• Journal of Power Electronics
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• v.19 no.1
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• pp.158-167
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• 2019

This research comparatively studies three kinds of flux regulation methods, namely, stored capacitor discharge pulse (SCDP), constant current source pulse (CCSP), and quantitative flux regulation pulse (QFRP), which are used for hybrid permanent magnet (PM) axial field flux-switching memory machines (HPM-AFFSMMs). Through an analysis of the operation principle and the series hybrid PM flux regulation mechanism of the objective machine, the circuit topologies and flux regulation process of these flux regulation methods are addressed in detail. On the basis of a simulation, the flux regulation characteristics of the researched machine during the magnetization and demagnetization processes are comparatively evaluated. Then, machine performance, including back EMF, direct and quadrature axis inductances, and magnetization and demagnetization characteristics, is quantitatively investigated. Results show that the QFRP enables the HPM-AFFSMM to achieve a less harmonic component of back EMF by approximately 7.28% and 7.97% at the magnetization and demagnetization states, respectively, and a more complete magnetization process than the SCDP and CCSP.

• Korean Journal of Applied Biomechanics
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• v.22 no.3
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• pp.373-378
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• 2012

The purpose of this study was to develop an electric riding machine for cycle fitting to control riding posture easily, to measure frame size quantitatively, and to overcome disadvantages of the traditional systems. The electric riding machine consisted of actuator, load controller, and display & control unit. The actuator unit by BLDC(BrushLess Direct Current) motor drives the saddle height up and down, the crank forward and backward, the handlebar up and down, and the handlebar forward and backward. The load controller unit controls loads by Eddy current controller with electromagnet and aluminum circular plate. The display & control unit consisted of frame size controller and display panel which shows top tube length(485~663mm), head tube length(85~243mm), seat tube length(481~671mm), and seat tube angle($62.7{\sim}76.4^{\circ}$). The range of frame size control for developed electric riding machine did not have difference compared to traditional commercial systems, but quantitative and precise control with 0.1 mm length and $0.1^{\circ}$ angle was possible through digital measurement. Unlike traditional commercial systems, frame size control was possible during riding through motor driven method, thus fitting duration decreased. It is necessary for further improvement to have feedback from users. It is believed that developed electric riding machine can help to develop domestic fitting system.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.11 no.9
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• pp.422-430
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• 2001

An electric drill is a handy tool used in a machine shop, which consists of motor, gear, bearing, shaft, and case, i.e., a gear driving system. Low level vibration and noise of the electric drill can bring the assurance of the quality and reliability of the machine. The vibration sources of the electric drill should be investigated for the reduction of the vibration and noise of the system. Through the experiments in laboratory and the various signal processing procedure for the measured vibration and sound signals, the characteristics of the vibration of the electric drill are investigated. And its propagation path is sought using partial coherence function.

• Journal of Electrical Engineering and Technology
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• v.5 no.1
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• pp.129-139
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• 2010

To be satisfied with complex load condition of electric vehicle, fuzzy logic control (FLC) is applied to improve speed response and system robust performance of induction traction machine based on indirect rotor field orientation control. The proposed propulsion system consists of two induction motors (IM) that ensure the drive of the two back driving wheels of lightweight electric vehicle by means the vehicle used for passenger transportation. The electronic differential system ensures the robust control of the vehicle behavior on the road. It also allows controlling, independently, every driving wheel to turn at different speeds in any curve. Our electric vehicle fuzzy inference system control's simulated in Matlab SIMULINK environment, the results obtained present the efficiency and the robustness of the proposed control with good performances compared with the traditional PI speed control, the FLC induction traction machine presents not only good steady characteristic, but with no overshoot too.

• Textile Coloration and Finishing
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• v.11 no.2
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• pp.64-74
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• 1999

The driving characteristics of the 1 tube 2 chamber bent silkworm type dyeing machine are reported. This dyeing machine is a newly developed energy saving machine. In this study, the driving characteristics of the 1 tube 2 chamber bent silkworm type dyeing machine are examined. Specially the relationship between main body pressure and the electric current of the blower motor, the relationship between main body pressure and the air pressure of the blower nozzle, the effect of the air pressure of the blower on the running speed of the fabric, and the effect of main body temperature were discussed experimentally. Through the experimental data, the following results were obtained. 1. Blower motor electric current and blower nozzle air pressure increased as main body pressure increased due to the temperature increase of the main body. 2. The running speed of the fabric increased as blower nozzle air pressure increased. The difference in running speed between winch reel driving and no winch reel driving at a blower frequency of 60Hz was higher than that of 70Hz. 3. The electric current of the blower rioter and blower nozzle air pressure increased rapidly at the initial state. As the experimental time passed, the main body pressure increased slowly. as the main body temperature increased.

• Journal of Electrical Engineering and Technology
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• v.13 no.2
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• pp.800-811
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• 2018

This paper presents a regenerative braking control scheme for Switched Reluctance Machine (SRM) drive in Electric Vehicles (EVs). The main purpose is to maximize the recovered energy during battery charging by taking into account the nonlinear physical characteristics of the Switched Reluctance Machine. The proposed regenerative braking method employs the back-EMF in the generation process as a complicated position-dependent voltage source. The proposed maximum power recovery (MPR) operation of the regenerative braking is first based on the maximization of the extracted power from the machine and then the maximization of the power transferred to the battery. The maximum power extraction (MPE) from SRM is based on maximizing the energy conversion ratio by the calculation of the optimum PWM switching duty cycle, turn-on, and turn-off angles. By using the impedance matching theorem that allows the maximum power transfer (MPT) of the MPE, the proposed MPR is achieved. The parametric averaged value modeling of the machine phase currents in the chopping control mode is used for MPR realization. By following this model, a nonlinear equivalent input resistance is derived for the battery internal resistance matching. The effectiveness of the proposed regenerative braking method is demonstrated through simulation results and experimental implementation.

• Tribology and Lubricants
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• v.37 no.2
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• pp.41-47
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• 2021

An experimental device was developed for analysis of hydraulic oil characteristics with dielectric constant sensors. Online analysis is the most effective method of the three methods used for analyzing lubricant oils. This is because it can monitor the machine condition effectively using oil sensors in real time without requiring excellent analysis skill and eliminates human errors. Determining the oil quality usually requires complex laboratory equipment for measuring factors such as density, viscosity, base number, acid number, water content, additive, and wear debris. However, the electric constant is another indicator of oil quality that can be measured on-site. The electric constant is the ratio of the capacitance of a capacitor using that material as a dielectric, compared with a similar capacitor that has a vacuum as its dielectric. The electric constant affects the factors such as the base oil, additive, temperature, electric field frequency, water content, and contaminants. In this study, the tendency of the electric constant is investigated with a variation of temperature, water content, and dust weight. The experimental device can control working temperature and mix the contaminants with oil. A machine condition monitoring program developed to analyze hydraulic oil is described. This program provides graph and digital values with variation of time. Moreover, it includes an alarm system for when the oil condition is bad.

• KEPCO Journal on Electric Power and Energy
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• v.6 no.1
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• pp.29-33
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• 2020

Despite the same system architecture and operation principle, Advanced Metering Infrastructure (AMI) and Internet of Things (IoT) are recognized as a heterogeneous system. This is due to the different object modeling and communication protocols used in smart meters and sensors. However, data interworking between AMI and IoT is expected to be inevitable in the future. In this paper, we propose Device Language Message Specification (DLMS) to Lightweight Machine to Machine (LwM2M) conversion model. The proposed interworking model can reduce the packet size by 46.5% compared to that of the encapsulation method.

• Journal of electromagnetic engineering and science
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• v.17 no.4
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• pp.186-190
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• 2017

Visible-near-infrared (VIS-NIR) spectroscopy is a fast and non-destructive method for analyzing materials. However, most commercial VIS-NIR spectrometers are inappropriate for use in various locations such as in homes or offices because of their size and cost. In this paper, we classified eight food powders using a portable VIS-NIR spectrometer with a wavelength range of 450-1,000 nm. We developed three machine learning models using the spectral data for the eight food powders. The proposed three machine learning models (random forest, k-nearest neighbors, and support vector machine) achieved an accuracy of 87%, 98%, and 100%, respectively. Our experimental results showed that the support vector machine model is the most suitable for classifying non-linear spectral data. We demonstrated the potential of material analysis using a portable VIS-NIR spectrometer.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1996.10b
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• pp.34-44
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• 1996

N-machine produces more than input energy at above 3000 rpm. any space energy is absorbed when the N-machine is rotating at a very high velocity. Laws of electromagnetics verify that normal conduction is due to that electrons moves from one three-dimensional crystallizing ${\pi}-bonding$ orbital to next. The ${\pi}-far$ infrared rays are generated from the resonance and rotation of the electrons on the orbitals of three-dimensional crystallizing ${\pi}-bonding$ atoms. Material in universe is composed of ${\pi}-rays$, which have alternative outward electric field. If the alternative outward electric fields of the ${\pi}-rays$ are resonant each other they make attraction force, which is the gravity. The collection of space energy is due to a attraction force between the radially alternating electric field and the ${\pi}-far$ infrared rays in the space. Electrons flow by absorbed density difference of ${\pi}-far$ infrared rays along a conduction wire, which also verifies that normal electron conduction is due to a flow from one three-dimensional crystallizing ${\pi}-bonding$ orbital to next.