• IEMEK Journal of Embedded Systems and Applications
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• v.13 no.2
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• pp.93-100
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• 2018

In this paper, we present a novel scheme of data transmission for logistics vehicles connected with 3G mobile communication networks. The proposed method enhances the efficiency of data transmission by varying the packet transmission period according to the vehicle speed and by reducing the amount of transmitted data using a reduced packet structure. The main contribution is to present the experimental verification in which the proposed method is applied to commercial logistics vehicles that operate with networked data transmission modules. Being compared with the existing method, the proposed scheme shows superior performance in terms of data reduction and transmission speed.

• Journal of Industrial Technology
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• v.20 no.B
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• pp.95-103
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• 2000

A model trains must have similitude with its original model not only in shape but also in motion. Motion characteristics of a model train under considerations are maximum velocity in straight and circular tracks and stopping distance. Equations of motions are derived to obtain maximum speed and stopping distance based on the Newton's Second Law and the energy principal. To accurately predict traction and resistance force between wheel and rail. wheel slip, or creepage, is taken into consideration. To verify the equations of motion, various experiments have been carried out including measurement of gear efficiency, location of mass center, rolling resistance force, traction force, slip, maximum velocity and stopping distance. This paper addresses how the experiments are setup and carried out in detail. Also the results of experiments are compared with the analytical prediction, which showed good agreements with each other.

• Journal of Auto-vehicle Safety Association
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• v.12 no.2
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• pp.14-20
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• 2020

This paper presents a vehicle mass and road grade estimator for developing an automated bus. To consider the dynamic characteristics of a bus varying with the number of passengers, the longitudinal controller needs the estimation of the vehicle's mass and road grade in real-time and utilizes the information to adjust the control gains. Discrete Kalman filter is applied to estimate the time-varying road grade, and the recursive least squares algorithm is adopted to account for the constant mass estimation. After being implemented in MATLAB/Simulink, the estimators are evaluated with the dynamic model and experimental data of the target bus. The proposed estimators will be applied to complement the algorithm of the longitudinal controller and proceed with algorithm verification.

• Proceedings of the Korea Concrete Institute Conference
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• 1997.04a
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• pp.392-397
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• 1997

In this paper, design and analysis of anchorage zone in prestressed concrete structure using nonlinear strut and tie model is presented. Nonlinear strut and tie model is an analysis and design model which constructs strut and tie model based on nonlinear analysis considering the nonlinear behavior of concrete. Based on the nonlinear strut and tie model, the analysis and design are performed for the anchorage zone having singular concentric tendons, singular eccentric tendons and multiple tendons, respectively. For verification of the model, comparisons are made with experimental results as well as results by linear strut and tie models. from the comparisons, it is shown that the design of the anchorage zone by the nonlinear model is still economical without loosing the degree of safety and the prediction of the ultimate load by the nonlinear model gives better accuracy than by the linear one.

• Transactions of The Korea Fluid Power Systems Society
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• v.1 no.4
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• pp.9-14
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• 2004

An estimation technique called the Extended Kalman filter is used to estimate viscous friction, spring initial contraction, and the spring constant on the swash plate of a variable displacement pump. The feasibility of the approach was established using a simulation study. It showed that these parameters could be estimated very accurately in a reliable and independent fashion. A special experimental system was set up to facilitate the measurement of certain states to enhance the Kalman Filtering approach. The aforementioned parameters were estimated and found to be reasonably repeatable for a common operating point. It was very evident that as the operating conditions changed (i.e. temperature) so did the estimated values of certain parameters such as viscous friction. This was believed to be a good verification test for the approach.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.3
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• pp.66-73
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• 2008

This paper presents a position sensorless control system of SRM over wide speed range. Due to the doubly salient structure of the SRM, the phase inductance varies along with the rotor position. Most of the sensorless control techniques are based on the fact that the magnetic status of the SRM is a function of the angular rotor position. The rotor position estimation of the SRM is somewhat difficult because of its highly nonlinear magnetizing characteristics. In order to estimate more accurate rotor position over wide speed range, Neural Network is used for this highly nonlinear function approximation. Magnetizing data patterns of the prototype 1-hp SRM are obtained from locked rotor test, and used for the Neural Network training data set. Through measurement of the flux-linkage and phase currents, rotor position is able to estimate from current-flux-rotor position lookup table which is constructed from trained Neural Network. Experimental results for a 1-hp SRM over 16:1 speed range are presented for the verification of the proposed sensorless control algorithm.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.12
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• pp.2145-2152
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• 2016

Internet generalization has led to increased demands for Internet banking. Various security programs to protect authentication information are being developed; however, these programs cannot protect the wireless communication sections of wireless keyboards. In particular, vulnerabilities have been reported in the radio communication sections of 27 MHz wireless keyboards. In this paper, we explain how to analyze M's 27 MHz wireless keyboard. We also experimentally show that an attacker can acquire authentication information during domestic Internet banking using a 27 MHz wireless keyboard. To do this, we set up an experimental encironment to analyze the electromagnetic signal of a 27 MHz wireless keyboard.

• Journal of Power Electronics
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• v.9 no.4
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• pp.575-581
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• 2009

In this paper two modes of operating a wound rotor induction machine as a generator at sub-and super-synchronous speeds in wind energy conversion systems are investigated. In the first mode, known as double fed induction generator (DFIG), the rotor circuit is fed from the ac mains via a controlled rectifier and a forced commutated inverter. Adjusting the applied rotor voltage magnitude and phase leads to machine operation as a generator at sub-synchronous speeds. In the second mode, the machine is operated in a slip recovery scheme where the slip energy is fed back to the ac mains via a rectifier and line commutated inverter. This mode is described as double output induction generator (DOIG) leading to increase the efficiency of the wind-to electrical energy conversion system. Simulated results of both modes are presented. Experimental verification of the simulated results are presented for the DOIG mode of operation, showing larger amount of power captured and better power factor when compared to conventional induction generators.

• The Transactions of the Korean Institute of Power Electronics
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• v.25 no.5
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• pp.404-411
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• 2020

Inductive power transfer (IPT) systems for electric vehicles generally require zero phase angle (ZPA) frequency tracking control to achieve high efficiency. Current sensors are used for ZPA frequency tracking control. However, the use of current sensors causes several problems, such as switching noise, degrading control performance, and control complexity. To solve these problems, this study proposes ZPA frequency tracking control without current sensors. Such control enables ZPA frequency tracking without real-time control and achieves stable zero voltage switching operation closed to ZPA frequency within all coupling coefficient and load ranges. The validity of the proposed control algorithm is verified on LCCL-S topology with a 3.3 kW rating IPT experimental test bed. Simulation verification is also performed.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.9
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• pp.768-772
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• 2001

This paper presents leakage magnetic field and leakage inductance calculations in current transformer by means of 3-D Integral methods. From the distribution diagram of leakage magnetic flux to be analyzed using program called TRACAL 3, ti confirms a parallel to the winding axis direction of the leakage flux lines in the air gap between the windings. The leakage inductances L$\sub$r1/ and L$\sub$r2/ of the primary and secondary winding were calculated, their values are 4.23 MH and 0.49 mH, respectively. They are also similar to the measured values of he leakage inductances of the experimental verification, 4.06 mH and 0.47 mH.