• Journal of the Korea Concrete Institute
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• v.16 no.3 s.81
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• pp.335-344
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• 2004

A general composite section of precast and cast-in-place concrete with prestressed and nonprestressed reinforcements was analyzed to calculate residual stresses and loss of prestressing force caused by internal constraints of concrete long-term deformation. From the analytical results, equations to design additional prestressing force and to evaluate resistant moment of the composite section were proposed. The equations shows that the additional prestressing force can be over-estimated if the loss rate of the first prestressing force is over-estimated from the lumped sum of a design code. The analytical procedure with the proposed equations has been applied to a composite section using the AASHTO Type 5 girder. The loss rates of the additional prestressing force appling to the precast concrete girder was less than those appling to the composite girder. However, the resistant moment of the additional prestressing force on the composite girder was much larger than that on the precast concrete girder. The additional prestressing force appling to the composite section was very effective for strengthening of the prestressed concrete composite girder.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.3A
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• pp.315-322
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• 2008

The present study applied the external post tensioning reinforcement method for reinforcing a non-ballast steel plate girder railway bridge, and the effects of the strength of tendons and the level of post-tensioning force on the dynamic behavior are experimented and analyzed. According to the results of this study, the natural frequency was increased by the strength of tendons but it was decreased by the rise of post-tensioning force and as a consequence the introduction of post-tensioning force decreased natural frequency slightly. It was analyzed that further study is need to establish the exact relations between post-tensioning force and natural frequency. In addition, it was found that the dynamic displacement, dynamic bending stress and vertical acceleration were decreased by the external post-tensioning. On the other hand, external post-tensioning increased horizontal acceleration by up to 20%, which was around 70% of vertical acceleration. This needs further study.

• Journal of Korean Society of Steel Construction
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• v.12 no.5 s.48
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• pp.549-558
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• 2000

In strengthening structure, the external post-tensioning method which secure clearness in the structure analysis process is adopted to bridges as well as architecture structure. In this study, to investigate the behavior of composite beam in the process of post-tensioning, the amount of prestress force loss, the amount of prestressed compression stress at the lower flange and the behavior of lower flange connected with anchorage are analyzed by comparing the results of finite element analysis with the measured results of installed strain gauges. After finishing the post-tensioning, the strengthening effect of external post-tensioning method is analyzed by static loading test. It is also investigated that the strengthening effect of shear section in the harped external post-tensioning specimens.

• International Journal of Highway Engineering
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• v.10 no.4
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• pp.257-267
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• 2008

This study was conducted to investigate the stress distribution in the prestressed concrete pavement (PSCP) when the transverse post tensioning was applied. By performing the structural analyses using a finite element model of PSCP, the effect of anchor spacing and the relationship between the longitudinal and transverse post tensioning were evaluated. The analysis results showed that as the anchor spacing became smaller, the stresses were more uniformly distributed and the ranges of the stress losses were reduced; however, the economy should be considered. As the anchor spacing became larger, the difference between the average transverse stress and the transverse stresses at various locations such as shoulder, wheel pass, and center of the slab, increased. The transverse post tensioning induced the additional tensile forces in the longitudinal tendons, but the magnitude was negligibly small, and the longitudinal and transverse post tensioning could be designed independently. The use of the transverse stress distribution for the design of the post tensioning was also discussed in this paper.

• Journal of Oral Medicine and Pain
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• v.34 no.1
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• pp.103-114
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• 2009

This study was designed to evaluate the Temporomandibular Disorders(TMD) with Tension-Type Headache(TTH) by age. Patients with TMD and/or TTH visited the Department of Oral Medicine, Kyung Hee University Dental Hospital were recruited to this study. Experimental group(n=170) is composed of TMD with TTH and control group(n=222) is composed of TMD without TTH. Evaluation list was pain quality, pain intensity, pain laterality, pain increase by routine physical activity and then it was analyzed statistically. The results were as follows ; 1. In the control group, pain quality was not significantly different by age. But, in the experimental group, pain quality was significantly different by age(p=0.042). 2. In the control group, pain intensity was significantly different by age(p=0.000). And, in the experimental group, pain intensity was significantly different by age(p=0.004). 3. In the control group, pain laterality was not significantly different by age. And, in the experimental group, pain laterality was not significantly different by age. 4. In the control group, pain increase by routine physical activity was not significantly different by age. And, in the experimental group, pain increase by routine physical activity was not significantly different by age. Therefore, it is considered that not temporomandibular disorder patients without tension-type headache but temporomandibular disorder patients with tension-type headache was influenced by age in the pain quality.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.8
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• pp.362-370
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• 2019

The internal pressure capacity of a modular containment structure requires analysis to prevent the release of radioactive material in the case of an accident. To analyze the capacity, FEM models were prepared while considering the tendon arrangements and the contact surfaces between precast concrete modules, and then static analyses were carried out. The changing characteristics in the displacement and stress under step-wise loading were analyzed, along with the effects of selected parameters. For comparison, the capacity of a monolithic containment structure was also analyzed. Parametric analyses were done to suggest ranges of parameters such as the tendon force, tendon spacing, tendon location in concrete thickness direction, friction coefficient, and concrete thickness. The tendon force and frictional force provide a combined effect between contact surfaces of modules. The same level of internal pressure capacity can be secured even in the modular containment structure as in the monolithic containment structure by increasing the tendon force with additional tendons.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.169-172
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• 2008

Carbon fiber reinforced polymer (CFRP) laminates can be used more efficiently in strengthening applications by applying prestress to the CFRP laminates. A key problem for prestressing with CFRP laminates is anchoring the laminates. These may include fracture to the CFRP laminates due to excessive gripping force or slippage of the CFRP laminates out of the anchorage zone caused by low friction between the anchor device and the lamiantes. The main objective of this study is the development of an applicative mold-type anchorage system for prestressed CFRP laminates through experimental study. The experimental parameters were the type of anchorage detail and the effect of surface treatment. The test results showed that the developed anchor assures 100% CFRP laminate strength.

• Journal of Korean Society of Steel Construction
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• v.14 no.1
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• pp.79-85
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• 2002

Recently, prestressed H-Beam bridges with external unbonded Tendons are increasingly built. The mechanical behavior of prestressed steel H-beams is different from that of normal bonded PSC beams in a point of the slip of tendons at deviators and the change of tendon eccentricity that occurs, when service load are applied in external unbonded steel H-beams. The concept of prestressing steel structures has been widely considered, in spite of long and successful history of prestressing concrete members. In the study, The flexural test on prestressed steel H-beams has been performed in the various aspects of prestressed H-beam including the tendon type and profile. The load was plotted against the deflection and the strain respectively in the steel beam and prestressing bars. The value expected with the equation of internal force equilibrium and compatibility between the deflection of the bars and the H-beam was found to correlate well with the measured data.

• Journal of Oral Medicine and Pain
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• v.36 no.2
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• pp.123-130
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• 2011

This study was designed to evaluate the pain characteristics of tension-type headache by the tongue ridge. Patients with tension-type headache visited the Department of Oral Medicine, K University Dental Hospital were recruited to this study. Experimental group(n=65) was composed of tension-type headache with the tongue ridge and control group(n=65) was composed of tension-type headache without the tongue ridge. Evaluation list was pain quality, pain intensity, pain laterality, pain increase by routine physical activity and then it was analyzed statistically. The results were as follows: 1. Pain quality of tension-type headache patient was significantly different by the tongue ridge(p=0.049). 2. Pain intensity of tension-type headache patient was significantly different by the tongue ridge(p=0.010). 3. Pain laterality of tension-type headache patient was not significantly different by the tongue ridge. 4. Pain increase by routine physical activity of tension-type headache patient was not significantly different by the tongue ridge. Therefore, it was considered that the tension-type headache patient was influenced by the tongue ridge in the pain quality and pain intensity.

• Journal of Oral Medicine and Pain
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• v.35 no.3
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• pp.203-212
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• 2010

This study was designed to evaluate the pain characteristics of tension-type headache by buccomucosal linea alba. Patients with tension-type headache visited the Department of Oral Medicine, K University Dental Hospital were recruited to this study. Experimental group (n=79) was composed of tension-type headache with buccomucosal linea alba and control group (n=79) was composed of tension-type headache without buccomucosal linea alba. Evaluation list was pain quality, pain intensity, pain laterality, pain increase by routine physical activity and then it was analyzed statistically. The results were as follows : 1. Pain quality of tension-type headache patient was not significantly different by buccomucosal linea alba. 2. Pain intensity of tension-type headache patient was significantly different by buccomucosal linea alba. (p=.043). 3. Pain laterality of tension-type headache patient was not significantly different by buccomucosal linea alba. 4. Pain increase by routine physical activity of tension-type headache patient was not significantly different by buccomucosal linea alba. Therefore, it was considered that the tension-type headache patient was influenced by buccomucosal linea alba in the pain quality.