• International Journal of Aeronautical and Space Sciences
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• v.16 no.2
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• pp.137-147
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• 2015

Hypersonic vehicles exhibit distinct dynamic and static characteristics, such as unstable dynamics, strict altitude angle limitation, large control bandwidth, and unconventional system sensitivity. In this study, compromise relations between the dynamic features and static performances for hypersonic vehicles are investigated. A compromise optimal design for hypersonic vehicles is discussed. A parametric model for analyzing the dynamic and static characteristics is established, and then the optimal performance indices are provided according to the different design goals. A compromise optimization method to balance the dynamic and static characteristics is also discussed. The feasibility of this method for hypersonic vehicles is demonstrated.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10a
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• pp.64-69
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• 1993

In this paper we present the performance bounds of the optimal FIR filter in continuous time systems with modeling uncertainty. The performance measure bounds are calculated from the estimation error covariance bounds of the optimal FIR filter and the suboptimal FIR filter. Performance error bounds range are expressed by the upper bounds on the estimation error covariance difference between the real and nominal values in case of the systems with noise uncertainty or model uncertainty. The performance bounds of the systems are derived on the assumption that the system uncertainty and the estimation error covariance are imperfectly known a priori. The estimation error bounds of the optimal FIR filter is compared with those of the Kalman filter via a numerical example applied to the estimation of the motion of an aircraft carrier at sea, which shows the former has better performances than the latter.

• Journal of Institute of Control, Robotics and Systems
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• v.11 no.3
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• pp.254-261
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• 2005

Time-optimal performances are analyzed in the sense of inner loop. A varying-time sharing thrusting logic is suggested as a new sequential paired thrusting logic for fast maneuvers of satellites with coupled thruster configuration. Its time-optimal maneuvering performance is compared with two conventional thrusting logics: separate thrusting logic and constant-time sharing sequential paired thrusting logic. It is found that the newly suggested varying-time sharing thrusting logic can be easily implemented by adjusting the conventional constant-time logic with its thrust on-time, while it can reduce the maneuvering time enormously as much as the separate thrusting logic. The performance of the logic is simulated on the agile maneuvering spacecraft model KOMPSAT-II.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.896-900
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• 1996

New approach to determine the optimal design of automotive tire profile was introduced. In this study, optimal design technology was combined with a finite element method. Through tire profile optimization, tire profile was obtained and its profile improved high speed durability and maneuverability Static and dynamic behavior analysis of new concepted tire was compared with conventional tire profile. Optimal design methodology will provide much informations to improve various tire performances.

• Journal of Magnetics
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• v.18 no.4
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• pp.454-459
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• 2013

This paper deals with an optimal angle error reduction method of magnetic position sensor using hall effect elements. The angle detection simulation for the magnetic position sensor is performed by 3 dimensional finite element method and Taguchi method, one of the design of experiments. The magnetic position sensor is required to generate ideal sine and cosine waveforms from its hall effect elements according to rotation angle for precise angle information. However, the output signals are easy to include harmonics due to uneven magnetic field distribution from permanent magnet in the air-gap in the vicinity of hall effect elements. For the Taguchi method, three design parameters related to position of hall effect elements and shape of back yoke are selected. The characteristics of optimal magnetic position sensor are compared with those of original one in terms of simulation as well as experiment. Finally, the performances of the motor adopting original model and optimal model are represented for the purpose of verification of motor performance due to signals from magnetic position sensor.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.2
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• pp.140-146
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• 2005

The on-line optimal control algorithm for central heating system has been researched for minimizing energy consumption while maintaining the comfort of indoor thermal environment in terms of the environmental variables such as indoor heating load and outdoor temperature variation. This study has been done by using TRNSYS Program in order to analyze the central heating system. The optimal control algorithm shows good energy Performances in comparison with the conventional one.

• Journal of Institute of Control, Robotics and Systems
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• v.1 no.1
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• pp.20-24
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• 1995

In this paper we analyze the performance bounds of the optimal FIR filter in continuous time systems with modeling uncertainty. The performance bounds are presented by the estimation error convariance and they are here expressed by the upper bounds of the difference of the estimation error covariance between the real and nominal values in case of the system with model uncertainties whose upper bounds are imperfrctly known a priori. The performance bounds of the optimal FIR filter are compared with those of the Kalman filter via a numerical example applied to the estimation of the motion of an aircraft carrier at sea, which shows the former has better performances than the latter.

• International Journal of Control, Automation, and Systems
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• v.6 no.2
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• pp.160-170
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• 2008

Temperature control of an enclosed thermal system which has many applications including Rapid Thermal Processing (RTP) of semiconductor wafers showed an input-constraint violation for nonlinear controllers due to inherent strong coupling between the elements [1]. In this paper, a constrained nonlinear optimal control design is developed, which accommodates input constraints using the linear algebraic equivalence of the nonlinear controllers, for the temperature control of an enclosed thermal process. First, it will be shown that design of nonlinear controllers is equivalent to solving a set of linear algebraic equations-the linear algebraic equivalence of nonlinear controllers (LAENC). Then an input-constrained nonlinear optimal controller is designed based on that LAENC using the constrained linear least squares method. Through numerical simulations, it is demonstrated that the proposed controller achieves the equivalent performances to the classical nonlinear controllers with less total energy consumption. Moreover, it generates the practical control solution, in other words, control solutions do not violate the input-constraints.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.43 no.5
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• pp.703-710
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• 1994

This paper describes for the applicability of optimal PID controller to the load frequency control of 2-area power systems. The proposed optimal PID controllers are designed by the optimization technique of P.I.D's gain coefficients using the relatively ingeneous simplex method, and we have considered the system sensitivity for the optimal gains and the stable effects of systems to speed regulation changes. This PID controller for load frequency control systems with exciter shows better performances and robustness than conventional tie-line bias controller.

• International Journal of Internet, Broadcasting and Communication
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• v.13 no.4
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• pp.48-54
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• 2021

In most existing researches on non-orthogonal multiple access (NOMA) with symmetric superposition coding (SSC), uniform sources have been usually considered. For the first part in this two-part paper, for the strongest channel gain user, we showed that the bit-error rate (BER) for the optimal maximum a-posteriori (MAP) receiver for the non-uniform source improves slightly, compared to that of the conventional receiver for the uniform sources. We demonstrate that in communication scenarios of the non-uniform source NOMA schemes, for the weakest channel gain user, the BER performance of the optimal MAP receiver for a non-uniform source improves greatly, compared to that of the conventional receiver for uniform sources. We first derive an analytical expression of the BER for non-uniform source NOMA with SSC. Then, simulations demonstrate that the BER of the optimal MAP receiver for the non-uniform source improves, compared with that of the conventional maximum likelihood (ML) receiver for the uniform sources. In result, the proposed optimal MAP receiver for the non-uniform source could be a promising scheme for SSC NOMA, with improved BER performances.