• Journal of the Computational Structural Engineering Institute of Korea
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• v.26 no.6
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• pp.463-470
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• 2013

In this paper, 2D simple analyses were performed in order to predict the large torsional oscillations in a suspension bridge based on Makenna and Tuama model(2001). The existing model(Makenna and Tuama, 2001) has shown unrealistic results as the wind speed increases and frequency decreases. Furthermore, resonance could not be simulated by the existing model. Therefore, in this study, new model was proposed with a consideration of the torsional resistance. The vertical and rotational behaviors of the deck in the suspension bridge were analyzed. Analysis results showed that at first vertical oscillations were observed and it was gradually transformed to the rotation oscillations. With the consideration of the torsional resistance, it was shown that vertical behavior were stabilized as time passed. However, the rotational behavior was not stabilized and was kept until the end of analysis. Beat periods decreased while the wind speed increased. The resonance of the rotational mode was dependent to the rotational resistance. Obtained results could be applied for the design of the suspension bridge under the wind load.

• Journal of the Earthquake Engineering Society of Korea
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• v.1 no.3
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• pp.37-44
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• 1997

In this paper, the inelastic behavior of an asymmetric tall building is investigated. The asymmetry in rigidity caused by the structural asymmetry induces torsional as well as lateral deformation. The inelastic analysis of such an asymmetric structure is difficult to carry out with a planar model and thus requires a full three dimensional model. In this paper a 102 story unsymmetric tall building is analized by static push-over procedure and its behavior is investigated. The analysis are performed with and without floor rotation to compare the results. According to the results the static behavior of the model building, as expected, turned out to be dependent heavily an the asymmetry of the plan shapes of the building.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.12
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• pp.1146-1151
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• 2008

In this paper, the effects of torsional flexibility on a flapping airfoil are investigated. The aerodynamic forces of a torsional flexible flapping airfoil is computed using 2-D unsteady vortex panel method. A typical-section aeroelastic model is used for the aeroelsatic calculation of the flapping airfoil. Torsional flexibility and excitation frequency are considered as main effective parameters. Under heavy airfoil condition , the thrust peak is observed at the points where the frequency ratio is about 0.75. Based on this peak criterion, there exists two different motions. One is an inertia driven deformation motion and the other is an oscillation driven deformation motion. Also, in the thrust peak condition, the phase angle is kept 85 degrees, independent of the torsional flexibility and the excitation frequency.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.746-747
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• 2015

전동기와 부하시스템은 직결, 혹은 커플링을 통하여 연결이 된다. 이때의 동력을 전달하는 커플링, 기어, 벨트 등의 특성에 따라 전달되는 토크의 특성이 달라진다. 본 논문에서는 동력 축과 부하 축을 기구적으로 분리가 가능한 영구자석 커플링을 적용한 구동 전동기-부하시스템에 축계 시스템 해석을 위하여 유한요소 해석을 통하여 비틀림 각도 변화에 따른 전달 토크를 얻고, 이를 활용하여 기구 해석 모델에 적용해 보고, 전동기-부하 시스템의 토크 변동 가능성에 대해 알아본다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.1A
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• pp.99-106
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• 2006

Due to single symmetry of cross section, T-shaped members are likely to buckle in a flexural-torsional mode when they are subjected to axial compression. Therefore, the flexural-torsional buckling can be regarded as a governing mode of global buckling. An experimental program has been carried out to investigate the flexural-torsional buckling behavior of pultruded T-shaped members. Two types of pultruded members were tested in the experiment, and they were made of either E-glass/vinylester or E-glass/polyester. Lay-up and thickness of reinforcing layers, volume fractions of each constituents in layers, mechanical properties were experimentally determined. Two sets of knife edge fixure were used to simulate simple support condition for flexure and twisting, and the lateral displacements and the angle of twist were measured using three potentiometers. Every specimen buckled in a flexural-torsional mode, and most of the specimens showed post-buckling strength.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.26 no.1
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• pp.89-97
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• 2013

With regard to complex-shaped tall buildings whose plans and constructions have been gradually on the increase, this study was aimed to analyze their structural behaviors during construction by applications of construction sequences analyses to prototype models. For twisted tall buildings, total 18 models of with three conditions of a lateral load-resisting system, a twisting angle, and a construction method were selected. A diagrid system and a braced tube system were applied as a lateral load-resisting system. For each lateral load-resisting system, three types of plan with $0^{\circ}$, $1^{\circ}$, and $2^{\circ}$ twisting angles and three construction methods with construction sequences of exterior tube and interior frame were assumed. The structural performances of tall buildings under constructions were analyzed with results of lateral displacements from construction sequence analyses. Also, construction performances of the construction period and the maximum lift weight were compared.

• Korean Journal of Optics and Photonics
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• v.14 no.1
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• pp.85-91
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• 2003

Intracavity frequency doubling of a single-mode Nd:YAG laser by using a nonplanar ring cavity is demonstrated. The nonplanar ring cavity consists of a Brewster-angled Nd:YAG crystal placed in a magnetic field, a KTP crystal, and two spherical mirrors. In this design the Nd:YAG block acts as both a nonreciprocal polarization rotator and a partial polarizer, and the nonplanar portion of the ring cavity, which is formed by a relative twist angle between the Brewster-angled end surfaces of the Nd:YAG block, serves as a reciprocal polarization rotator. An eigenpolarization theory for the cavity configuration is presented and suitable values of the relative twist angle for unidirectional operation are estimated. A single-mode output power of 22 ㎽ at 532 nm and an optical to optical conversion efficiency of 1.8% are obtained with a 1.2 W diode laser at 809 nm.

• Proceedings of the KIEE Conference
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• 2008.10a
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• pp.151-152
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• 2008

본 논문에서는 전극간의 비틀림 각도가 아크거동에 미치는 영향을 알아보기 위해 고속카메라를 이용한 아크촬영과 아크전압측정을 동반한 전류차단시험을 실시하였다. 측정결과를 이용한 아크거동 분석결과를 각 모델에 대한 유한요소해석을 통한 로렌츠 힘 계산결과와 결부시켜 비틀림 각도가 아크거동에 미치는 영향을 분석하였다.

• Journal of Power System Engineering
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• v.13 no.1
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• pp.33-38
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• 2009

In this study, the nose of cam in the automobile engine was modelled into circular disk to analyze the torsional vibration of the cam shaft. The distance between disks was fixed, but the diameter of disks was changed. The torsional vibration of the cam shaft was studied experimentally by the motion of the modelled disk with changing the disk diameter. And the sizes of the modelled disk were selected not to show the natural frequencies over all the experimental ranges. The torsional vibration meter used in this study has a laser system with non-contact measurement method, which can measure both torsional angular vibration velocity and torsional angular vibration displacement simultaneously. The Experimental analysis shows that the characteristics of the torsional vibration in the horizontal rotating shaft can be considerably affected by the arrangement of the modelled disks.

• Proceeding of EDISON Challenge
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• 2015.03a
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• pp.184-190
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• 2015

On wide variety of fields, studies on active twist control are becoming more active. For effective twist control, blades have to have low torsional stresses with high torsional deformations to the same magnitude of torque acting on its cross-section. In this study, 2D sectional analysis and 3D finite element analysis were made for 5 different blades with each having different cross - sections which have different spars. The results from 2D sectional analysis, were then put into 3D blade deformation and stress calculations which lead to analysis. Outcomes from 2D and 3D analysis, showed that on the same torque and concentrated load conditions, the blade with 'C' shaped spar was the best of all the blades which were used in this study.