• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.1
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• pp.52-58
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• 2005

Among various modern control theories, PID control has been well used for several decades. PID algorithms need some tuning methods which are used for selecting PID parameters. But in some cases various kinds of performance indices are used instead of well-known tuning rules, and so variable type of performance index must be tested so that controllers, output characteristics and disturbance rejection property meet some specifications. In this paper, linear conbinational type of performance index using error signal, time, control input and robustness is used to the PID control of air conditioning system. By use of the 2 DOF PID parmeters minimizing perfromacne index controllers, output characteristics and robustness properties are analyzed. Simulations are done by use of MATLAB with Simulink.

• Journal of Drive and Control
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• v.13 no.3
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• pp.15-23
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• 2016

The direct-drive servo valve(DDV) is a kind of one-stage valve because the main spool valve is directly driven by the dc motor. Since the DDV structure is simple, it is less expensive, more reliable, and offers a reduced internal leakage and a reduced sensitivity to fluid contamination. The control system of the DDV is highly nonlinear due to a current limiter, a voltage limiter, and the flow-force effect on the spool motion. The shape of the step response of the DDV-control system varies considerably according to the magnitudes of the step input and the load pressure. The system-design requirements mean that the overshoots should be less than 20%, and the errors at 0.02s should be less than 2%, regardless of the reference-step input sizes of 1V and 5V and the load-pressure magnitudes of 0MPa and 20.7MPa. To satisfy the system-design requirements, the PID-controller parameters of $K_c$, $T_i$ and $T_d$, and the derivative-feedback gain of $K_{der}$ are designed using the root locus and manual tuning.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.10 no.2
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• pp.113-118
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• 2010

This paper proposed an ECAM (Electronic cam) control system which has simple and general structure. The proposed cam controller adopted the linear and polynomial curve-fitting method to generates a smooth cam profile curve function. Smooth motion trajectory of master actuator guarantees the good performance of slave motion and has an important effect on the interpolation quality of ECAM. The auto-tuning PID velocity controller was applied to overcome the uncertainties in ECAM, and the gains of the controller are updated continuously to ensure the consistency of system performance under varying working conditions. The robustness of system against the varying load torque disturbances and noises is guaranteed by using the load torque disturbance observer to suppress the disturbance on master actuator. The velocity compensator was applied to compensate the degradation of performance of slave motion caused from the varying driving speed of master motion. The stability and validity of the proposed ECAM control system was verified by simulation results.

• Proceedings of the KIEE Conference
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• 2003.07b
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• pp.1111-1113
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• 2003

This paper proposes an effective self-turning algorithm based on Artificial Neural Network (ANN) for fuzzy speed control of the indirect vector controlled induction motor. Indirect vector control method divides and controls stator current by the flux and the torque producing current so that the dynamic characteristic of induction motor may be superior. However, if motor parameter changes, the flux current and the torque producing one's coupling happens and deteriorates the dynamic characteristic. The fuzzy speed controller of an induction motor has the robustness over the effect of this parameter variation than a conventional PI speed controller in some degree. This paper improves its adaptability by adding the self-tuning mechanism to the fuzzy controller. For tracking the speed command, its membership functions are adjusted using ANN adaptation mechanism. This adaptability could be embodied by moving the center positions of the membership functions. Proposed self-tuning method has wide adaptability than existent fuzzy controller or PI controller and is proved robust about parameter variation through Matlab/Simulink simulation.

• Korean Journal of Optics and Photonics
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• v.14 no.6
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• pp.657-662
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• 2003

Optimum Hamming apodized acousto-optic 2${\times}$2 add/drop multiplexers, using SiO$_2$ film loaded acoustic waveguide with angular offset to the Ti:LiNbO$_3$ waveguide, were fabricated. The four-port device consists of two input waveguides, a polarization beam splitter (PBS), two polarization conversion/acoustooptic tuning waveguide sections, a second PBS and two output waveguides. Insertion loss <7.1 ㏈ has been obtained and side-lobe of -19 ㏈ for -32 ㎽ RF driving power has been realized. Add/drop performance has been confirmed and a linear tuning rate of 8.1 nm/MHz and a 3 ㏈ spectral width of -1.5 nm were demonstrated.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.16 no.11
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• pp.3619-3637
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• 2022

Big data analytics offers endless opportunities for operational enhancement by extracting valuable insights from complex voluminous data. Hadoop is a comprehensive technological suite which offers solutions for the large scale storage and computing needs of Big data. The performance of Hadoop is closely tied with its configuration settings which depends on the cluster capacity and the application profile. Since Hadoop has over 190 configuration parameters, tuning them to gain optimal application performance is a daunting challenge. Our approach is to extract a subset of impactful parameters from which the performance enhancing sub-optimal configuration is then narrowed down. This paper presents a statistical model to analyze the significance of the effect of Hadoop parameters on a variety of performance metrics. Our model decomposes the total observed performance variation and ascribes them to the main parameters, their interaction effects and noise factors. The method clearly segregates impactful parameters from the rest. The configuration setting determined by our methodology has reduced the Job completion time by 22%, resource utilization in terms of memory and CPU by 15% and 12% respectively, the number of killed Maps by 50% and Disk spillage by 23%. The proposed technique can be leveraged to ease the configuration tuning task of any Hadoop cluster despite the differences in the underlying infrastructure and the application running on it.

• Proceedings of the KIPE Conference
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• 2016.07a
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• pp.519-520
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• 2016

BLSRM is a nonlinear, strong coupling and multi-variable system. The conventional control method is vulnerable to uncertain factors such as the load disturbance and satellite parameters change. It is difficult to obtain satisfactory control effect. Basing on a 8/10 BLSRM, whose suspending force control is separated with the torque control, this paper presents adaptive fuzzy PID controller for levitation control, which apply the fuzzy logic control to the conventional PID controller for parameters self-tuning. Both fuzzy and parameters of PID controller are self-tuning on-line, which improve the performance of controller. Finally, simulation and experimental results show the performance of the proposed method.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.597-602
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• 2006

In this paper, a proper support tuning method is established by identifying the dynamic characteristics of the machine, the floor. and the inertia force. Also, the limitation of a passive isolation is presented. To simplify the dynamic analysis and to establish a proper design method for supporting system, each of the machine and the floor is modeled as a single degree of freedom spring-mass-damper system under careful investigation of the dynamic characteristics of each system and appropriate assumptions. Then, the dynamic behavior of a 2DOF system and the effect of the mass and the damping are investigated. Also, the characteristics of motion profiles are investigated. In addition, a quasi-static analysis on the transmitted force through support is performed and related tests are performed.

• Journal of Institute of Control, Robotics and Systems
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• v.13 no.4
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• pp.329-334
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• 2007

This paper deals with self-tuning of fuzzy control systems. The fuzzy logic controller(FLC) has parameters that an: input and output scaling factors to effect control output. Tuning method is proposed for the scaling factor. In this paper. it is studied to control and to monitor the remote system statues using SOAP for communicate between the server part and the client part. The remote control system is controlled by using a web browser or a application program. The server part is waiting for the request of client part that uses internet network for communication each other and then the request is reached. the server part saves client data to the database and send a command set to the client part and then the client part sends command to controller in a cool chamber. The administrator can control and monitor the remote system just using a web browser. The effects of membership functions, defuzzification methods and scaling factors are investigated in the FLC system.

• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.11
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• pp.1736-1742
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• 1989

In this thesis, to verify input-output characteristics of GaAs MESFET, light is illuminated to C-band oscillator which already designed and manufactured, thus input-output variation of GaAs MESFET is to be shown. Experimental results of two kinds of optical effects, optical tuning and opticla switching, of GaAs MESFET Oscillators are presented. For optical tuning, the Oscillation frequency decreases with optical illumination and the Oscillator power output generally increases with optical illumination, the increase being around 1 to 3 dBm at 1mW/mm\ulcornerlight intensity. While the DC-lingt illuminated Oscillator response data provide information of the optical senditivity of GaAs-MESFET Oscillators. Pulse-light illuminated transient response data can be invoked to understand the detailed optical-electrical interaction mechanisms response. Thus, it is shown that direct control of micro-devices is realisable, if we use optical effect of GaAs semiconductor compound.