• KCI Concrete Journal
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• v.12 no.2
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• pp.45-54
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• 2000

Precast R.C. slabs are being used widely for the construction of bridge structures due to their simplicity in construction processes. However, one of the disadvantages in precast R.C. slabs is the existence of transverse joints between two precast slabs. The transverse joints are structurally fragile and the task of strengthening the joints is difficult one due to their structural discontinuity. The aim of this study was to improve the behavior of transverse joints between precast R.C. slabs by introducing prestress with external cables. Three steel-concrete composite bridge specimens, which were prestressed with the external cables anchored on steel girders, were fabricated in the laboratory. Both pretension and post-tension methods were applied to introduce prestressing on the concrete slab with a straight tendon arrangement. Static tests were conducted at service load and ultimate load test was performed to evaluate punching shear capacity of the transverse joint. In this paper, two prestressing methods were tested and their effects were evaluated with respect to the elastic behavior and ultimate loading capacity of the transverse joints.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2006.04a
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• pp.898-905
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• 2006

In the present paper, for a quantitative assessment of early-age cracking in an RC wall, an improved analytical model is proposed. First of all, a three-dimensional finite element model for the analysis of stresses due to hydration heat and differential drying shrinkage is introduced. A discrete steel element derived using the equivalent nodal force concept is used to simulate reinforcing steels, embedded in a concrete matrix. In advance, to quantitatively calculate the cracking potential, an analytical model that can estimate the post-cracking behavior in an RC tension member is proposed Subsequent comparisons. of analytical results with test results verify that the combined use of both the finite element model for the stress analysis as well as the analytical model for the estimation of the post-cracking behavior in an RC tension member make it possible to accurately predict the cracking ,behavior of RC walls.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2009.11a
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• pp.35-39
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• 2009

Recently, the flat-plate structure is widely used because it has many advantages such as reduction of story height, long span etc than the RC rahmen structure. Furthermore, application of the flat-plate is on the increase because of flexible plan unlike wall structure. Long span have been at a disadvantage for vibration serviceability evaluation, however studies about vertical direction vibration of flat-plate structure has not been carried out. This study analysis the characteristics according to slab structure to make an experiment on vibration and floor impact noise for the flat-plate structure in construction performance laboratory in Kolon E&C R&D center, the flat-plate structure applied to the post-tension method, and the wall structure in apartment houses.

• Journal of Korean Association for Spatial Structures
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• v.11 no.1
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• pp.22-27
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• 2011

• Computational Structural Engineering
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• v.27 no.1
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• pp.57-61
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• 2014

• Journal of the Korea Institute of Building Construction
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• v.9 no.3
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• pp.10-19
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• 2009

• Journal of Korean Society of Disaster and Security
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• v.15 no.3
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• pp.67-77
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• 2022

In South Korea, U-type girder development was attempted as a means to increase the length of I-type girder, but due to the large self-weight according to the post-tension method, the application of rail bridges of 30m or less is typical. There are not many examples of application of pre-tension type girder. This study does not limit the post-tension method, but applies the pre-tension method to induce a reduction in self-weight and materials used due to the reduction of the cross-section. In addition, we intend to apply the on-site pre-tensioning method using the internal reaction arm of the U-type girder. The prestressed concrete U-type girder bridge is composed of a concrete deck slab and a composite section. Compared to the PSC I-type, which is an open cross-section because the cross section is closed, structural performance such as resistance and rigidity is improved, the safety of construction is increased during the manufacturing and erection stage, and the height ratio is reduced due to the reduction of its own weight. Therefore, it is possible to secure the aesthetic scenery and economical of the bridge. As a result, it is expected that efficient construction will be possible with high-quality factory-manufactured members and cast-in-place members. In this paper, the introduction of the pre-tension method on-site and the analytical performance verification of the anchoring block for tension are included.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.5
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• pp.91-96
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• 2018

The oleophobic property of surfaces modified with micro-post structures are investigated for a range of micro-post diameter ($11-23{\mu}m$) and pitch ($20-40{\mu}m$). The contact angle of an oil droplet on surfaces with various micro-post dimensions was calculated using the Cassie-Baxter model and did not show a good agreement with the measured contact angle. From measurement, the micro-post with diameter of $23{\mu}m$ and pitch of $32{\mu}m$ was found to have the highest contact angle ($134.3^{\circ}$).

• Journal of Trauma and Injury
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• v.29 no.1
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• pp.22-27
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• 2016

Purpose: The optimal method of fixation of symphysis pubis (SP) diastasis in pelvic ring injuries is still controversial. In this study, we investigated the radiological and the clinical results of a precontoured 4.5-mm symphysis pubis (SP) plate with tension band wiring (TBW) after an anterior pelvic injury in pelvic fractures. Methods: We treated 25 patients with traumatic SP diastasis by open reduction and internal fixation with plates and wires. We used a four-hole 4.5-mm precontoured SP plate with a tension band wiring. Results: Patients with a SP with TBW fixation achieved excellent or good results at final follow-up. Post-operative complications included two (8%) patients with metal work movement. The mean symphyseal width was smaller in 4.5 mm SP plate with TBW during 1-year follow up period. Conclusion: A precontoured symphysis pubis plate (4.5 mm) with figure-of-eight fashion tension band wiring shows favorable radiological results, excellent or good clinical outcome, and a lower complication (hardware failure and revision surgery).

• The Journal of Korean Physical Therapy
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• v.21 no.4
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• pp.9-16
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• 2009

Purpose: This study was done to assess the effect of changes in forward head posture (FHP), neck mobility and headache clinical parameters on episodic tension-type headache (ETTH) and chronic tension-type headache (CTTH) who did craniocervial exercises. Methods: Twelve CTTH subjects and twelve ETTH subjects were studied. Side-view pictures of subjects were taken in both sitting and standing positions, in order to assess FHP by measuring the craniovertebral angle. Cervical range of motion (CROM) was employed to measure cervical mobility. A headache diary was kept to assess headache intensity, frequency, and duration. All subjects did three types of craniocervical exercise over 8 weeks. Measurements were done at pre-treatment, and at 4 and 8 weeks post-treatment. Results: Forward head posture and headache-related clinical parameters showed a significant improvement after craniocervical exercise (p<0.05). Flexion/extension and left/right rotation of CROM was significantly increased after the intervention (p<0.05), whereas changes in left/right bending did not reach statistical significance. Conclusion: This study indicates that craniocervical exercise may be effective in the management of tension-type headache.