• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 추계 학술발표회 논문집
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• pp.365-368
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• 2006

RBSN Method, Rigid-Body-Spring Network Method, is a structural analysis method that overcomes the problems faced in FEM analysis of concrete or crack forming structures. In RBSN, irregular lattices are used to model structural components consisting of bulk material, curvilinear reinforcements, and their interfaces. Because reinforcements and their interfaces in the bulk material are freely positioned, meshing is irrespective of the geometry of the representing bulk material. In this paper, RBSN method of 3D is applied in simulating the pull-out test of FRP (Fiber Reinforced Polymer) embedded in concrete. The comparison of analysis results to experimental results shows that RBSN method simulates the shear-slip behavior very precisely. From the analysis results, 3D RBSN method is proven to be an effective and accurate analysis method for concrete structural analysis. Also, the results show that RBSN method can be a potential analysis method for concrete structures that can replace the current FEM analysis.

• 한국가스학회지
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• 제6권1호
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• pp.52-58
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• 2002

가스 배관 진단 시스템은 배관 내부에 투입되어 배관 내부의 여러 정보를 수집한다. 배관 진단을 위한 센서로는 배관 내부의 상태를 측정하는 캘리퍼(caliper) 센서와 온도, 압력센서가 있다. 그리고 정확한 위치 정보를 제공할 수 있는 IMU(Inertial Measurement Unit)와 주행 거리계를 사용하는 결합 항법 시스템도 필요하다. 본 논문에서는 가스 배관 진단시스템을 위한 항법 데이터 저장 시스템을 개발한다. 항법 데이터 저장 시스템은 실시간 동작을 위하여 마스터/슬레이브 구조를 가진다. 마스터 시스템은 항법 데이터를 저장하거나 통신하는데 사용하며 슬레이브 시스템은 센서 데이터를 처리한다. 개발된 항법 데이터 저장 시스템의 성능은 Pull Rig 실험을 통하여 검증한다.

• 터널과지하공간
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• 제21권5호
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• pp.377-385
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• 2011

본 연구는 록볼트가 크게 인장되더라도 주입재의 인장파괴를 최소화하여 전면접착식 볼트의 지보효과를 극대화 할 수 있는 새로운 개념의 록볼트를 개발하기 위해 수행하였다. 전면접착식 볼트의 거동 메커니즘을 분석하기 위하여 실내모형시험을 실시하였다. 압축성 간격재를 설치한 록볼트를 고안하고, 실내인발시험을 실시하여 간격재의 최적설치간격을 결정하였으며, 실대형 인발시험을 통하여 압축성 간격재를 설치한 볼트의 인발저항력을 측정하였다. 그 결과 압축성 간격재를 설치한 볼트가 기존의 전면 접착식 볼트보다 약 15% 증가된 인발 저항력을 나타내었다.

• Steel and Composite Structures
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• 제33권1호
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• pp.1-18
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• 2019

In the present study, the behavior of steel plate shear walls (SPSW) with variable column flexural stiffness is experimentally and numerically investigated. Altogether six one-bay one-story specimens, three moment resisting frames (MRFs) and three SPSWs, were designed, fabricated and tested. Column flexural stiffness of the first specimen pair (one MRF and one SPSW) corresponded to the value required by the design codes, while for the second and third pair it was reduced by 18% and 36%, respectively. The quasi-static cyclic test result indicate that SPSW with reduced column flexural stiffness have satisfactory performance up to 4% story drift ratio, allow development of the tension field over the entire infill panel, and cause negligible column "pull-in" deformation which indicates that prescribed minimal column flexural stiffness value, according to AISC 341-10, might be conservative. In addition, finite element (FE) pushover simulations using shell elements were developed. Such FE models can predict SPSW cyclic behavior reasonably well and can be used to conduct numerical parametric analyses. It should be mentioned that these FE models were not able to reproduce column "pull-in" deformation indicating the need for further development of FE simulations with cyclic load introduction which will be part of another paper.

• Advances in concrete construction
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• 제11권5호
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• pp.387-396
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• 2021

The behavior of headed bars in concrete is investigated through 108 pullout tests having an embedment depth of eight times the bar diameter in the M20 concrete mix. Headed bars are designed based on ASTM A970-16 and ACI 318-19 recommendations. The primary parameters used in this study are the steel bar diameter, the steel fibers percentage, and the head shapes. Three failure modes namely, Steel, Concrete-Blowout & Pull-Through failure have been observed. Based on load-deflection curves which are plotted to investigate the bond capacity of headed bars, it is observed that the circular-headed bars have displayed the highest peak load. The comparative analysis shows the smaller differences in the ultimate bond strength between MC2010 (0.89-2.26 MPa) and EN 1992-1-1 (2.32 MPa) as compared to ACI-318-19 (11-22 MPa) which is due to the absence of embedment depth and peak load factor in MC2010 and EN 1992-1-1 respectively.

• 디지털산업정보학회논문지
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• 제19권1호
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• pp.57-76
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• 2023

This study analyzes the factors and effects on the users' intention to switch from contact center-oriented to AI chatbot-oriented customer services by combining Push-Pull-Mooring Model and provides insights for companies considering the adoption of AI chatbots. To test the model, we surveyed users with experience using chatbots at least once across different age groups. Finally, we analyzed 176 cases for the analysis using IBM SPSS Statistics and SmartPLS 4.0. The results of hypotheses testing rejected the hypotheses for variables of inconsistent quality and low availability of push factors and low switching cost of mooring factor while accepting the hypotheses for the tardy response of push factors and all pull factors. Therefore, these findings provide important implications for researchers and practitioners who wish to conduct research or adopt AI chatbots. In conclusion, users do not feel inconvenienced by the contact center-oriented service but also perceive high trust and convenience with AI chatbot-oriented service. However, despite low switching costs, users consider chatbots a complementary tool rather than an alternative. So, companies adopting AI chatbots should consider what features the users expect from AI chatbots and facilitate these features when implementing AI chatbots.

• 수산해양기술연구
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• 제41권1호
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• pp.78-84
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• 2005

The main goal of this work is to study the effects of temperature and volume fraction of fiber on the Charpy impact test with GF/PP composites. The critical fracture energy and failure mechanisms of GF/PP composites are investigated in the temperature range of 60^{\circ}C$ to -50^{\circ}C$ by impact test. The critical fracture energy increased as the fiber volume fraction ratio increased. The critical fracture energy shows a maximum at ambient temperature and it tends to decreases as temperature goes up or goes down. Major failure mechanisms can be classified such as fiber matrix debonding, fiber pull-out and/or delamination and matrix deformation.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.40-44
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• 2008

The interfacial adhesion energy between resist and a substrate is very important due to resist pull-off problems during separation of mold from a substrate in nanoimprint process. And effect of substrate surface roughness on interfacial adhesion energy is very important. In this paper, we have treated glass wafer surface using $CF_4$ gas for increase surface roughness and it has tested interfacial adhesion properties of UV resin/glass substrate interfaces by 4 point bending test. The interfacial adhesion energies by bare, 30, 60 and 90 sec surface treatments are 0.62, 1.4, 1.36 and 2 $J/m^2$, respectively. The test results showed quantitative comparisons of interfacial fracture energy (G) effect of glass wafer surface roughness.

• 한국기계가공학회지
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• 제19권3호
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• pp.86-91
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• 2020

An important factor of rough road modeling is analyzing the shear behavior properties of the rough road. These properties influence the drawbar pull of the tool when interacting with the soil used in agriculture. Furthermore, shear behavior properties are important because sinkage and shear stress are generated when wheels drive on rough roads. In this study, we performed a direct shear test to investigate the shear behavior properties of soils and compare with the direct shear simulation; shear force derived by the coupled analysis of discrete element method; and multi-body dynamics. Soil contact parameters were measured in a wheel and soil contact simulation followed by comparison of the simulated and experimentally measured shear force.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 추계 학술발표회 논문집
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• pp.629-632
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• 2006

The various rib geometry of hybrid fiber reinforced polymer (FRP) reinforcing bars were analyzed by finite element method. From the analysis result, two types of hybrid FRP reinforcing bars such as spiral and cross type with the same dimension of rib geometry were fabricated in this study. To evaluate the bond properties of them, direct pull-out test was performed. All testing procedures including specimens preparation, set-up of test equipments and measuring devices were made in accordance with the recommendations of CSA Standard S806-02. From the test results, it was found that cross type hybrid FRP reinforcing bars showed the highest bond strength than that of the others due to the higher relative rib area.