• Tribology and Lubricants
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• v.14 no.1
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• pp.70-78
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• 1998

Two different friction materials (organic and low-metallic pads) for automotive brakes were studied to investigate the anti-fading phenomena during stop. The anti-fading phenomena were pronounced more in the case of using low metallic friction materials than organic friction materials. The main cause of the anti-fading phenomena was the high dependence of friction coefficient on a sliding speed. The anti-fading was prominent when the initial brake temperature was high in the case of low-metallic friction materials due to the strong stick-slip event at high temperature. On the other hand, the anti-fading was not severe in organic friction materials and the effect was reduced at high braking temperature due to the thermal decomposition of organic friction materials. The strong stickslip phenomena of low metallic friction materials at high temperature induced high torque oscillations during drag test. During this experiment two different braking control modes (pressure controlled and torque controlled modes) were compared. The type of the control mode used for brake test significantly affected the friction characteristics.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.17 no.2
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• pp.85-91
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• 1981

An equation was derived which describes the slip force that occurs at the casting of initial state due to unequilibrium with support bar weight, liquid metal, casting velocity, thickness, control roller, hydraulic motor and etc. The slip force equations are solved on the basis of velocity, gravity and thickness in casting ingot. In this paper the auther assumed that the other mechanisms are normal. The behaviour of slip force in many characteristics is calculated as a function of velocity, gravity and thickness with variation. The conclusion with this phenomena is reached that the present theory realistically predicts the growth of slip force in a flat plate ingot continuous casting machine.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.55 no.1
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• pp.41-46
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• 2006

In electric motor coaches, the rolling stocks move by the adhesive effort between rail and driving wheel. Generally, the adhesive effort is defined by the function of both the weight of electric motor coach and the adhesive effort between rails and driving wheel. The characteristics of adhesive effort is strongly affected by the conditions between rails and driving wheel. When the adhesive effort decreases suddenly, the electric motor coach has slip phenomena. This paper proposes a anti-slip control algorithm which uses the maximum adhesive effort by instantaneous estimation of adhesion force using load torque disturbance observer. Based on this estimated adhesive effort, the anti-slip control is performed to obtain the maximum transfer of the tractive effort.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.54 no.1
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• pp.48-55
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• 2005

Mobility of an indoor wheeled robot is affected by adhesion force that is related to various floor conditions. When the adhesion force between driving wheels and floor decreases suddenly, the robot begins slip. In order to overcome this slip problem, optimal slip velocity must be decided for stable movement of wheeled robot. First of all, this paper shows that conventional PI control can not be applied to a wheeled robot of the light weight. Secondly, proposed fuzzy logic is applied to the Takagi-Sugeno model for the configuration of fuzzy sets. For the design of Takagi-Sugeno model and fuzzy rule, proposed algorithm uses FCM(Fuzzy c-mean clustering method) algorithm. In additionally, this algorithm adjusts the driving torque for restraining re-slip. The proposed fuzzy logic controller(FLC) is pretty useful with prevention of the slip phenomena for the controller performance in the re-adhesion control strategy, These procedures are implemented using a Pioneer 2-DXE wheeled robot parameter.

• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.877-878
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• 2006

In electric motor coaches, the rolling stocks move by the adhesive effort between rail and driving wheel. Generally, the adhesive effort is defined by the function of both the weight of electric motor coach and the adhesive effort between rails and driving wheel. The characteristics of adhesive effort is strongly affected by the conditions between rails and driving wheel. When the adhesive effort decreases suddenly, inertia conversion the electric motor coach has slip phenomena. This paper proposes a anti-slip control algorithm which uses the maximum adhesive effort by instantaneous estimation of adhesion force using load torque disturbance observer. Based on this estimated adhesive effort, the anti-slip control is performed to obtain the maximum transfer of the tractive effort.

• Earthquakes and Structures
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• v.9 no.3
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• pp.503-539
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• 2015

A new constitutive model for the representation of the seismic behaviour of steel bars including hardening phenomena is presented. The model takes into account relative slip between bars and concrete, necessary for the estimation of the structural behaviour of r.c. elements and of the level of strain induced by earthquakes on bars. The present work provides the analytical formulation of the post-yielding behaviour of reinforcements, resulting in a continuous axial stress-slip relationship to be implemented in engineering software. The efficacy of the model is proved through the application to a cantilever column, for whose bars the constitutive law is derived.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.04a
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• pp.214-215
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• 2009

The friction is inevitable and unpredictable phenomena, so most mechanical systems are designed to low friction effect by using bearings and lubricants. However, the slip-stick actuator applies the friction force to its movement. The slip-stick mechanism is applied the piezoelectric actuator to overcome short displacement. Fast response of piezoelectric actuator is also good characteristic for the slip-stick mechanism. However, the piezoelectric actuator with slip-stick mechanism isn't common, because its cost and driving voltage are too high. In this paper, a voice-coil actuator with slip-stick mechanism is introduced. The cost and the driving voltage of a voice-coil actuator are much less than the piezoelectric actuator. And a dynamic vibration amplifier is proposed to adjust the dynamic performance of the actuator. By the results of numerical analysis, the feasibility of a dynamic vibration amplifier is verified.

• Korea-Australia Rheology Journal
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• v.17 no.4
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• pp.207-215
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• 2005

We present a finite difference solution for electrokinetic flow in rectangular microchannels encompassing Navier's fluid slip phenomena. The externally applied body force originated from between the nonlinear Poisson-Boltzmann field around the channel wall and the flow-induced electric field is employed in the equation of motion. The basic principle of net current conservation is applied in the ion transport. The effects of the slip length and the long-range repulsion upon the velocity profile are examined in conjunction with the friction factor. It is evident that the fluid slip counteracts the effect by the electric double layer and induces a larger flow rate. Particle streak imaging by fluorescent microscope and the data processing method developed ourselves are applied to straight channel designed to allow for flow visualization of dilute latex colloids underlying the condition of simple fluid. The reliability of the velocity profile determined by the flow imaging is justified by comparing with the finite difference solution. We recognized the behavior of fluid slip in velocity profiles at the hydrophobic surface of polydimethylsiloxane wall, from which the slip length was evaluated for different conditions.

• The Transactions of the Korean Institute of Power Electronics
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• v.8 no.4
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• pp.366-374
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• 2003

In electric motor coaches, the rolling stocks move by the adhesive effort between rail and driving wheel. Generally, the adhesive effort is defined by the function of both the weight of electric motor coach and the adhesive effort between rails and driving wheel. The characteristics of adhesive effort is strongly affected by the conditions between rails and driving wheel. When the adhesive effort decreases suddenly, the electric motor coach has slip phenomena. This paper proposes a re-adhesion control algorithm which uses the maximum adhesive effort by instantaneous estimation of adhesion force using load torque disturbance observer. Based on this estimated adhesive effort, the re-adhesion control Is peformed to obtain the maximum transfer of the tractive effort.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.05a
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• pp.103-108
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• 2007

This paper presents a friction model to realize self-excited vibration of multi-body systems. The friction coefficient is modeled with a spline function in most commercial codes. Even if such a function resolves the problem of discontinuity in friction force, it cannot realize self-excited vibration phenomena. Furthermore, as the relative velocity approaches zero, the friction coefficient approaches zero with the conventional model. So, slip occurs when small force is applied to the system. To avoid these problems a new friction model is proposed in this study. With the new friction model, the self-excited vibration can be realized since the friction coefficient changes with the relative velocity. Furthermore, the slip phenomena could be reduced significantly with the proposed model.