• Journal of Korea Society of Industrial Information Systems
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• v.24 no.5
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• pp.121-127
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• 2019

This paper proposes an operator-centric velocity generation and control algorithm for differential-drive mobile robots, which are widely used in many industrial applications. Most of the previous works use a robot centric velocity generation and control for the operators to control the differential-drive mobile robots, which makes the robot control difficult for the operators. Such robot-centric control can cause the increase of accidents and the decrease of work efficiency. The experimental results with a real differential-drive mobile robot testbed demonstrate the efficiency of operator-centric mobile robot control.

• Advances in nano research
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• v.13 no.4
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• pp.369-378
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• 2022

Dynamic study of concrete plates under impact load is presented in this article. The main objective of this work is presenting a mathematical model for the concrete plates under the impact load. The concrete plate is reinforced by carbon nanoparticles which the effective material proprieties are obtained by mixture's rule. Impacts are assumed to occur normally over the top layer of the plate and the interaction between the impactor and the structure is simulated using a new equivalent three-degree-of-freedom (TDOF) spring-mass-damper (SMD) model. The structure is assumed viscoelastic based on Kelvin-Voigt model. Based on the classical plate theory (CPT), energy method and Hamilton's principle, the motion equations are derived. Applying DQM, the dynamic deflection and contact force of the structure are calculated numerically so that the effects of mass, velocity and height of the impactor, volume percent of nanoparticles, structural damping and geometrical parameters of structure are shown on the dynamic deflection and contact force. Results show that considering structural damping leads to lower dynamic deflection and contact force. In addition, increasing the volume percent of nanoparticles yields to decreases in the deflection.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.14 no.1
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• pp.78-90
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• 2021

The purpose of this study was to develop the mathematic algorithm for energy expenditure calculation during cycling as a part of the development of a higher value-added cycle. Participants were 60 university students (male 30, female 30). Energy expenditure was measured with breathing gas at 10 sec intervals by gas analyzer connected with stationary cycle ergometer. Values presented by commercial speedometer and preceding researches were used for verification of actual measurement values in this study. In conclusion, the mathematic algorithms for energy expenditure calculation during cycling were as follows. For male, energy expenditure(Kcal)=5.048×cycling time(min)-2.258, energy expenditure(Kcal)=(0.05×cycling velocity(kph))×(4.750×cycling time(min)+0.091). For female, energy expenditure(Kcal)=4.466×cycling time(min)-1.605, energy expenditure(Kcal)(cycling velocity≤20kph)=(0.05×cycling velocity(kph))×(4.151× cycling time(min)-0.736), energy expenditure(Kcal)(cycling velocity>20kph)=(0.04×cycling velocity(kph)) ×(4.151×cycling time(min) -0.736). And it is suggested that the developed algorithm with cycling time and velocity should be applied for the development of a higher value-added cycle.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.8
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• pp.1592-1598
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• 2011

In this paper, a formation control method based on the leader-following approach for nonholonomic mobile robots is proposed. In the previous works, it is assumed that the followers know the leader's velocity by means of communication. However, it is difficult that the followers correctly know the leader's velocity due to the contamination or delay of information. Thus, in this paper, an adaptive approach based on the parameter projection algorithm is proposed to estimate the leader's velocity. Moreover, the adaptive backstepping technique is used to compensate the effects of a dynamic model with the unknown time-invariant and time-varying parameters. From the Lyapunov stability theory, it is proved that the errors of the closed-loop system are uniformly ultimately bounded. Simulation results illustrate the effectiveness of the proposed control method.

• Tribology and Lubricants
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• v.5 no.2
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• pp.60-67
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• 1989

For the life prediction and fatigue failure prevention of the constant velocity joint, the maximum equivalent stress and its location in depth from the contact area are essential. These values give the fundamental information to determine the depth of the surface hardening treatment at the contact area. Contact stresses are evaluated at the surface and subsurface of the ball groove of the Weiss type constant velocity joint. The maximum contact pressure and the maximum equivalent stress are obtained. The effects of various parameters such as the radius of ball groove, friction coefficient, and residual stress are studied. The maximum equivalent stress and the maximum contact pressure increase as the radius of the ball grove increases. The location of the maximum equivalent stress moves toward surface as the friction coefficient increases. It was also found that the maximum equivalent stress becomes minimum when the compressire residual stress is about 0.16 times of the maximum contact pressure.

• Journal of Biomedical Engineering Research
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• v.7 no.2
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• pp.169-182
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• 1986

Pulsed ultrasonic Doppler system is a useful diagnostic instrument to measure blood-flow-velocity, velocity profile, and volume-blood-flow. This system is more powerful compare with 2-dimensional B-scan tissue image. A system has been deve- loped and ii being evaluated using TMS 32010 DSP. We use this DSP for the purpose of real-time spectrum analyzer to obtain spectrogram in singlegate pulsed Doppler system and for the serial comb filter to cancel clutter and zero crossing counter to estimate Doppler mean frequency in multigate pulsed Doppler system. The Doppler shift of the backscattered signals is sensed in a phase detector. This Doppler signal corresponds to the mean velocity over a some region in space defined by the ultrasonic beam dimensions, transmitted pulse duration, and transducer ban(iwidth. Multi- gate pulsed Doppler system enable the transcutaneous and simultaneous assessment of the velocities in a number of adjacent sample volumes as a continuous function of time. A multigate pulsed Doppler system processing the information originating from presented.

• Proceedings of the KIEE Conference
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• 1987.07b
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• pp.1239-1242
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• 1987

With the convention CW Doppler velocity meter, bi-directional velocities cannot be separated. The new CW Doppler system usee quadrature detection and phase rotation to Produce simultaneous independent audio and velocity signals for forward and reverse blood flow direction, is fabricated. Specially, this system shows that phase rotation method for flow direction separation provides easy and satisfactory feature. From in vivo blood flow measurement, can easily differentiate typical artery flow from vein flow. and measure both velocity characteristics qualitatively.

• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.7
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• pp.98-105
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• 1989

To characterize the biological tissue, the new method to measure the ultrasonic velocity is presented in this paper. The influence of the dispersion effect on the estimation of the ultrasonic velocity is mostly neglected. A more efficient method determining the minimum phase spectrum is developed to characterize the frequency dispersion form the spectral magnitude function. To eliminate the frequency dispersion, the signal-decomposition method is also proposed. Computer simulations are performed to verify the algorithms.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.31A no.1
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• pp.54-60
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• 1994

In this paper, we present the analytical models for the change of the lateral electric field distribution and the velocity saturation region length with the electron trapping of stressed SC-PMOSFET in the saturation region. To derive the hot-electron-induced lateral electric field of stressed SC-PMOSFET. Ko's pseudo two dimensional box model in the saturation region which illustrates the analysis of the velocity saturation region is modified under the condition of electron trapping in the oxide near the drain region. From the results, we have the following lateral electric field in the y-direction, that is, E(y) ES1satT.cosh(y/l) qNS1tT.sinh(y/l)/lCox. It is shown that the trapped electrons influence the field in the drain region. decreasing the lateral electric field. Calculated velocity saturaion length increases with the trapped electrons. increasing the drain current of stressed SCPMOSFET. This results well explain the HEIP phenomenon of PMOSFET's.

• The Bulletin of The Korean Astronomical Society
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• v.39 no.2
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• pp.67.1-67.1
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• 2014

Abell 2537 has been regarded as one of relaxed galaxy clusters because the X-ray emission is regular and symmetric, while there is also evidence to the contrary that the brightest cluster galaxy (BCG) is offset from the velocity center. To investigate the dynamical state of A2537 we obtain the redshift information of cluster galaxy candidates using Hectospec mounted on the MMT 6.5 m and compile those in the literature. The velocity distribution of member galaxies appears bimodal, with the main peak including the BCG and a secondary peak at velocity difference ~2000 km s-1. Based on the three-dimensional analysis and statistical tests we conclude that A2537 has at least two substructures and is not fully relaxed from a merger near the line-of-sight. We discuss more about the dynamical state of A2537 based on the color-magnitude diagram and X-ray scaling relation.