• Journal of Mechanical Science and Technology
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• v.19 no.2
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• pp.529-539
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• 2005

The development of a fast, accurate, and inexpensive position-controlled pneumatic actuator that may be applied to various practical positioning applications with various external loads is described in this paper. A novel modified pulse-width modulation (MPWM) valve pulsing algorithm allows on/off solenoid valves to be used in place of costly servo valves. A comparison between the system response of the standard PWM technique and that of the modified PWM technique shows that the performance of the proposed technique was significantly increased. A state-feedback controller with position, velocity and acceleration feedback was successfully implemented as a continuous controller. A switching algorithm for control parameters using a learning vector quantization neural network (LVQNN) has newly proposed, which classifies the external load of the pneumatic actuator. The effectiveness of this proposed control algorithm with smooth switching control has been demonstrated through experiments with various external loads.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.1509-1512
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• 1996

This paper presents an intelligent autopilot for STT missiles with multiple controllers. The mixed H$_{2}$/H$_{\infty}$ control technique is applied for each controller and implemented by using the genetic searching algorithm. To facilitate automatic switching of multiple controllers under different operating conditions, an error based switching scheme is also combined with the multiple controllers at the higher level, which constitutes a hierarchical intelligent control system. It is shown via computer simulation that the proposed autopilot outperforms the conventional one..

• 전기의세계
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• v.28 no.3
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• pp.57-64
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• 1979

The static state estimation are divided into two groups; estimation and detection & identification. This paper centers on detection and identification algorithm. Especially, the identification of line errors is focused on and is performed by the extended W.L.S. algorithm with line swithching states. Here, line switching states mean the discrete values of line admittance which are influenced by unexpected line switching. The numerical results are obtained from the assumption that the noise vector is independent zero mean Gaussian random variables.

• The Journal of the Acoustical Society of Korea
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• v.37 no.2
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• pp.110-117
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• 2018

In this paper, we propose a low delay window switching MDCT (Modified Discrete Cosine Transform) method for speech/audio coder. The window switching algorithm is used to reduce the degradation of sound quality in non-stationary trasient duration and to reduce the algorithm delay by using the low delay TDAC (Time Domain Aliasing Cancellation). While the conventional window switching algorithms uses overlap-add with different lengths, the proposed method uses the fixed overlap add length. It results the reduction of algorithm delay by half and 1 bit reduction in frame indication information by using 2 window types. We apply the proposed algorithm to G.729.1 based on MDCT in order to evaluate the performance. The propose method shows the reduction of algorithm delay by half while speech quality of the proposed method maintains same as the conventional method.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.7
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• pp.3433-3446
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• 2019

Aiming at the high complexity of traditional single-channel demodulation algorithm for PCMA signals, a new demodulation algorithm based on neural network is proposed to reduce the complexity of demodulation in the system of non-cooperative PCMA communication. The demodulation network is trained in this paper, which combines the preprocessing module and decision module. Firstly, the preprocessing module is used to estimate the initial parameters, and the auxiliary signals are obtained by using the information of frequency offset estimation. Then, the time-frequency characteristic data of auxiliary signals are obtained, which is taken as the input data of the neural network to be trained. Finally, the decision module is used to output the demodulated bit sequence. Compared with traditional single-channel demodulation algorithms, the proposed algorithm does not need to go through all the possible values of transmit symbol pairs, which greatly reduces the complexity of demodulation. The simulation results show that the trained neural network can greatly extract the time-frequency characteristics of PCMA signals. The performance of the proposed algorithm is similar to that of PSP algorithm, but the complexity of demodulation can be greatly reduced through the proposed algorithm.

• Proceedings of the KIEE Conference
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• 1991.11a
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• pp.171-174
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• 1991

Among the various PWM methods, the hysteresis-band current control PWM method is popularly used because of its simplicity of implementation, fast response characteristics and inherent peak current limiting capability. However, the current control PWM method with a fixed hysteresis-band has the disadvantage that switching frequency decreases and current ripple is high as the increasing of back-EMF. As a result, load current contains excess harmonics. This paper describes a adaptive hysteresis-bandwidth control algorithm so as to maintain the average switching frequency constant and decrease the current ripple where the hysteresis bandwidth is derived as a relation with the switching frequency. This control algorithm is applied to the surface-type brushless DC motor with separated winding and using the computer simulation, the validity of its algorithm is proved.

• Journal of Electrical Engineering and Technology
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• v.9 no.6
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• pp.2168-2180
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• 2014

In this paper, a generalized power loss algorithm for multilevel neutral-point clamped (NPC) PWM inverters is presented, which is applicable to any level number of multilevel inverters. In the case of three-level inverters, the conduction loss depends on the MI (modulation index) and the PF (power factor), and the switching loss depends on a switching frequency, turn-on and turn-off energy. However, in the higher level of inverters than the three-level, the loss of semiconductor devices cannot be analyzed by conventional methods. The modulation depth should be considered in addition, to find the different conducting devices depending on the MI. In a case study, the power loss analysis for the three- and five-level NPC inverters has been performed with the proposed algorithm. The validity of the proposed algorithm is verified by simulation for the three-and five-level NPC inverters and experiment for three-level NPC inverter.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.47 no.6
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• pp.51-57
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• 2010

In this paper, we propose a new adaptive MIMO switching algorithm that provides the optimal trade-off between throughput and reliability of data in MIMO system. The proposed algorithm is based on the variable packet error predictor which is robust for channel estimation error, and we show that our algorithm has a better spectrum efficiency than the conventional MIMO switching techniques about 8 percent point.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.37 no.11
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• pp.826-833
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• 1988

In this paper we studied the control of overload which could bring the degradation of performance and threaten the stability of the electronic switching system. In order to get the essential requirement for overload control algorithm, we tried to extract the characteristics of commonly used algorithms by means of simulating overload control alogrithms in numerical stored program control switching model. As the result, we could find that the overload control algorithm which monitored the CPU occupancy had the best call complete rate and good response characteristecs and the algorithm using the offered load as a system state variable had a good grade of service which was represented by a short dial tone delay and 3rd quartile of deal tone delay. however, these control algorithms have no generality and need to get the control parameters by the trial-and-error method. We suggested the guidelines on the design of the overload control algorithm.

• Journal of the Korean Society for Precision Engineering
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• v.32 no.6
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• pp.553-562
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• 2015

This paper presents a strategy and an algorithm for levitation control of an over-actuated passive maglev tray system. The passive maglev tray system has more actuators than its degrees of freedom. The actuators of the system are switching when the tray travels longitudinally. Furthermore, the levitation forces of the actuators are non-homogeneous because the actuation devices are not in the moving platform. These characteristics make a limit in using conventional control approaches for levitation. For smooth actuator switching, the actuator force generation should be dependent on longitudinal positions of the tray. To enable constant pose tracking, this research introduces a control strategy and a control algorithm based on integral controllers on virtual variables. The states of the tray are estimated using a Kalman filter and fed to the proposed controller. The performances of the proposed control strategy and the algorithm are validated through tests.