• Journal of the Society of Disaster Information
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• v.18 no.3
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• pp.646-659
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• 2022

Purpose: In this study, we developed a 4-way sway prevention brace that efficiently reduces the installation area and has excellent stability and seismic performance compared to the conventionl sway prevention brace used in existing firefighting facilities. The performance and reliability of the developed 4-way way prevention brace were analyzed by the tensile, compression tests and seismic tests. Method: As the static test, 4-way sway prevention braces were installed on the horizontal and vertical pipes to perform the tensile and compression tests based on the KFI certification standard and the maximum movement was measured at the rated load. As a dynamic test, 4-way sway prevention braces were installed in the pipes filled with water, and the test response spectrum to the input excitation wave were measured through the acceleration sensors. After the seismic tests, separation, failure, and local deformation of the pipes, and 4-way sway prevention braces were not observed. Result: The results of the tensile and compression tests indicated that the maximum movement of the pipe during tension and compression was 50% to 70% or less compared to the certification values, indicating that the performances of the 4-way sway prevention braces were very excellent. The results of the the seismic tests indicated that the test response spectrum of the 4-way sway prevention braces is within the required response spectrum. Conclusion: In this study, it was found that the 4-way sway prevention braces satisfied the KFI certification standard and were superior compared to the existing sway prevention brace in terms of the stability, cost, and installation area.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.361-364
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• 2008

To design structures with Ultra High Performance Concrete (UHPC), it is necessary to estimate the mechanical properties first of all. The most attractive characteristics of UHPC are the considerable tensile strength and behavior. Therefore the most important thing in order to properly design UHPC structures is to establish the constitutive model to represent the tensile behavior of UHPC. In this study, it was tried to find out the tensile behavior of UHPC by experiments and analyses. Through comparisons with the French SETRA/AFGC recommendations and the Japanese recommendations for the Ultra High-Strength Fiber-Reinforced Concrete Structures, a reasonable model which could represent the tensile stress-strain relationship in the structural design was proposed

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.6A
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• pp.577-585
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• 2009

A 9-node degenerated shell finite element(FE), which has been developed for assessment of ultimate pressure capacity and nonlinear analysis for nuclear containment building is described in this paper. Reissner-Midnlin(RM) assumptions are adopted to develop the shell FE so that transverse shear deformation effects is considered. Material model for concrete prior to cracking is constructed based on the equivalent stress-equivalent strain relationship. Tension stiffening model, shear transfer mechanism and compressive strength reduction model are used to model the material behavior of concrete after cracking. Niwa and Aoyagi-Yamada failure criteria have been adapted to find initial cracking point in compression-tension and tension-tension region, respectively. Finally, the performance of the developed program is tested and demonstrated with several examples. From the numerical tests, the present results show a good agreement with experimental data or other numerical results.

• Journal of the Korean Geosynthetics Society
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• v.9 no.3
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• pp.67-75
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• 2010

The tensile strength, permeability and discharge capacity of biodegradable plastic drain boards made with poly lactic acid (PLA) have been tested and verified prior to their usage at field. Based on test results, the tensile strength of biodegradable plastic drain board made with PLA has relatively lower tensile strain and tensile strength than those of plastic drain board. Performance of PLA filter having good permeability and low opening size is proper for the filter of vertical drain board. In case of improving stiffness of PLA filter, biodegradable plastic drain board also satisfies required discharge capacity as use of vertical drain board too.

• Journal of the Korean Recycled Construction Resources Institute
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• v.10 no.2
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• pp.152-158
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• 2022

The purpose of this study is to investigate experimentally the compressive strength and tensile behavior of cement composites reinforced by selvedge short fiber from high performance fabric. Four types of mixtures according to the types of selvedge short fibers were prepared and compressive strength and tension tests were performed. Test results showed that the compressive strength values of composites investigated in this study ranged from 64 MPa to 66 MPa and all composites showed strain-hardening behavior. The tensile strain capacity values of composites ranged from 2.6 % to 2.8 % and multiple cracking behavior was observed in all composites.

• Journal of the Korea institute for structural maintenance and inspection
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• v.16 no.1
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• pp.55-63
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• 2012

This paper presents materials and processing technique to manufacture low viscous strain-hardening cementitious composite which is suitable for structures requiring low viscosity of materials. The micromechanics and fracture mechanics tools coupled with processing techniques were adopted to achieve low viscosity of composites as well as high tensile strain capacity. Optimal volume and length of fibers and interfacial properties between fibers and matrix for composites with tensile strength of 2~3MPa were determined on the basis of the micromechanical analysis and the steady-state cracking theory. Then six mixtures were determined and the experiment was carried out to evaluate the viscosity and uniaxial tensile performance of those. From the test results, it is verified that the strain-hardening cementitious composite with low viscosity suitable for grouting applications in fresh state as well as high ductility over 1.5% in hardened state can be feasible.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.269-272
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• 2008

This paper reports on the cracking mitigation and flexural behavior experimentally observed in concrete prisms layered with strain-hardening cement composites (SHCCs) which is micro-mechanically designed cement composite and exhibits pseudo tensile strain-hardening behavior accompanied by multiple cracking while using a moderate amount of fiber, typically less than 2 percent in term of fiber volume fraction. In this study, SHCC is reinforced with 1.3 percent polyvinyl alcohol (PVA) and 0.20 percent polyethylene (PE) in volume fraction. Tests were conducted using $100{\times}100{\times}400mm$ long prisms supported over a simply supported span of 350mm. The four point load was applied using MTS servo control machine. The thickness patched with SHCC is the main variable for this study. Experimental study shows that when subject to monotonic flexural loading, the SHCC layered repair system showed 2.7 - 4.2 times increased load carrying capacity, and mitigated cracking damage of concrete beams layered with SHCC compared with plain concrete beams.

• Journal of the Korea institute for structural maintenance and inspection
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• v.27 no.6
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• pp.1-12
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• 2023

This paper assesses the suitability of existing standards for plastic material models and performance level evaluation methods in seismic performance evaluations of concrete dam piers during Maximum Credible Earthquakes (MCE). Dynamic plastic analysis was conducted to examine the applicability of the plastic material model under various conditions. As a result reveal that when the minimum reinforcement ratio is not met, the average stress-average strain method recommended in current dam seismic performance evaluation guidelines tends to underestimate pier responses compared to the predicted outcomes of dynamic elastic analysis. Consequently, the paper proposes an improvement plan that treats dam piers with an insufficient minimum reinforcement ratio as unreinforced and integrates fracture energy into concrete tensile behavior characteristics for performance level evaluation. Implementing these improvements can lead to more conservative evaluation outcomes compared to current seismic performance evaluation methods.

• Journal of Korean Association for Spatial Structures
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• v.7 no.6
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• pp.53-60
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• 2007

The hole for the insertion of the pin in the shank is exist at ball joint connection of the space frame. It brings about the brittle fracture caused by stress concentration. Consequently it cannot expect the deformation performance or energy absorption performance from ball joint connection. In this study we developed a new connection details which will increase the plastic deformation performance at ball joint connection and can absorb the error in construction, which expect the plastic deformation performance at the reduced shank without brittle fracture at the screw of bolt and pin. Also it's capacity is verified by the performance in numerical analysis and test. We confirmed bolt's plastic deformantion performance through controled shank and pin's area.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2000.11a
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• pp.28-28
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• 2000

HTPB/AP/AI 추진제는 none-reinforcing filler가 다량 함유되어 있어 기계적 특성은 바인더와 고체 충진제의 계면 접착력에 따라 크게 영향을 받으며 이를 향상시키기 위해 결합제의 연구가 다수 진행되었고 추진제의 인장 변형율을 증가시키기 위해 HTPB의 관능기수에 따른 가교밀도, 경화제와 경화촉매, 가소제등 최적의 바인더조성을 위해 가능한 원료 및 함량 연구에 많은 노력을 기울여 왔다. 또한 추진제의 주원료로서 AP는 추진제의 성능 및 내탄도 관점에서 입자크기에 따른 연소특성 및 고성능을 위한 충전 분율에 대해 주로 연구되었으며 특히 Oberth와 Farris는 고체추진제 분야에서 많은 업적을 이루었다.(중략)