• Journal of Power Electronics
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• v.4 no.1
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• pp.1-11
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• 2004

A stable adaptive sensorless speed controller for three-level inverter fed induction motor direct torque control (DTC) system using the radial-basis function network (RBFN) is presented in this paper. Torque ripple in the DTC system for high power induction motor could be drastically reduced with the foregoing researches of switching voltage selection and torque ripple reduction algorithms. However, speed control performance is still influenced by the inherent uncertainty of the system such as parametric uncertainty, external load disturbances and unmodeled dynamics, and its exact mathematical model is much difficult to be obtained due to their strong nonlinearity. In this paper, the inherent uncertainty is approximated on-line by the RBFN, and an additional robust control term is introduced to compensate for the reconstruction error of the RBFN instead of the rich number of rules and additional updated parameters. Control law for stabilizing the system and adaptive laws for updating both of weights in the RBFN and a bounding constant are established so that the whole closed-loop system is stable in the sense of Lyapunov, and the stability proof of the whole control system is presented. Computer simulations as well as experimental results are presented to show the validity and effectiveness of the proposed system.

• Smart Structures and Systems
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• v.19 no.5
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• pp.523-538
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• 2017

A series of field vibration tests are conducted on the Runyang Suspension Bridge during both the construction and operational stages. The purpose of this study is devoted to the analysis of the dynamic characteristics of the suspension tower. After the tower was erected, an array of accelerometers was deployed to study the evolution of its modal parameters during the construction process. Dynamic tests were first performed under the freestanding tower condition and then under the tower-cable condition after the superstructure was installed. Based on the identified modal parameters, the effect of the pile-soil-structure interaction on dynamic characteristics of the suspension tower is investigated. Moreover, the stiffness of the pile foundation is successfully identified using a probabilistic finite model updating method. Furthermore, challenges of identifying the dynamic properties of the tower from the coupled responses of the tower-cable system are discussed in detail. It's found that compared with the identified results from the freestanding tower, the longitudinal and torsional natural frequencies of the tower in the tower-cable system have changed significantly, while the lateral mode frequencies change slightly. The identified modal results from measurements by the structural health monitoring system further confirmed that the vibrations of the bridge subsystems (i.e., the tower, the suspended deck and the main cable) are strongly coupled with one another.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 1997.06a
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• pp.75-81
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• 1997

A new DTPP (Desk-Top Program Production) system has been developed that enables multiple program producers (directors) working at different locations to collaborate over a computer network and prepare a single program for broadcasting. In this system, information is shared among users by exchanging data edited on non-linear editing terminals in program post-production work over a network in real time. In short, the new DTPP system provides a collaborative work space for producing TV programs. The system does not make use of a special server for collaborative work but rather multiple interconnected editing terminals having the same functions. In this configuration, data at a terminal which has just been edited by some operation is forwarded to all other connected terminals for updating. This form of information sharing, however, requires that some sort of data synchronizing method be established since multiple terminals are operating on the same data simultaneously. We therefore adopt a method whereby the system synchronizes the clocks on each terminal at the time of connection and sends an operation time stamp together with edited data. This enables most recently modified data to be identified and all information on all terminals to be updated appropriately. This paper provides an overview of this new collaborative DTPP system and describes the techniques for exchanging edited data and synchronizing data.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.480-483
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• 1997

A fossil power plant can be modeled by a lot of algebraic equations and differential equations. When we simulate a large, complicated fossil power plant by a computer such as workstation or PC, it takes much time until overall equations are completely calculated. Therefore, new processing systems which have high computing speed is ultimately needed to develope real-time simulators. Vital points of real-time simulators are accuracy, computing speed, and deadline observing. In this paper, we present a enhanced strategy in which we can provide powerful computing power by parallel processing of DSP processors with communication links. We designed general purpose DSP modules, and a VME interface module. Because the DSP module is designed for general purpose, we can easily expand the parallel system by just connecting new DSP modules to the system. Additionally we propose methods about downloading programs, initial data to each DSP module via VME bus, DPRAM and processing sequences about computing and updating values between DSP modules and CPU30 board when the simulator is working.

• Journal of Information Technology Applications and Management
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• v.10 no.3
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• pp.45-54
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• 2003

Security system with web camera remarkably has been developed at an Internet era. Using transmitted images from remote camera, the system can recognize current situation and take a proper action through web. Existing motion detection methods use simply difference image, background image techniques or block matching algorithm which establish initial block by set search area and find similar block. But these methods are difficult to detect exact motion because of useless noise. In this paper, the proposed method is updating changed background image as much as $N{\times}M$pixel mask as time goes on after get a difference between imput image and first background image. And checking image pixel can efficiently detect motion by computing fixed distance pixel instead of operate all pixel.

• Proceedings of the KSME Conference
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• 2001.06c
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• pp.565-571
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• 2001

As a method of structural optimization, a practical algorithm based on the Taguchi method is developed. The Taguchi method is applied iteratively updating the level values of design variables. The design region is translated or reduced during optimization and by appropriate choice of reduction factor and initial level intervals, a near-optimum solution can be found very efficiently. To treat inequality constraints, a variable penalty method is utilized. A software system named 'DS/Taguchi' is developed by integrating the proposed algorithm and commercial finite element analysis codes on the parametric CAD platform. Two examples are taken to examine the performance of the proposed algorithm and the developed software system.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.750-753
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• 2005

An equivalent linearization technique based on Rayleigh peak distribution for friction damper and brace system (FDBS) under stochastic excitation is proposed. For verification, shaking table test of a small scale 3-story building model with the FDBS is conducted for various slip moment levels. Using experimental result, equivalent linearization of the FDBS is conducted based on Rayleigh peak distribution, which is compared with measured peak distribution. For comparative study, model updating technique is applied based on identified modal properties. Finally, complex modal analysis and time history analysis for the obtained equivalent linear systems are conducted and compared with experimental result

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.10
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• pp.1021-1027
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• 2009

Finite element models of dynamic systems can be updated in two stages. In the first stage, mass and stiffness matrices are updated neglecting damping. In the second stage, a damping matrix is estimated with the mass and stiffness matrices fixed. Methods to estimate a damping matrix for this purpose are proposed in this paper. For a system with proportional damping, a damping matrix is estimated using the modal parameters extracted from the measured responses and the modal matrix calculated from the mass and stiffness matrices from the first stage. For a system with non-proportional damping, a damping matrix is estimated from the impedance matrix which is the inverse of the FRF matrix. Only one low or one column of the FRF matrix is measured, and the remaining FRFs are synthesized to obtain a full FRF matrix. This procedure to obtain a full FRF matrix saves time and effort to measure FRFs.

• International Journal of High-Rise Buildings
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• v.1 no.1
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• pp.53-59
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• 2012

With the rise in CPU power and the generalization and popularity of computers, engineering practice also changed from hand calculations to 3D computer models, from elastic linear analysis to 3D nonlinear static analysis and 3D nonlinear transient dynamic analysis. Thanks to holistic design approach and current trends in freeform and contemporary architecture, BIM concept is no longer a dream but also a reality. BIM is not just providing a media for better co-ordination but also to shorten the round-the-clock time in updating models to match with other professional disciplines. With the parametric modeling tools, structural information is also linked with BIM system and quickly produces analysis and design results from checking to fabrication. This paper presents a new framework which not just linked the BIM system by means of parametric mean but also create and produce connection FE model and fabrication drawings etc. This framework will facilitate structural engineers to produce well co-ordinate, optimized and safe structures.

• Journal of the Korean Institute of Intelligent Systems
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• v.11 no.5
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• pp.395-399
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• 2001

This paper describes modular fuzzy inference systems(MFIS) with adaptive capability to extract fuzzy inference modules from observation data through the learning process. The proposed MFIS is based on the structural similarity to Tagaki-Sugeno fuzzy models and a modular neural architecture. The learning of MFIS is done by assigning new fuzzy inference modules and by updating the parameters of existing modules. The fuzzy inference modules consist of local model network and fuzzy gating network. The parameters of the MFIS are updated by the standard LMS algorithm. The performance of the MFIS is illustrated with adaptive control of a nonlinear dynamic system.