• Tribology and Lubricants
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• v.2 no.1
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• pp.61-68
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• 1986

Effects of the ram-pressure on the THD-performance of pivoted pad thrust bearings are investigated experimentally. A sector-shaped tilting pad thrust bearing and a rotating disk are used. Temperature distribution on the disk surface as well as on the pad surface, distribution of the pressure generated within the fluid film, and the film thickness are measured continuously in the circumferential direction after thermal equilibrium is established. The ram-pressure is proportional to the mean pressure of oil film and to the rotational speed of the disk and affects the maximum pressure and the pressure distribution. The temperature rise on the mating surface of the disc and the pad, contacting with the oil film, is proportional to to the bearing load and the disk speed. The ram-pressure and the temperature rise on the disk surface are dominant factors that affect the THD-performance of pivoted pad thrust bearings.

• KSTLE International Journal
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• v.1 no.2
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• pp.95-100
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• 2000

The thermal behaviors of disk-pad braking models has been analyzed for a high-speed train brake system using the coupled thermal-mechanical analysis technique. The temperature distribution, thermal distortion, and contact stress in the disk-pads contact model have been investigated as functions of the convective heat transfer rate. The FEM results indicate that multiple spot type pads show more stabilized thermal characteristics compared with those of the flat type pads for the increased convective heat transfer rate. The maximum contact stress for a friction pad loaded against a rubbing disk was occurred on the edge of the pad at the disk-pad interface.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.1 no.1
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• pp.89-100
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• 2002

The purpose if this research was to improve the pressure distribution on the disk brake pad Not uniform pressure distribution on the disk brake pad generate the unbalance wear of it and the unbalance wear of disk brake pad generate vibration, noise, heat and reduce the braking capacity. For improve the pressure distribution on the pad in this research, upper face of caliper housing finger was cut. Two kinds of caliper which uncut and cut of finger face were compared the stress distribution by FEM analysis and real experiment. Also natural frequency and deforming displacement ware calculated. It was understood that pressure distribution could Improve by cut inside upper face of caliper housing finger.

• Proceedings of the KSR Conference
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• 2006.11b
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• pp.274-280
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• 2006

The study is to analyze dynamo test results for various commercial pads in order to verify the performance of brake disk with CV-NCM cast iron. The developed brake disk will apply to 200 km/h tilting trains that is being developed as one part of project for speed-up on Korean existing railroad. The test program is made out suitably for braking condition and performance of test equipment by referring UIC 541-3. Two kinds of resin pad and one kind of foreign sintered pad suitable for 200 km/h trains are used as various commercial pad for the dynamo test. The data aquisition for the maximum and smallest temperature, hot spot, etc. on disk and pad is performed by using the thermocouples and thermal imaging cameras. From this research, we obtained braking characteristics between CV-NCM cast iron disk and pad of various material and will be utilized usefully as basis data of performance optimization of developing sintered pad.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.11a
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• pp.359-361
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• 2006

As circuits become increasingly complex and devices sizes shrinks, the demands placed on global planarization of higher level. Chemical Mechanical Polishing (CMP) is an indispensable manufacturing process used to achieve global planarity. In the CMP process, Diamond Disk (DD) plays an important role in the maintenance of removal rate. According to studies, the cause of removal rate decrease in the early or end stage of diamond disk lifetime comes from pad surface change. We also presented pad cutting rate (PCR) as a useful cutting ability index of DD and studied PCR trend about variable parameters that including size, hardness, shape of DD and RPM, pressure of conditioner It has been shown that PCR control ability of pressure and shape is superior to RPM and size. High pressure leads to a decrease of cell open ratio of pad surface because polyurethane of pad is destroyed by pressure. So low pressure high RPM condition is a proper removal rate sustain. By examining correlations between RPM and pressure of conditioner, it has been shown that PCR safe zoneto satisfy proper removal rate has the range 0.06mm/hr to 0.12mm/hr.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.563-564
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• 2006

Recently, CMP (Chemical Mechanical Polishing) is one of very important processing in semiconductor technology because of large integration and application of design role. CMP is a planarization process of wafer surface using the chemical and mechanical reactions. One of the most important components of the CMP system is the polishing pad. During the CMP process, the pad itself becomes smoother and glazing. Therefore it is necessary to have a pad conditioning process to refresh the pad surface, to remove slurry debris and to supply the fresh slurry on the surface. A diamond disk use during the pad conditioning. There are diamonds on the surface of diamond disk to remove slurry debris and to polish pad surface slightly, so density, shape and size of diamond are very important factors. In. this study, we characterized diamond disk with 9 kinds of sample.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.10a
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• pp.445-450
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• 2004

Recently, many studies have been performed and good results have been reported in literature on the prediction of the brake disk temperature. However, study on the brake fluid temperature is rarely found despite of its importance. In this study, brake fluid temperature is predicted according to material property of brake piston. For the analysis, a typical disk-pad brake system is modeled including the brake disk, pad, caliper, piston and brake fluid. Vehicle deceleration, weight distribution by deceleration, disc-pad heat division and the cooling of brake components are considered in the analysis of heat transfer. Unsteady-state temperature distribution are analyzed by using the finite element method and numerical results are compared with the vehicle test data

• Journal of the Korea Convergence Society
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• v.9 no.1
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• pp.283-289
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• 2018

In automotive disc brake systems, frictional heat is not uniformly dispersed for reasons such as heat flux and thermal deformation. The thermoelastic deformation due to the frictional heat affects the contact pressure distribution and the contact load may be concentrated on the contact portion on the the disc brake surface, resulting in thermoelastic instability. In this study, thermal analysis and thermal deformation analysis considering the contact between disk and pad occurred during braking through 3D axial symmetry model with reference to the experimental equation and Kao's analysis method of contact pressure of disk and pad. ANSYS is used to analyze the thermal and elastic instability problems occurring at the contact surface between the disk and the pad, considering both the thermal and mechanical loads. A 3D axisymmetric model with direct contact between the disk and the pad was constructed to more accurately observe the thermal behavior of the disk by observing the frictional surface temperature, thermal deformation and contact thermal stress of the disk.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2000.06a
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• pp.211-218
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• 2000

Hot spot behaviors on the disk-pad contact surface during a braking operation have been analyzed for a ventilated disk brake using the finite element method. Hot spots which were studied using a coupled thermal-mechanical analysis technique are influenced by all of the mechanical, thermal, elastic and plastic processes that are involved in braking cycles, but their temperature gradients are most affected by rubbing speeds, braking forces, and design parameters between the disk and the pad. Undesirable hot spots that are generated by local thermoelastic instabilities are intended to be removed by optimized design parameters and material properties. In this study, a three-dimensional numerical method for the demonstration of hot spot behaviors has been applied to the rubbing surfaces between the disk and the pad.

• Tribology and Lubricants
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• v.40 no.2
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• pp.67-70
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• 2024

Chemical mechanical planarization (CMP) is an essential process for ensuring high integration when manufacturing semiconductor devices. CMP mainly requires the use of polyurethane-based polishing pads as an ultraprecise process to achieve mechanical material removal and the required chemical reactions. A diamond disk performs pad conditioning to remove processing residues on the pad surface and maintain sufficient surface roughness during CMP. However, the diamond grits attached to the disk cause uneven wear of the pad, leading to the poor uniformity of material removal during CMP. This study investigates the pad wear rate profile according to the swing motion of the conditioner during swing-arm-type CMP conditioning using deep learning. During conditioning, the motion of the swing arm is independently controlled in eight zones of the same pad radius. The experiment includes six swingmotion conditions to obtain actual data on the pad wear rate profile, and deep learning learns the pad wear rate profile obtained in the experiment. The absolute average error rate between the experimental values and learning results is 0.01%. This finding confirms that the experimental results can be well represented by learning. Pad wear rate profile prediction using the learning results reveals good agreement between the predicted and experimental values.