• Geomechanics and Engineering
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• v.30 no.3
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• pp.273-280
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• 2022

A certain amount of random vibration excitation to subway track is caused by subway operation. This excitation is transmitted through track foundation, tunnel, soil medium, and ground building to the ground and ground structure, causing vibration. The vibration affects ground building. In this study, the results of ANSYS numerical simulation was used to establish back-propagation (BP) neural network model. Moreover, a back-propagation neural network model consisting of five input neurons, one hidden layer, 11 hidden-layer neurons, and three output neurons was used to analyze and calculate the vertical Z-vibration level of New Capital's ground buildings of Qingdao Metro phase I Project (Line M3). The Z-vibration level under different working conditions was calculated from monolithic roadbed, steel-spring floating slab roadbed, and rubber-pad floating slab roadbed under the working condition of center point of 0-100 m. The steel-spring floating slab roadbed was used in the New Capital area to monitor the subway operation vibration in this area. Comparing the monitoring and prediction results, it was found that the prediction results have a good linear relationship with lower error. The research results have good reference and guiding significance for predicting vibration caused by subway operation.

• Journal of Biosystems Engineering
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• v.27 no.4
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• pp.273-282
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• 2002

This study was intended to measure and analyze hand-transmitted vibrations from cultivator in idle and operation modes for three different types of field works. Based on this analysis a time for the white finger syndrome to appear on 10% of the operators was estimated assuming that their daily exposure is 3 hours. The 4 methods to reduce the hand vibration were also proposed and compared with each other. The results of the study were summarized as follows : The highest vibration level was recorded during trenching operation, resulting in a total average vibration of 11.5 m/s$^2$. Followings were 7.6 m/s$^2$ during rotary tillage and 7.0 m/s$^2$ for weeding. When exposed to these levels of vibrations three hours a day, the white finger syndrome is likely to appear in 4 years for trenching, 6.2 years for rotary tillage and 6.8 years for weeding operations. Isolation of hand vibration performed by a rubber pad, anti-vibration gloves, a handle anti-vibration device and engine mounts were respectively 15.7%, 16.5%. 26.1% and 27.0%, resulting in most effective methods of the handle anti-vibration device and engine mounts. A better performance of about 33.9% was achieved when both the handle anti-vibration device and engine mounts were used.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.22 no.2
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• pp.310-317
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• 2013

In this paper, the contact pressure of the wafer and polishing pad for final polishing process for 300 mm-wafer were investigated through numerical analysis using FEM tool, ANSYS. The distribution of the contact pressure is one of main parameters which affects on the flatness and surface roughness of polished wafers. Two types of polishing head, a hard type head with ceramic disk and a soft type head with air bag were considered. The effects of the deformation and initial shape of table on the contact pressure were also examined. Both heads and tables were modeled as 3D finite element model from solid model, and the material properties of polishing pads and rubber plate for the air-bag head were obtained from tensile tests. The contact pressure deviation on wafer surface was smaller with air bag head than hard type head even when the table had form errors such as convex or concave. From this 3D analysis, it could be concluded that the air-bag head has better uniformity of the contact pressure on wafer. Also, the effects of inner diameter of air bag and radial clearance between wafer and retainer were investigated as view point of contact pressure concentration on the edge of wafer.

• Journal of the Earthquake Engineering Society of Korea
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• v.23 no.1
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• pp.1-8
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• 2019

In this study, the effectiveness of a multi-action hybrid damper (MHD) composed of lead rubber bearing (LRB) and friction pad was verified in terms of seismic performance improvement of a frame structure. The LRB and the friction elements are connected in series, so the LRB governs the intial small deformation and the friction determines large deformation behavior. Cyclic loading tests were conducted by using a half scale steel frame structure with the MHD, and the results indicated that the structure became to have the stable trilinear hysteresis with large initial stiffness and first yielding due to the LRB, and the second yielding due to the friction. The MHD could significantly increase the energy dissipation capacity of the structure and the hysteresis curves obtained by tests were almost identical to the analytically estimated ones.

• Proceedings of the Korean Geotechical Society Conference
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• 1999.03a
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• pp.241-248
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• 1999

The existing bridge with deck joint has many problems during construction and maintenance. To overcome these difficulties, an integral bridge, which is defined as the practice of constructing bridges without deck joints, is proposed in this study. A test bridge with 3 spans of PC beam was selected to verify the function of the bridge and is under construction. Characteristics of integral bridge are followings: $\circled1$ Flexible H-piles under the abutment are installed to accommodate thermal movements of the superstructures of bridge. $\circled2$ PC beam of the superstructure and the abutment are integrated. $\circled3$ The existing approach and relief slabs are applied to minimize the stress transfer occurred from the bridge deck to the pavement. $\circled4$ A cyclic control joint is installed between approach and relief slabs to absorb the thermal movement. $\circled5$ It is used a dual direction bearing which is cheaper than single direction bearing and has a good workability as well. It is also installed a shear block on the top of pier coping to protect the lateral movement caused by temperature change and earthquake.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.05a
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• pp.255-258
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• 2002

Dental chewing masticator, which is an essential device for evaluating the wear of dental resin and the interfacial failure between the filling resin and enamel of tooth used in conservative dentistry, was developed. This dental chewing masticator mimics the chewing motion and loading by adapting DC motor and rotary cam system. Chewing loading of 49N was imposed by computer-displacement control, loadcell, LM guide, and spring system. Extracted tooth was fixed into a holding jig, and this jig was mounted with rubber pad on the $15^{\circ}$inclined surface to consider the lateral movement of periodontal ligament. A water bath was installed for providing the environment of inside mouth and for circulating the $5^{\circ}C-55^{\circ}C$ water to evaluate the effect of hydrothermal cycling on the damage of resin filled teeth during long-term chewing activity.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.11
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• pp.1962-1969
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• 2008

According to the increase of power demand and expansion of downtown, it is necessary to install transformers additionally in operating substations and construct substations in residential area. But the public complaint is increased due to the transformer noise of the substation. KEPCO has used a vibration preventing pad, various soundproof walls and an encloser to transformers in outdoor substations, and a soundproof door, shutter and wind-path soundproof equipment in indoor substations to block the sound propagation of the transformers. But these noise reduction methods are not satisfied. It should be considered to reduce transformer noise itself. In this paper, we investigated core noise reduction techniques to develope a low noise transformer. The techniques to reduce core noise of the transformer are application of high permeability grain oriented silicon sheets, decrease of magnetic flux density of core, application of 6step-lap core stacking method, improvement of core binding method(binding addition, band fixing) and application of rubber damper in oder to reduce transmission of core vibration, etc.

• Journal of the Korean Society for Precision Engineering
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• v.29 no.10
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• pp.1056-1061
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• 2012

FEM analysis is essential to shorten the development time and reduce the cost for developing high-performance machine tools. Mount joint parts play important role to ensure static and dynamic stability of machine tools. This paper suggests a computational modeling of mount joint part of machine tools. MATRIX27 element of ANSYS is adopted to model mount joint parts. MATRIX27 allows the definition of stiffness and damping matrices in matrix form. The matrix is assumed to relate two nodes, each with six degrees of freedom per node. Stiffness and damping values of commercial mount products are measured to build a database for FEM analysis. Jack mounts with rubber pad are exemplified in this paper. The database extracted from the experiments is also used to estimate of stiffness and damping of untested mounts. FEM analysis of machine tools system with the suggested mount computational model is performed. Static and dynamic results prove the feasibility of the suggested mount model.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.11
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• pp.1849-1855
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• 2003

Newly commercialized wireless capsule endoscope has many advantages compared to conventional push-type endoscopes. However, it is moved by the peristaltic waves. Therefore, it can not diagnose desired zones actively. In this paper, a locomotive mechanism for wireless capsule endoscope is proposed to increase the efficiency of endoscopy. We designed and fabricated a prototype using SMA springs and bio-mimetic clamping device. The hollow space in the prototype is allocated for further system integration of a camera module, a RF module and a battery. And the sequential control scheme is employed to improve the efficiency of its locomotion. To validate the performance of the locomotive mechanism, experiments on a silicone rubber pad and in vitro tests are carried out. The results of the experiments indicate that proposed mechanism is effective in harsh environments such as digestive organs of a human.

• Transactions of Materials Processing
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• v.15 no.1 s.82
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• pp.9-14
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• 2006

In the present research, the simultaneous punching of ultra small size hole of $2\~10\;{\mu}m$ in diameter on flat rolled thin metal foils was conducted with elastic polymer punch. Workpiece used in the present investigation were the rolled pure copper of $3{\mu}m$ in thickness and CP titanium of 1.5fm in thickness. The metal foils were punched with the dies and arrays of circular and rectangular holes were made. The process set-up is similar to that of the flexible rubber pad farming or Guerin process. Arrays of holes were punched successfully in one step forming. The punched holes were examined in terms of their dimensions. The effects of the wafer die hole dimension and heat treatment of the workpiece on ultra small size hole formation of the thin foil were discussed. The process condition such as proper die shape, pressure, pressure rate and diameter-thickness ratio (d/t) were also discussed. The results in this paper show that the present method can be successfully applied to the fabrication of ultra small size hole away in a one step operation.