• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.68-71
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• 2004

In the shear strengthening with FRP sheets, beams are wrapped around the webs and tension face of critical shear span by fiber sheets. The shear strength of RC beam strengthened with FRP sheets must be calculated based on the effective strain that can be developed in the FRP sheets at ultimate stage because the final failure modes of beams are governed by premature debonding of FRP sheet due to the limitation of bonded length by beam depth. An experimental study is carried out to evaluate the shear strengthening effect of AFRP or GFRP sheets with respect to shear reinforcement ratio of rebar. From the test results, it was found that the additional shear strength provided by GFRP or AFRP can be estimated by $p_w{\cdot}f_w$ based on the maximum effective strain of FRP sheet $4,000m{\mu}$ proposed by ACI 440 committee.

• Proceedings of the KSR Conference
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• 2004.06a
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• pp.1090-1095
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• 2004

Umbrella Arch Method(UAM), among others. is commonly applied to increase the facial stability during tunnel excavation and, depending on the field condition, additional reinforcement techniques can be used simultaneously. UAM, together with grouting method, is normally used to reduce ground permeability and improve stability of the tunnel by inserting a series of steel pipes into the ground around the crown inclined to the longitudinal axis of the tunnel. However. there has not been much rigorous study on the effectiveness of UAM, and most of UAM installations depend on empirical judgement rather than on engineering calculation, .In this study, the effectiveness of UAM is demonstrated based on the constitutive relationship involving UAM derived from the mechanics of composite material, and the numerical investigation is compared with small scale experiments on the tunnel reinforcement.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.11a
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• pp.101-108
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• 2000

This paper presents the results of finite element analysis on the seismic response of a soil-reinforced segmental retaining wall subjected to a prescribed earthquake record. The results of finite element analysis indicate that the maximum wall displacement occurs at the top, exhibiting a cantilever type of wall movement. Also revealed is that the increase in reinforcement force is more pronounced in the upper part of the reinforced zone, resulting in a more or less uniform distribution. None of the design guidelines appears to be able to correctly predict the dynamic force increase when compared with the results of finite element analysis. The results demonstrated that there exist critical stiffness and length of reinforcement beyond which further increase would not contribute to additional reinforcing effect. Based on the findings from this study, a number of implications to the current design methods are discussed.

• International Journal of Concrete Structures and Materials
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• v.6 no.1
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• pp.3-18
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• 2012

Observed wall damage in recent earthquakes in Chile and New Zealand, where modern building codes exist, exceeded expectations. In these earthquakes, structural wall damage included boundary crushing, reinforcement fracture, and global wall buckling. Recent laboratory tests also have demonstrated inadequate performance in some cases, indicating a need to review code provisions, identify shortcomings and make necessary revisions. Current modeling approaches used for slender structural walls adequately capture nonlinear flexural behavior; however, strength loss due to buckling of reinforcement and nonlinear and shear-flexure interaction are not adequately captured. Additional research is needed to address these issues. Recent tests of reinforced concrete coupling beams indicate that diagonally-reinforced beams detailed according to ACI 318-$11^1$ can sustain plastic rotations of about 6% prior to significant strength loss and that relatively simple modeling approaches in commercially available computer programs are capable of capturing the observed responses. Tests of conventionally-reinforced beams indicate less energy dissipation capacity and strength loss at approximately 4% rotation.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.04a
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• pp.498-503
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• 2009

This paper presents the vibration problem of the Engine Casing (E/C) "B" deck in the handymax vessel and describes a method to avoid resonance. The first ship of the series did not have any vibration issue on the "B" deck. However, resonance condition occurred when additional machine was installed to the following vessels. To understand the dynamic characteristics of the deck, the normal mode analysis and impact test have been performed. Within the normal operating range of the vessel, the $1^{st}$ natural frequency of the E/C "B" deck is close to the main engine's $6^{th}$ order. Based on these analysis, a reinforcement on the deck was suggested and it proved to be effective. Since actual impact test after the reinforcement also confirmed the resonance avoidance.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2001.05a
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• pp.228-233
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• 2001

In this case study, under conideration of field situations, such as increase of water level, height increment of the marine structure, dredging and backfill, the stability analysis of sliding and lateral flow of the marine structure in OOOharbor was carried out, and foundation reinforcement methods was presented. based on the results of site investigation, the stability analysis of slope sliding and lateral flow was performed as following. In section BH-1, 2, the analysis was performed in two cases that the marine structure was heightened and filled, and not heightened and filled. In section BH-1, 4, heightened and filled. The analysis results showed that the stabilities of slope sliding and lateral flow in section BH-1, 2, 3, 4 were unstable. After additional reinforcements with Deep Mortar Pile, the stabilities in section BH-1, 2, 3, 4 were evaluated as efficiently large.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.930-937
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• 2008

From the result of precise field investigation and stability analysis for the cut slope, following results were acquired. 1. The cause of the collapse of cut slope came from circle sliding collapse by fault zone which remained inner weathering zone. 2. The existing destructed soil and rock can be removed by reinforcement. And to prevent the additional destruction, it is judged that applying the method after relaxing the slope would be reasonable. 3. To make cut slope stable, soft rock layer should be done cutting 1:1.5 and 1:2.0 ~ 1:2.5 for weathered rock and soil layer. 4. Heavy water leakage section should be applied horizontal drain method so that water pressure should not act to the cut slope.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.11
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• pp.520-526
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• 2019

I-type girders are widely applied as very economical sections in plate girder bridges. There has been research on developing composite laminated panels, curved plates reinforced with closed-end ribs, and new forms of ribs and compression flanges for steel box girders. However, there is a limitation in analyzing the exact cause of local buckling caused by an I-type girder's webs. Therefore, an I-type girder's web was modeled using the finite element analysis program LUSAS 17.0 before and after reinforcement. We checked for the minimum thickness criteria presented in the Korea highway bridge design code, and the cause of buckling after performing a linear elastic buckling analysis of dead and live loads was analyzed. Before reinforcement, an eigenvalue (λ₁) at the 1st mode was 0.7025, the critical buckling load was smaller than the applied load, and there is a buckling. After reinforcement, when applying vertical and horizontal stiffeners to the web part of the girder at support, a Nodal line was formed, the eigenvalue was 1.5272, and buckling stability was secured. To improve buckling trace of the girder at the support, an additional plate was applied to the web at the support to ensure visual and structural safety, but buckling occurs at center of web. The eigenvalue (λ₁) was 3.5299, and this method is efficient for reinforcing the web of the support.

• Journal of the Korean Geotechnical Society
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• v.34 no.1
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• pp.47-57
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• 2018

In recent years, vertical extension remodeling of apartment building is considered as one of the efficient ways to broaden and enhance the utilization of existing buildings due to the rapid development of population and decrement of land resources. The reinforcement of foundation is of great importance to bearing the additional load caused by the added floors. However, because of the additional load, the carried load by the existing piles would be in excess of its allowable bearing capacity. In this study, a conceptual construction method called preloading method was presented. The preloading method applies force onto the reinforcing pile before vertical extension construction. The purpose of preloading is to transfer partial load applied on the existing piles to reinforcing piles in order to keep each pile not exceeding the allowable capacity and to mobilize resistance of reinforcing pile by developing relative settlement. The feasibility and effect of preloading method was investigated by using finite numerical method. Two simulation models, foundation reinforcement with preloading and without preloading, were developed through PLAXIS 3D program. Numerical results showed that the presented preloading method is capable of sharing partial carried load of existing pile and develops the mobilization of reinforcing pile's frictional resistance.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2012.11a
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• pp.287-289
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• 2012

The building construction industry of Korea was going through difficulties in improving productivity and competitiveness in international market. Therefore we expected to see the improvement in productivity by applying six-sigma based approach to general reinforced concrete construction work. As a result of applying DMAIC method, one of 6 sigma tools, we found that the most effective inspection items are 'Gap of forms' and 'status of clean'. We could see from this case study that the percentage of additional work days has decreased to 37.7% as a result of applying six-sigma based approach to reinforced concrete construction.