• International Journal of Precision Engineering and Manufacturing
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• v.2 no.2
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• pp.26-30
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• 2001

This paper deals with the feasibility assessment of hybrid linear motor that operates based on self-moving cell concept. The moving cell is composed of Magnetostrictive actuator and a ring structure, and a cell train is constructed by connecting two cells in series. Since this motor uses strong push force of Terfenol-D actuators and friction of the cells, it can essentially produce long stroke and large force. The overall performance of the motor was measured in terms of speed and force.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.17-24
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• 2002

Terfenol-D is one of magnetostrictive materials which have the property of converting the energy in magnetic fields into mechanical movement and vice versa. We designed and fabricated a linear magnetostrictive actuator using Terfenol-D. It has 25mm diameter and 100mm long. To grasp the characteristics of it, n series of tests were performed in the range of 50Hz below. Induced-strain actuation displacements of the actuator measured by test and predicted by magnetic analysis agreed well. And blocked forces according to the input currents were estimated from the testing results. Modelling method representing the exerting force of a linear magnetostrictive actuator was confirmed through some testing results.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.11 no.1
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• pp.26-31
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• 1975

Mordern Ocean-going ships utilize stabilization techniques in order to minimize the effects of oscillations due to the unwanted disturbances. In this paper, as an elementary design of automatic control system with linear-state vari;tble feedback and series compensator for ship stabilization, analysis and design is limited to the linear time-invariant single input and output system. In order for the Controlled system to meet the requirements of stability, accuracy and transient response, a model of the automatic control system is proposed. For the analysis and design of this model, the state-space method, that is, the mordern way, or an alternative to the transfer function method of describing a linear system that utilize the state variables and state equations, is applied.

• Journal of the Korean Mathematical Society
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• v.48 no.4
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• pp.775-795
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• 2011

The disturbance attenuation problem for a class of discretetime switched linear systems with exponential uncertainties via switched state feedback and switched dynamic output feedback is investigated, respectively. By using Taylor series approximation and convex polytope technique, exponentially uncertain discrete-time switched linear system is transformed into an equivalent switched polytopic model with additive norm bounded uncertainty. For such equivalent switched model, one designs its switching strategy and associated state feedback controllers and dynamic output feedback controllers so that whole switched model is asymptotical stabilization with H-in nity disturbance attenuation base on switched Lyapunov function and LMI approach. Finally, two numerical examples are presented to illustrate our results.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.53 no.11
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• pp.747-752
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• 2004

This paper presents an iterative linear matrix inequality (LMI) approach to the design of a static output feedback (SOF) stabilization controller. A linear penalty function is incorporated into the objective function for the non-convex rank constraint so that minimizing the penalized objective function subject to LMIs amounts to a convex optimization problem. Hence, the overall procedure results in solving a series of semidefinite programs (SDPs). With an increasing sequence of the penalty parameter, the solution of the penalized optimization problem moves towards the feasible region of the original non-convex problem. The proposed algorithm is, therefore, convergent. Extensive numerical experiments are Deformed to illustrate the proposed algorithm.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.51 no.4
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• pp.137-143
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• 2002

Because Block Pulse functions are used in a variety of fields such as the analysis and controller design of systems, it is necessary to find the more exact value of the Block Pulse series coefficients. This paper presents a method for the state estimation of the time-invariant linear systems via the improved estimation method for the Block Pulse coefficients by using the Simpson's rule. The proposed method using the Simpson's rule improve the accuracy of the Block Pulse coefficients.

• Journal of the Korean Institute of Telematics and Electronics
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• v.19 no.2
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• pp.1-6
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• 1982

This paper reviews and describes some applications of perturbation theory in the practical analysis of linear systems which involve random parameters. Statistical measures of the system outputs are derived in terms of statistical measures of the system parameters and inputs (i.e., in the way of perturbed linear operator equations). Perturbed state transition matrix is also derived. With simple first-order and second-order linear system models, we compare the accuracy of perturbation results with the exact ones. And the convergence of perturbation series is also investigated.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.1
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• pp.64-71
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• 2015

This paper deals with analysis of armature reaction magnetic field of linear generator with three phases coreless/cored type concentrated winding. On the basis of a magnetic vector potential and Maxwell's equations, governing equations to predict armature reaction field are derived, and current density modeling is also performed analytically by using the Fourier series expansion. The analytical method used in this paper is confirmed by comparing with finite element analysis results.

• 한국전산유체공학회:학술대회논문집
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• 1998.11a
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• pp.121-126
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• 1998

A numerical optimization procedure is developed to find the inlet velocity profile that yields the most uniform epitaxial layer in a vertical MOCVD reactor. It involves the solution of fully elliptic equations of motion, temperature, and concentration; the finite volume method based on SIMPLE algorithm has been adopted to solve the Navier-Stokes equations. The overall optimization process is highly nonlinear and has been efficiently treated by the sequential linear programming technique that breaks the non-linear problem into a series of linear ones. The optimal profile approximated by a 6th-degree Chebyshev polynomial is very successful in reducing the spatial non-uniformity of the growth rate. The optimization is particularly effective to the high Reynolds number flow. It is also found that a properly constructed inlet velocity profile can suppress the buoyancy driven secondary flow and improve the growth-rate uniformity.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.310.2-310
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• 2002

Terfenol-D is one of magnetostrictive materials which have the property of converting the energy in magnetic fields into mechanical movement and vice versa. We designed and fabricated a linear magnetostrictive actuator using Terfenol-D. It has 25mm diameter and 100mm long. To grasp the characteristics of it, a series of tests were performed in the range of 50㎐ below. Induced-strain actuation displacements of the actuator measured by test and predicted by magnetic analysis agreed well. (omitted)