• Journal of the Korean Society of Manufacturing Process Engineers
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• v.5 no.3
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• pp.71-79
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• 2006

ABS is a safety device for preventing wheel locking in a sudden baking. Its control methods are classified into three types; deceleration control, wheel slip control and deceleration/acceleration control. The braking force takes the influence of the friction coefficient between road and tire, which in turn depends on the wheel slip as well as road conditions. In this paper, it has been proposed the wheel slip control system to apply the adaptive control method at the ABS. To maintain wheel slip to desired wheel slip, it have been done the linearization and designed the adaptive controller to apply gradient method based on the reference model. It is illustrated by computer simulations that the proposed control system gives good performances and adaptation to parameter variation.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.474-478
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• 2004

A bushing is a device used in automotive suspension systems to reduce the load transmitted from the wheel to the frame of the vehicle. A bushing is a hollow cylinder, which is bonded to a solid steel shaft at its inner surface and a steel sleeve at its outer surface. The relation between the force applied to the shaft and the relative deformation of a bushing is nonlinear and exhibits features of viscoelasticity. A force-displacement relation for bushings is important for multibody dynamics numerical simulations. For the nonlinear viscoelastic axial response, Pipkin-Rogers model, the direct relation of force and displacement, has been derived from Lianis model and the sinusoidal input was used for Pipkin-Rogers model, and the affection of displacement with frequency change was studied with Pipkin-Rogers model.

• Journal of the Semiconductor & Display Technology
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• v.11 no.2
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• pp.53-57
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• 2012

This paper is for accurately simulating the breakdown of MHEMTs with an InP-etchstop layer. 2D-Hydrodynamic simulation parameters are investigated and calibrated for the InP-epitaxy layer. With these calibrated parameters, simulations are performed and analyzed for the breakdown of devices with an InP-etchstop layer. In the paper, the impact-ionization coefficients, the mobility degradation due to doping concentration, and the saturation velocity for InP-epitaxy layer are newly calibrated for more accurate breakdown simulation.

• ETRI Journal
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• v.35 no.4
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• pp.644-654
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• 2013

In this paper, a signal detection scheme for cognitive radio (CR) based on the Bussgang theorem is proposed. The proposed scheme calculates the statistical difference between Gaussian noise and the primary user signal by applying the Bussgang theorem to the received signal. Therefore, the proposed scheme overcomes the noise uncertainty and gives scalable complexity according to the zero-memory nonlinear function for a mobile device. We also present the theoretical analysis on the detection threshold and the detection performance in the additive white Gaussian noise channel. The proposed detection scheme is evaluated by computer simulations based on the IEEE 802.22 standard for the wireless regional area network. Our results show that the proposed scheme is robust to the noise uncertainty and works well in a very low signal-to-noise ratio.

• Journal of Institute of Control, Robotics and Systems
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• v.12 no.9
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• pp.861-867
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• 2006

This paper presents the robust mobile robot localization method exploiting redundant motion information acquired from three optical mice that are installed at the bottom of a mobile robot in a regular triangular form. First, we briefly introduce a low-cost optical motion sensor, HDNS-2000, and a commercial device driver development tools, WinDriver, to be used in this research. Second, we explain the basic principle of the mobile robot localization using the motion information from three optical mice, and propose the least squares based localization algorithm which is robust to the noisy measurement and partial malfunctioning of optical mice. Third, we describe the development of the experimental optical odometer using three PC optical mice and the user-friendly graphic monitoring program. Fourth, simulations and experiments are performed to demonstrate the validity of the proposed localization method and the operation of the developed optical odometer. Finally, along with the conclusion, we suggest some future work including the installation parameter calibration, the optical mouse remodelling, and the high-performance motion sensor adoption.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.29A no.7
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• pp.48-55
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• 1992

In this paper, fSDF/POF, BPOF spatial matched filters are designed and implemented by CGH. The correlation characteristics for the suggested filters are analyzed for the distorted input images. Input patterns are obtained from the out-of-plane aircraft images by gradually rotating it, and then used for SDF training images. Modified version of LCD is used for a real-time input device of an optical correlator, and CGH-based fSDF filters are fabricated on film mask for spatial matched filter in order to recognize the distorted images. Total optical corrlator system size is effectively reduced to 148.8 cm by using lens combinations. Computer simulations and experimental results show that the suggested phase filters have nearly uniform correlation characteristics and have good classification capabilities between two classes.

• JSTS:Journal of Semiconductor Technology and Science
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• v.13 no.2
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• pp.139-144
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• 2013

Negative bias temperature instability (NBTI) has become a major factor determining circuit reliability. The effect of the NBTI on the circuit performance depends on the duty cycle which represents the stress and recovery conditions of each device in a circuit. In this paper, we propose an analytical model to perform more accurate duty cycle estimation at the gate-level. The proposed model allows accurate (average error rate: 3%) computation of the duty cycle without the need for expensive transistor-level simulations Furthermore, our model estimates the waveforms at each node, allowing various aging effects to be applied for a reliable gate-level circuit aging analysis framework.

• International journal of advanced smart convergence
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• v.4 no.2
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• pp.163-169
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• 2015

This study proposes a sports simulation device with various harmonics generation. The proposed system is composed of 6 degrees of freedom simulator devices and three types of sports simulation such as walking, snowboard, and jet-ski. In this research, every joint movement is designed with a crank-and-slider mechanism, which is efficient for generating continuous curvature smoothly. Contrary to the conventional spatial simulator with linear actuators, harmonics generation and its spatial combinations become the crucial issue in this research. The harmonic pattern in each joint is modelled for generating smooth curvatures that are also superposed for achieving overall motions. In addition, the targeted motions of sports simulations have different physical factors of periodic gait motion, frictionless surface, and buoyant effects, which are respectively designed by integrating three dimensional graphics information.

• International Journal of Internet, Broadcasting and Communication
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• v.7 no.1
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• pp.20-22
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• 2015

Recently, the study of smart phone user habits has become a highly focused topic due to the rapid growth of the smart phone market. Indeed, sequential pattern analysis methods were efficiently used for web-based user habit mining long time ago. However, by means of simulations, it has been observed that these methods might fail for smart phone-based user habit mining. In this paper, we propose a novel approach that leads to a considerably increased performance of the traditional sequential pattern analysis methods by reasonably cutting off each chronological sequence of user logs on a device into shorter ones, which represent the sequential user activities in various periods of a day.

• The Journal of the Acoustical Society of Korea
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• v.18 no.2E
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• pp.45-52
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• 1999

This paper presents the integrated speech enhancement system for hands-free mobile communication. The proposed integrated system incorporates both acoustic echo cancellation and engine noise reduction device to provide signal enhancement of desired speech signal from the echoed plus noisy environments. To implement the system, a delayless subband adaptive structure is used for acoustic echo cancellation operation. The NLMS based adaptive noise canceller then applied to the residual echo removed noisy signal to achieve the selective engine noise attenuation in dominant frequency component. Two sets of computer simulations are conducted to demonstrate the effectiveness of the system; one for the fixed acoustical environment condition, the other for the robustness of the system in which, more realistic situation, the acoustic transmission environment change. Simulation results confirm the system performance of 20-25dB ERLE in acoustic echo cancellation and 9-19 dB engine noise attenuation in dominant frequency component for both cases.