• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1996년도 봄 학술발표회 논문집
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• pp.241-246
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• 1996

A new solution for the dynamic analysis of as asphalt concrete pavements under moving loads has been developed. The asphalt concrete pavement can be modeled in elastic or viscoelastic medium of multi-layered structure. The subgrade can be modeled as either a rigid base or a semi-infinite halfspace. The loads may be constant or arbitrary circular loads into one direction. The method utilizes the Complex Response Method of transient analysis with a continuum solution in the horizontal direction and a finite-element solution in the vertical direction. This proposed method incorporates such important factors as wave propagation, inertia and damping effects of the medium as well as frequency-dependent asphalt concrete properties. The proposed method has been validted with the full-scale field truck test, which was conducted on instrumented asphalt concrete section on a test track at PACCAR Technical Center in Mount Vernon, Washington. Comparison with field strain data from full-scale pavement tests has shown excellent agreement. Theoretical results have shown that the effect of vehicle speed is significant and that it is in part due to the frequency-dependent

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 Proceedings ICPE 98 1998 International Conference on Power Electronics
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• pp.287-292
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• 1998

This paper presents some results of performance evaluation test via actual machines of a new hybrid vector control utilizing a new indirect orientation scheme and stable filter embedded direct orientation scheme for induction motors without speed or position sensor. It is shown through the test by 0.3(kW) and 3.7(kW) motors that the proposed sensorless vector control has the following high potentialities: 1) speed range is 0 to 600(rad/s) or more, 2) zero-speed command is accepted and settles the machines at a stable standstill with no vibration 3) it can make machines to track variable command of acceleration and deceleration $\pm$6,000(rad/s2), 4) it can make machines to drive directly load of at least 26 times larger inertia than that of the machine, 5) it can make machines to produce much larger torque than the rating in torque control mode even at standstill. The performance confirmed by the test is far away for previous schemes or sensorless drive apparatuses.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1996년도 추계학술대회 논문집
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• pp.419-424
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• 1996

As track density increases, the effects of nonlinearity in pivot bearing of hard disk drive on the servo performance are becoming more important in considering the range of inertia force and the input torque during settling and tracking mode. Recently, an increasing attention is given to more precise experimental observations and modelings of pivot nonlinearity for achieving higher performance of servo control. In this paper, we propose a new model that shows an improved prediction of the pivot nonlinearity than existing preload-plus-two-slope model at matching simulations and experimental results in both time and frequency domains. Experimental measurements are carried out to validate and identify the specific nonlinearity presents in the pivot bearing when its in fine motion. Using the experimental results new model along with the existing one are characterized and compared for relevancies.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집B
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• pp.410-415
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• 2001

Hydraulic mounts have been used as an alternative to the conventional rubber mounts for they can provide more desirable stiffness and damping properties which may vary with frequency and excitation amplitude. Although a lumped-parameter non-linear model of the hydraulic mount developed by a simple fluid dynamic analysis can be successfully used for representing the inertia track dynamics, a linear model is still preferred. In this paper, an analytic technique for making a linear model of the hydraulic mount is proposed.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 B
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• pp.821-823
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• 2004

In this paper, a backstepping speed controller applied in SRM is presented. The driver of SRM is generally planned with a PI controller. A PI controller is becomes a satisfied structure in the system. it is used in position and speed control loops. However, when the system parameter uncertainties large inertia and load disturbance, it will not be able to expect a satisfied efficiency. Therefore, a backstepping control law was researched, which is able application even to a linear system as well as a nonlinear and it is more excellent than a origin adaptive control law. In this paper, a backstepping control law applied the drive system of SRM was used in the drive controller. The computer simulation result clearly show that the applied backstepping controller can track the speed reference signal generated by internal signals.

• Journal of Mechanical Science and Technology
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• 제19권3호
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• pp.768-777
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• 2005

This paper shows that the performance of a nonlinear fluid engine mount can be improved by an optimal design process. The property of a hydraulic mount with inertia track and decoupler differs according to the disturbance frequency range. Since the excitation amplitude is large at low excitation frequency range and is small at high excitation frequency range, mathematical model of the mount can be divided into two linear models. One is a low frequency model and the other is a high frequency model. The combination of the two models is very useful in the analysis of the mount and is used for the first time in the optimization of an engine mount in this paper. Normally, the design of a fluid mount is based on a trial and error approach in industry because there are many design parameters. In this study, a nonlinear mount was optimized to minimize the transmissibilities of the mount at the notch and the resonance frequencies for low and high-frequency models by a popular optimization technique of sequential quadratic programming (SQP) supported by $MATLAB^{(R)}$subroutine. The results show that the performance of the mount can be greatly improved for the low and high frequencies ranges by the optimization method.

• Journal of Astronomy and Space Sciences
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• 제20권4호
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• pp.375-382
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• 2003

위성을 설계함에 있어 질량제어 계획을 작성하고 질량자료를 유지하며 시스템의 질량특성을 계산하고 제어하는 것은 기계 시스템 담당자가 수행하는 임무 중에 하나이다. 위성의 질량특성은 자료수집, 특성예측 그리고 실제 측정의 순서로 설계 및 제작이 진행됨에 따라 수행된다. 질량특성 데이터베이스는 설계과정을 통하여 작성하게 되며 질량특성 측정 시험을 수행하여 데이터베이스의 신뢰성을 확인할 수 있어야 한다. 본 논문에서는 위성에서의 질량 제어계획의 일반적인 내용과 시스템 수준의 질량중심 및 관성 모멘트 계산과 관련된 여러 가지 구체적인 사항을 고려한 이론적 질량 특성 데이터베이스를 개발하고, 다목적실용위성 2호 개발을 수행하면서 얻게 된 실제적인 자료와 경험을 토대로 본 연구에서 개발된 데이터베이스의 신뢰성을 확인하였다.

• 항공우주기술
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• 제3권2호
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• pp.1-6
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• 2004

위성을 설계함에 있어 질량제어 계획을 작성하고 질량자료를 유지하며 시스템의 질량특성을 계산하고 제어하는 것은 기계 시스템 담당자가 수행하는 임무 중에 하나이다. 위성의 질량특성은 자료수집, 특성예측 그리고 실제 측정의 순서로 설계 및 제작이 진행됨에 따라 수행된다. 질량특성 데이터베이스는 설계과정을 통하여 작성하게 되며 질량특성 측정 시험을 수행하여 데이터베이스의 신뢰성을 확인할 수 있어야 한다. 본 논문에서는 위성에서의 질량 제어계획의 일반적인 내용과 시스템 수준의 질량중심 및 관성 모멘트 계산과 관련된 여러 가지 구체적인 사항을 고려한 이론적 질량 특성 데이터베이스를 개발하고, 다목적 실용위성 2호 개발을 수행하면서 얻게 된 실제적인 자료/경험을 토대로 본 연구에서 개발된 데이터베이스의 신뢰성을 확인하였다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.786-791
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• 2003

This paper proposes an adaptive control algorithm for nonholonomic mobile robots with unknown parameters and the proposed control method is used in numerical simulations for applying to a practical twowheeled welding mobile robot(WMR). The proposed adaptive controller to track an arbitrary given welding path is designed by using back-stepping technique and is derived for a nonlinear model under the assumption such that the system parameters are partially known. Moreover, the proposed adaptive control system is stable in the sense of Lyapunov stability. Inertia moments of system are considered to be unknown parameters and their values can be estimated simply by using update laws proposed in an adaptive control scheme of this research. The simulation results are provided to show the effectiveness of the accurate tracking capability of the proposed controller for two-wheeled welding mobile robot with a smooth curved reference welding path.

• 제어로봇시스템학회논문지
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• 제22권7호
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• pp.502-507
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• 2016

In this paper, we propose a tracking control method for a quadrotor equipped with a 2-DOF manipulator, which is based on the multiple sliding surface control (MSSC) method. To derive the model of a quadrotor equipped with a 2-DOF manipulator, we obtain the models of a quadrotor and a 2-DOF manipulator based on the Lagrange-Euler formulation separately - and include the inertia and the reactive torque generated by a manipulator when these obtained models are combined. To make a quadrotor equipped with a manipulator track the desired path, we design a double-loop controller. The desired position is converted into the desired angular position in the outer controller and the system's angle tracks the desired angular position through the inner controller based on the MSSC method. We prove that the position-tracking error asymptotically converges to zero based on the Lyapunov stability theory. Finally, we demonstrate the effectiveness of the proposed control system through a computer simulation.