• Journal of Power System Engineering
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• v.2 no.3
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• pp.68-73
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• 1998

The propulsion diesel engine have been widely applied with a mechanical governor to control the truck speed for a long time. But it was recently very difficult for mechanical governor to control the speed of long stock and diesel engine of truck because of hunting by dead time between fuel injection and power output. This study is aimed to configure the modeling for performance simulation regarding to diesel truck operation which could be suppressed for hunting. The modeling have been made on the base of dynamic characteristic such as electronic governor, injection of fuel system and operating states of diesel engine truck. Real model system have been introduced for deciding reacting parameters and for the comparison of resulting performance in simulation. In results of simulation, we obtained items which diesel truck drives for suppressed hunting.

• Proceedings of the KIEE Conference
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• 1993.11a
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• pp.110-113
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• 1993

The MOSFET synchronous rectification in the Active-Clamp Forward converter is presented. The Active-Clamp Forward converter has little dead time during the off time of the main switch and it is suitable for the MOSFET synchronous rectification comparing to the other Forward converter topologics. Using the MOSFET synchronous rectification on the Active-Clamp Forward converter with 3.3[V] output and 500[kHz] switching frequency, the improvement of efficiency is achieved comparing with the conventional Schottky barrier diode rectification.

• Journal of Institute of Control, Robotics and Systems
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• v.22 no.8
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• pp.619-626
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• 2016

This paper proposes the design and performance evaluation of a marine engine fault detection system using a proximity sensor for marine engine. Non-linearity is greatly reduced by using the sensor without increasing the response time by applying the CANopen protocol. The CANopen protocol enables the sensor to send initial values and measurement data. The marine engine fault detection system measures crankshaft deflection and the bottom dead center of the crosshead in real-time, which maintains stability and prevents the serious breakdown of the marine engine by use of an interlocking alarm monitoring system.

• Proceedings of the KIEE Conference
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• 1989.07a
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• pp.567-570
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• 1989

A constant V/F control system of voltage contrlled PWM inverter has a unstable operation of the low- speed and the light-load. In this paper, the authors propose stability control with idealized operation of induction motor by the neglect of primary leakage inductance and resistance. Also ldealized operation system is adopted voltage error, feed back impedance circuit, and increasing resistance from dead time of switching is compensated by the soft ware with u-processors. The proposed simulation of the idealized control method is proved at the low-speed operation for three phase induction motor.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.31B no.9
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• pp.36-46
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• 1994

A analog disturbance observer, which is suitable for servo motor drive, was employed to suppressi control of the impact drop disturbance. The main advantage of the observer is that a fast response disturbance estimation is obtained using the detected motor cuttent and speed. And the new M/T method for motor speed detection is proposed. The method should be able to reduce the detection dead time compared with the Ohmae's M/T method. Also, the low speed control of a servo motor using instantaneous speed detection method is described. To estimate the instantaneous speed from the average speed, the speed estimator of the first order is proposed. Actually we confirmed that these methods improve the speed control performance of the servo system with experiments.

• Journal of Institute of Control, Robotics and Systems
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• v.7 no.4
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• pp.288-294
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• 2001

In this study, a new PWM method considering the actuation delay of high speed solenoid valves is proposed to improve the response characteristics of electro hydraulic servo systems controlled by high speed solenoid valves. In addition, the decision method for the system gain, the basic period of PWM, and the sampling time is proposed, Since the conventional system controlled by high speed solenoid valves is too slow to apply this method, a high speed driving circuit(Quick-Drive) which enables rapid switching of the high speed solenoid valve at a high speed sampling mode is applied to realize this method. The experimental result shows that it is possible to achieve precision and quiet control without occurrence of limit cycle and wide range dead band.

• Proceedings of the KIEE Conference
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• 1998.07b
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• pp.775-777
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• 1998

The Ziegler-Nichols parameter tuning has been widely known as a fairly heuristic method to good determine setting of PID controllers, for a wide range of common industrial processes. We extract process knowledge required for rule base controller through tuning experiment and simulation study, such as set point weighting and normalised gain and dead time of process. In this paper, we presents a rule base PID controller by extracted process knowledge and the modified Ziegler-Nichols tuning. Computer simulation are provided demonstrate the feasibility of this approach.

• Proceedings of the KIEE Conference
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• 2000.07d
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• pp.2648-2650
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• 2000

The PID tuning algorithm which can be applied generally to processes with varies dynamic characteristics is proposed by Wang[7]. However, it can be applied well to process model without zeros and with $\angle$G(jw)=-${\pi}$/2 and -${\pi}$ point in Nyquist curve, but it gives unsatisfactory tuning performance for processes with zeros and without $\angle$G(jW)=-${\pi}$/2 and -${\pi}$ in Nyquist curve. In this paper, the method which improve it using Pade reduction method is proposed. Satisfactory responses can be expected for processes with various dynamics, including those with low or high order, small or large dead time, monotonic or oscillatory responses. Simulation examples are given to show the effectiveness and flexibility of the controller in handling processes of different characteristics.

• Journal of Advanced Marine Engineering and Technology
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• v.3 no.1
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• pp.19-31
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• 1979

Recently the adaptive control system, which keeps the control system always optimal by adjusting the control parameters automatically according to the variations of the plant parameters, have become very important in the field of control engineering. The adaptive control systems are usally composed of the plant identification, the decision of the optimal control parameters, and the adjustment of the control parameters. This paper deals with a method of the adaptive control system when PI or PID controller is used in the feed back control system. Its controlled object (the plant) is assumed to be described by the transfer function of $\frac{ke^{-LS}}{1+TS}$ where k, T and L are steady state gain, time constant and pure dead time respectively, and their values are variable in accordance with the change of environmental circumstance. It has been known that a pseudo-random binary signal is quite effective for the measurement of an impulse response of a plant. In adaptive control systems, however, the impulse response itself is not appropriate to determine the control parameters. In this paper, the authors propose a method to estimate directly the parameters of the plant k, T and L by means of the correlation technique using 3 level M-sequence signal as a test signal. The authors also propose a method to determine the optimal parameters of the PI or PID controller in the sense of minimizing the square integral of the control error in the feed back control system, and the values of the optimal parameters are computed numerically for various values of T and L, and the results are examined and compared with those of the conventional methods. Finally the above-mentioned two methods are combined and an algorithm to struct an adaptive control system is suggested. The experiments for the indicial responses by means of both the model of the temperature control system using SCR actuater and the analog simulations have shown good results as expected, and the effectiveness of the proposed method is verified. The M-sequence generator and the time delay circuit, which are manufactured for the experiments, are operated in quite a good condition.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.11
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• pp.2115-2121
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• 2009

This paper proposes the new reclosing scheme considering the recovery time of SFCL in distribution systems which is based on variable dead time control. The main idea is that it uses the carrier signal to distinguish whether the fault is instantaneous or permanent after tripping the line by recloser. The system and SFCL is modeled by using Electromagnetic Transient Program(EMTP) and the validity of the reclosing scheme presented in this paper is analyzed according to the fault resistance, the recovery time of SFCL and the fault clearing time.