• Journal of IKEEE
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• v.26 no.3
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• pp.462-467
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• 2022

The feedback buffer structure is proposed to alleviate the overshoot and undershoot phenomenon and the regulation of the output voltage. The conventional LDO regulator undergoes a regulation voltage change caused by a constant load current change. An LDO regulator with a feedback voltage sensing structure operates in the input voltage range of 3.3 to 4.5 V and has a load current of up to 150 mA at output voltage of 3 V. According to the simulation results, a regulation value of 6.2 mV was ensured when the load current uniformly changed to 150 mA.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.60 no.2
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• pp.179-185
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• 2024

The model ship of this study, the Baek-Kyung fisheries training ship of Pukyong National University, has a length between perpendiculars of 85 meters, making it not subject to the IMO maneuverability standards. However, understanding the maneuvering characteristics of the vessel is essential for safe navigation. In this regard, this study was conducted to analyze the results from the sea trials of the model ship conducted in accordance with the IMO maneuverability standards. The results of the turning tests met the standards well while in the zig-zag tests, the first overshoot angle exceeded the standard in the 10°/10° test; however, such results met with a difference of 1.8° in the 20°/20° test. Additionally, using the course-stability discrimination formula, the calculated value was -0.0051, indicating unstable course-stability. The results of the stopping tests met the standards well. It is hoped that the analyzed maneuvering characteristics of the model ship from the study results will contribute to the safety of ship navigation.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.3
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• pp.725-733
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• 1990

An analysis of laminar mixed convection flow adjacent to the inclined flat surface which is subjected to a uniform temperature in a uniform free stream is performed. Nonsimilar boundary layed equation are derived by using the mixed convection parameters such that smooth transition from the purely forced convection limit to the purely free convection limit is possible. The governing equations are solved by a finite difference method using the coupled box scheme of sixth order. Numerical results are presented for prandtl numbers of 0.7 and 7 with the angle of inclination ranging from 0 to 90 degree from the vertical. The velocity distributions for the buoyancy assisting flow exhibit a significant overshoot above the free stream value in the region of intense mixed convection and the velocity field is found to be more sensitive to the buoyancy effect than the temperature field. The separation point near the wall was obtained for the buoyancy opposing flow. The local Nusselt number increases for buoyancy assisting flow and decreases for opposing flow with increasing value of the local Grashoff number in the mixed convection parameter. For large Prandtl number, the Nusselt number and the friction factor decrease significantly near the separation point. Present numerical predictions are in good agreement with recent experimental results by Ramachandran.

• Journal of Environmental Impact Assessment
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• v.27 no.1
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• pp.56-72
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• 2018

North Korea has been in ecologically deficit state since 1966, despite of lack of energy and food resources. Trends of the Biocapacity (BC), the Ecological Footprint (EF), and the Ecological Deficit (ED) of North Korea were shown and five factors influencing on the Overshoot Rate (OSR) which is the ratio of the BC and the EF in North Korea was analyzed in this study. The five factors consist of two factors affecting to the EF and three factors affecting to the BC in North Korea. Two of the five factors are affecting to the EF those are population, the EF per capita (EFPC) which indicates the individual environmental consumption intensity, and three are affecting to the BC those are the land area, the yield factor, and the value multiplying the equivalence factor and the intertemporal yield factor. The EF has contributed more than the BC to the OSR. From 1966 to mid-1990s, the EFPC was the most contributing factor at about 60%, and after mid-1990s, population at about 40~60%. Contribution ratio of land area and the yield factor have increased after mid-1990s up to 15% and 18%, respectively. The BC of cropland which has decreased due to a decrease in productivity. In order to reduce the ED of North Korea, improvement of productivity of cropland and restoration of forest. Forest area has decreased significantly since 1990 in NK. And ways to solve the food shortage problem which influences on decrease of both productivity of cropland and forest area.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.1
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• pp.134-145
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• 2021

It is common to optimize the propulsion control system through a so-called tuning process that modifies the parameter values of the propulsion control software during a ship commissioning. However, during this process, if the error of the initial setting value is large, the tuning time may take too long, or the propulsion equipment can be seriously damaged. Therefore, we conducted research on the design of a propulsion controller that applied a Processor lever controller even for inexperienced people with relatively little experience in tuning propulsion control software to be able to reduce the tuning time while protecting the propulsion system. Through simulation, by comparing the execution result of propulsion control lever commands through the PI controller without applying the Processor lever controller. We analyzed the improvement of the Overshoot and propulsion performance. The simulation results showed that the safety of the propulsion system increased because Overshoot of approximately 9.74%, which occurred when the Processor lever function was not applied.

• The KIPS Transactions:PartC
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• v.10C no.5
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• pp.617-624
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• 2003

This paper proposes a modified DCPC (Distributed Constrained Power Control, M-DCPC) algorithm that can improve the performance of a CDMA power control system. The control performance of the proposed method is verified using two performance measures : the SIR response of each mobile and the outage probability in a cell. As regards the SIR response, in simulations, the M-DCPC algorithm has shown a faster convergence and lower overshoot in transient time than the other power control algorithms when the desired SIR value was varying. For the outage probability. M-DCPC converged to a fixed outage rate faster than CSOPC while also maintaining the system capacity to make as high a connection as CSOPC. In particular, when the desired SIR was varying, CSOPC showed an abrupt outage probability increase during the desired SIR Increase, yet M-DCPC was unaffected.

• Journal of Institute of Control, Robotics and Systems
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• v.17 no.9
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• pp.897-901
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• 2011

This paper presents a TS (Takagi-Sugeno) type FLC (Fuzzy Logic Controller) with only 3 rules. The choice of parameters of FLC is very difficult job on design FLC controller. Therefore, the choice of appropriate linguistic variable is an important part of the design of fuzzy controller. However, since fuzzy controller is nonlinear, it is difficult to analyze mathematically the affection of the linguistic variable. So this choice is depend on the expert's experience and trial and error method. In the design of the system, we use a variety of response characteristics like stability, rising time, overshoot, settling time, steady-state error. In particular, it is important for a stable system design to predict the steady-state error because the system's steady-state response of the system is related to the overall quality. In this paper, we propose the method to choose the consequence linear equation's parameter of T-S type FLC in the view of steady-state error. The parameters of consequence linear equations of FLC are tuned according to the system error that is the input of FLC. The full equation of T-S type FLC is presented and using this equation, the relation between output and parameters can represented. As well as the FLC parameters of consequence linear equations affect the stability of the system, it also affects the steady-state error. In this study, The system according to the parameter of consequence linear equations of FLC predict the steady-state error and the method to remove the system's steady-state error is proposed using the prediction error value. The simulation is carried out to determine the usefulness of the proposed method.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.3
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• pp.173-179
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• 2017

This paper analyzes actuator characteristics for main wing and tail surfaces of an ornithopter by using a motion capture test. Experiments with the ornithopter are conducted indoor, and its fuselage is held on a jig to reduce interaction with vibration generated by flapping motion. The motion capture system detects the movement of markers attached on the main wing and tail wing tip. Experimental results show that the main wings tend to change its amplitude according to the flapping frequency, and the lift and thrust generation simulation is implemented by applying the experimental results and the ornithopter specification to Modified Strip Theory. Step input excitation is applied for experimental analysis of the tail wing in horizontal and vertical directions. As a result, horizontal and vertical tail wings have different characteristics in terms of overshoot, final value, damping ratio and natural frequency because they have different wing structures and linkages.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.480-480
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• 2000

In this paper, we proposed a fuzzy-neuro controller to control the speed of wound rotor induction motor with slip energy recovery. The speed is limited at some range of sub-synchronous speed of the rotating magnetic field. Control speed by adjusting resistance value in the rotor circuit that occurs the efficiency of power are reduced, because of the slip energy is lost when it passes through the rotor resistance. The control system is designed to maintain efficiency of motor. Recently, the emergence of artificial neural networks has made it conductive to integrate fuzzy controllers and neural models for the development of fuzzy control systems, Fuzzy-neuro controller has been designed by integrating two neural network models with a basic fuzzy logic controller. Using the back propagation algorithm, the first neural network is trained as a plant emulator and the second neural network is used as a compensator for the basic fuzzy controller to improve its performance on-line. The function of the neural network plant emulator is to provide the correct error signal at the output of the neural fuzzy compensator without the need for any mathematical modeling of the plant. The difficulty of fine-tuning the scale factors and formulating the correct control rules in a basic fuzzy controller may be reduced using the proposed scheme. The scheme is applied to the control speed of a wound rotor induction motor process. The control system is designed to maintain efficiency of motor and compensate power factor of system. That is: the proposed controller gives the controlled system by keeping the speed constant and the good transient response without overshoot can be obtained.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.48 no.5
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• pp.586-592
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• 1999

We investigate the characteristic of 소데 responses of the Manabe standard form which is used recently for design of the controller. We obtain some theorems and these theorems have the properties of the relationship between the roots of the polynomial and the stability indices which are used for the Manabe standard form. The Manabe standard form has the following properties: The sum of the squal to zero, the sum of the reciprocal of the squared roots is greater than zero and the parameter $\tau$ is the negative value of the sum of the reciprocal of the roots. We compare the step responses of the Manabe standard form with those of the ITAE form, the dead beat response and Bessel forms. We choose the 6th order closed loop polynomial and keep the same settling time for the four forms. Under these conditions we find that the Manabe standard form have faster 90% rising time than the Bessel and dead beat response. We see that the ITAE, bessel and dead beat responses have some overshoot, whereas the Manabe standard form has none. We also compare the Manabe form with the other three forms for the controller design using the pole assignment technique. If the open loop transfer function is a type-1 system (transfer functions having one integrator), then, for the closed loop system associated with the open loop transfer function, the steady state error of the unit ramp input is obtained in terms of the parameter $\tau$ of the Manabe standard form.