• Journal of the Korean Society for Railway
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• v.12 no.6
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• pp.887-894
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• 2009

There is no standard rule for the test of the railway abrasion measurement system composed of the line laser and the camera. This paper is proposed of the method to estimate the performance of the railway abrasion measurement system. The performance estimation is achieved by the quantitative analysis parameters such as MTF, NPS and DQE.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1998.04a
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• pp.328-334
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• 1998

In this work, friction materials with three different formulations containing different amounts of the solid lubricants were investigated to study the role of lubricants on the friction performance. The three friction materials contained graphite 10 vol. %, graphite 7 vol. % + MoS$_2$ 3 vol.%, and graphite 7 vol. % + $Sb_2S_3$ 3 vol. %, respectively, with the same amount of other ingredients. Results of this work showed that each formulation with different lubricants had unique advantages and disadvantages. The friction materials containing graphite 7 vol. % + MoS$_2$ 3 vol. % and graphite 7 % + $Sb_2S_3$ 3 vol. % showed better resistance to fading and improved friction stability compare to the friction materials containing graphite only as a lubricant. However, the friction materials with two lubricants (graphite + MoS$_2$ or $Sb_2S_3$) showed disadvantages on stick-slip phenomena, amplitude of torque, and rotor wear.

• Transactions on Control, Automation and Systems Engineering
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• v.3 no.2
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• pp.111-116
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• 2001

A neural network compensator for stick-slip friction phenomena in meashartonics servo systems is practically proposed to supplement the traditionally available position and velocity control loops for precise motion control. The neural network compensa-tor plays the role of canceling the effect of nonlinear slipping friction force. It works robustly and effectively in a real control system. This enables the mechatronics servo systems to provide more precise control in the digital computer. It was confirmed that the con-trol accuracy is improved near zero velocity and points of changing the moving direction through numerical simulation. However, asymptotic property on the steady state error of the normal operation points is guaranteed by the integral term of traditional velocity loop controller.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.968-973
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• 1991

Seven axis modular type pneumatic manipulator is composed of electro-pneumatic automation system which contributes to factory automation by performing loading & unloading process successively which is simple routine work of dealing item of machine tool, catapult, assembly machine, welding machine and so on. In this study, we obtained soft and quick movement in a large space and good reliability motion of various function by combining several actuators which perform rotation movement as well as linear movement at the same time. Gripper which apply to rotary sensor transmitted a structure to demanded position. This development item of 5kgf load prevent stick-slip phenomena of stroke end by designing high cushion internal. We develope flexible manipulator which conforms to demand of user by applying multiple sequence program.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.04a
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• pp.208.2-212
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• 1997

In a model based friction comensation for a frictional system,the performance of the system is inflenceed by the selection of the friction model. Especially, when a real plant have dynamic friction characteritics, the compensation of friction with a static friction model may deteriorate the perfomance. For the system we constlucted an adaptiv parameter estimation and friction compensation with a newly introduced dynamic friction model proposed by Canudas et.[1]. The model depicts varios frictional phenomena,such as Stibeck effect,frictional memory, Stick-slip motion. Parmeter identification algorithm are followed conventional RLSM adaptive rule. The stability for the closed system was proved by the Lyapunov stability. The result say that if a real system have dynamic friction property,the friction compensation with the dynamic friction model will improve the perfomance moreover static friction model based compensation may lead to the system unstable.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.476-480
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• 2003

This paper presents an effective method to analyze the dynamic characteristics for the shilling transients of power transmission system using the multibody dynamics, which is composed of subsystem equation, subsystem assemble, and the self-determining technique for the system degree of freedom. Using the advantages of multibody dynamics, the proposed method can be used easily for mathematical models of mechanical systems, such as a power transmission, compared with newtonian method. With this theory, dynamic simulation program was developed. The program can be used to verify system performances, transient phenomena, and other dynamic problems. The simulation of a target system was presented, and its validity was attained by being compared with the previous analysis using newtonian method.

• KSTLE International Journal
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• v.10 no.1_2
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• pp.43-47
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• 2009

Influences of carbonaceous ingredient as a solid lubricant in automotive friction materials on friction properties were studied. Three types of carbonaceous ingredients such as natural graphite, artificial graphite, and cokes were mixed using a constrained mixture design. A 1/5 scale brake dynamometer was used to obtain tribological properties. Results showed that cokes substantially increased the friction coefficient, and natural graphite effectively reduced stick-slip phenomena. This significant difference was attributed to the formation of the friction film on the brake pad which was shown to be strongly dependent on the graphite types. The different crystal structures of the carbonaceous solid lubricants played a significant role in the formation of friction film at the interface.

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.6
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• pp.175-181
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• 2004

This paper presents the main method to analyze the dynamic characteristics of power transmission system using the multi-body dynamics, which is based on the concept of subsystem equation, subsystem assembling, and the self-determination technique for the system degree of freedom. We can model the mechanical components of power transmission system easily with the advantage of multi-body dynamics. Based on the theory, a dynamic simulation program was developed to analyze system performances, transient phenomena, and other dynamic problems. The driving performance of automatic transmission was simulated with using the multi-body dynamics and Newtonian method, and the validity of program was proved by comparing the two kinds of result.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.405-410
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• 2004

There are two types of noises in running the rail vehicle. The one is periodic by electric motors, dehumidifiers, and dusting machines. And the other is aperiodic squeal noise by the frictions between the wheels and the rail or the disks and pads. The periodic noises in rail vehicle have been reduced by changing DC motors to AC motors with silencers, and by improving the lubricants. However, almost nothing relating a periodic noise has been studied. In this paper, the experimental methods were applied to understand phenomena of the squeal noise, which was occurred by the friction variation due to aperiodic stick and slip with low repeatability in the process of dry friction of the disk and the pad when a rail vehicle was being braked. By the experimental acoustic test, it was found the specific frequencies relating the squeal noise. And by modal testing, it was measured the resonant frequencies in the disk and the pad-plate which were the components of the braking system, and in the whole braking system, and it was found the specific frequencies having the effects on the squeal noise.

• Journal of the Korean Society for Railway
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• v.8 no.6 s.31
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• pp.573-580
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• 2005

Model I interlaminar fracture behaviors of the carbon/epoxy composite, one of the candidate composites for a tilting train carbody, were investigate by the use of DCB(Double cantilever beam) specimens. These specimens were made of CF3327 plain woven fabric with epoxy resin, and an artificial starter delamination was fabricated by inserting Teflon film with the thickness of $12.5{\mu}m$ of $25.0{\mu}m$ at the one end of the specimen. Mode I interlaminar fracture toughness was evaluated for the specimens with the different thickness of an inserter. Also delamination propagating behaviors and interlaminar fracture surface were examined through an ooptical travelling scope and a scanning electron microscope. We found that abruptly unstable crack propagation called as stick-slip phenomena was observed. In addition, interlaminar fracture behaviors were affected on the location and the morphology of a crack tip as well as an interface region.