• Proceedings of the KSR Conference
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• 2007.11a
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• pp.1515-1521
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• 2007

In this paper, a unified regenerative inverter system for railway with DC line voltage simulator is proposed. In order to determine the operation characteristics of the regenerative inverter, the DC line voltage simulator is proposed. The DC line voltage simulator, which is based on the AC-DC PWM converter, varies the DC voltage according to the fluctuating voltage which is measured in the actual DC line. The suitable operating point of the regenerative inverter can be estimated from the simulation result. The regenerative inverter operates two modes. When the DC line voltage exceed the operating point, already set up, it works as regenerative inverter to return the excessive power of DC line to the grid. When the DC line voltage is under the operating point, it works as active power filter to compensate harmonic currents. In this paper, the control algorithm of the DC line voltage simulator and that of the regenerative inverter is proposed.

• Journal of the Korean Society for Precision Engineering
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• v.12 no.5
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• pp.57-68
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• 1995

A general procedure for the numerical solution of coupled, nonlinear, differential two-point boundary-value problems, solutions of which are crucial to the controller design, has been developed and demonstrated. A fixed-end-points, free-terminal-time, optimal-control problem, which is derived from Pontryagin's Maximum Principle, is solved by an extension of Davidenko's method, a differential form of Newton's method, for algebraic root finding. By a discretization process like finite differences, the differential equations are converted to a nonlinear algebraic system. Davidenko's method reconverts this into a pseudo-time-dependent set of implicitly coupled ODEs suitable for solution by modern, high-performance solvers. Another important advantage of Davidenko's method related to the time-optimal problem is that the terminal time can be computed by treating this unkown as an additional variable and sup- plying the Hamiltonian at the terminal time as an additional equation. Davidenko's method uas used to produce optimal trajectories of a single-degree-of-freedom problem. This numerical method provides switching times for open-loop control, minimized terminal time and optimal input torque sequences. This numerical technique could easily be adapted to the multi-point boundary-value problems.

• Proceedings of the IEEK Conference
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• 1998.10a
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• pp.229-232
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• 1998

Modern telecommunications are increasingly demanding the addition of complex switching features to switching system software. These improvements also should satisfy customer demands for quick provisioning of new service features. But whenever we have developed the switching system in various types, we met problems that are lack of system engineers and short developments terms. We need new guidelines of software design to meet the demands and overcome our problems. So we propose new software platform, scenario driven call control engine (SDCCE) for ATM switching system software and implement an effective call control software using scenarios for ATM Switching System. A scenario is a set of procedures and supplementary scenarios written in data structure and gives benefits to easy adapt new or modified function by adding a scenario. The goal of SDCCE is to increase reusability and readability of software. Especially, it gives a good software extensibility and maintainability. And when we developed ptmp call processing control software, we could get high productivity by reusing scenarios and procedures of ptp call processing control software. We applied the scenario driven call control software to ATM switching system.

• Proceedings of the KIEE Conference
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• 1992.07b
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• pp.1231-1234
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• 1992

In this paper a self-tuning control algorithm has been utilized to control speed of a rolling mill DC drive system. Inner current control loop is composed of predictive current controller and the outer speed control loop is composed of the self-tuning PI or IP controller. Computer simulation results reveal that the adaptive control algorithm using self-tuning control is capable of following the typical set point variations required for a rolling mill in conjunction with load torque variations on the shaft of the drive.

• Proceedings of the KIEE Conference
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• 1992.07a
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• pp.333-336
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• 1992

In this paper, We propose a PID-type of self-tuning algorithm which is based on the parameter estimation and the minimization of the cost function. We use the CARIMA model for parameter estimation and determine the discrete PID controller parameters by minimizing the cost function which considers the quadratic deviations of the predicted output over the set-point as well as the control efforts. Also, The algorithm is extended by incorporating constraints of the control signal. Simulations are performed to illustrate the efficiency of the proposed method.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.99-104
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• 1991

An adaptive predictive control method for SISO and MIMO plants is proposed. In this method, future predictions of process output based on a bilinear CARIMA model are used to calculate the control input. Also, a classical recursive adaptation algorithm, equation error method, is used to decrease the uncertainty of the process model. As a result of the application on distillation process, the ability of the set-point tracking and the disturbance rejection is acceptable to apply to the industrial distillation processes.

• Proceedings of the IEEK Conference
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• 2003.07a
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• pp.569-572
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• 2003

The broadband wireless access industry, which provides high-tate network connections to stationary sites, has matured to the point at which it now has a standard for second-generation wireless metropolitan area networks. IEEE Standard 802.16, with its WirelessMAN air interface, set the stage for widespread and effective deployments worldwide. This paper presents an implementation of media access control that can be applied to BWA (Broadband Wireless Access) system. Medium access control (MAC) is a key issue in multi-access networks where a common channel is shared by many users. The designed MAC prototype roughly consists of MAC Hardware and MAC Software. The MAC Hardware part includes timing process, MAC transmission control, MAC reception control, and CRC/HCS process. The MAC Software part includes control of MAC signaling, network interface, and Physical (PHY) control. The designed MAC protocol will be integrated with the PHY of BWA in future and we can test overall system performance of MAC and PHY.

• Journal of the Korea Safety Management & Science
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• v.13 no.4
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• pp.225-235
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• 2011

Autoregressed Controller, which have trend algorithm, seeks to minimize variability by transferring the output variable to the related process input variable, while multivariate process control techniques seek to reduce variability by detecting and eliminating assignable causes of variation. In the case of process control, a very reasonable objective is to try to minimize the variance of the output deviations from the target or set point. We also investigate algorithm with relevant Shewhart chart, Theoretical control charts, precontrol and process capability. To help the people who want to make the theoretical system, we compare the main techniques in "a study on the relation between multivariate process control techniques and trend algorithms".

• Korean Journal of Chemical Engineering
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• v.36 no.3
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• pp.356-367
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• 2019

This work presents an advanced and systematic approach to analytically design the optimal parameters of a two parameter second-order internal model control (IMC) filter that satisfies operational constraints on the output process, the manipulated variable as well as rate of change of the manipulated variable, for a first-order plus dead time (FOPDT) process. The IMC parameters are designed to minimize a control objective function composed of the weighted sum of the error between the process variable and the set point, and the rate of change of the manipulated variable, and to satisfy the desired constraints. The feasible region of the constrained IMC control parameters was graphically analyzed, as the process parameters and the constraints varied. The resulting constrained IMC control parameters were also used to find the corresponding industrial proportional-integral controller parameters of a Smith predictor structure.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.7
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• pp.923-929
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• 2021

TCP communication and packet communication require transmission control technology to ensure high quality and high reliability. However, in the case of real-time data transmission, an inefficient transmission problem occurs. In order to overcome this problem and transmit the packet reliability, in general, early congestion control using the buffer level as an index was used. Control of the congestion control point and the cancellation point is delayed because the point at which congestion is controlled is based on the buffer level. Therefore, in this paper, not only the buffer level indicator, but also the ideal buffer level, which determines the packet discard probability, is classified so that the transmission rate and buffer level that measure network congestion are close to the level above the optimal setting. As a result, it was shown that the average buffer level can be directly controlled by maintaining the average buffer level by the ideal buffer level set in the experiment to prove the proposed method.