• Wind and Structures
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• v.21 no.4
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• pp.443-460
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• 2015

In this paper, an integrator based method to estimate the effective wind speed in wind turbine systems is proposed. First, the aerodynamic torque was accurately estimated through a proportional gain based observer where the generator speed is the measured output of the system. The torque signal contains not only useful frequencies of the wind, but also high frequencies and the ones due to structural vibration. The useful information of the wind signal is low frequency. A spectral analysis permitted the determination of the useful frequencies. The high frequencies were then filtered before introducing the torque signal in the wind speed observer. The desired effective wind speed was extracted through an integrator based observer using the previously estimated aerodynamic torque. The strength of the method is to avoid numerical solutions used in literature of the wind speed estimation. The effectiveness of the proposed wind speed estimator and its use to control the generator speed has been tested under turbulent situations using the FAST software (Fatigue, Aerodynamics, Structures, and Turbulence), for large scale Megawatt turbine.

• Journal of Communications and Networks
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• v.12 no.3
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• pp.275-284
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• 2010

The current multihome-aware protocols (like stream control transmission protocol (SCTP) or parallel TCP for concurrent multipath data transfer (CMT) are not designed for high-capacity and large-latency networks; they often have performance problems transferring large data files over shared long-distance wide area networks. It has been shown that SCTP-CMT is more sensitive to receive buffer (rbuf) constraints, and this rbuf-blocking problem causes considerable throughput loss when multiple paths are used simultaneously. In this research paper, we demonstrate the weakness of SCTP-CMT rbuf constraints, and we then identify that rbuf-blocking problem in SCTP multihoming is mostly due to its loss-based nature for detecting network congestion. We present a simulation-based performance comparison of FAST TCP versus SCTP in high-speed networks for solving a number of throughput issues. This work proposes an end-to-end transport layer protocol (i.e., FAST TCP multihoming as a reliable, delaybased, multihome-aware, and selective ACK-based transport protocol), which can transfer data between a multihomed source and destination hosts through multiple paths simultaneously. Through extensive ns-2 simulations, we show that FAST TCP multihoming achieves the desired goals under a variety of network conditions. The experimental results and survey presented in this research also provide an insight on design decisions for the future high-speed multihomed transport layer protocols.

• Journal of Advanced Marine Engineering and Technology
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• v.33 no.6
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• pp.918-924
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• 2009

This paper deals with the experimental assessment of the vibration suppression of the smart structures. First, we have presented the paper about the new high-speed active control system that we have developed using the DSP320C6713 microprocessor and a peripheral system composed of a data acquisition system, A/D and D/A converters, piezoelectric (PZT) actuator/sensors, and drivers using PA95. Since fast data processing is very important in the active vibration control of the structures, we utilized the fast processing DSP320C6713 microprocessor as a main processor to the controller and fast peripheral devices for fast control loop. To realize a fast active vibration control, we have analyzed and tested the processing time of the peripheral devices and provided the corresponding test results. Especially, we have focused on achieving the fast signal amplification of the PA95 device since it takes most of loop times of the control system. Finally, we performed numerous experiments of active vibration control of the aluminum plate to validate the superior performance of the developed control system based on previous mode tests of the plate.

• 제어로봇시스템학회:학술대회논문집
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• 1987.10b
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• pp.419-421
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• 1987

The high-speed tendency of Programmable Controller requires a fast processing of instruction. This project investigate the instruction execution system for a fast processing in Programmable Controller.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.9
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• pp.1686-1692
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• 2015

This paper proposes a modified genetic algorithm that has the same beamforming performance and a fast convergence speed using general genetic algorithm in order to form a beam for the mobile node in a mesh network. The proposed beamforming genetic algorithm selects a part of chromosome a high fitness value in mating process to obtain fast convergence speed, and rest part of chromosome with longer fitness value in order to avoid local solution. Furthermore, the reference beam pattern with Gaussian shape reduces additional convergence speed. Simulation shows that the convergence speed of proposed algorithm improves 20% compared with that of conventional beamforming genetic algorithm.

• The Journal of Korean Physical Therapy
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• v.10 no.1
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• pp.127-138
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• 1998

This study was carried out tn invstigate and compare biomechanical characteristics during free speed gait in hemiplegic patients after stroke who took therapeutic exercise by analyzing kinematic and kinetic data in the sagital plane and electromyographic data. Six patients($41\~69$ years old) and age-matched six volunteers in good health(51-61 years old) wire studied. The patients were sorted into two groups, depending on their self-speed of walking : fast speed group(3 patients) and slow speed group(3 patients). The results were as fellows. : 1. In spatio-temparal parameters, affected and unaffected side of fast group showed symetry but blew group showed asymetry of single limb support, opposite foot contact and stance phase (p<0.05). Compared with normal group, patient group showed slower velocity, shoter stride length and longer double limb support (p<0.05). 2. In the pelvic anterior tilt, patient group showed lower valued than normal group. It. In the ground reaction force-vertical force, fast group showed similar double peak gragh compared with normal group, butvslow group showed lower values without double peak (p<0.05).

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.9
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• pp.4240-4258
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• 2016

A practical iterative channel estimation technique is proposed for the multiple-input-multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) system in the high-speed mobile environment, such as high speed railway scenario. In the iterative algorithm, the Kalman filter and data detection are jointed to estimate the time-varying channel, where the detection error is considered as part of the noise in the Kalman recursion in each iteration to reduce the effect of the detection error propagation. Moreover, the employed Kalman filter is from the canonical state space model, which does not include the parameters of the autoregressive (AR) model, so the proposed method does not need to estimate the parameters of AR model, whose accuracy affects the convergence speed. Simulation results show that the proposed method is robust to the fast time-varying channel, and it can obtain more gains compared with the available methods.

• Korean Journal of Applied Biomechanics
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• v.22 no.1
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• pp.35-42
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• 2012

The aim of the present study was to investigate effect of running speed conditions on the kinematic pattern of the metatarsus, mid-foot, calcaneus. Twenty-two healthy young adults were made to run on treadmill at three different running speeds(normal speed, 9.2; slow speed, 7.4; fast speed, 11.1km/hr.) and the trajectories of the 10 reflective markers for each subject were recorded by an eight-camera motion capture system at 200 Hz. Three-dimensional angles for the foot segment in the support phase during running were calculated according to Euler's technique. Results showed that running speed did not affect the peak of the dorsi/plantar flexion, inversion/eversion, and adduction/abduction or their range of motion for each foot segment. However, when the running speed was fast, significant differences were found in the peak of the plantar flexion, eversion, and adduction and ROM(range of motion) of the dorsi/plantar flexion, inversion/eversion, and adduction/abduction between the foot segments, metatarsus, mid-foot, and calcaneus. It was proposed that the foot segment should be analyzed from a multi-segment system point of view on the basis of anatomical reference during locomotion.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.640-643
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• 1997

This paper describes speed controller of a induction motor for electric vehicles using PLL and Fuzzy logic. The proposed system is combined precise speed control of PLL and robust, fast speed control of Fuzzy logic. The motor speed is adaptively incremented or decremented toward the PLL locking range by the Fuzzy logic using information of sampled speed errors and then is maintained accurately by PLL. The results of experiment show excellence of proposed system and that the proposed system is appropriates to control the speed of induction motor for electric vehicles.

• Proceedings of the IEEK Conference
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• 2003.07b
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• pp.1201-1204
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• 2003

This paper described a replica-delay adaptive lock-acquisition scheme for high-speed DLLs. The proposed scheme provides the fast and correct locking cycle that is variable according to the magnitude of the arbitrary replica delay (fixed delay). The scheme guarantees the wide operation range and the fast lock-aquisition time. It has been confirmed by HSPICE simulations in a 0.35${\mu}{\textrm}{m}$ CMOS process.