• Tribology and Lubricants
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• v.36 no.1
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• pp.27-33
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• 2020

Self-equalizing tilting pad thrust bearings are usually employed in turbomachines to achieve high stability and reliability. A tilting pad bearing can incorporate self-equalizing links to handle the misalignment between the bearing and the thrust collar. In this popular design method, the pads sit on the upper-level plates and the lower-level plates stay on the retainer base. With misalignment, the pads that are heavily loaded are pushed down. Consequently, the link pushes up the pads on the opposite side, keeping the bearing surface parallel to the thrust collar surface. The self-equalizing link is used to handle the misalignment from the thermal and mechanical effects. In this study, the experimental investigation deals with the performance of self-equalizing tilting pad thrust bearings. The test rig for evaluating the performance of bearing is developed which can control the misalignment angle. Simultaneous measurements are taken for the force acting on each pad. Pad metal temperature and oil film thickness are functions of the shaft speed, bearing load, misalignment angle, and design of leveling plates. The effect of misalignment on bearing performance is discussed. The results demonstrate that the load on each pad depends on the test conditions(especially misalignment angle), and the load influences the performance of bearings.

• Nuclear Engineering and Technology
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• v.56 no.1
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• pp.78-91
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• 2024

Double steel plate concrete composite shear wall (SCSW) has been widely utilized in nuclear power plants and high-rise structures, and its shear connectors have a substantial impact on the seismic performance of SCSW. Therefore, in this study, the mechanical properties of SCSW with angle stiffening ribs as shear connections were parametrically examined for the reactor containment structure of nuclear power plants. The axial compression ratio of the SCSW, the spacing of the angle stiffening rib arrangement and the thickness of the angle stiffening rib steel plate were selected as the study parameters. Four finite element models were constructed by using the finite element program named ABAQUS to verify the experimental results of our team, and 13 finite element models were established to investigate the selected three parameters. Thus, the shear capacity, deformation capacity, ductility and energy dissipation capacity of SCSW were determined. The research results show that: compared with studs, using stiffened ribs as shear connectors can significantly enhance the mechanical properties of SCSW; When the axial compression ratio is 0.3-0.4, the seismic performance of SCSW can be maximized; with the lowering of stiffener gap, the shear bearing capacity is greatly enhanced, and when the gap is lowered to a specific distance, the shear bearing capacity has no major affect; in addition, increasing the thickness of stiffeners can significantly increase the shear capacity, ductility and energy dissipation capacity of SCSW. With the rise in the thickness of angle stiffening ribs, the improvement rate of each mechanical property index slows down. Finally, the shear bearing capacity calculation formula of SCSW with angle stiffening ribs as shear connectors is derived. The average error between the theoretical calculation formula and the finite element calculation results is 8% demonstrating that the theoretical formula is reliable. This study can provide reference for the design of SCSW.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.11a
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• pp.185-188
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• 2005

Bond between reinforcing bar and surrounding concrete is supposed to transfer load safely in the process of design of reinforced concrete structures. Bond strength of ribbed reinforcing bars tends to split concrete cover, by wedging action, or shear the concrete in front of the ribs. In this study, using a reducing bearing angle theory, bond strengths of beam end specimen are predicted. Values of bond strength obtained using the analytical model are in good agreement with the bond test results. The analytical model provides insight into bond mechanism and the effects of bearing angle on the bond strength of deformed bars to concrete.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.2 no.4
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• pp.5-10
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• 2003

This paper presents the formed tool to machine a milli-structure mold. The formed tool is used to machine the geometrical shape of bearing rubber seal for precision machining. The bearing rubber seal has milli-sized complex geometry. Because it is difficult to machine the unique shape exactly by the conventional tool, the formed tool is used in machining die of the bearing seal. In this paper, it is performed to investigate properties of the formed tool; tool wear, cutting force and machined surface roughness. Tool wear increases rapidly with clearance angle Increase. Thus, the dimension accuracy is affected by the clearance angle.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.4
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• pp.725-733
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• 2001

Flying attitudes of the slider, which are flying height, pitch and roll, are affected by the air flow velocity, the skew angle, and the manufacturing tolerances. Traditional designs of the air bearing surface have considered only the flying performances for the variations in the air flow velocity and the skew angle, which are determined by the radial position. In this study, we present the new shape design of the air bearing surface by considering the track seek performance and the air bearing stiffness as well as the traditional design requirements. The optimization technique is used to improve the dynamic characteristics and operating performance of the newly proposed air bearing surface shape design further. The optimized configuration is obtained automatically and the optimally designed sliders show the enhanced flying and dynamic characteristics.

• Steel and Composite Structures
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• v.51 no.4
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• pp.417-440
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• 2024

Artificial neural networks (ANN) have been the focus of several studies when it comes to evaluating the pile's bearing capacity. Nonetheless, the principal drawbacks of employing this method are the sluggish rate of convergence and the constraints of ANN in locating global minima. The current work aimed to build four ANN-based prediction models enhanced with methods from the black hole algorithm (BHA), league championship algorithm (LCA), shuffled complex evolution (SCE), and symbiotic organisms search (SOS) to estimate the carrying capacity of piles in cold climates. To provide the crucial dataset required to build the model, fifty-eight concrete pile experiments were conducted. The pile geometrical properties, internal friction angle 𝛗 shaft, internal friction angle 𝛗 tip, pile length, pile area, and vertical effective stress were established as the network inputs, and the BHA, LCA, SCE, and SOS-based ANN models were set up to provide the pile bearing capacity as the output. Following a sensitivity analysis to determine the optimal BHA, LCA, SCE, and SOS parameters and a train and test procedure to determine the optimal network architecture or the number of hidden nodes, the best prediction approach was selected. The outcomes show a good agreement between the measured bearing capabilities and the pile bearing capacities forecasted by SCE-MLP. The testing dataset's respective mean square error and coefficient of determination, which are 0.91846 and 391.1539, indicate that using the SCE-MLP approach as a practical, efficient, and highly reliable technique to forecast the pile's bearing capacity is advantageous.

• Journal of Korean Foot and Ankle Society
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• v.15 no.3
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• pp.159-164
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• 2011

Purpose: This study was performed to analyze the results of radiologic parameters between weight bearing affected single ankle anteroposterior (AP) view and both ankle AP view in ankle osteoarthritis (OA). Materials and Methods: Between January 2009 and August 2010, 41 patients (50 ankles) who visited our institution to treat ankle OA were reviewed retrospectively. In radiographic assessment, weight bearing affected single ankle AP view and both ankle AP view were checked, and measured tibial anterior surface angle (TAS), tibial medial malleolar angle (TMM), talar tilting angle (TT), maximum and minimun joint space width (JSW) of ankle, width between articular surface of medial malleolar and medial articular surface of talus as radiologic parameters. Results: On weight bearing both ankle AP view, TAS was $85.4{\pm}4.1^{\circ}$, TMM was $33.1{\pm}9^{\circ}$, TT was $5.4{\pm}6.1^{\circ}$, maximum JSW was $3.2{\pm}2.7$ mm, minimum JSW was $1.1{\pm}1.3$ mm, width between articular surface of medial malleolar and medial articular surface of talus was $1.8{\pm}1.8$ mm and on weight bearing affected ankle AP view, TAS was $85.3{\pm}3.9^{\circ}$, TMM was $34.3{\pm}10.9^{\circ}$, TT was $5.4{\pm}6.5^{\circ}$, maximum JSW was $3.2{\pm}2.7$ mm, minimum JSW was $1.1{\pm}1.3$ mm, width between articular surface of medial malleolar and medial articular surface of talus was $1.6{\pm}1.7$ mm. Conclusion: There is no statistical significance in radiologic parameters between weight-bearing affected single ankle AP view and both ankle AP view in ankle OA.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.14 no.5
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• pp.88-95
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• 2015

The thickness of adsorbed molecular layers is the most critical factor in studying thin-film lubrication, and it is the most essential parameter that distinguishes thin-film from thick-film lubrication analysis. The thin film between the shaft and bearing surface within a very narrow gap was considered. The general Reynolds equation has been derived for calculating thin-film lubrication parameters affecting the performance of the circular journal bearing. Investigation of the load-carrying capacity and pressure distribution for the journal bearing considering the adsorbed layer thickness has been carried out. A Reynolds equation appropriate for the journal bearing is used in this paper for the analysis, and it is discussed using the finite difference method of the central difference scheme. The parameters, such as eccentricity and attitude angle, are used for discussing the load-carrying capacity of the journal bearing. The results reported in this paper should be applied to analysis of the journal bearing with different lubrication factors. The steady-state analysis of the journal bearing is conducted using the Reynolds model under thin-film lubrication conditions. For a journal bearing, several parameters, such as a pressure, load capacity, and pressure components of the bearing can be obtained, and these results can be stored in a sequential data file for later analysis. Finally, their distribution can be displayed and analyzed easily by using the MATLAB GUI technique. The load-carrying capability of the journal bearing is observed for the specified operating conditions. This work could be helpful for the understanding and research of the mechanism of thin-film lubrication.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1998.04a
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• pp.300-306
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• 1998

A high precision angular contact ball bearing is developed by Hanwha Machinery Co. The developed bearing is 7004C with P4 class. The performance test was succeful until 60,000 rpm.

• Journal of the Korean Geotechnical Society
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• v.31 no.6
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• pp.5-13
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• 2015

Micropile was mainly used as one of underpinnig methods, and recently has been used for the various purposes such as foundation for new structure or slope stability etc. However, despite of the increase of the usage of micropile, studies about the horizontal bearing characteristic of micropile are insufficient. Thus the model test has been conducted to investigate the horizontal bearing characteristics of micropile with the length ratio and installation angle of pile. Consequently, micropiles at the installation angle of $+30^{\circ}$ and $-30^{\circ}$ effectively increase the horizontal bearing capacity, respectively for L/d ${\leq}25$ and L/d > 50.