to the adjacent girder where the tendon was cut, the structural performance was likely to be maintained due to the influence of the entire structural system. The change in deflection was difficult to observe visually, while the concrete strain exceeded the cracking strain. Therefore, it is recommended that future monitoring and inspection of PSC I girder bridges should focus on concrete strain or cracking.

• Clinics in Shoulder and Elbow
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• v.17 no.1
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• pp.44-47
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• 2014

Typically, massive rotator cuff tears have stiff and retracted tendon with poor muscle quality, in such cases orthopaedic surgeons are confronted with big challenging to restore the cuff to its native footprint. Furthermore, even with some restoration of the footprint, it is related with a high re-tear rate due to less tension free repair and less tendon coverage. In this tough circumstance, the partial repair has yielded satisfactory outcomes at relatively short follow-up by re-creating the transverse force couple of the rotator cuff. Through this partial repair, the massive rotator cuff tear can be converted to the "functional rotator cuff tear" and provide improvement in pain and functional outcomes in patient's shoulder.

• Journal of Veterinary Science
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• v.24 no.3
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• pp.45.1-45.6
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• 2023

Bovine spastic paresis (BSP) is a neuromuscular disorder characterized by hypertension and stiffness of hindlimb. Two Korean native cattle (Hanwoo) calves developed BSP or BSP-like symptoms, and a tenotomy of superficial tendon of medial head and deep tendon of lateral head of gastrocnemius muscle was performed for treatment. A cast was applied postoperatively to prevent muscle rupture and was removed three weeks later. The prognosis was evaluated at 3 weeks, 6 and 18 months postoperatively. Neither calf showed any other postoperative sequelae. This is the first case study to report the diagnosis, treatment, and prognosis of BSP in Hanwoo.

• Applied Microscopy
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• v.36 no.2
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• pp.93-99
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• 2006

Gemifloxacin is a synthetic fluoroquinolone antimicrobial agent that exhibits potent activity against most Gram-negative and Gram-positive organisms, and has a comparatively low chondrotoxic potential in immature animals. This study examined the effects of gemifloxacin on the Achilles tendons in immature Sprague-Dawley rats treated by oral intubation once daily for 5 consecutive days from postnatal week 4 onward at doses of 0 (vehicle), and 600mg/kg body weight Ofloxacin was used for comparison. The Achilles tendon sperimens were examined by electron microscopy. In comparison with the vehicle-treated controls, there were ultrastructural changes in all samples from the gemifloxacin- and ofloxacin-treated rats. Degenerative changes were observed in the tenocytes, and the cells that detached from the extracellular matrix were recognizable. The degree of degenerative changes and the number of degenerated cells in the Achilles tendon were significantly higher in the treated group than in the control group. Moreover, among the quinolone treated groups, these findings were more significant in the ofloxacin treated group, and less significant in the gemifloxacin treated group. It is unclear what these findings mean with respect to the possible risk ill juvenile patients treated with gemifloxacin or other quinolones. However, these results show that gemifloxacin causes fewer changes in the connective tissue structures.

• 대한정형외과스포츠의학회:학술대회논문집
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• 2004.09a
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• pp.17-17
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• 2004

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05a
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• pp.239-242
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• 2005

The purpose of this research was focused on substantiating an effects of tendon-layouts and compressed stress($=f_{pc}$) induced by post-tensioning on seismic performance of post-tensioned flat plate slab-column connection designed as non-participating system. To accomplish this purpose, an experimental research of flat plate exterior slab-column connections subjected to gravity load and reversed lateral displacement history are presented. As a result, tendon-layout is a main variable to influence failure mechanism, dissipated energy and lateral deformation capacity. Furthermore, compressed stress ($=f_{pc}$) induced by post-tensioning enhanced the seismic performance of flat plate slab.

• Computers and Concrete
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• v.13 no.4
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• pp.501-516
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• 2014

The purpose of this study was to investigate the performance of precast concrete pier cap system. The proposed precast pier cap provides an alternative to current cast-in-place systems, particularly for projects in which a reduced construction time is desired. Five large-scale pier cap specimens were constructed and tested under quasistatic monotonic loading. The computer program, RCAHEST (Reinforced Concrete Analysis in Higher Evaluation System Technology) was used for the analysis of reinforced concrete structures. A bonded tendon element is used based on the finite element method, and can represent the interaction between the tendon and concrete of a prestressed concrete member. A joint element is used in order to predict the inelastic behaviors of segmental joints with a shear key. This study documents the testing of the precast concrete pier cap system under monotonic loading and presents conclusions and design recommendations based on the experimental and analytical findings. Additional full-scale experimental research is needed to refine and confirm design details, especially for actual detailing employed in the field.