• Proceedings of the KSR Conference
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• 2008.06a
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• pp.1729-1734
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• 2008

This study developed a new separated shperical bridge bearing that can be used for replacement of existing bridge bearings without crushing bearing-concrete. The separated spherical bearing have the upper and lower sole plate connected by bolts to the upper plate under bridge-girders and the lower plate on bearing-concrete. The targets of the separated spherical bearing are the maximum 3 mm of up-lifting height during replacement and the maximum required time of 30 minutes. Four separated spherical bearings are manufactured and replaced the existing bearings of a railway bridge in service and the replacing tests was performed. The number of the tests is two and the target of maximum 3 mm and 30 minutes was satisfied.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.578-584
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• 2003

This paper presents a method to investigate the characteristics of a ball bearing and the dynamics of a HDD spindle system due to temperature variation. Finite element model is developed fer the rotating and stationary parts of a HDD spindle system separately to determine their thermal deformations by using ANSYS, a finite element program. Then, the relative position of the rotating part with respect to the stationary part is determined by solving the equilibrium equation of the contact force between upper and lower ball bearings. The validity of the proposed method is verified by comparing the theoretical natural frequencies of a HDD spindle system with the experimental ones before and after temperature variation. It shows that the elevated temperature results in the increase of contact angle and the decrease of bearing deformation, contact force and bearing stiffness, which result in the decrease of the natural frequencies of a HDD spindle system.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.1107-1114
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• 2003

In this thesis, the dynamic characteristic analysis of carriage structure supported by air bearings were peformed. Toward this end, the characteristics of air bearing were numerically analyzed to estimate the stiffness of the air bearing and the clearance between air bearing and guide surface. The modal analysis of the carriage structure was peformed by using finite element method, and the experimental modal analysis was also performed to validate the finite element model, where rigid body modes were compared to validate the stiffness of the air bearings. From the results, the air spring stiffness can be estimated within the range of acceptable accuracy under any pressure and clearance condition.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.325-329
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• 2003

Nowadays many peoples are using helicopter in various fields, not only military use but also common people applications such as air-measurement, photography, transportation of goods and persons, saving life and fire fighting etc. And it will be expected more popular than now. Most important part of helicopter to increasing performance and to reducing noise is rotor hub-system. Hub system consists of rotor-blade and rotor-hub. We participate to develop next-generation rotor hub system with elastomeric bearing, part of rotor hub. In this paper we introduce about the role and shape of elastomeric bearing in next-generation helicopter hub system. Then we study about bearing-material requirements and measuring methods. Finally we represent some experimental results.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.784-791
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• 2008

This study is to evaluate the characteristics of bearing capacity for granite soils by N-value. The partial data is investigated for practical evaluation of weathering degree and bearing capacity on granite soils. The settlement is linearly decreased when the N-value is less than 50, but the settlement isn't constant when the N-value is more than 50. This is the affect of ground water. Therefore ground water is detailed evaluated. The bearing capacity is linearly increased when the N-value is less than 30, is inactively increased when the N-value is between 30 to 50, is constant when the value is more than 50.

• Proceedings of the KSME Conference
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• 2001.06b
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• pp.448-453
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• 2001

This paper presents an analytical evaluation of the effect of motion on seismic responses of base isolated low-level building and experimental studies to evaluate isolation performances of a rubber bearing. Dynamic responses induced by earthquake were evaluated by response analyses, taking the rubber bearing of the base isolation devices into account. In the experiment, vibration tests were carried out using a model for rubber bearings as isolation devices against earthquake in order to investigate the isolation performances of the rubber bearings. Several kinds of rubber bearing for base isolated low-level building against earthquake are examined. As a result, it is shown that the effect of the motion on the response of the building and the base response is well controlled from a seismic design standpoint.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2000.11a
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• pp.378-384
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• 2000

This paper presents the results of the repeated sliding tests to determine the wear-life of TiN coated AISI 52100 bearing balls deposited by PVD method and to show the wear mechanisms of those. The sliding tests were carried out using a ball-on-disk tribometer under ambient conditions. The coefficient of friction, wear volume and the cycles to failures of TiN coated bearing balls were measured with different normal loads and roughness of lower specimens. On the wear-life diagram, the normal loads and the cycles to failure showed the good linear relation on log-log coordinate. With a decreasing normal load, the diagram showed that the wear-limits, at which the coated bearing balls survived more than 4000cycles were under 0.1N of the normal load.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.792-795
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• 2005

The guide-ways of precision machine tools are one of important element of machine tools. It has usually a pair of surfaces for constraint of one direction with bearing. In the case of precision machine tools, non-contact bearing such as hydrostatic bearing and aerostatic bearing is adopted usually. In this case, profiles of rails has effect on straightness and the clearance of bearing has effect on stiffness of guide way, which changes to higher if clearance changes to smaller. The clearance is varied along moving table according to relative distance of pair of rails. The relative distance of pair of rail can be divided by three properties. First and second properties are straightness of each pair of rail and bearing pad. And, third is parallelism about pair of rails and pairs of bearing pad. There are several methods for measuring straightness of each surface such as reversal method, sequential two point method, and way straightness. These straightness measuring methods are always acquiring deviation of profile from eliminating linear fitted inclined line and don't have the information of parallelism. Therefore, to get the small clearance for high stiffness, the straightness of rail and bearing pad and parallelism about pair of rails and pair of bearing pads are measured for correction such as regrinding, reassembling and lapping. In this research, new and easy method for measuring parallelism of pair of rails is suggested. Two displacement probe and sensor stage, which is carry on the displacement sensor, are needed. The simulation and experiment was accomplished about pair of horizontal guide way to confirm the measurement of parallelism. And, the third probe is added to measure the straightness of each rails by sequential two point method. From the estimation of combined these two methods, it is confirmed that the profiles of a pairs of rails can be measured.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.189-193
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• 2008

Performance of refrigerant oil at the thrust-bearing and at the journal-bearing of a scroll compressor is a significant factor. This paper presents the friction and anti-wear characteristics of nano oil with a mixture of a refrigerant oil and carbon nano particles in the journal bearing of scroll compressors. The characteristics of friction and anti-wear using nano-oil is evaluated using the disk on disk tester and the journal bearing tester for measuring friction surface temperature and the coefficient of friction at the journal bearing tester. In journal bearing test, the average friction coefficient of high concentration nano-oil was decreased down to 18% compared to raw oil under 4,500 N and 3,600 rpm. It is believed that nano particles can be coated on the wear surfaces and the interaction of nano particles between surfaces can be improved the lubrication in the friction surfaces. Worn surfaces of frictional specimen were measured with straightness. carbon nano oil enhances the characteristics of the anti-wear and friction at the joural bearing of scroll compressors.

• Proceedings of the Korean Geotechical Society Conference
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• 2003.03a
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• pp.333-340
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• 2003

In Korea, drilled shaft are generally socketed into rock. Driven pile has environmental problems such as vibration and noise. Therefore, applications of the drilled shaft are increasing in Korea. In this paper, static load test data of the rock socketed drilled shaft at Gwangandaero and Suyeong 3hogyo are analyzed. The bearing capacities from field test data and theoretical formula are compared and analyzed. From this study, design approaches for drilled shafts in Korea are examined and several suggestions are proposed.