• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.6
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• pp.1148-1159
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• 1997

In the broadband integrated service digital networks (B-ISDN), ATM switches hould be abld to accommodate diverse types of applications ith different traffic characteristics and quality ddo services (QOS). Thus, in order to increase the utilization of switches and satisfy the QOS's of each traffic type, some types of priority control schemes are needed in ATM switches. In this paper, a nonblocking input and output queueing ATm switch with capacity C is considered in which two classes of traffics with different loss probability constraints are admitted. 'Partial push-out' algorithm is suggested as a loss priority control schemes, and the performance of this algorithm is analyzed when this is adopted in input buffers of the switch. The quque length distribution of input buffers and loss probabilities of each traffic are obtained using a matrix-geometric solution method. Numerical analysis and simulation indicate that the utilization of the switch with partial push-out algorithm satisfying the QOS's of each traffic is much higher than that of the switch without control. Also, the required buffer size is reduced while satisfying the same QOS's.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.12A
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• pp.1185-1190
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• 2008

In this paper, we propose an simplified successive minimum mean square error ($S^{2}MMSE$) algorithm that can simplify the computational complexity for precoding matrix generation in the successive minimum mean square error (SMMSE) precoding method, which is adopted as a multiuser multiple-input multiple-output (MU-MIMO) precoding technique in the IST (information society technologies)-WINNER (wireless world initiative new radio) project. The original algorithm generates the precoding matrix by calculating all individual precoding vectors with each requiring its own MMSE nulling matrix, over all receive antennas for all users. In contrast, this proposed algorithm first calculates the MMSE nulling matrix for each user, and then calculates all precoding vectors for respective receive antennas of the corresponding user by using the identical MMSE nulling matrix, in which only a simple matrix-vector multiplication is required for each vector. Consequently, it can simplify significantly the computational complexity to generate a precoding matrix for SMMSE precoding.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.892-895
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• 1996

An unknown input observer is proposed that can be used in wheelbase preview control of commercial vehicles. The preview and state information, required to calculate actuator force, are reconstructed from the measurement variables such as heave and pitch acceleration. Gain matrix of observer is optimally selected so that influence of system and measurement noises on the estimation error can be minimized. Estimated preview information requires low pass filtering to eliminate high frequency components resulting from differentiation of noisy output signals. Effectiveness of the proposed method is demonstrated by numerical simulation of half car model.

• 제어로봇시스템학회:학술대회논문집
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• 1987.10b
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• pp.168-173
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• 1987

The optimal Input design problem for linear system Which have the common parameters in the system and noise transfer functions. Exploiting the assumed Model structure and deriving the information matrix structure in detail, D-optimal open-loop stochastic input can be realized as an ARMA process under the Input or output variance constraints. In spite of the reduced order, It Is necessary to develop an efficient algorithms for the optimation with respect to the .rho..

• Journal of Power Electronics
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• v.16 no.3
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• pp.936-945
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• 2016

Large magnitude common-mode voltage (CMV) and its variation dv/dt have an adverse effect on motor drives that leads to early winding failure and bearing deterioration. For matrix converters, the switch states that connect each output line to a different input phase result in the lowest CMV among all of the valid switch states. To reduce the output CMV for matrix converters, this paper presents a new space vector modulation (SVM) strategy by utilizing these switch states. By this mean, the peak value and the root mean square of the CMV are dramatically decreased. In comparison with the conventional SVM methods this strategy has a similar computation overhead. Experiment results are shown to validate the effectiveness of the proposed modulation method.

• Journal of Power Electronics
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• v.19 no.2
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• pp.475-486
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• 2019

This paper proposes the modulation and control of a three-to-six-phase matrix converter with an asymmetrical six-phase output. The matrix converter (MC) outputs consist of two sets of three-phase spatially shifted by $30^0$, where the two sets have two isolated neutrals. The space vector approach is considered for the modeling and subsequent modulation of the three-to-six phase MC. The intelligent selection of voltage space vectors is made to synthesize the reference voltages and to obtain a sinusoidal output. The dwell times of selected voltage space vectors are adjusted in such a way that the effect of the second and the third auxiliary plane vectors (i.e., x1-y1, and x2-y2) are nullified. To achieve the maximum output voltage gain and to ensure that no reactive power is drawn from the utility supply, the input side power factor is maintained at unity. Nevertheless, the source side power factor is controllable. The modulation technique is implemented in dSPACE working in conjunction with a FPGA. Hardware results that validate the proposed control algorithm are discussed.

• Journal of Power Electronics
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• v.15 no.3
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• pp.702-711
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• 2015

In this paper, an effective carrier-based modulation (CBM) strategy to reduce the switching losses for indirect matrix converters (IMCs) is presented. The discontinuous pulse width modulation method is applied to decrease the switching numbers in one carrier cycle, and an optimum offset voltage is selected to avoid commutations of the high output phase currents. By decreasing the switching numbers along with avoiding commutation of the high currents, the proposed CBM strategy significantly reduces the switching losses in IMCs. In addition, the proposed CBM strategy is independent of load conditions, such as load power and power factor, and it has good performance in terms of the input/output waveforms. Simulation and experimental results are provided to verify the effectiveness of the proposed CBM strategy.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.9 s.90
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• pp.801-810
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• 2004

Parameter modification of a linear finite element model(FEM) based on modal sensitivity matrix is usually performed through an effort to match FEM modal data to experimental ones. However, there are cases where this method can't be applied successfully; lack of reliable modal data and ill-conditioning of the modal sensitivity matrix constitute such cases. In this research, a novel concept of introducing feedback loops to the conventional modal test setup is proposed. This method uses closed-loop natural frequency data for parameter modification to overcome the problems associated with the conventional method based on modal sensitivity matrix. We proposed the whole procedure of parameter modification using the closed-loop natural frequency data including the modal sensitivity modification and controller design method. Proposed controller design method is efficient in changing modes. Numerical simulation of parameter estimation based on time-domain input/output data is provided to demonstrate the estimation performance of the proposed method.

• Journal of Institute of Control, Robotics and Systems
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• v.7 no.3
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• pp.183-192
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• 2001

In this paper, the decoupling H(sub)$\infty$ controller which minimizes the maximum energy in the output signal is designed to reduce the coupling properties between the input/output variables which make it difficult to control a system efficiently. The state-space formulas corresponding to the existing transfer matrix formulas of the controller are derived for computational efficiency. And for a given decoupling $H_{\infty}$ problem, an efficient method are sought to find the controller coefficients through the LMI(Linear Matrix Inequalities) method by which the problem is formulated into a convex optimization problem.

• Journal of Power Electronics
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• v.16 no.3
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• pp.1122-1130
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• 2016

This paper presents a novel approach for achieving both a tight DC voltage regulation and a power factor control by applying the Reaching Law Sliding Mode Control (RL-SMC) and the conventional Sliding Mode Control (SMC). Applying these strategies on a matrix rectifier (MR) can achieve a unity grid side power factor when the DC load changes widely and it can provide a ripple-free output voltage that is easily affected by distortions of the three-phase ac voltage supply. Furthermore, by employing the reaching law on the SMC can solve the chatting problem of the sliding motion. Comparative Matlab simulations and experimental verifications for these strategies have been presented and discussed in this paper. The results show that by applying the SMC and RL-SMC on a MR can achieve a unity grid side power factor and a regulated ripple-free DC output.