• Journal of the Korea Concrete Institute
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• v.22 no.6
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• pp.797-803
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• 2010

A dynamic analysis procedure is developed to provide a better estimation of the dynamic responses of pre-stressed concrete (PSC) box girder bridges on the Korea high speed railway. Particularly, a three dimensional numerical model including the structural interaction between high speed vehicles, bridges and railway endures to analyze accurately and evaluate with in-depth parametric studies for dynamic responses of bridge due to the high speed railway vehicles. Three dimensional frame element is used to model the PSC box girder bridges, simply supported span lengths 40 m. The high-speed railway vehicles (K-TGV) including a locomotive are used as 38-degree of freedom system. Three displacements (vertical, lateral, and longitudinal) as well as three rotational components (pitching, rolling, and yawing) are considered in the 38-degree of freedom model. The dynamic analysis by Runge-Kutta method which are able to analyze considering the dynamic impact factors are compared and contrasted. It is proposed as an empirical formula that the impact factors damaged the bridge load-carrying capacities occurs to the bride due to high-speed vehicle.

• Journal of Electrical Engineering and Technology
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• v.6 no.5
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• pp.618-625
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• 2011

This paper presents a double excited three degree-of-freedom (3DOF) motor. The proposed 3DOF motor is designed with a laminated structure, making it easy to manufacture. In addition, it has windings on the stator and rotor, and does not require an expensive permanent magnet. We explain the structure, principle of motion, and design of the proposed motor, and perform an analysis of the static characteristics using the two- and three-dimensional finite element methods (3D FEM). The feasibility of 3D FEM analysis is confirmed by comparing the 3D FEM analysis and experimental results for the rolling and pitching motion. We also confirm the occurrence of holding torque in every motion.

• Journal of the Korean Society for Precision Engineering
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• v.10 no.4
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• pp.216-226
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• 1993

Three dimensional cutting is considered as an equivalent orthogonal cutting through the plane containing both the cutting velocity vector and the chip flow velocity vector in dynamic cutting process. An analytical expression of dynamic cutting force is obtained from the cutting parameters determined by the static cutting. Particular attention is paid to the energy supplied to the vibratory system of cutting tool with two degree of freedom. In this approach, the phase lag of the horizontal vibration of the tool behind the vertical vibration and the direction angle of the fluctuating cutting force is considered in point of stability limits. Chatter vibration can be effectively suppressed by relatively increasing the spring constant and the damping coefficient of the cutting system in the vertical cutting force direction. A good agreement is found between the stability limits predicted by theoretical value and experimental results.

• Journal of Institute of Control, Robotics and Systems
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• v.5 no.3
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• pp.288-296
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• 1999

A force-reflecting hand controller can provide the kinesthetic information obtained from a slave manipulator to the operator of a teleoperation system. The goal is to construct a compact hand controller that can provide large workspace and good force-reflecting capability. This paper presents the design and the analysis of a 6-degree-of-freedom force-reflecting hand controller using fivebar parallel mechanism. The forward kinematics of the fivebar parallel mechanism has been calculated in real-time using three pin-joint sensors in addition to six actuator position sensors. A force decomposition approach is used to compute the Jacobian. To evaluate the characteristics of the fivebar parallel mechanism, it has been compared with the other three parallel mechanisms in terms with workspace and manipulability measure. The hand controller using the fivebar parallel mechanism has been constructed and tested to verify the feasibility of the design concept.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.1545-1548
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• 1997

A Force-refecting hand controller can provide the kinesthetic information obtained from a slave manipulator to the operator of a teleoperation system. This thesis presents the desgn and the analysis of a 6-degree-of-freedom force-reflecting hand controller using fivebar parallel mechanism. The goal of this thesis is to construct a superior hand controller that can provide large workspace and good force-reflecting ability. The forward kinematics of the fivebar paprallel mechanism has been calculated in real-time using three pin-joint sensors in addition to six actuator position sensors. A force decomposition approach is used to comput the Jacobin. To analyze the characteristics of the fivebar parallel mechanism, it has been compared with the other three parallel mechanisms in terms with workspace and manipulability measure. The force-reflecting hand controller using the fivebar parallel mechanism has been constructed and tested to verify the feasibility of the design concept.

• Transactions of the Korean Society of Mechanical Engineers
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• v.10 no.3
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• pp.305-315
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• 1986

Redesign of the mounting system to minimize vibration of a variable displacement engine through computer simulation is considered. A three degree of freedom model is established for an in-line four-cylinder automobile engine with a three point mounting system. The engine mount locations and angles, and isolator sizes are chosen as design parameters. Constraints on isolator deformations and design parameters are imposed. The gradient projection method is utilized for optimization. Simulation studies show significant vibration reduction can be obtained especially at idling speed.

• 제어로봇시스템학회:학술대회논문집
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• 1995.10a
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• pp.444-447
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• 1995

The satellite in a circular orbit about a planet with disturbances and a three-degree-of-freedom (3DOF) structure under seismic excitations are modeled by the linear stochastic differential equations. Then the risk-sensitive optimal control method is applied to those equations. The mean and the variance of the cost function varies with respect to the risk-sensitivity parameter, .gamma.$_{RS}$ . For a particular risk-sensitivity parameter value, risk-sensitive control reduces to LQG control. Furthermore, the derivation of the mean square value of the state and control action are given for a finite-horizon full-state-feedback risk-sensitive control system. The risk-sensitive controller outperforms a classical LQG controller in the mean square sense of the state and the control action.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1993.10a
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• pp.333-338
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• 1993

In this paper, we introduce an industrial three degree of freedom manipulator which loads/unloads various freight on an AGV(automated Guided Vehicle). We design and implement the industrial controller for the manipulator with P-I) gain variation method. Since this battery-powered manipulator is opten driven in an instufficient power condition, the gravity effects on the robot joints can be a significant problem. The objectives of this paper are twofold : the presentation of a PI)-controller which can compensate the gravity effects, and the design and implementation of an industrial three degree of freedom manipulator for loading/unloading.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.24 no.1
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• pp.1-9
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• 2016

In this paper, we integrate three degree of freedom(3DOF) point-mass model for aircraft and three-dimensional path generation algorithms using dubins curve and nonlinear path tracking law. Through this integration, we apply the path generation algorithm to the path planning, and verify tracking performance and feasibility of using the aircraft 3DOF point-mass model for air traffic management. The accuracy of modeling 6DOF aircraft is more accurate than that of 3DOF model, but the complexity of the calculation would be raised, in turn the rate of computation is more likely to be slow due to the increase of degree of freedom. These obstacles make the 6DOF model difficult to be applied to simulation requiring real-time path planning. Therefore, the 3DOF point-mass model is also sufficient for simulation, and real-time path planning is possible because complexity can be reduced, compared to those of the 6DOF. Dubins curve used for generating the optimal path has advantage of being directly available to apply path planning. However, we use the algorithm which extends 2D path to 3D path since dubins curve handles the two dimensional path problems. Control law for the path tracking uses the nonlinear path tracking laws. Then we present these concomitant simulation results.

• Earthquakes and Structures
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• v.18 no.4
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• pp.519-526
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• 2020

Non-stationary random seismic response and reliability of multi-degree of freedom hysteretic structure system are studied based on the cumulative damage failure mechanism. First, dynamic Eqs. of multi-degree of freedom hysteretic structure system under earthquake action are established. Secondly, the random seismic response of a multi-degree freedom hysteretic structure system is investigated by the combination of virtual excitation and precise integration. Finally, according to the damage state level of structural, the different damage state probability of high-rise frame structure is calculated based on the boundary value of the cumulative damage index in the seismic intensity earthquake area. The results show that under the same earthquake intensity and the same floor quality and stiffness, the lower the floor is, the greater the damage probability of the building structure is; if the structural floor stiffness changes abruptly, the weak layer will be formed, and the cumulative damage probability will be the largest, and the reliability index will be relatively small. Meanwhile, with the increase of fortification intensity, the reliability of three-level structure fortification is also significantly reduced. This method can solve the problem of non-stationary random seismic response and reliability of high-rise buildings, and it has high efficiency and practicability. It is instructive for structural performance design and estimating the age of the structure.