• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.5
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• pp.489-495
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• 2016

This study focuses on a detailed ball-bearing model for spur gears. The nonlinear ball-bearing stiffness with radial clearance is derived and calculated. The bearing stiffness is used to the 3-degree-of-freedom (DOF) spur gear system model. The mode characteristics of the gear system model are analyzed and verified by performing finite-element analysis (FEA). From the results, the bearing stiffness on the radial clearance was more sensitive under low-load conditions compared to high-load conditions. The bearing stiffness significantly affected the gear dynamics in the low-frequency region, while the mesh stiffness affected the high natural frequency.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.8 no.2
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• pp.32-39
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• 2009

This paper describes mathematical models of the torsional geared driving system for the indexing path and the mill driving path in a mill turret. The eigenvalue analysis for the models is conducted both with and without the gear contact stiffnesses. The natural frequency leads to the effect of gear contact stiffnesses on the vibration of torsional geared systems in a mill turret. It is necessary to analyze eigenvalues of the complex geared torsional system in order to prevent the unexpected vibrations.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.1D
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• pp.49-54
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• 2009

The excellent load transfer at transverse joints ensures the high performance of jointed plane concrete pavements(JPCP). Load transfer efficiency(LTE) is affected by dowel-bars, aggregate interlock and types of underlying layers, and these factors have to be modelled adequately for a reasonable analysis of JPCP. Generally, the joint stiffness has been represented by a spring model for the shear transfer by aggregate interlock or dowels. However dowel-bars, aggregate interlock and types of underlying layers have not been considered together in the design of joints. In this study, the joint stiffness that considered those factors was presented by comparing LTE obtained using FWD(Falling Weight Deflectometer) with theoretical results obtained using the finite element analysis. In addition, the effects of temperature and concrete age, on the joint stiffness were investigated.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.5
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• pp.1534-1542
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• 1996

Gear vibration is caused by the mesh stiffness, gear accuracy, and assembling errors. For these reasons, helical gear has the azial, radial, and rotational vibrations. In this study, the mesh stiffness is calculated by considering the tooth bending, contact, and foundation deformations. Rotational vibration of helical gear with tooth error is modeled by the nonlidear equation of motion with single degree of freedom and is anlyzed numerically. Also, by a specially designed experimental set-up, the analysis are cross-checked and the vibration characteristics of helical gear are discussed.

• Journal of Power System Engineering
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• v.4 no.1
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• pp.60-67
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• 2000

As the speed of rotating machines increases and also their weight decreases, the coupling between lateral and torsional vibrations must be considered. In the past, rotordynamics and geardynamics have tended to treat the lateral and torsional vibrations of the system elements as separate and decoupled mechanisms. In the paper, the coupled lateral-torsional free and forced vibration of rotors trained by gears is analyzed using finite element method. Also the complicated variation of the meshing stiffness as a function of contact point along the line of action is estimated correctly. The gear mesh model is assumed to be linear with constant average mesh stiffness.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.04a
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• pp.408-414
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• 2014

After drilling operations at the offshore plant to production to crude oil to high pressure. After that time the low pressured of pipe inside when the secondary produce so oil recovery is reduced. At that time injection sea water at the pipe inside through water injection pump that the device Increase recovery so to be research and development at many industry. So developing 3-stage water injection pump at the domestic company. A variety of mathematical analysis during the detailed design analysis was not made through the dynamics characteristic. In this paper, a 2D finite element analysis is performed through the dynamics of the present study was the validation of the model.

• International Journal of Highway Engineering
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• v.10 no.1
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• pp.105-115
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• 2008

It is known that the long-term behavior and performance of jointed concrete pavement due to slab curling are affected by the environmental factors such as temperature, moisture, and so on. However, any relationships between the curling and its factors have not been defined clearly yet because of insufficient detailed investigation. The temperature, relative humidity, strain, vertical displacement of a concrete slab, and horizontal movement of its transverse joints were investigated by various sensors and devices instrumented in the slab of a concrete pavement section constructed for this study. The constraint of the curling by joint stiffness was investigated in addition to effect of the temperature and moisture on the early aged concrete slab by analyzing the field data measured for approximately 4days from concrete placement. The curling of the concrete slab showed 24hour cycles mainly because of the temperature effect, and the upward curling gradually increased because of the long-term effect of drying shrinkage of the concrete. The magnitude and variation of the curling were significantly affected by the joint stiffness which is comprised of aggregate interlocking and other factors. The effect of the variation of the seasonal joint stiffness varying with the temperature and long-term drying shrinkage on the slab curling will be investigated as a further study.

• Journal of the Earthquake Engineering Society of Korea
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• v.5 no.4
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• pp.39-49
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• 2001

In this paper, inelastic analysis procedures are presented for the seismic performance evaluation of RC bridge piers with premature termination of main reinforcement. The mechanical characteristic of cracked concrete and reinforcing bar in concrete has been modeled, considering the bond effect between reinforcing bars and concrete, the effect of aggregate interlocking at crack surface and the stiffness degradation after the crack. The smeared crack approach is incorporated. In boundary plane at which each member with different thickness is connected, local discontinuous deformation due to the abrupt change in their stiffness can be taken into account by introducing interface element. The increase of concrete strength due to the lateral confining reinforcement has been also taken into account to model the confined concrete. The proposed numerical method for seismic performance evaluation of RC bridge piers with premature termination of main reinforcement will be verified by comparison with reliable experimental results.

• Magazine of the Korea Concrete Institute
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• v.2 no.4
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• pp.91-98
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• 1990

Joints are provided in cement concrete pavements to control transverse and longitudinal cracking that occur due to restrained deformations caused by moisture and temperature variations in the slab. But the constuction of joints reduces the load-carrying capacity of the pavement at the joints, and pavements have been deteriorated by cracks at the slab edges along the joints due to traffic loads. Therefore, it is important to analyze the behavior of joints accurately in the design of cement concrete pavements. In this study, the mechanical behavior of cement concrete pavement slabs is analyzed by the plate-finite element model, and Winkler foundation model is adopted to analyze the subgrades. The load transfer mechan¬ism of joints are composed of dowel action, aggregate interlocking, and tied-key action, and the analytical pro¬gram is developed using these joint models. Using this numerical model as an analysis tool, the effects of joint parameters on the behavior of pavements are investigated.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.24 no.6
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• pp.462-469
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• 2014

After drilling operations at the offshore plant, crude oil is producted under high pressure. After that time, oil recovery is reduced, because the pressure of the pipe inside is low during the secondary produce. At that time injection sea water at the pipe inside through water injection pump that the device increase to recovery. A variety of mathematical analysis during the detailed design analysis was not made through the dynamics characteristic at the domestic company. 2D model has reliability of analysis results for the uncomplicated model. Also element and the node the number of significantly less than in the 3D model. So, the temporal part is very effective. In addition, depending on the quality of mesh 3D is a real model and FEM model occurs error. So, user needs a lot of skill. In this paper, a 2D finite element analysis was performed through the dynamics analysis and the study model was validated.