• Restorative Dentistry and Endodontics
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• 제15권1호
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• pp.141-152
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• 1990

The purpose of this study was to evaluate the effects of dentin adhesives(Gluma$^{(R)}$ and Scotchbond 2$^{(R)}$) on the marginal adaptation of light cured composite resin (Heliosit$^{(R)}$) by using SEM. The recently extracted 30 teeth were used and round cavities were prepared on the occlusal surfaces of the teeth with predesigned depth and diameter. The teeth were divided into three groups. Group 1 : Gluma$^{(R)}$ + Heliosit$^{(R)}$ Group 2 : Scotchbond 2$^{(R)}$ + Heliosit$^{(R)}$ Group 3 : Enamelbond$^{(R)}$ + Heliosit$^{(R)}$ Filling with Heliosit, the teeth were stored in saline solution for 24 hours. After the thermocycling procedure, the teeth were cut vertically into the restorations. The SEM observation was carried out to evaluate the marginal adaptation of the composite resin. The following results were obtained. The following results were obtained. 1. The groups using Gluma$^{(R)}$ and Scotchbond 2$^{(R)}$ showed better than the control group on marginal adaptation to the dentin. 2. The group using Gluma$^{(R)}$ was superior to the group using Scotchbond 2$^{(R)}$, but the difference was not significant. 3. In all groups, the marginal gaps were wider on the pulpal walls than on the lateral walls of restorations.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 추계 학술발표회 논문집
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• pp.257-260
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• 2006

Coupled shear walls consist of two or more in-plane walls inter-connected with coupling beams. In order to effectively resist seismic loads, coupling beams must be sufficiently stiff, strong and posses a stable load-deflection hysteretic response. Much of requirements to the civil and building structures have recently been changed in accordance with the social and economic progress. Ductility of high performance fiber reinforced cementitious composites(HPFRCCs), which exhibit strain hardening and multiple crackling characteristics under the uniaxial tensile stress is drastically improved. This paper provides background for design guidelines that include a design model to calculate the shear strength of pseudo strain hardening cementitious composite steel coupling beam.

• Steel and Composite Structures
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• 제14권5호
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• pp.473-491
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• 2013

The primary objectives of this paper are to describe the buckling patterns and to determine the squash load of steel plate-concrete (SC) walls. The major variables in this study were the width-thickness (B/t) ratio and yield strength of surface steel plates. Six SC walls were tested, and the results include the maximum strength, buckling pattern of steel plates, strength of headed studs, and behavior of headed studs. Based on the test results, the effects of the B/t ratio on the compressive strength are also discussed. The paper also presents recommended effective length coefficients and discusses the effects of varying the yield strength of the steel plate, and the effects of headed studs on the performance of SC structures based on the test results and analysis.

• Steel and Composite Structures
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• 제31권1호
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• pp.85-98
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• 2019

Nonlinear seismic performances of code designed Perforated Steel Plate Shear Walls (P-SPSW) were studied. Three multi-storey (4-, 8-, and 12-storey) P-SPSWs were designed according to Canadian seismic provisions and their performance was evaluated using time history analysis for ground motions compatible with Vancouver response spectrum. The selected code designed P-SPSWs exhibited excellent seismic performance with high ductility and strength. The current code equation was found to provide a good estimation of the shear strength of the perforated infill plate, especially when the infill plate is yielded. The applicability of the strip model, originally proposed for solid infill plate, was also evaluated for P-SPSW and two different strip models were studied. It was observed that the strip model with strip widths equal to center to center diagonal distance between each perforation line could reasonably predict the inelastic behavior of unstiffened P-SPSWs. The strip model slightly underestimated the initial stiffness; however, the ultimate strength was predicted well. Furthermore, applicability of simple shear-flexure beam model for determination of fundamental periods of P-SPSWs was studied.

• Steel and Composite Structures
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• 제51권5호
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• pp.487-498
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• 2024

Steel moment resisting frames (MRFs) typically have inter-story drift concentrations at lower stories during earthquakes as found from previous research. Hinged walls (HWs) can be used as structural strengthening components to force the MRFs deform uniformly along the building height. However, large moment demands are often observed on HWs and make the design of HWs non-economical. This paper proposes a method to reduce the moment demand on HWs using a ductile connection system between the MRFs and the HWs. The ductile connection system is designed with a yield strength and energy dissipation capacity, for the purpose of limiting the seismic forces transferred to the HWs and dissipating seismic energy. Nonlinear time history analyses were performed using 10 far-filed earthquakes at maximum considered earthquake level. The analysis results show that the proposed ductile connection system can reduce: (1) seismic moment demands in the HWs; (2) floor accelerations; (3) the connection force between HWs and MRFs.

• 콘크리트학회논문집
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• 제21권3호
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• pp.327-335
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• 2009

지진이 빈번하게 발생하는 지역에서는 비내진상세구조물은 지진 발생시 연약층을 형성하고 취성적 붕괴를 일으키게 된다. 그러나, 기존 구조물을 해체하고 내진상세 구조물을 신축하는 방법은 건설폐기물, 환경오염 및 민원 등 여러가지 문제들을 가지는 등 비경제적 방법이라 할 수 있다. 따라서 기존 구조물이 내진성능을 만족하도록 내진보강에 관한 많은 연구가 이루어졌으며, 이러한 내진보강방법에는 끼움벽, 철골브레이스, 연속벽, 부벽, 날개벽, 기둥/보의 자켓팅 등이 있다. 이 중 끼움벽 골조는 큰 변형과 접합부에서의 회전이 발생하는 골조와, 비교적 작은 변형에서도 전단파괴를 야기하는 끼움전단벽 등 복합적인 거동특성을 나타낸다. 따라서, 이러한 시스템의 거동특성은 개개의 골조나 벽에서 나타나는 거동특성과 매우 다르게 된다. 본 연구에서는 끼움벽의 내진성능을 평가하고자 하였으며, 손상에너지의 효과적 흡수를 위해 변형경화형 시멘트 복합체 (SHCC)를 사용하였다. 실험은 1/3 축소모형의 끼움벽을 반복가력하는 것으로 계획하였다. 실험 결과, SHCC 끼움벽에서는 섬유의 가교작용을 통해 시멘트 복합체 내 응력을 재분배함으로써 미세균열이 발생하였으며, 강도 및 에너지소산능력이 우수한 것으로 나타났다.

• 한국CDE학회논문집
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• 제20권2호
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• pp.124-132
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• 2015

When Building Information Modeling (BIM) was introduced at the early stage, it was only utilized as a three-dimensional visualization tool. Nowadays, however, BIM is being studied for increasing design productivity and managing enormous information on building life cycle. One of the representative research is developing 'common prototype BIM libraries'. BIM data made of common prototype libraries should be utilized in various ways, quantity takeoff, code checking, energy analysis and so on. However, common prototype BIM libraries are not enough to estimate accurate cost. For example, composite wall libraries should be divided into several single objects, wall structure and finishes, for the quantity takeoff and construction cost calculation. In this paper, we are suggesting an automated division algorithm of composite wall and developing a system prototype for it. This study is expected to reduce extra modeling work and contribute to fast and accurate cost calculation in the construction.

• KIEAE Journal
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• 제11권4호
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• pp.95-101
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• 2011

Earth has been used as a building material not only our country but also many foreign countries in the world. In foreign countries, we can often find the high-storied earthen houses which have been maintained for over several hundred years, which means the fact that earth differs in durability according to the methods of utilizing earth. So, the purpose of this study is to progress the fundamental research for utilizing earth as a wall material. Also, the another purpose of this study is to utilize the optimum micro-filler effect which adjusts the grain size of earth and the lime composite which promotes chemical combining power, and so examine whether earth material ensures its high compressive strength. This study applied both of rammed earth method and pour earth method among earth architecture methods. This study investigated compressive strength, slump, and air content according to unit binder weight. On the basis of such experimental results, this study derived the following conclusions. 1) Optimum micro-filler mixtures reduce a lot of fine particles contained in earth. If optimum micro-filler mixtures are used as aggregates, they develop lower W/B and relatively higher strength than general earth. 2) In this study, which uses optimum micro-filler earth mixtures and lime composite, rammed earth method develops 29MPa and pour earth method develops 28MPa in 28 days compressive strength. Such strengths can be utilized in building walls.

• Restorative Dentistry and Endodontics
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• 제43권4호
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• pp.38.1-38.9
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• 2018

The restoration of endodontically treated teeth (ETT) with more than one cusp missing and thin remaining walls is challenging for the general practitioner. The use of posts combined with full coverage restorations is a well-established approach, yet not following the minimal invasive principles of adhesive dentistry. Endocrowns are indirect monoblock restorations that use the pulp chamber of the ETT for retention. In this study the fabrication of 4 endocrowns and their clinical performance will be discussed. Two clinical cases include computer-aided design/computer-aided manufacturing manufactured molar endocrowns (one feldspathic ceramic and one hybrid composite-ceramic restoration) and the other two are dental laboratory manufactured resin composite premolar endocrown restorations. The modified United States Public Health Service criteria were used to assess the clinical behavior of the restorations at different follow up periods. Endocrown restorations present a satisfactory clinical alternative, either by the use of resin composite or glass ceramic and hybrid materials. Specific guidelines with minimal alterations should be followed for an endocrown restoration to be successful. Due to limited evidence regarding the long term evaluation of this restorative technique, a careful selection of cases should be applied.

• Structural Engineering and Mechanics
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• 제90권4호
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• pp.345-356
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• 2024

This paper aims to investigate the seismic behavior of double steel plate and concrete composite shear wall (DSCW) of shield buildings in nuclear power engineering through experimental study. Hence, a total of 10 specimens were tested to investigate the hysteretic performance of DSCW specimens in detail, in terms of load vs. displacement hysteretic curves, skeleton curves, failure modes, flexural strength, energy dissipation capacity. The experimental results indicated that the thickness of steel plate, vertical load and stiffener have great influence on the shear bearing capacity of shear wall, and the stud space has limited influence on the shear capacity. And finally, a novel simplified formula was proposed to predict the shear bearing capacity of composite shear wall. The predicted results showed satisfactory agreement with the experimental results.