• Composites Research
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• v.29 no.3
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• pp.111-116
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• 2016

The tilting pad journal bearing for the turbo compressor application has a role to support high speed and heavy loading rotor. White metal has been widely used for the bearing material but the conventional bearing is immediately suspended and induces serious serious damage to the rotor under the unexpected oil cut situation or the insufficient oil film formation. The carbon fiber reinforced composite having high specific stiffness, specific strength and excellent tribological characteristics can solve these seizure problems. In this work, the study on the durability of high thermal resistance carbon fiber/epoxy composite tilting pad journal bearing under oil cut situation was conducted. The material properties of the composite materials including tensile, compressive and interlaminar properties were measured at room and high temperature of oil cut situation. To investigate the possibility of failure of composite tilting pad journal bearing under oil cut situation, the stress distribution of the composite bearing was analyzed via finite element analysis and the Tsai-Wu Failure index was calculated. To verify the failure analysis results, the oil cut tests for the composite tilting pad journal bearing were conducted using industrial test bench.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2010.05a
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• pp.542-543
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• 2010

• Tribology and Lubricants
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• v.8 no.2
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• pp.73-79
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• 1992

The pressure distribution between the piston pad and the cylinder wall is analyzed to reduce the friction and to get the dynamic stability in the low friction piston. The calculated results indicate that the rectangular pad may reduce the friction in comparison to the square one. And the low friction piston can be stabilized when the pressure difference between the top and bottom of the piston skirt is very small.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2000.11a
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• pp.186-192
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• 2000

The heat generated in contact type braking system can cause an unacceptable braking performance. Thermal behavior of ventilated disk brake system is presented in this paper. The temperature and velocity fields of 3-D unsteady simulated model are obtained using a software package "FLUENT". The numerical results show that there exits a temperature nonuniformity between the disk faces contacting with pads. The conduction rate through the disk and pad is calculated and the effect of material conductivity is also investigated.estigated.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.12
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• pp.1206-1212
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• 2012

The brake squeal propensity due to the friction-velocity curve is numerically investigated. The finite element models for the disc and pad are correlated with the modal test. In the friction-engaged system modeling, the friction function is linearized at the equilibrium. The damping term induced by friction-velocity slope is incorporated into the equations of motion. In the complex eigenvalue analysis, it is found that the pad shear mode is very sensitive to the friction curve. The results shows that the squeal propensity of the pad shear mode can be controlled by the design parameters such as pressure and stiffness.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.2
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• pp.163-169
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• 2012

The brake squeal propensity associated with friction curve is investigated by using the hybrid finite element(FE)-analytical model. The modal analysis of an actual disc and pad is conducted by FE method. Also, the modeling for the accurate contact and disc rotation is analytically achieved. The eigenvalue analysis for the hybrid model provided the squeal dependency on the friction curve. Particularly, some pad modes and the disc torsion mode are shown to be sensitive for the friction curve.

• Transactions of the Korean Society of Automotive Engineers
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• v.2 no.5
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• pp.93-100
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• 1994

Friction-induced vibration characteristics of automotive brake lining pad are investigated on the basis of experimental observations from a pin-on-disk type friction-induced vibration experimental apparatus. The measured responses of the experimental apparatus show limit cycles of quasi-harmonics type and beat phenomena due to the velocity dependence of friction force. To deduce the friction coefficient vs. relative velocity Lienard method is adopted with least square fit. It shows Scurve which characterizes a quasi-harmonic vibration. The calculation of amplitudes and friquencies of the limit cycles is done using slowly changing phase and amplitude method. The theoretical and numerical results show fairly good agreements with those of experiments.

• Proceedings of the Korean Reliability Society Conference
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• 2004.07a
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• pp.297-301
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• 2004

세탁기의 Shaft Ass'y는 모터로부터 동력을 전달 받아 세탁 및 탈수행정의 제어 기능을 수행하는 세탁기의 핵심부품으로 사용 중 브레이크 밴드소음을 유발하여 소비자의 불만족 요소로 작용하고 있다. 그러나 드럼과 브레이크 페드의 정확한 마찰소음 현상 규명이 안되어 불량 개선에 많은 어려움이 있다. 이를 해결하고자 소음, 진동, 소재 분석 및 ESPI(Electronic Speckle Pattern Interferometry) 분석을 통해 고장원인을 규명하였다. 특히 ESPI는 비접촉, Full Field 정밀 변형 가시화 장치로 Shaft Ass'y의 동작 중 공진소음 발생 부위를 변형 가시화를 통해 정확하게 찾을 수 있었다. 밴드소음 원인은 브레이크 Lever의 공진에 의해 발생하였고 브레이크 밴드 패드의 접촉면적 불균일로 인한 국부적 마찰력 증대가 소음원으로 작용하였다. 밴드소음의 정확한 고장 메커니즘 규명을 통해 개선안을 도출하여 적용하였고 밴드소음 개선효과를 얻을 수 있었다.

• Journal of the Korea Convergence Society
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• v.10 no.12
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• pp.287-292
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• 2019

This paper analyzes the thermal behaviors of genuine discs used in automobiles and discs coming out of tuning products through FEM analysis. Modeling with genuine disk modeling and tuning disks Model-1, Model-2, Model-3 and analyzing the disk rotation speed was set to 1000rpm. When the brake is operated, the thermal behavior of the disk surface, such as the operating temperature caused by the disk and pad contact, the friction surface temperature after the disk stop, and the thermal deformation, were analyzed. When the brake was activated (0-4.5 seconds), the tuning disk showed 34℃ higher than the original disk, and after the disk stopped (40.5 seconds), the tuning disk was analyzed 18℃ lowe, deformation due to the disk heat was deformed by 0.3mm for the tuning disk. Although there is an effect to reduce the fading phenomenon due to the thermal behavior of the pure disk and the tuning disk, it can be observed that there is no significant change in the thermal behavior due to the hole processing and the disk surface processing of the tuning disk.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.12
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• pp.1351-1358
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• 2014

This study numerically simulates brake squeal and validates it experimentally by using a lab-scaled brake dynamometer. The system frequencies of the disc brake are traced with respect to the brake pressure by using a modal test and FEM. Then, the squeal frequencies measured from the brake dynamometer are found to correspond to the brake system mode with the dominant displacement of the caliper and pad. Furthermore, a complex eigenvalue analysis conducted using the finite element model confirms that the caliper mode generating the rotational displacement of the pad becomes unstable owing to the negative friction-velocity slope.