• Transactions of the Korean Society of Automotive Engineers
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• v.21 no.5
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• pp.25-33
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• 2013

All-wheel steering (AWS) system is applied to articulated vehicles to reduce turning radius. The swing-out suppression algorithm is applied to AWS ECU, a key component of AWS system. The swing-out suppression algorithm applied to AWS ECU has a problem when velocity of vehicle is changed. In this paper, new algorithm based on moving distance that solve velocity problem is proposed. The HILS simulation and the test articulated bus is used to validate algorithm.

• Proceedings of the KIEE Conference
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• 1998.07b
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• pp.666-668
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• 1998

An adaptive nonlinear observer-based longitudinal control law for vehicles is presented in this paper. It is assumed that for vehicle i knows only the distance between vehicle i and the preceding vehicle, i-1. An adaptive nonlinear state observer for vehicle i is developed to estimate the velocity and acceleration of the preceding vehicle, i-1. The communication of the position, velocity, and acceleration information is not used in the proposed method. It will be shown by mathematical analysis that the longitudinal control of vehicle can be implemented without an communication of the informations. It will be proven that the observation errors of the nonlinear states converge to zero asymptotically. To show the effectiveness of the proposed method, the simulation results are presented for the longitudinal control of the vehicle.

• International Journal of Control, Automation, and Systems
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• v.6 no.4
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• pp.559-570
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• 2008

This paper proposes an improved particle swarm optimization named PSO with Controllable Random Exploration Velocity (PSO-CREV) behaving an additional exploration behavior. Different from other improvements on PSO, the updating principle of PSO-CREV is constructed in terms of stochastic approximation diagram. Hence a stochastic velocity independent on cognitive and social components of PSO can be added to the updating principle, so that particles have strong exploration ability than those of conventional PSO. The conditions and main behaviors of PSO-CREV are described. Two properties in terms of "divergence before convergence" and "controllable exploration behavior" are presented, which promote the performance of PSO-CREV. An experimental method based on a complex test function is proposed by which the proper parameters of PSO-CREV used in practice are figured out, which guarantees the high exploration ability, as well as the convergence rate is concerned. The benchmarks and applications on FCRNN training verify the improvements brought by PSO-CREV.

• Journal of the Korean Institute of Telematics and Electronics
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• v.27 no.1
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• pp.74-80
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• 1990

The transconductance of short channel LDD MOSFETs in the saturation region (high Vd)has shown different characteristics from that of conventional device. The transconductance in saturation regime of short channel LDD MOSFETs is reduced from maximum value at higher gate voltage. This decline is analyzed as the velocity saturation effects of carrier at LDD region but accurate analytical expressions for the drain current Idsat and the transconductance Gmsat in the saturation regime are still not in existence. Recently the drain current dependence of parasitic source resistance Rs has been modeled from the velocity saturation of carriers in LDD region. In this study, we approximate that Rmsat that Rs is linearly dependent on the applied gate voltage. Analytical expressions for Idsat and Gmsat obtained from this approximation show the same general behavior as experimental results of short channel LDD NMOSFETs.

• Geophysics and Geophysical Exploration
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• v.5 no.1
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• pp.46-55
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• 2002

We investigated the distorting factors of velocity structure reconstructed by traveltime inversion. The set of models that fit the data in a numerical sense usually contains unrealistic models. Reconstructed velocity structure was enhanced because unreasonable models were eliminated by defining constraint of variable grid using a priori information. To correct time delay of source explosion, which distorts traveltime tomograms, terms for correction of time delay was formulated into equation of travel time tomography.

• Proceedings of the Safety Management and Science Conference
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• 2004.05a
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• pp.219-231
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• 2004

The Charpy and Izod impact tests are the most prevalent techniques used to characterize the effects of high impulse loads on polymeric materials. An analysis method for rubber toughened PVC is suggested to evaluated critical dynamic strain energy release rates(G$_c$) from the Charpy impact tester was used to extract ancillary information concerning fracture parameters in additional to total fracture energies and maximum critical loads. The dynamic stress intensity factor KID was computed for varying amounts of rubber contents from the obtain maximum critical loads and also toughening effects were investigated as well. The fracture surfaces produced under low velocity impact for PVC/MBS composites were investigated by SEM. The results show that MBS rubber is very effective reinforcement material for toughening PVC.

• Journal of Institute of Control, Robotics and Systems
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• v.6 no.9
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• pp.803-812
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• 2000

In this paper we introduce a model based centralized hierarchical controller for cooperative team of soccerplaying multiple mobile robots. The hierarchical controller is composed of high-level and low-level controllers. Using the coordinates information of objects from the vision are simple models of multiple mobile tobots on the playground. Subsequently, the high level controller selects and action model corresponding to the perceived state transition model and generates subgoal and goal-velocity, from which the low level controller generates trajectory of each wheel velocity of the robot. This two layered simplicity. The feasubility of the control strategy has been demonstrated in an implementation for real soccer games at a MiroSot league.

• JSTS:Journal of Semiconductor Technology and Science
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• v.9 no.1
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• pp.55-60
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• 2009

The channel backscattering coefficient and injection velocity have been extracted experimentally in 65nm MOSFETs. Thanks to an experimental extraction methodology taking into account multi-subband population, we demonstrate that the short channel ballistic efficiency is slightly greater than long channel ballistic efficiency.

• The Bulletin of The Korean Astronomical Society
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• v.38 no.1
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• pp.29.1-29.1
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• 2013

We investigate the direct determination of expansion history using redshift distortions without plugging into detailed cosmological parameters. The observed spectra in redshift space include a mixture of information: fluctuations of density-density and velocity-velocity spectra, and distance measures of perpendicular and parallel components to the line of sight. Unfortunately it is hard to measure all the components simultaneously without any specific prior assumption. The degeneracy breaking, between the effect of cosmic distances and redshift distortions for example, depends on the prior we assume. An alternative approach is to utilize the cosmological principle inscribed in the heart of the Friedmann-Lematre-Robertson-Walker (hereafter FLRW) universe, that is, the specific relation between the angular diameter distance and the Hubble parameter, in this degeneracy breaking.

• Proceedings of the KSME Conference
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• 2001.06b
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• pp.565-570
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• 2001

Vehicle dynamics control (VDC) system requires more information on driving conditions compared with ABS and/or TCS. In order to develop the VDC system, tire slip angles, vehicle side-slip angle, and vehicle lateral velocity as well as road friction coefficient are needed. Since there are not any cheap and reliable sensors, recent researches on parameter estimation have given rise to a number of parameter estimation techniques. This paper presents new vehicle model to estimate vehicle's yaw rate. This model is improved from the conventional 2 degrees of freedom vehicle model, so-called bicycle model, taking nonlinear effects into account. These nonlinear effects are: (i) tyre nonlinearity; (ii) lateral load transfer during cornering; (iii) variable gear ratio with respect to vehicle velocity. Estimation results are validated with the experimental results.