• Journal of the Korean Society of Hazard Mitigation
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• v.5 no.1 s.16
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• pp.69-76
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• 2005

The pull-out capacity of expansion anchor(heavy duty anchor and wedge anchor) was studied experimentally in this paper. Loading conditions included tension, shear, and combined tension and shear. The heavy duty anchor and wedge anchor were manufactured in domestic and installed In plain concrete. The failure mode of steel and concrete were studied carefully for the analytical formula of the anchorage design and the experimental data were compared with different models for the interaction of tension and shear capacities. Based on the research, the following conclusion may be drawn : The interaction of forces is well-described by an elliptical interaction relationship.

• Structural Monitoring and Maintenance
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• v.4 no.1
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• pp.69-84
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• 2017

Delamination is the most common failure mode in layered composite materials. The author have found that the electrical potential change (EPC) technique using response surfaces method is very effective in assessment delamination in basalt fiber reinforced polymer (FRP) laminate composite pipe by using electrical capacitance sensor (ECS). In the present study, the effect of the electrodes number on the method is investigated using FEM analyses for delamination location/size detection by ANSYS and MATLAB, which are combined to simulate sensor characteristic. Three cases of electrodes number are analyzed here are eight, twelve and sixteen electrodes, afterwards, the delamination is introduced into between the three layers [$0^{\circ}/90^{\circ}/0^{\circ}$]s laminates pipe, split into eight, twelve and sixteen scenarios for cases of eight, twelve and sixteen electrodes respectively. Response surfaces are adopted as a tool for solving inverse problems to estimate delamination location/size from the measured EPC of all segments between electrodes. As a result, it was revealed that the estimation performances of delamination location/size depends on the electrodes number. For ECS, the high number of electrodes is required to obtain high estimation performances of delamination location/size. The illustrated results are in excellent agreement with solutions available in the literature, thus validating the accuracy and reliability of the proposed technique.

• Journal of the Earthquake Engineering Society of Korea
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• v.5 no.3
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• pp.37-43
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• 2001

The energy concept has been extended to compare the hysteretic performance between various structural systems. As a result, the energy absorption efficiency is defined as the cumulative energy absorption capacity of a structural system normalized by that of the elasto-perfectly plastic system as a benchmark for comparisons. For this, the construction of energy curves from the experimental results obtained by cyclic loading tests is required. Using the proposed procedure, structures differing from each other in geometry, material and construction can be relatively and objectively compared for seismic performance. Also the beauty of this method is in its irrelevance to the structural failure mode. The proposed procedure was validated by application to the experimental results of two different specimens.

• Journal of Korean Society of Steel Construction
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• v.14 no.2
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• pp.357-364
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• 2002

The study performed a series of flexural tests on Closed Cold-Formed Steel Sections for stud, joist, and roof truss. Results were compared with analytical values. Each 2.4-m long and 0.9-m wide specimen consisted of two steel beams set at 0.46 m interval. The steel beams were attached to the specimens using either plaster board or ply wood. Another specimens did not use any attachment material. Positive and negative bending tests were conducted to investigate the composite behavior, including the effects of plaster board or ply wood on the buckling behavior of steel beam. Full-scale roof truss tests were also performed to study the buckling behavior and failure mode of the truss members.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2006.11a
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• pp.502-506
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• 2006

For advanced construction safety, there frequently are repeated accident. Most of them are serious disasters which are continually concerned. But technical method of Safety organizations for construction project is still short, simple and unscientific. We suggest FMEA(Failure Mode and Effect Analysis) process on the safety management. The purpose of study is an establishment of safety system focused on scientific method by selecting priority unit and by figuring importance.

• Journal of Applied Reliability
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• v.9 no.4
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• pp.275-290
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• 2009

This paper considers accelerated thermal degradation tests which are performed for rubber seal materials used for undersea tunnels constructed by immersion method. Three types of rubber seals are tested; rubber expansion seal, omega seal, and shock absorber hose. Main ingredient of rubber expansion seal is EPDM(Ethylene Propylene Diene Monomer) and that of both omega seal and shock absorber hose is SBR(Styrene Butadiene Rubber). The accelerated stress is temperature and an Arrhenius model is introduced to describe the relationship between the lifetime and the stress. From the accelerated degradation tests, dominant failure mode of the rubber seals is found to be the loss of elongation. The lifetime distribution and the service life of the rubber seals at use condition are estimated from the test results. The acceleration factor for three types of rubber seals are also investigated.

• Structural Engineering and Mechanics
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• v.41 no.4
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• pp.509-525
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• 2012

In recent years, CFRP material usage in strengthening applications gradually became widespread. Especially, the studies on the strengthening of shear deficient reinforced concrete beams with CFRP strips are chosen as a subject to numerous experimental studies and research on this subject are increased rapidly. The most important variable, that is affected on the failure mode of CFRP strips and that is needed for determining the shear capacity of the strengthened reinforced concrete beams, is the strain distribution between CFRP strips and concrete. Numerous experimental studies are encountered in the literature about the determination of strain distribution between CFRP strips and concrete. However, these studies mainly focused on the CFRP strips under axial tension. There are very limited numbers of experimental and analytic studies examining the strain distribution between concrete and CFRP strips, which are under combined stresses due to the effects of shear force and bending moment. For this reason, existing experimental study in the literature is used as model for ANSYS finite element software. Nonlinear finite element analysis of RC beams strengthened against shear with CFRP strips under reverse cyclic loading is performed. The strain distributions between CFRP strips and concrete that is obtained from finite element analysis are compared with the results of experimental measurements. It is seen that the experimental results are consisted with the results derived from the finite element analysis and important findings on the strain distribution profile are reached by obtaining strain values of many points using finite element method.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.780-788
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• 2008

As a railway is receiving attention as an environment-friendly transportation mode, many high speed, inter-city and urban railway are constructed and remodeled in the world. With this trend, railway RAMS was included in the international standard IEC 62278 in 2002. RAMS activity in domestic market is also increased with this international trend. However, IEC 62278 does not describe the methodology of substantial contents like how reliability target is set although it can be used as an overall guideline when RAMS requirements are included in the purchase specification. That is because RAMS requirements should be set with the specific railway condition. It is required to fully understand the meaning of railway RAMS parameters and apply those correspond to the specific railway system and environment condition especially when a quantitative RAMS requirement is set. In this study, the meaning and characteristics of RAMS parameters applicable to the development of quantitative RAMS requirement of rolling stock is described. And the basic concept of RAMS and the definition of failure that IEC 62278 describes is modified and suggested in order to make more suitable to the development of quantitative RAMS requirement.

• KEPCO Journal on Electric Power and Energy
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• v.6 no.2
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• pp.119-122
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• 2020

With recent ESS (Energy Storage System) fire accident, the fault protection performance is becoming more important. However, there has never been any experiments with the protection performance on the faults in the ESS system level. In this study, the effect of AC ground fault and IGBT (Insulated Gate Bipolar mode Transistor) short-circuit failure on MW class ESS was performed experimentally for the first time in the world. First of all, the effect of the AC single line ground fault on battery was analyzed. Moreover, the transient voltage was investigated as a function of the battery capacity and the power level. Finally, the breaking capability and insulation performance of ESS were examined under PCS short-circuit fault condition. Through the tests, it was found that ESS protection system safely blocked the faulty current regardless of the faults, whereas the electronic parts such as IGBT and MC (Magnetic Contactor) were broken by the fault current. Also, the electrical breakdown in ESS resulted from the transient voltage during the protection process.

• Steel and Composite Structures
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• v.24 no.4
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• pp.441-453
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• 2017

In Y-shaped eccentrically braced frame fabricated with high strength steel (Y-HSS-EBF), link uses conventional steel while other structural members use high strength steel. Cyclic test for a 1:2 length scaled one-bay and one-story Y-HSS-EBF specimen and shake table test for a 1:2 length scaled three-story Y-HSS-EBF specimen were carried out to research the seismic performance of Y-HSS-EBF. These include the failure mode, load-bearing capacity, ductility, energy dissipation capacity, dynamic properties, acceleration responses, displacement responses, and dynamic strain responses. The test results indicated that the one-bay and one-story Y-HSS-EBF specimen had good load-bearing capacity and ductility capacity. The three-story specimen cumulative structural damage and deformation increased, while its stiffness decreased. There was no plastic deformation observed in the braces, beams, or columns in the three-story Y-HSS-EBF specimen, and there was no danger of collapse during the seismic loads. The designed shear link dissipated the energy via shear deformation during the seismic loads. When the specimen was fractured, the maximum link plastic rotation angle was higher than 0.08 rad for the shear link in AISC341-10. The Y-HSS-EBF is a safe dual system with reliable hysteretic behaviors and seismic performance.