• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.384-387
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• 2006

Vertical L/UL (Load/Unload) velocity is very important parameter to determine the L/UL performance, and the vertical velocity is determined by the actuator velocity and the ramp profile. However, it is not easy to precisely control the actuator rotating velocity during the L/UL process. Especially in emergency parking, servo system doesn't operate, it is impossible to control an actuator velocity. Then, the vertical unloading velocity depends on only ramp profile. The ramp height and the sliding length for L/UL process in SFF (Small Form Factor) HDD are restricted due to slimness and small media. For these reasons, it is very difficult to design the ramp profile in SFF HDD. Therefore, this study analyzes the unloading dynamic characteristics for various ramp profiles and makes the thesis for ramp profile design.

• Transactions of the Society of Information Storage Systems
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• v.2 no.2
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• pp.150-155
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• 2006

Vertical L/UL (Load/Unload) velocity is very important parameter to determine the L/UL performance, and the vertical velocity is determined by the actuator velocity and the ramp profile. However, it is not easy to precisely control the actuator rotating velocity during the L/UL process. Especially in emergency parking, servo system doesn't operate, it is impossible to control an actuator velocity. Then, the vertical unloading velocity depends on only ramp profile. The ramp height and the sliding length for L/UL process in SFF (Small Form Factor) HDD are restricted due to slimness and small media. For these reasons, it is very difficult to design the ramp profile in SFF HDD. Therefore, this study analyzes the unloading dynamic characteristics for various ramp profiles and makes the thesis for ramp profile design.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 1996.10a
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• pp.180-183
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• 1996

This work discusses simulation results for the fuzzy logic controller tested the project“Fuzzy Ramp Metering Algorithm Implementation.”The performance objectives were, in order of priority, to maximize total vehicle-miles, maximize mainline speeds, and minimize delay per vehicle while maintaining an acceptable ramp queue. In the fuzzy logic controller, the sensors from the on-ramps were helpful in maintaining reasonable ramp queue and mainline congestion because it considered these factors simultaneously. Each metered ramp had a parameter input file, which allowed the controller to be modified without recompiling the software. Consequently, maintenance costs should be minimal.

• Journal of Electrical Engineering and Technology
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• v.12 no.5
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• pp.2031-2042
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• 2017

In this paper, a novel traffic flow control method based-on ramp metering and speed regulation using an adaptive sliding mode control (ASMC) method along with a deadzoned parameter adaptation law is proposed at a stochastic macroscopic level traffic environment, where the influence of the density and speed disturbances is accounted for in the traffic dynamic equations. The goal of this paper is to design a local traffic flow controller using both ramp metering and speed regulation based on ASMC, in order to achieve the desired density and speed for the maintenance of the maximum mainline throughput against disturbances in practice. The proposed method is advantageous in that it can improve the traffic flow performance compared to the traditional methods using only ramp metering, even in the presence of ramp storage limitation and disturbances. Moreover, a prior knowledge of disturbance magnitude is not required in the process of designing the controller unlike the conventional sliding mode controller. A stability analysis is presented to show that the traffic system under the proposed traffic flow control method is guaranteed to be uniformly bounded and its ultimate bound can be adjusted to be sufficiently small in terms of deadzone. The validity of the proposed method is demonstrated under different traffic situations (i.e., different initial traffic status), in the sense that the proposed control method is capable of stabilizing traffic flow better than the previously well-known Asservissement Lineaire d'Entree Autoroutiere (ALINEA) strategy and also feedback linearization control (FLC) method.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.53 no.12
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• pp.606-615
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• 2004

The discharge characteristics of a ramp reset waveform in the alternating current plasma display panel(ac PDP) were studied using a 2-dimensional numerical simulation. We analyzed the wall charge variation during the reset discharge, address discharge and sustain discharge adopting a ramp reset waveform. Then we investigated the principal parameters for a successful discharge. In this paper, we suggest a new parameter, printing particles' density and its effects on the stability of the ramp discharge. The maximum current flows of the three electrodes during the ramp reset period were decreased with the increase in the priming particles's density which was explained with the wall charge characteristics and the current flow characteristics obtained by a 2-D simulation.

• Journal of Korean Society of Transportation
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• v.21 no.3
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• pp.107-120
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• 2003

Over the decades, a lot of studies have dealt with the traffic characteristics and phenomena at a merging area. However, relatively few analytical techniques have been developed to evaluate the traffic flow at the area and, especially, the ramp merging capacity has rarely been. This study focused on the merging behaviors that were characterized by the relationship between the shoulder lane flow and the on-ramp flow, and modeled these behaviors to determine ramp merge capacity by using gap acceptance theory. In the process of building the model, both an ideal mergence and a forced mergence were considered when ramp-merging vehicles entered the gap provided by the flow of the shoulder lane. In addition, the model for the critical gap was proposed because the critical gap was the most influential factor to determine merging capacity in the developed models. The developed models showed that the merging capacity value was on the increase as the critical gap decreased and the shoulder lane volume increased. This study has a meaning of modeling the merging behaviors including the forced merging type to determine ramp merging capacity more precisely. The findings of this study would help analyze traffic phenomena and understand traffic behaviors at a merging area, and might be applicable to decide the primary parameters of on-ramp control by considering the effects of ramp merging flow.

• Journal of Power Electronics
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• v.19 no.1
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• pp.190-200
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• 2019

The flyback converter, which can be regarded as a nonlinear time-varying system, has complex dynamics and nonlinear behaviors. These phenomena can affect the stability of the converter. To simplify the modeling process and retain the information of the output capacitor branch, a special sampled-data model of a peak current-mode (PCM) controlled flyback converter is established in this paper. Based on this, its dynamic behaviors are analyzed, which provides guidance for designing the circuit parameters of the converter. With the critical stability boundary equation derived by a Jacobian matrix, the stable operation range with a varied output capacitor, proportional coefficient of error the amplifier, input voltage, reference voltage and slope of the compensation ramp of a PCM controlled flyback converter are investigated in detail. Research results show that the duty ratio should be less than 0.5 for a PCM controlled flyback converter without ramp compensation to operate in a stable state. The stability regions in the parameter space between the output capacitor and the proportional coefficient of the error amplifier are enlarged by increasing the input voltage or by decreasing the reference voltage. Furthermore, the ramp compensation also can extend to the stable region. Finally, time-domain simulations and experimental results are presented to verify the theoretical analysis results.

• Journal of Institute of Control, Robotics and Systems
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• v.21 no.3
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• pp.283-289
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• 2015

In this paper, a GNSS interference detection algorithm based on an adaptive fading Kalman filter is proposed to detect a spoofing signal which is one of the threatening GNSS intentional interferences. To detect and mitigate the spoofing signal, the fading factor of the filter is used as a detection parameter. For simulation, the effect of the spoofing signal is modeled by the ramp type bias error of the pseudorange to emulate a smart spoofer and the change of the fading factor value according to ramp type bias error is quantitatively analyzed. In addition, the detection threshold is established to detect the spoofing signal by analyzing the change of the error covariance and the effect of spoofing is mitigated by controlling the Kalman gain of the filter. To verify the performance analysis of the proposed algorithm, various simulations are implemented. Through the results of simulations, we confirmed that the proposed algorithm works well.

• Journal of Korean Society of Transportation
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• v.14 no.3
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• pp.7-26
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• 1996

The estimation of real-time Origin-Destination(O-D) parameters, which gives travel demand between combinations of origin and destination points on a urban freeway network, from on-line surveillance traffic data is essential in developing an efficient ATMS strategy. On this need a real-time O-D parameter estimation model is formulated as a parameter adaptive filtering model based on the extended Kalman Filter. A Monte Carlo test have shown that the estimation of time-varying O-D parameter is possible using only traffic counts. Tests with field data produced the interesting finding that off-ramp volume predictions generated using a constant freeway O-D matrix was replaced by real-time estimates generated using the parameter adaptive filter.

• Korean Journal of Applied Biomechanics
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• v.19 no.3
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• pp.435-448
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• 2009

The purpose of this study was to investigate the kinemaitc gait parameter of lower extremities with different gait conditions(level walking, stairs, ramp) in old adults. Fourteen healthy older adults participated in this study and kinematic data were measured using 3D motion analysis system(Vicon, Oxford Metrics, England). Statistical analysis was used one-way ANOVA to know the difference of lower extremities angle at each gait phase with a different gait conditions. In sagittal plane, pelvic anterior tilt increased in stairs and ramp climbing and hip and knee flexion increased in stairs climbing but ankle dorsiflexion increased in ramp climbing. In frontal plane, pelvic was up in stairs and hip abduction and adduction more changed in stairs climbing than level walking. Knee varus and ankle inversion increased in stair climbing. In horizontal plane, pelvic internal rotation increased in stairs and ramp climbing and knee internal rotation increased in stairs climbing but ankle external rotation increased in stairs climbing. This results was shown that the stairs and ramp climbing changed the kinematic gait parameters of lower extremities in healthy old adults.