• Proceedings of the Korea Concrete Institute Conference
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• 2001.05a
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• pp.691-698
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• 2001

Recent trends in the construction of long span or tall building frames feature the increase use of composite members that steel and concrete is functioning together in what terms of mixed structural systems. One of such systems, RCS (reinforced concrete column and steel beam) system is introduced and closely examined focusing on bearing strength of the composite joint in this paper. The main objective of this study was to develope detail to increase bearing capacity while bearing failure is one of the two primary modes of failure in RCS system. The results show that specimens with the U-type bearing reinforcement detail developed in this study enhanced the bearing strength by 1.20-1.50. The U-type reinforcement is the effective details to increase joint bearing strength compared to others like vertical reinforcement welded to beam flanges.

• Design & Manufacturing
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• v.6 no.1
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• pp.45-51
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• 2012

The main goal of this paper is to establish an interference tolerance for determining optimal amount of clearance in the shaft-bearing system supported by radial ball bearings. The 2-D frictional contact model was employed for the FE analysis between the shaft and the inner raceway. Several examples were simulated using different material properties for the solid shaft. Efforts were focused on the deformation applied in the radial direction to select suitable bearings. The analysis results showed that the initial axial preload applied on the bearings plays a significant role to reduce bearing fatigue life. The proposed design parameters obtained by numerical simulations can approximately predict a rate of bearing life reduction as a function of shaft diameter ratio. This analysis can also be used to calculate the optimal initial radial clearance in order to obtain a shaft-bearing system design for high accuracy and long life.

• Tribology and Lubricants
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• v.29 no.4
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• pp.218-222
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• 2013

Water-lubricated ball bearings consist of rolling elements, an inner raceway, an outer raceway, a retainer, and an operating lubricant. In the water environment, ball bearings are required to sustain high loads at high speeds under poorly lubricated conditions. For the analysis of bearing behavior, friction torque is considered as the main factor at various flow rates, rotating speeds, and roughnesses between the rolling element and raceways. When the bearing operates at high rotating speeds, the friction torque between the raceway and rolling elements increases considerably. This frictional torque is an important factor affecting bearing reliability and life cycle duration. For understanding the flow conditions in the inner part of the bearing, this study focuses on the flow around the rotating and revolving rolling elements. A simple model of fluid flow inside the ball bearing is designed using the commercial CFD program ANSYS.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.18 no.2
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• pp.214-220
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• 2009

The spindle is the main component in machine tools. The static and dynamic stiffness of the spindle directly affect the machining productivity and surface integrity of the workpiece. The static and dynamic stiffness of the spindle depend on the shaft size, bearing arrangement, bearing span length, and so on. Therefore, the selection of shaft size and bearing span length are important to improve the spindle stiffness. This paper presents the determination of shaft size and bearing span length in spindle design step. In order to select the optimal bearing and built-in motor locations with constraint conditions, the extreme vertices design was applied. The results show that extreme vertices design is usable for spindle design with design constraints.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.420-429
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• 2009

This study concerns bearing capacity of shallow and deep foundations on jointed rock mass. The main focus of this research lies on getting insight into the applicability of bearing capacity estimation methods developed by other researchers. First, an extensive literature review was performed on previous studies concerning bearing capacity of foundation on jointed rock mass. Second, a parametric study on a number of jointed rock conditions using the finite-element analysis. The results of the analysis were then compared with those computed by the bearing capacity estimation method.

• Geomechanics and Engineering
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• v.8 no.2
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• pp.221-235
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• 2015

A series of laboratory model tests were conducted to investigate the effects of buried pipes location on the bearing capacity of strip footing in cohesionless soil. The variables examined in the testing program include relative density of the sand, loading rate of tests, burial depths of pipe and horizontal distance of pipe to footing. The test results showed a significant increase in bearing capacities when embedment ratio of pipe and horizontal distance of pipe to footing were increased. Based on the test results, it can be concluded that the location of pipes and relative density of sand are main parameters that affect the bearing capacity of strip footing. However, loading rate has not considerable effect on bearing capacity.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2005.03a
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• pp.429-436
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• 2005

In this study, we made two types of main control room floor systems (Type I, Type II) and several shaking table tests with and without isolation system were conducted to evaluate floor isolation effectiveness of LRB(Lead Rubber Bearing). Both type showed large difference according to input earthquake signals, but showed little difference according to floor type. It is required to make LRB of which design frequency is below 1Hz when applied to main control room of NPP, but considering much difficulties in making such LRB, it is recommended that consideration should be taken into account when applied to main control room of NPP.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.6
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• pp.1667-1676
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• 2014

Because of the different flexural rigidity between longitudinal and transverse direction, orthotropic plate theory may be suitable for describing the behavior of composite deck. The ratio of flexural rigidity between longitudinal and transverse direction affects the live load moment. Because of the ratio of flexural rigidity of concrete unfilled steel grid deck has a direct relationship with main bearing bar spacing, it is concluded that the study for the distribution factor which is effected by main bearing bar spacing and aspect ratio is needed. In this study, evaluate the live load moment of concrete unfilled steel grid deck using the AASHTO LRFD Bridge Design Specification and presents the distribution coefficient equation for concrete unfilled steel grid deck.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.04a
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• pp.697-703
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• 2000

In design step of an active vibration control system, the stability analysis is required for obtaining a stable control region so that the system is protected from it violent natural vibration. This paper describes the procedure of stability simulation for the active magnetic bearing-main spindle of a machine tool. The characteristic equation of the overall system is derived by assembling the dynamic equation of a flexible shaft and the transfer functions of feedback components. And the stable region is obtained by calculating the eigenvalues of the characteristic equation. The simulated control stable region is good agreement by comparing the experiment. Therefore the stable control gain is selected in this paper.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.5
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• pp.1477-1485
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• 1996

Since the spindle bearing systme is the main source of the total cutting point compliance of machine tool structures, in this work, the static and dynamic characteristics of the spndle bearing systme driven by the gear located on the bearing span were investigated using analytical and finite elemtn methods to improve the performance of the spindle bearing system. Based on the theretical results, a specially designed prototype spindle bvearing systme was manufactured. Using the manufactured spindle bearing system, the static and dynamic characteristics were measured. From the comparison of the experimental results with the theoretical results, it was found that the finite elemetn method predicted well the static and dynamic characteristics of the spindle bearing system.