• Proceedings of the Korea Concrete Institute Conference
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• 2009.05a
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• pp.11-12
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• 2009

The small height to depth ratio column dominated by shear after tension steel yielded and the energy dissipation capacity reduce remarkably due to the affection of axial force. This procedure incur in the plastic hinge region and not in all of the region at the same time but from somewhere where the energy was concentrated. This study was reported about the variation of length of the plastic hinge under cyclic loading of the RC columns through the test.

• Proceedings of the Korea Concrete Institute Conference
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• 2009.05a
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• pp.181-182
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• 2009

A numerical model is suggested to calculate the long-term resisting capacity of slender Reinforced Concrete(RC) columns subject to axial load with biaxial bending moments. In this model, geometric nonlinearities by the long-term behavior of concrete and P- $\Delta$ effect as well as material nonlinearities by cracking of concrete and yielding of steel are considered. Experimental result from other researchers are compared to verify the proposed model.

• The Transactions of the Korea Information Processing Society
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• v.3 no.3
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• pp.608-616
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• 1996

In this paper, we propose a multimedia hardware architecture for desktop video-conferencing in view of the multimedia data flow and analyze system operation using queueing model. We analyze the bottleneck of multimedia data flow for video- conferencing by simulation, varying the video size, frame rate, the number of participants, and video data compression rate, And we also implement and test the archiecture, that almost includes the analyzed requirements for video-conferencing, to confirm the simulation results. This paper describes the considerations in designing a multimedia I/O system.

• Journal of the Korea Concrete Institute
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• v.28 no.2
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• pp.129-139
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• 2016

Cast-in-place concrete-filled hollow PC (HPC) columns are used to reduce lifting load of heavy-weight PC columns and to improve the structural integrity of joints. In the present study, a new type of HPC column was proposed to improve the productivity and structural integrity of the concrete. To form the hollow PC columns, a permanent inner form was prefabricated using structural deck plates and penetrated lateral bars. Half-scale specimens of four HPC columns were tested under combined axial compression and lateral cyclic loading to evaluate the seismic resistance. In the design of test specimens, various parameters such as the spacing of lateral re-bars, the use of steel fiber, and the thickness of PC cover were considered. The test results showed that the proposed HPC columns generally exhibited satisfactory load-carrying capacity and deformation capacity without brittle failure of PC. If closely spaced hoops or fiber reinforcements are used for PC, the deformation capacity can be improved further by restraining PC spalling.

• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.4
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• pp.79-86
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• 2008

Four RC shear wall specimens with a/d of 2.2 are designed. And a flexural retrofitting is performed for one specimen by both enlarging wall section and adding additional vertical reinforcements. Also the effectivity of jaketting wall sides is evaluated for the two methods using only steel plate or welded wire mesh with enlargement of section. Cyclic loads are applied to the retrofitted specimens according to the loading history proposed by ACI under constant axial force. Test result showed that the strength and ductility of specimen were improved where the section was enlarged after the installation of additional vertical reinforcements. Confining the ends of wall by U shape W.W.F. with enlargement of section showed most excellent structural capacity regarding to the strength and ductility. Retrofitting by using steel plate was much effective not only to protect the abrupt decrease of strength after yield but also to improve the deformation capacity.

• Journal of Korean Society of Steel Construction
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• v.13 no.3
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• pp.223-232
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• 2001

Column tests subjected to compressive loading were carried out for the estimation of compression buckling strength of steel plate SM570 in beam-column member under high axial load. It was found that the maximum strength of column member was determined by local buckling when satisfied with a limit of width-to-thickness ratio in current steel structure design specifications, but decreased suddenly by local buckling before the maximum strength in case of not satisfying with that ratio. Also, the compression buckling strength of SM570 plate was higher than the design specification value of 4$4.1tonf/cm^2$.

• Journal of Korean Society of Steel Construction
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• v.13 no.2
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• pp.123-131
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• 2001

The objective of this study is to investigate the criteria of the width-to-thickness ratio and to evaluate the buckling strength of high strength steel beam-columns and to compare their buckling strength with design codes, which are the Limit State Design code and the Allowable Stress Desogn code(drift). SM520TMC and SM570Q class steels are used for high strength steels. The coupon test and the stub column test were carried out to investigate the properties of high strength steels and the stress-strain curves of stub columns. The buckling strength of high strength steel beam-columns are assessed by numerical analysis used axial force, moment and curvature relationships.

• Journal of the Korea Concrete Institute
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• v.26 no.1
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• pp.35-46
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• 2014

Two types of cast-in-place concrete-filled hollow PC (HPC1, HPC2) columns were developed to reduce lifting load of heavy-weight PC columns and to improve the structural integrity of joints. To form the hollow PC columns, a couple of prefabricated PC panels was used for HPC1, and special hoops were used for HPC2. Lateral pressure of wet concrete on PC faces was measured while placing the concrete inside the columns. To evaluate the seismic resistance, full scale specimens of two HPC columns and a conventional RC column were tested under combined axial compression and lateral cyclic loading. The test results showed that the structural performance of the proposed HPC columns such as intial stiffness, maximum strength, and displacement ductility was comparable to that of the conventional RC column, but the energy dissipation of HPC2 slightly decreased after rebar-buckling. However, all the test specimens satisfied the energy dissipation requirement specified in ACI 374.

• Journal of Korean Society of Steel Construction
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• v.24 no.6
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• pp.711-723
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• 2012

Structural tests were performed to investigate the structural performance of concrete-filled steel tube column using different strength steels in their flange and web with high-strength steel HSA800 and mild steel SM490, respectively. The test parameters included the strength of column flange and infill concrete, and effect of concrete infill. Connection between different grade steels were welded using the electrode appropriate for mild steel and verified its performance. To evaluate the behavior of test specimens, eccentric loading tests were performed and the results were compared with the prediction by current design codes. Axial load and moment carrying capacity of test specimens increased with the yield strength of compression flange and weld fracture occurred after the specimen shows full strength. The prediction result for axial load-bending moment relationship and effective flexural stiffness gave good agreement with the test result.

• Journal of the Korea Concrete Institute
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• v.15 no.6
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• pp.866-876
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• 2003

Experiments were performed for the real sized 12 reinforced concrete columns of 350${\times}$350${\times}$3350 mm with normal concrete in order to observe the fire-damaged behavior of these columns. Columns were heated according to the ISO heating curve. Main experimental parameters were: magnitude of axial load, heating time, cover thickness, and eccentricity. Effects of these parameters on the axial expansion and contraction, rotation, buckling, ISO fire resistance, and structural stability were experimentally quantified. It has been observed that the contraction rate of axial deformation was affected mostly by the duration of heating time and buckling of reinforcement or member by the magnitude of axial load, duration of heating time, cover thickness and eccentricity in order. Based on the experimental observations, ISO fire resistance criteria were qualiatively criticized.