• Transactions of the Korean Society of Machine Tool Engineers
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• v.10 no.1
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• pp.23-29
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• 2001

Cylindrical type of self-controlled restrictor are designed for hydrostatic bearing of grinding wheel spindle. Typical hydrostatic journal bearing with the designed restrictor is analytically model. According to the model, the affect of oper-ation parameters, such as, initial cross distance, supply pressure, diameter of two supply holes, pre-load of spring, and clearance between spindle and housing, on bearing stiffness are analyzed. From the results of the analysis, the optimum conditions of operation parameters that maximize the bearing stiffness are estimated.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.05a
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• pp.1021-1026
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• 2000

The thermal characteristics of high-speed air spindle system with built-in motor are studied. Experiment and finite element method analysis obtain temperature rise and temperature distribution of housing. For the analysis three-dimensional model is built and temperature rise and distribution in thermal steady state are computed for each rotational frequency. Generally. It is said that the heat generation of air bearing is negligible. But it is certain that the heat generation of air bearing can not be negligible especially in high-speed conditions Frequency response test for air spindle system is executed. In case that the heat generation of air spindle system is high, natural frequency of the system becomes lower when it reaches thermal steady-state and it means that the stiffness of air hearing becomes smaller due to the change of bearing clearance. It is shown that the temperature rise of all spindle system causes thermal expansion md induces the variation of hearing clearance. In consequence the st illness of air bearing becomes smaller.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.31-36
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• 2002

Even through the problem of misalignment is of great importance, not much work has been reported in the literature on the effect of misalignment on the vibrations of the gear-bearing systems. Therefore, the nonlinear dynamic characteristics of the gear drive system due to misalignment are investigated in this work. Transmission error for helical gear and bearing nonlinear stiffness is calculated. The equation of motion of the gear drive system is modelled using the time-varying gear meshing stiffness, bearing nonlinear stiffness, and bearing pre-load due to the housing deformation. Numerical analysis lot the gear drive system show the result of misalignment effect - sub-harmonic component, bearing pre-load effect, and another nonlinear phenomenon. And the numerical analysis are verified by the experimental result.

• Journal of Powder Materials
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• v.4 no.4
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• pp.275-282
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• 1997

Sintered oilless bearing using fluid-dynamic mechanism for high revolution of over 10,000 rpm was developed by Powder metallurgy Process. Developed bearing was composed of Fe-40-60%Cu of which inner face consisted of six-regular-prominence-and-depression. Inner face has controlled pore size and amount according to application. Jitter and friction properties were tested under assembled conditions with housing and motor. Bearing-own properties and precision were also tested because of demanding for assembled properties. Measurement-skill as well as mould-production-skill were investigated for the precision of bearing. Final precision reached 2 ${\mu}m$ in inner diameter tolerance and 5 ${\mu}m$ in coaxiality under assembled conditions.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2005.11a
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• pp.219-223
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• 2005

In this work, a hybrid composite proceeding bearing (HCJB) composed of carbon/phenolic laminated composite bush and steel housing was designed for marine vessels because the composite proceeding bearing reduces the possibility of the seizure problem between the proceeding and bearing. The two components of bearing were assembled by interference fit joining method and a series of durability tests were conducted using the laboratory bench with the lubricants of SAE 30 oil, water, and sea water. That the HCJB was found reliable under the interference fitting loads and environmental temperature change.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1999.10a
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• pp.425-431
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• 1999

Nowadays development of electric and optical devices needs precision more and more. This study focuses on hydrostatic journal bearing of grinding wheel spindle. It presents theoretical analysis about cylinder type self-controlled restrictor to control flux of oil flowing into pockets around the hydrostatic journal bearing. As a result of this analysis, optimal properties to maximize bearing stiffness such as initial cross distance, supply pressure, diameter of two supply holes, pre-load of spring and clearance between spindle and housing can be obtained. Therefore, by using them it is possible to estimate bearing stiffness and the performance of grinding wheel spindle can be improved.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1998.04a
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• pp.524-529
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• 1998

Analogous problem for a gear dynamics where helical gears excite logitudinal forces in the shaft is studied. These shaft forces excite the supporting gear housing through bearing, causing structural vibration. In this study, shaft is modeled as a rod, and bearing is modeled by a massless spring. A simple model for gear housing is a clamped circular plate. To model this force transmission, the transfer functions from the shaft to a clamped circular plate are analytically derived by using the spectral method and four-pole parameter. Finally, radiated noise is computed, using the acoustic relations due to plate surface vibration.

• Journal of KSNVE
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• v.8 no.5
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• pp.908-913
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• 1998

Analogous problem for a gear dynamics where helical gears excite logitudinal forces in the shaft is studied. These shaft forces excite the supporting gear housing through bearing, causing structural vibration. In this study, shaft is modeled as a rod, and bearing is modeled by a massless spring. A simple model for gear housing is a clamped circular plate. To model this force transmission, the transfer functions from the shaft to a clamped circular plate are analytically derived by using the spectral method and four-pole parameter. Finally, radiated noise is computed, using the acoustic relations due to plate surface vibration.

• Land and Housing Review
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• v.2 no.2
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• pp.183-188
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• 2011

Recently, the depth of tunnel constructed is getting deeper, which increases difficulty in construction works. Deliberate tunneling techniques are needed as the span and length of tunnels are increased. As one of the technical developments for tunnel, U-shaped and reinforced spider lattice girders are developed by optimizing the spider used in 95mm lattice girder as tunnel steel ribs. In order to evaluate the load bearing capacity of the lattice girder, the 4-point flexural tests are carried out. For the laboratory tests, straight specimens are made for the existing lattice girder and the new lattice girder. The results of the flexural tests showed that the maximum load bearing capacity of the new lattice girders was higher than the traditional one. The load-displacement behavior of the test specimens showed the elasto-plastic behavior in the existing lattice girder and the stress softening behavior in the new lattice girder. It was found that the load bearing capacities are changed depending on the location of the loading points.

• Land and Housing Review
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• v.4 no.2
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• pp.185-192
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• 2013

This study presents application effects of hybrid seismic isolation system to realize high seismic performance for low-rise lightweight buildings through a non-linear analysis and onsite experiments. The complex seismic isolation system applied in this study is a method of mixing sliding bearing and laminated rubber bearing in order to overcome limitation of laminated rubber bearing in increasing natural period of the whole seismic isolation system. As a result of the non-linear analysis, seismic isolation buildings designed with complex seismic isolation system are safe because its maximum response displacement is within allowable design displacement even for a strong earthquake which rarely occurs and its maximum response shear is less than design seismic force. As a result of the onsite experiment, the rigidity of seismic isolation stories corresponds to approximately 95.8% of the design equivalent stiffness value. This indicates that actual properties of the whole seismic isolation system correspond to design values.