• 한국공간구조학회논문집
• /
• 제15권3호
• /
• pp.103-110
• /
• 2015

Various hybrid dampers have been developed as increasing tall buildings in Korea. To minimize the installment space and cost, the new hybrid friction damper was developed using friction components. It is composed of two one-nodal rotary frictional components and a slotted bolted frictional connection. Because of these components, hybrid friction damper can be activated by building movements due to lateral forces such as a wind and earthquake. In this paper, displacement amplitude dependency tests were carried out to evaluate on the structural performance and the multi-slip mechanism of the hybrid damper. Test results show that the multi-slip mechanism is verified and friction coefficients are increasing as displacement amplitudes are increasing.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2010년도 하계학술대회 논문집
• /
• pp.93-93
• /
• 2010

We developed friction welded bimetallic sleeve for 220kV aluminum conductor XLPE cable. Not only friction welded bimetallic sleeve for Termination(EB-A, EB-G) but also friction welded sleeve for Joint of Al to Cu conductor was developed regardless of this project. Generally, friction welded sleeve used to connect Al conductor cable to Cu conductor cable and used for improvement of mechanical property of terminal by offer the copper side of friction welded bimetallic sleeve at the Termination. Connection method for Al-Cu conductor has mainly used friction welding at the solid state, because it is difficult to connect by using conventional welding method. this investigation introduces development of friction welded bimetallic sleeve by friction welding and test result of 220kV Al conductor XLPE cable and accessories using friction welded sleeve.

• Steel and Composite Structures
• /
• 제28권6호
• /
• pp.767-778
• /
• 2018

The purpose of this study is to investigate how a fully restrained bolted beam splice affects the connection behavior as a column-tree connection in steel special moment frames under cyclic loading when located within the plastic hinge zone. The impacts of this attachment in protected zone are observed by using nonlinear finite element analyses. This type of splice connection is designed as slip-critical connection and thereby, the possible effects of slippage of the bolts due to a possible loss of pretension in the bolts are also investigated. The 3D models with solid elements that have been developed includes three types of connections which are the connection having fully restrained beam splice located in the plastic hinge location, the connection having fully restrained beam splice located out of the plastic hinge and the connection without beam splice. All connection models satisfied the requirement for the special moment frame connections providing sufficient flexural resistance, determined at column face stated in AISC 341-16. In the connection model having fully restrained beam splice located in the plastic hinge, due to the pretension loss in the bolts, the friction force on the contact surfaces is exceeded, resulting in a relative slip. The reduction in the energy dissipation capacity of the connection is observed to be insignificant. The possibility of the crack occurrence around the bolt holes closest to the column face is found to be higher for the splice connection within the protected zone.

• International Journal of Naval Architecture and Ocean Engineering
• /
• 제7권1호
• /
• pp.195-211
• /
• 2015

Flat plate friction lines have been used in the process to estimate speed performance of full-scale ships in model tests. The results of the previous studies showed considerable differences in determining form factors depending on changes in plate friction lines and Reynolds numbers. These differences had a great influence on estimation of speed performance of full-scale ships. This study was conducted in two parts. In the first part, the scale effect of the form factor depending on change in the Reynolds number was studied based on CFD, in connection with three kinds of friction resistance curves: the ITTC-1957, the curve proposed by Grigson (1993; 1996), and the curve developed by Katsui et al. (2005). In the second part, change in the form factor by three kinds of friction resistance curves was investtigated based on model tests, and then the brake power and the revolution that were finally determined by expansion processes of full-scale ships. When three kinds of friction resistance curves were applied to each kind of ships, these were investigated: differences between resistance and self-propulsion components induced in the expansion processes of full-scale ships, correlation of effects between these components, and tendency of each kind of ships. Finally, what friction resistance curve was well consistent with results of test operation was examined per each kind of ships.

• The Journal of Advanced Prosthodontics
• /
• 제11권3호
• /
• pp.147-154
• /
• 2019

PURPOSE. This study aimed to evaluate the effect of two different implant-abutment connection structures with identical implant design on peri-implant bone level. MATERIALS AND METHODS. This clinical study was a patient-blind randomized controlled trial following the CONSORT 2010 checklists. This trial was conducted in 24 patients recruited between March 2013 and July 2015. Implants with internal friction connection were compared to those with external hex connection. One implant for each patient was installed, replacing the second molar. Implant-supported crowns were delivered at four months after implant insertion. Standardized periapical radiographs were taken at prosthesis delivery (baseline), and one year after delivery. On the radiographs, distance from implant shoulder to first bone-to-implant contact (DIB) and peri-implant area were measured, which were the primary and secondary outcome, respectively. RESULTS. Eleven external and eleven internal implants were analyzed. Mean changes of DIB from baseline to 1-year postloading were 0.59 (0.95) mm for the external and 0.01 (0.68) mm for the internal connection. Although no significant differences were found between the two groups, medium effect size was found in DIB between the connections (Cohen's d = 0.67). CONCLUSION. Considering the effect size in DIB, this study suggested the possibility of the internal friction connection structure for more effective preservation of marginal bone.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2000년도 가을 학술발표회논문집(I)
• /
• pp.769-774
• /
• 2000

The first thing in developing precast post-tensioned concrete frame system verify the shear resistance capacity of the beam-column connection at which the transfer of member forces become discontinuous. Complying with the necessity of such experimental research, shear tests have been performed for six test specimens which were cast and cured at Dong-Ah Concrete Manufacturing Company and post-tensioning at Concrete Laboratory of Inha University. Shear key and magnitude of post-tensioned force are taken test variables. From the test results, it has been observed that the shear resistance of the specimens attained to higher values than those of theoritical calculations based on the shear friction with shear friction coefficient being 0.6.

• 콘크리트학회논문집
• /
• 제29권1호
• /
• pp.93-100
• /
• 2017

이 연구에서는 시공성이 단순한 연성형 절점을 갖는 HSRC 하이브리드 보 시스템의 콘크리트 보 영역에서의 일축 전단 및 연결절점 영역에서의 전단마찰 거동을 평가하였다. 일축 전단의 실험은 내민보 시스템으로써 파괴경간의 전단경간비는 1.6이다. 연결절점 영역에서의 전단마찰 거동을 평가하기 위한 실험은 상부 2점 집중하중으로써 순 전단경간비는 0.1이다. 실험 결과, 연결절점에서 배근된 장부철근이 HSRC 보의 균열 진전에 미치는 영향은 미미하였지만, 부재의 전단내력은 약 25% 향상시켰다. HSRC 보의 일축 전단 및 전단마찰 내력은 장부철근의 유무와 상관없이 ACI 318-14 및 EC2 설계식을 이용하여 안전 측에서 평가될 수 있었다.

• 한국강구조학회 논문집
• /
• 제12권2호통권45호
• /
• pp.177-185
• /
• 2000

본 논문에서는 대기 중에 폭로한 내후성강재의 고장력볼트 마찰이음부 미끄럼계수 평가를 위한 실험연구를 수행하였다. 표면 상태는 흑피 부착된 시험체와 숏브라스트로 흑피를 제거한 시험체를 각각 3개월 및 6개월 폭로한 후 수동솔질, 전동솔질 및 청소하지 않은 표면 등을 고려하였다. 또한, 6개월 폭로 시험편의 각 표면 상태에 대하여 600 시간 동안 볼트축력 감소율을 측정하였다. 실험으로부터 모든 시험체에서 폭로 기간에 따라 미끄럼 계수는 증가하였으며 흑피부착 표면을 전동솔질로 청소한 경우를 제외하곤 모두 0.6 이상의 값을 보였다. 볼트 축력 감소율 역시 초기 비폭로 시험체에 비해 폭로한 시험 체에서 증가하였으며 최대 감소율은 약 10%에 이르렀다.

• 콘크리트학회논문집
• /
• 제16권4호
• /
• pp.573-579
• /
• 2004

For the fast construction and replacement of bridges in urban area, a prefabricated bridge system can be an excellent alternative. Details of prefabricated slabs for PSC girders were developed and static tests on shear connections were conducted to propose design equations of the shear connection. Stirrups and stud connectors were used as shear connectors and non-shrink mortar was used for the filling material in shear pockets for shear connectors. Stirrups and studs were fabricated to insert embedded nut-type devices in PSC girders. Shear strength of the shear connection considering chemical bond, friction and mechanical connectors was evaluated and empirical equations were suggested. Due to the mechanical connectors, ultimate slip capacity of the shear connection was sufficient for shear load redistribution, and suggested details of the shear connection showed good performance in terms of strength and ductility.

• 한국전산구조공학회논문집
• /
• 제20권2호
• /
• pp.207-216
• /
• 2007

본 논문에서는 볼트로 체결된 강재 조립 합성보의 휨거동에 대한 유한요소해석을 통하여 휨거동 특성을 분석하였다. 두개의 강재보가 볼트로 체결되어 횡하중을 받을 때 발생하는 볼트의 합성효과, 강판사이의 마찰특성을 고려하였다. 체결에 사용된 볼트의 갯수 및 마찰계수의 변화에 따른 변위, 휨응력 그리고 전단응력을 쉘 요소를 사용한 유한요소해석에 의해 계산하였다. 이런 결과들은 완전 비합성보, 부분 합성보와 완전 합성보의 해석치와 비교되었다. 해석결과 합성보의 거동은 강재의 마찰보다 볼트의 갯수로 표현되는 합성률에 크게 영향을 받았다. 합성률이 $50{\sim}60%$에 도달할 때 합성보의 거동은 완전 합성보와 유사함을 보였다.