• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.546-551
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• 2004

In this paper, a level controller is designed with the neuro-fuzzy model based on Takagi-Sugeno fuzzy system. The fuzzy system is employed as the controller, which can be tuned by the neural network mechanism based on a gradient descent technique. The tuning mechanism will provide an optimal process input by forcing the process error to zero. The proposed controller provides the online tunable mode to adjust the consequent membership function parameters. The controller is implemented with M-file and graphic user interface (GUI) of Matlab program. The program uses MPIBM3 interface card to connect with the industrial processes In the experimentation, the proposed method is tested to vary of the process parameters, set points and load disturbance. Processes of one tank and two tanks are used to evaluate the efficiency of our controller. The results of the both processes are compared with two PID systems that are 3G25A-PIDO1-E and E5AK of OMRON. From the comparison results, our controller performance can be archived in the case of more robustness than the two PID systems.

• Journal of Electrical Engineering and Technology
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• v.11 no.6
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• pp.1645-1655
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• 2016

A Dynamic Voltage Restorer (DVR) model is proposed to eliminate the short-term voltage disturbances that occur in the grid-connected mode, the switching between grid-connected mode and the stand-alone mode of a Microgrid. The proposed DVR structure is based on a conventional cascaded H-bridge multilevel inverter (MLI) topology; a novel composite control strategy is presented, which could ensure the compensation ability of voltage sag by the DVR. Moreover, the compensation to specified order of harmonic is added to implement effects that zero-steady error compensation to harmonic voltage in specified order of the presented control strategy; utilizing wind turbines-batteries units as DC energy storage components in the Microgrid, the operation cost of the DVR is reduced. When the Microgrid operates under stand-alone mode, the DVR can operate on microsource mode, which could ease the power supply from the main grid (distribution network) and consequently be favorable for energy saving and emission reduction. Simulation results validate the robustness and effective of the proposed DVR system.

• Journal of Astronomy and Space Sciences
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• v.34 no.3
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• pp.213-223
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• 2017

The deep space orbit determination software (DSODS) is a part of a flight dynamic subsystem (FDS) for the Korean Pathfinder Lunar Orbiter (KPLO), a lunar exploration mission expected to launch after 2018. The DSODS consists of several sub modules, of which the orbit determination (OD) module employs a weighted least squares algorithm for estimating the parameters related to the motion and the tracking system of the spacecraft, and subroutines for performance improvement and detailed analysis of the orbit solution. In this research, DSODS is demonstrated and validated at lunar orbit at an altitude of 100 km using actual Lunar Prospector tracking data. A set of a priori states are generated, and the robustness of DSODS to the a priori error is confirmed by the NASA planetary data system (PDS) orbit solutions. Furthermore, the accuracy of the orbit solutions is determined by solution comparison and overlap analysis as about tens of meters. Through these analyses, the ability of the DSODS to provide proper orbit solutions for the KPLO are proved.

• IE interfaces
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• v.22 no.1
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• pp.95-103
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• 2009

During the past few years, design of experiments (DOE) has been gaining acceptance in the telecommunications research community as a mean for designing and analyzing experiments economically and efficiently. In addition, the need for introducing a systematic robust design methodology (i.e., one of the most popular DOE methodologies) to network simulations has been increasing. In this paper, we present an architecture of voice over IP (VoIP) application and the E-Model for calculating the perceived quality of service (QoS). Then, we apply the Taguchi robust design methodology to optimize the perceived QoS of VoIP application, and describe the detailed step-by-step procedures. We have used ns-2 simulator to collect experimental data in which the SN ratio, a robustness measure, is analyzed to determine an optimal design condition. The analysis shows that "initial delay time in playout buffer" is a major control factor for ensuring robust behaviors of the perceived QoS of VoIP. Finally, we verify the proposed optimal design condition using a confirmation experiment.

• Journal of the Korean Institute of Intelligent Systems
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• v.25 no.1
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• pp.97-104
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• 2015

An 'associative cube', a class of auto-associative memories, is revisited here, in which training data and hidden orthogonal basis functions such as wavelet packets or Fourier kernels, are combined in the weight cube. This weight cube has hidden units in its depth, represented by a three dimensional cubic structure. We develop an unsupervised incremental learning mechanism based upon the adaptive least squares method. Training data are mapped into orthogonal basis vectors in a least-squares sense by updating the weights which minimize an energy function. Therefore, a prescribed orthogonal kernel is incrementally assigned to an incoming data. Next, we show how a decoding procedure finds the closest one with a competitive network in the hidden layer. As noisy test data are applied to an associative cube, the nearest one among the original training data are restored in an optimal sense. The simulation results confirm robustness of associative cubes even if test data are heavily distorted by various types of noise.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.6
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• pp.1092-1098
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• 2002

This paper discusses the composition of the theory of reinforcement teaming, which is applied in real-time teaming, and evolutionary strategy, which proves its the superiority in the finding of the optimal solution at the off-line teaming method. The individuals are reduced in order to team the evolutionary strategy in real-time, and new method that guarantee the convergence of evolutionary mutations are proposed. It is possible to control the control object varied as time changes. As the state value of the control object is generated, applied evolutionary strategy each sampling time because of the teaming process of an estimation, selection, mutation in real-time. These algorithms can be applied, the people who do not have knowledge about the technical tuning of dynamic systems could design the controller or problems in which the characteristics of the system dynamics are slightly varied as time changes. In the future, studies are needed on the proof of the theory through experiments and the characteristic considerations of the robustness against the outside disturbances.

• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.2179-2183
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• 2009

As urbanization is progressed, the network for distributing water in a basin become complex due to the spatial expansion and parameter uncertainties of water supply systems. When a long range water supply plan is determined, the total construction and operation cost has to be evaluated with the system components and parameter uncertainties as many as possible. In this paper, the robust optimization approach of Bertsimas and Sim is applied in a hypothetical system to find a solution which remains feasible under the possible parameter uncertainties having the correlation effect between the uncertain coefficients. The system components to supply, treatment, and transport water are included in the developed water supply system and construction and expansion of the system is allowed for a long-range period. In this approach, the tradeoff between system robustness and total cost of the system is evaluated in terms of the degree of conservatism which can be converted to the probability of constraint violation. As a result, the degree of conservatism increases, the total cost is increased due to the installation of large capacity of treatment and transportation systems. The applied robust optimization technique can be used to determine a long-range water supply plan with the consideration of system failure.

• Journal of Korea Multimedia Society
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• v.23 no.3
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• pp.483-489
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• 2020

Advancements in mobile phone hardware and network connectivity made communication becoming more and more convenient. Compared to pictures or texts, people prefer to share videos to convey information. For intentions clearer, the way to annotating comments directly on the video are quite important issues. Recently there have been many attempts to make annotations on video. These previous works have many limitations that do not support user-defined handwritten annotations or annotating on local video. In this sense, we propose an augmented reality based real-time video annotation system which allowed users to make any annotations directly on the video freely. The contribution of this work is the development of a real-time video annotation system based on recent augmented reality platforms that not only enables annotating drawing geometry shape on video in real-time but also drastically reduces the production costs. For practical use, we proposed a real-time collaboration system based on the proposed annotation method. Experimental results show that the proposed annotation method meets the requirements of real-time, accuracy and robustness of the collaboration system.

• Journal of Advanced Marine Engineering and Technology
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• v.27 no.1
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• pp.24-32
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• 2003

The PID controller has been widely used in industrial applications due to its simple structure and robustness. Even if it is initially well tuned, the PID controller must be retuned to maintain acceptable performance when there are system parameter changes due to the change of operation conditions. In this paper, a self-tuning control scheme which comprises a parameter estimator, a NN-based rule emulator and a PID controller is proposed, which can cope with changing environments. This method involves combining neural networks and real-coded genetic algorithms(RCGAs) with conventional approaches to provide a stable and satisfactory response. A RCGA-based parameter estimation method is first described to obtain the first-order with time delay model from over-damped high-order systems. Then, a set of optimum PID parameters are calculated based on the estimated model such that they cover the entire spectrum of system operations and an optimum tuning rule is trained with a BP-based neural network. A set of simulation works on systems with time delay are carried out to demonstrate the effectiveness of the proposed method.

• Journal of Electrical Engineering and Technology
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• v.12 no.5
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• pp.1729-1742
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• 2017

In designing System Protection Schemes (SPSs) in power systems, protecting transmission network against extreme undesired conditions becomes a significant challenge in mitigating the transmission line overloading. This paper presents an intelligent Special Protection and Control Scheme (SPCS) using of Differential Evolution with Adaptive Mutation (DEAM) approach to obtain the optimum generation rescheduling to solve the transmission line overloading problem in system contingency conditions. DEAM algorithm employs the attraction-repulsion idea that is applied in the electromagnetism-like algorithm to support the mutation process of the conventional Differential Evolution (DE) algorithm. Different N-1 contingency conditions under base and increase load demand are considered in this paper. Simulation results have been compared with those acquired from Genetic Algorithm (GA) application. Minimum severity index has been considered as the objective function. The final results show that the presented DEAM method offers better performance than GA in terms of faster convergence and less generation fuel cost. IEEE 30-bus test system has been used to prove the effectiveness and robustness of the proposed algorithm.