• Steel and Composite Structures
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• 제7권5호
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• pp.391-404
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• 2007

This paper presents push-out tests of stud shear connectors to examine their fatigue behavior for developing a new composite bridge deck system. The fifteen push-out specimens of D16 mm stud welded on 9 mm steel plate were fabricated according to Eurocode-4, and a series of fatigue endurance test and residual strength test were performed. Additionally, the stiffness and strength variations by cyclic loading were compared. The push-out test, when the stiffness reduction ratio of the specimens was 0.95 under cyclic load, resulted in the failure of the studs. The stiffness variation of the push-out specimens additionally showed that the application of cyclic loads reduced the residual strength. The fatigue strength of the shear connectors were compared with the design values specified in the Eurocode-4, ASSHTO LRFD and JSSC codes. The comparison result showed that the fatigue endurance of the specimens satisfies the design values of these codes.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2008년도 춘계학술대회 논문집
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• pp.517-520
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• 2008

Recently, use of adhesive bonding technology is increased to achieve the multi-material design for lightweight structure in automobile industry. In this paper, the fracture strength of adhesive has been studied with the single lap shear test conducted at different temperatures. The joint specimens are made from Al 5052 and SPRC 440 bonded with structural epoxy adhesive. The operating temperature has been considered up to $150[^{\circ}C]$ and the single lap shear test has been conducted with 5mm/min tensile rate. Fracture strength of adhesive bonded joint has been decreased with increase of operating temperature. The fracture strength at the $100[^{\circ}C]$ was shown about half of that at room temperature.

• Architectural research
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• 제23권1호
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• pp.11-17
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• 2021

A concrete-filled circular steel tube beam was fabricated, and a bending test was performed to analyze its failure modes, displacement ductility, bending-shear strength, and load-central deflection relationship. For the bending test, the installation position of the shape memory alloy (SMA) inside and outside the double-skin steel tube was used, and the rebar installation position, the concrete strength, the mixing of fibers, and the inner-outer diameter ratio as the main parameters. The test results showed that the installation positions of the reinforcements inside and outside the double-skin steel tube and the inner-outer diameter ratio of the steel tube affected the ductility, maximum load, and failure mode. In general, the specimen made of general concrete with SMA installed outside and inside (OI) the double-skin steel tube showed the best results.

• Steel and Composite Structures
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• 제21권2호
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• pp.289-302
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• 2016

A new kind of partially precast or prefabricated castellated steel reinforced concrete beam, which is abbreviated here as CPSRC beam, was presented and introduced in this paper. This kind of CPSRC beam is composed of a precast outer-part and a cast-in-place inner-part. The precast outer-part is composed of an encased castellated steel shape, reinforcement bars and high performance concrete. The cast-in-place inner-part is made of common strength concrete, and is casted with the floor slabs simultaneously. In order to investigate the shear performance of the CPSRC beam, experiments of six CPSRC T-beam specimens, together with experiments of one cast-in-place SRC control T-beam specimen were conducted. All the specimens were subjected to sagging bending moment (or positive moment). In the tests, the influence of casting different strength of concrete in the cross section on the shear performance of the PPSRC beam was firstly emphasized, and the effect of the shear span-to-depth ratio on that were also especially taken into account too. During the tests, the shear force-deflection curves were recorded, while the strains of concrete, the steel shapes as well as the reinforcement stirrups at the shear zone of the specimens were also measured, and the crack propagation pattern together with the failure pattern was as well observed in detail. Based on the test results, the shear failure mechanism was clearly revealed, and the effect of the concrete strength and shear span-to-depth ratios were investigated. The shear capacity of such kind of CPSRC was furthermore discussed, and the influences of the holes on the steel shape on the shear performance were particularly analyzed.

• 한국전산구조공학회논문집
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• 제28권3호
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• pp.259-266
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• 2015

본 논문에서는 유공형 강판의 횡방향 보강간격에 따른 넓은 보의 전단성능을 실험적으로 평가하기 위하여 횡방향 전단보강 간격과 넓은 보의 유효깊이를 변수로 고려하였다. 시험체는 총 8개로 유공형 강판으로 전단보강한 시험체가 5개, 무보강 시험체가 3개이다. 균열 및 파괴유형, 변형률과 하중-변위 곡선을 분석하였다. 유공형 전단보강재의 전단강도 기여분을 분석하고, 횡방향 전단보강의 최대간격을 제안하였다. 횡방향 전단보강 개수가 2개인 시험체에 비해 3개인 시험체에서 전단강도가 크게 나타났으며 유효깊이가 증가할수록 전단강도가 크게 나타났다.

• Smart Structures and Systems
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• 제22권3호
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• pp.335-340
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• 2018

The behavior of concrete slabs in composite beam with C and L shaped angle shear connectors has been studied in this paper. These two types of angle shear connectors' instalment have been commonly utilized. In this study, the finite element (FE) analysis and soft computing method have been used both to present the shear connectors' push out tests and providing data results used later in soft computing method. The current study has been performed to present the aforementioned shear connectors' behavior based on the variable factors aiming the study of diverse factors' effects on C and L shaped angle in shear connectors. ANFIS (Adaptive Neuro Fuzzy Inference System), has been manipulated in providing the effective parameters in shear strength forecasting by providing input-data comprising: height, length, thickness of shear connectors together with concrete strength and the respective slip of shear connectors. ANFIS has been also used to identify the predominant parameters influencing the shear strength forecast in C and L formed angle shear connectors.

• Journal of the Korean Wood Science and Technology
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• 제30권4호
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• pp.96-105
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• 2002

전단벽은 현대식 경골목조건축에서 바람이나 지진 등에 의한 측방하중에 대한 저항력을 제공하는 가장 중요한 요소 중의 하나이다. 전단벽에서 건물에 전달된 측방하중은 벽의 스터드와 덮개재료 사이의 못접합부를 통하여 덮개재료로 전달되고 덮개재료에 전달된 하중은 판재의 면전단력에 의하여 지지된다. 따라서 실제 전단벽에서 측방하중에 대한 저항력을 결정하는 가장 중요한 요소는 못접합부라고 할 수 있을 것이다. 이 연구에서는 스터드와 판재 사이의 못접합부에 대한 강성 및 강도를 측정하였으며 이 값들은 전단벽의 찌그러짐 저항력을 예측하는 이론모형의 입력자료로 사용되었다. 이론모형의 예측치의 정확성을 검증하기 위하여 판재 한 장으로 구성된 전단벽의 전단시험을 수행하였다. 못접합부의 강성은 스터드 부재의 섬유방향에 의하여 영향을 받았으나 판재의 방향은 거의 영향을 미치지 않는 것으로 나타났다. 전단하중 하에서 못접합부나 전단벽의 거동은 3개의 직선구간으로 나나낼 수 있었으며 이론모형 I보다 이론모형 II의 예측치가 더 정확하였다.

• The Journal of Advanced Prosthodontics
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• 제9권2호
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• pp.85-92
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• 2017

PURPOSE. The aim of this study was to evaluate the effect of tooth surface pre-treatment steps on shear bond strength, which is essential for understanding the adhesive cementation process. MATERIALS AND METHODS. Shear bond strengths of different cements with various tooth surface treatments (none, etching, priming, or etching and priming) on enamel and dentin of human teeth were measured using the Swiss shear test design. Three adhesives (Permaflo DC, Panavia F 2.0, and Panavia V5) and one self-adhesive cement (Panavia SA plus) were included in this study. The interface of the cement and the tooth surface with the different pre-treatments was analyzed using SEM. pH values of the cements and primers were measured. RESULTS. The highest bond strength values for all cements were achieved with etching and primer on enamel ($25.6{\pm}5.3-32.3{\pm}10.4MPa$). On dentin, etching and priming produced the highest bond strength values for all cements ($8.6{\pm}2.9-11.7{\pm}3.5MPa$) except for Panavia V5, which achieved significantly higher bond strengths when pre-treated with primer only ($15.3{\pm}4.1MPa$). Shear bond strength values were correlated with the micro-retentive surface topography of enamel and the tag length on dentin except for Panavia V5, which revealed the highest bond strength with primer application only without etching, resulting in short but sturdy tags. CONCLUSION. The highest bond strength can be achieved for Panavia F 2.0, Permaflo DC, and Panavia SA plus when the tooth substrate is previously etched and the respective primer is applied. The new cement Panavia V5 displayed low technique-sensitivity and attained significantly higher adhesion of all tested cements to dentin when only primer was applied.

• 한국도로학회논문집
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• 제13권1호
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• pp.169-175
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• 2011

콘크리트에서 강도는 콘크리트의 물리적 특성을 평가할 수 있는 중요한 인자 중 하나이며 콘크리트에 가장 많은 부피를 차지하는 것이 골재이다. 또한 시멘트는 콘크리트 만드는 결합재로서 이 역시 강도와 매우 밀접한 관계가 있다. 이러한 골재와 시멘트의 특성이 콘크리트 압축강도와 전단파 속도의 상관관계에 미치는 영향을 파악하고자 굵은 골재 최대치수와 시멘트 종류별로 실험을 실시하였다. 시멘트는 1종 시멘트와 초속경 시멘트를 사용했고, 골재는 서로 다른 지역의 3가지 골재를 사용하였다. 골재의 입도는 굵은 골재 최대치수 19mm와 13mm의 단입도 골재를 사용하여 동일 배합시 압축강도와 전단파 속도의 상관관계를 살펴보았다. 또한 골재의 특성을 정량화 하고자 LA마모시험을 실시하였다. 그 결과 압축강도와 전단파 속도의 상관관계는 시멘트 종류에 따라 달랐으나, 골재의 종류, 입도 및 마모감량에 관계없이 일정한 상관성을 보이는 것으로 나타났다.

• 대한치과기공학회지
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• 제39권4호
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• pp.243-251
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• 2017

Purpose: The purpose of this study was to investigate the effects of etching by monitoring the etched surfaces and the shear bonding strength of resin and porcelain with etched zirconia. Methods: The CAD/CAM was used to produce 24 zirconia blocks in groups of six. The zirconia specimen surfaces were sandblasted, and they were then divided into 12 specimens with surface etching and 12 specimens without etching for the control group. 12 specimens of composite resin were bonded using a curing light, and 12 specimens of porcelain underwent vita porcelain build-up sintering and the shear bonding strength was measured using a universal testing system. The SEM photographs were taken in order to observe any differences in the surfaces before and after etching, and they were magnified by a factor of 8 in order to observe fractured surface types. Results: The results of the shear bonding strength measurements are as follows: For the composite resin tests, between zirconia and resin, the shear bonding strength of the control group (NZR) without surface etching was 4.68 Mpa and the experimental group (EZC) with surface etching was 9.65 Mpa, which is significantly higher. The crystal structure of the zirconia was confirmed to be different in observations of the surfaces before and after etching. Conclusion : In comparing the shear bonding strength of zirconia and composite resin, the effects of etching were found to be significant. The effects of surface etching were also observed in fractured surfaces between zirconia and porcelain. This is expected to be applicable to various prosthetics as surface etching on zirconia is used in clinics.