• Structural Engineering and Mechanics
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• 제21권5호
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• pp.591-620
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• 2005

A general analytical model for thin-walled composite beams with an arbitrary open/(or/and) closed cross section and arbitrary laminate stacking sequence i.e., symmetric, anti-symmetric as well as un-symmetric with respect to the mid plane of the laminate, is developed in the first paper. All the mechanical properties, mechanical centre of gravity and mechanical shear centre of the cross section are defined in the function of the geometry and the material properties of the section. A program "fungen" and "clprop" are developed in Fortran to compute all the mechanical properties and tested for various isotropic sections first and compared with the available results. The locations of mechanical centre of gravity and mechanical shear centre are given with respect to the fibre angle variation in composite beams. Variations of bending and torsional stiffness are shown to vary with respect to the fibre angle orientations.

• 대한기계학회논문집A
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• 제24권5호
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• pp.1246-1253
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• 2000

Wire ropes are widely used in cable car, suspension bridge and elevator, etc. and there has been a growing need for ropes of large diameter. The theoretical procedures to obtain the stiffness coefficients of wire ropes, using previously reported theory, are programmed and the verification of the program is made. The effects of lay angle on the stiffness of strand are researched and comparisons on stiffness of rope are made according to the lay type. Axial stiffness optimization problems with coupling and torsional stiffness constraints are formulated and the effects of constraints on other stiffness coefficients on axial stiffness optimization are investigated.

• 한국소음진동공학회논문집
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• 제22권7호
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• pp.659-666
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• 2012

A nonlinear dynamic model for the shaft-disk-blade unit is developed in this study. In this regard, the rotating flexible blade, with a pre-twist angle, attached to a rigid disk driven by a shaft which is flexible in torsion is developed. The rotor-blade coupled model is derived using Lagrange equation in conjunction with the assumed mode method to discretize the blade deformation. The equations of motion are analyzed based on the small deformation theory for the blade and shaft torsional deformation to obtain the system natural frequencies for various system parameters.

• 한국공작기계학회논문집
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• 제10권6호
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• pp.8-14
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• 2001

We develop a method to analyze dynamic behavior off multi-stage gear train system. The example system consists of three shafts supported by ball bearings at the ends of them and two pairs of spur gear set. For exact analysis, the meshing tooth pair of gear set is modeled as spring and damper having time-dependent meshing stiffness and damping. The bearing is modeled as spring. The result of this analysis is compared to that of other model having mean mesh stiffness. The effect of the excitation force by the unbalance off rotor off motor is also analyzed. Finally, the change ova natural frequency of the whole system due to the change of an angle between three shafts is compared in each case, and from this analysis, the avoiding angle for design is advised.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1999년도 춘계학술대회 논문집
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• pp.99-104
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• 1999

In this paper, dynamic behavior of a two stage gear train system is analyzed. This system consists of three shafts supported by ball bearing at the ends of them and two pairs of spur gear sets. For exact analysis, the meshing tooth pair of gears is modeled as spring having time-dependent meshing stiffness and damping. The result of this analysis is compared to that of analysis using other model of spring having mean mesh stiffness. The effect of the excitation force by the imbalance of a rotor of a motor on the vibration of a gear train system is also analyzed. Finally, the change of a natural frequency of the whole system due to the change of an angle between three shafts is compared in each case, and from this analysis, the avoiding angle for design is advised.

• 전기학회논문지
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• 제57권4호
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• pp.617-624
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• 2008

This paper proposes design and implementation of wind turbine simulators which incorporate the turbine dynamic characteristics. At first, the turbine output characteristic in steady state is modelled as a function of wind speed and then dynamic characteristics are modelled such as pitch angle control, torsional vibration, tower shadow effect, wind shear effect, and inertia effect. In addition, a wind speed simulator is developed which can generate the real wind speed pattern. The wind turbine simulator is implemented with 3[kW] M-G set(cage-type induction motor coupled with doubly-fed induction generator) at laboratory.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2001년도 춘계학술대회 논문집
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• pp.140-145
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• 2001

The purpose of this study is the design of composite shaft which is wound by Filament Winding method. Classical laminated plate theory was used for analyzing the stress, and for structure design. The diameter and thickness of composite shaft were calculated by this theory. The result that if tensile stress was zero, torsion stress was a certain value below 0.4(diameter rate) and torsion strength was the highest value on 45$^{\circ}$(winding angle). In case of 90$^{\circ}$(winding angle), we have to consider the torsional moment when the composites shaft was load.

• Computers and Concrete
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• 제11권5호
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• pp.399-410
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• 2013

A nonlinear finite element analysis of R/C hybrid deep T-beam with web opening subjected to pure torsion is presented. Hexahedral 8-nodes and space truss element were used for modeling concrete and reinforcement. The reinforcement was assumed perfectly bonded to the corresponding nodes of the concrete element. The constitutive relations for concrete and reinforcement are based on the modified field theory and elastic perfectly plastic. The smear crack approach was adopted for modeling the crack. The torque-twist angle relationship curve based on the finite element analysis was compared to the experimental results. The comparison shows that the curve of torque-twist angle predicted by the nonlinear finite element analysis is linear before cracking and close to the experimental result. After cracking, the curve becomes nonlinear and stiffer compared to the experimental result.

• 대한건축학회논문집:구조계
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• 제35권8호
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• pp.149-156
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• 2019

In this study, dynamic responses of high - rise buildings were analyzed through the change of horizontal stiffness and yield strength among characteristics of seismic isolation system by applying middle - layer seismic isolation system to high - rise buildings of 120m height. As a result in order to prevent the displacement of the isolation layer and to control the maximum torsion angle, it is possible to appropriately control by increasing or decreasing the horizontal stiffness and the yield strength. However, depending on the maximum torsional angle and the hysteretic behavior of the seismic isolation system, excessive yield strength and horizontal stiffness increase may induce the elastic behavior of the structure and amplify the response. Therefore, it is considered that it is necessary to select the property value of the appropriate isolation device.

• 한국기계가공학회지
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• 제20권6호
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• pp.51-58
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• 2021

The notion of leisure has changed with industrial development and improvement in life quality. Bicycling is a healthy sport; it is an exercise performed while enjoying nature. There have been many changes in the materials that are used to manufacture the bicycle frame. Iron and aluminum have been mainly used in bicycle frames. However, carbon-based materials are lighter and stronger than metal frames. The bicycles made of carbon composite changes frame rigidity depending on the direction of the carbon sheet sacking angle. We study the direction of composite material and how they affect the stiffness of frames based on the stacking angle.