• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.547-551
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• 1996

In this paper, robust vibration control of a one-link flexible robot arm based on variable structure system is discussed. We derive dynamic equations of it using a Lagrangian assumed modes method based on Bernoulli-Euler Beam theory. The optimal sliding surface is designed and the problem of chattering is also solved by the adoption of a continuous control law within a small neighborhood of the switching hyperplane.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.1
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• pp.29-35
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• 2014

This paper aims to obtain the effect of lightweight on Radius rod. The response surface method used in the paper is the statistical method. Optimization method is performed with the Radius rod using the lightweight material. Structural analysis is executed by using the ANSYS program to find static and dynamic responses. From this study result, it is verified that the response surface method has the advantage of optimum value in comparison with other optimization methods. The analysis is also performed by response surface method to derive optimal design values. Steel model and aluminium initial model are obtained by finite element analysis to clarify design criteria and the results are compared with three models each other. The weights can be reduced by optimal design analysis results of these models similar to those of existing products. The quantitative goals in this study can also attained through results of fatigue analyses. The reliability on optimal design of Radius rod can be improved by use of structural and fatigue analysis results.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.11
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• pp.1327-1334
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• 2012

This study shows the conformance-based design results of a fourth-order dynamic actuator showing a performance variation caused by variation in the components as well as aero-induced disturbances. The actuator comprises a BLDC motor, spur gear and worm gear assembly, and canard. The actuator performance was evaluated by using time-variant angle information of the canard. Based on the response surface models, critical system variables were screened using F-tests, and then, the performance was approximated as a function of the variables because it is difficult to determine the performance of a high-order dynamic system as a function of system variables through analytical approaches. In this study, the conformance of uncertain performance to the specification was defined as a probability measure. The design variables obtained by optimizing the measure can provide actuator performance conforming to the specifications considered, even though there is a variation in both the components and the aero-induced disturbances.

• The Journal of Korea Robotics Society
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• v.12 no.3
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• pp.339-349
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• 2017

In this paper, we present a finite-time sliding mode control (FSMC) with an integral finite-time sliding surface for applying the concept of graph theory to a distributed wheeled mobile robot (WMR) system. The kinematic and dynamic property of the WMR system are considered simultaneously to design a finite-time sliding mode controller. Next, consensus and formation control laws for distributed WMR systems are derived by using the graph theory. The kinematic and dynamic controllers are applied simultaneously to compensate the dynamic effect of the WMR system. Compared to the conventional sliding mode control (SMC), fast convergence is assured and the finite-time performance index is derived using extended Lyapunov function with adaptive law to describe the uncertainty. Numerical simulation results of formation control for WMR systems shows the efficacy of the proposed controller.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.10
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• pp.139-145
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• 1996

The machining accuracy and performance is largely influenced by the static, dynamic and thermal characteristics of spindle systems in machine tools, because the spindle system is a intermedium for cutting force from tool and machine powef from motor. Large cutting force and power are transmitted by bearing with a point or line contact. So, the spindle system is the static and dynamic weakest point in machine structure. For improvement of static stiffness of spindle system can be changed design parameters, such as diameter of spindle, stiffness of bearing and bearing span. But for dynamic stiffness, the change of the design parameters are not useful. In this paper, the combined bearing arrangement is suggested for high damping spindle system. The combined bearing arrangement is composed of tandem double back to back arrangement type ball bearins and a high damping hydrostatic bearing. The variation of static deflection and amplitude in first natural frequency is evaluated with the location of hydrostatic bearing between front and rear ball bearing. The optimized location of hydrostatic bearing for high static and dynamic stiffness is determined rapidly and exactly using the mode shape and transfer function of spindle. The calculation of damping effect on vibration by unbalance of grinding wheel and pulley in optimized spindle system is carried out to verify the validity of the combined bearing arrangement. Finally, the simulation of grinding process show that the surface roughness of workpiece with high damping spindle system is 60% better than with ball bearing spindle system.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.11a
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• pp.401-406
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• 2008

This paper proposes a method to calculate the static characteristics of the FDBs with the curved surface. The general Reynolds equations are derived for the curved surfaces in the ${\theta}s$ plane. And the Reynolds equation is transformed to the finite element equations by considering the continuity of pressure and flow at the interface between the curved, journal and the thrust bearings. It also includes the Reynolds boundary condition in the numerical analysis to simulate the cavitation phenomenon. The static characteristics of the coupled journal and conical bearings were investigated due to the variation of conical angle. It shows that the conical angle is one of the important design parameters affecting the static and dynamic characteristics of FBBs.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.04a
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• pp.85-90
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• 1997

In the stroke sensitive shock absorber, the oil path is formed along the internal cylinder surface to make the eli flow during piston's upper-lower reciprocation movement. With constraint to the conventional shock absorbers which show one dynamic characteristic curve, stroke sensitive shock absorber shows two kins of dynamic characteristic according to the stroke, In the study, analysis on the damping force generation process and dynamic behaviour characteristics of stroke sensitive shock absorber is performed, the valve characteristics being considered more precise information about design and damping performance analysis.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.04a
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• pp.244-249
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• 1997

Internal and external heat sources will cause to deform to machine elements in the contact joint of structure,which results in the change of contact pressure distribution different from initial assembly. Heat induced variations of contact pressure will change the static and dynamic properties such as contact stiffness,damping as well as contact heat conduction in the structure. In order to design and control the intelligent machine tool operating in variant conditions more sophisticatedly, the good prediction for the changes of prescribed propeties are strongly required especially in the contact elements adjacent to the rotational or linear bearing This paper presents some computational and experimental results in regard to static and dynamic characteristics of the press-fitted bush and shaft assembly which is a model of the bearing innerrace and shaft assembly. In the condition of heat generation on the outer surface of the bush,the effects of changes in the negative clearance and the heat flux on pressure distribution and dynamic properties are investigated. Results of this study show that the edge effect of the bush and the initial clearance have effects on the transient dynamic characteristics significantiy.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.453-457
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• 2007

AGT system is a kind of light railway train. AGT system use of concrete track and rubber tire, so it can be reduce the noise and vibration, compare to the normal train system. And, the dynamic responses of normal bridge are influenced by the dynamic characteristics of bridge, the speed of vehicle and the surface roughness of railway. But the AGT system bridge is influenced not only the above facts but also the guiderail unevenness, because, AGT vehicle steered by guiderail. So, in this study, optimized service condition is suggested for the design and operation of AGT system, by the means of experimental study. The experiments are executed for PSC bridge with length of 30m, at the AGT test line in Kyongsan. The test results are compared and investigated according to the prominence. In the test result, the guiderail prominence influenced on the dynamic response of bridge. It shows a increase as compared with no guiderail prominence in the dynamic response value acceleration, displacement, stain.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.862-863
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• 2008

This paper presents the improvement of dynamic characteristics in Interior Permanent Magnet (IPM) type BLDC motor with notch. The notch is applied on the surface of the rotor to reduce the cogging torque and to improve dynamic characteristics. The current, inductance and torque of initial model and optimal model are analyzed by FEA. The validity of improved dynamic characteristics is confirmed.