• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.804-807
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• 1996

In this paper, a new model of TDF(two degree of freedom) spin-stabilized platform has been suggested. The platform driving signal modulated in the spinning frequency is described in demodulated form keeping its precession angular velocity. When a strong spinning torque exists, the cross-axis spring constant cannot be neglected in modelling of the platform precession dynamics. A linearized dynamic model of spin-stabilized platform pointing loop is derived and validated through the comparison between simulation and experimental results.

• Journal of Biomedical Engineering Research
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• v.14 no.3
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• pp.251-256
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• 1993

The conduction velocity of the nerve is of importance to the diagnosis of various negromuscular disorders. A major technical problem encountered in nerve stimulation technique is the control of stimulus artifact and the convenience of nerve stimulator. The remained artifacts must be removed by processing the contaminated signal. This paper discusses about the artifact cancellation algorithms in constant voltage type nerve stimulator(CVS) and constant current type nerve stimulator(CCS).

• Journal of the Institute of Convergence Signal Processing
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• v.9 no.2
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• pp.164-172
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• 2008

This paper presents the efficient localization of a mobile robot traveling on the floor with tags installed, using the spatial and temporal information acquired from passive RFID environment. Compared to previous research, the proposed localization method can reduce the position estimation error and also cut down the initial cost tag installation cost. Basically, it is assumed that a mobile robot is traveling over a series of straight line segments, each at a certain constant velocity, and that the number of tags sensed by a mobile robot at each sampling instant is at most one. First, the velocity and position estimation of a mobile robot starting from a known position, which is valid for all segments except the first one. Second, for the first segment in which the starting position is unknown, the velocity and position estimation is made possible by enforcing a mobile robot to traverse at least two tags at a constant velocity with the steering angle unchanged. Third, through experiments using our passive RFID localization system, the validity and performance of the mobile robot localization proposed in this paper is demonstrated.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.9
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• pp.1788-1795
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• 1992

Numerical simulations have been performed to investigate various spectral estimators used in LDV signal processing. In order to simulate a particle arrival time statistics known as the doubly stochastic poisson process, an autoregressive vector model was adopted to construct a primary velocity field. The conditional Poisson process with a random rate parameter was generated through the rescaling time process using the mean value function. The direct transform based on random sampling sequences and the standard periodogram using periodically resampled data by the sample and hold interpolation were applied to obtain power spectral density functions. For low turbulent intensity flows, the direct transform with a constant Poisson intensity is in good agreement with the theoretical spectrum. The periodogram using the sample and hold sequences is better than the direct transform in the view of the stability and the weighting of the velocity bias for high data density flows. The high Reynolds stress and high fluctuation of the transverse velocity component affects the velocity bias which increases the distortion of spectral components in the direct transform.

• Journal of the Korea Convergence Society
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• v.6 no.4
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• pp.249-255
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• 2015

The study was to investigate the effects of stimulus velocity and passer's skill level on anticipation timing performance. Fourteen subjects(seven novices and seven experts) were required to make a total 12 passes in coincidence with an experimentally manipulated moving light signal in randomly presented three different conditions(4m/s, $3m/s{\rightarrow}5m/s$, $5m/s{\rightarrow}3m/s$). Results of analyses showed that absolute error(AE) and constant error(CE) were greater in constant acceleration of the moving stimulus. In addition, experts were more accuracy and consistency than novices on absolute, constant and variable error(VE). These findings indicated that stimulus velocity served as the major determination of anticipation timing performance of passing.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.28 no.6
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• pp.635-643
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• 2015

In this study, the experimental test results are given to confirm the control efficiency of the linear control algorithm used for designing the active mass dampers(AMD) which are supposed to be installed at Incheon international airport control tower. The comparison between the results from test and numerical analysis is conducted and it was observed that the AMD showed the control performance expected by the numerical model. The effects of the gain scheduling and constant-velocity signal added to the control signal calculated by the algorithm is identified through the observation that the AMD always show behavior within the given stroke limit without any loss of the desired control performance. The phase difference between the accelerations of the structure and the AMD were almost close to 90 degree, which implies that the AMD absorbed the structural energy effectively.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.1
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• pp.47-58
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• 2011

MTI filter is used to separate target signal from clutter in many radar signal processing. By suppressing clutter before CFAR detection, the detection performance can be improved. As a radar system designed, a design engineer generally takes averaged SNR and CNR into account and does not include the effect of MTI filter's frequency response. In practice, when the signals including clutter are pass through the filter, SNR is widely varying according to target velocity and CNR is also varying according to clutter center frequency and spectrum spreading. In this paper, we have derived the relationship between the MTI filter's frequency response and a target's velocity and a clutter's spectrum characteristics. With the variation of SNR and CNR at the filter output, the detection performance of CFAR has been analyzed by the simulation and has made certain of their influences on the performance.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.8
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• pp.1061-1070
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• 2003

A triple flame in a mixing layer was studied experimentally with concentration gradient and mean velocity by using a multi-slot burner, which can stabilize the lift-off flame. Flame stabilization condition, lift-off heights, and some other characteristics were examined for methane and propane flame within a range of very low concentration gradient. Pitot-tube and LDV(Laser Doppler Velocimetry) were used for velocity. Mass spectroscopy and Rayleigh scattering signal were used for concentration gradients. Thermo-couples and SiC TFP(Thin Filament Pyrometer) were used for temperature. It was found that minimum values of the lift-off heights exist at a certain concentration gradient for constant mean velocity and this means that the propagation velocity has a maximum value. The scales of flame to the burner nozzle and intensity variation of the diffusion flame were suspected as the cause.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.8
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• pp.29-36
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• 2008

An optical rotary encoder is easy to implement for automation system applications. In particular, the output of the encoder has a digital form pulse, which is also easy to be connected to a popular digital controller. By using an incremental encoder and a counting device, it is easy to measure angular displacement, as the number of the output pulses is proportional to the rotational displacement. This method can only detect the angular placement once a pulse signal comes out of the encoder. The angular displacement detection period is strongly subject to the change of the angular displacement in case of ultimate low velocity range. They have ultimate long detection period or cannot even detect angular displacement at near zero velocity. This paper proposes an algorithm for detecting angular displacement by using a dual encoder system with two encoders of normal resolution. The angular displacement detecting algorithm is able to keep detection period moderately at near zero velocity and even detect constant angular displacement within nominal period. It is useful for motion control applications in case of changing rotational direction at which there occurs zero velocity. In this paper, various experimental results are shown for the angular displacement detection algorithm.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.271-272
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• 2006

This paper presented a new experimental gain tuning technique for a Multi-Axis Servo System. First, the investigation for proportional gain of velocity control loop by using a Dynamic Signal Analyzer (DSA) was performed. Using the FUNCTION characteristic of DSA based on the Bode plot, the Bode plot of open loop transfer function was obtained. In turn, the integral gain of a servo controller can be found out by using the Integration time constant extracted from the Bode plot of open loop transfer function. In the meanwhile, the positional gain of the servo controller has been obtained by using the Bode plot of the closed loop transfer function. We have also proposed the technique to find out an optimal parameter of a notch filter, which has a great influence on vibration reduction, by using the damping factor extracted from the Bode plot of closed loop transfer function.