• KEPCO Journal on Electric Power and Energy
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• 제7권2호
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• pp.249-254
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• 2021

As the spreading speed of electric vehicles increases rapidly, those are expected to be able to use them as flexible resources in the power system beyond the concern for the supply of its charging power. Especially when the Renewable Energy sources (RES) which have no intrinsic control capability have replaced the synchronous generators more and more, the power system needs to secure the additional frequency control resources to ensure its stability. However, the feasibility of using electric vehicles as the frequency control resources should be analyzed from the perspective of the power system operation and it requires the existing simulation frameworks for the power system. Therefore, this paper proposes the grid connected modeling of the primary frequency control provided by electric vehicles which can be integrated into the existing power system model. In addition, the proposed model is implemented considering technical performances constrained by the characteristics of the Vehicle-Grid Integration (VGI) system so that the simulation results can be accepted by the power utilities operating the power system conservatively.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제54권11호
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• pp.511-518
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• 2005

This paper presents the design and drive characteristics of a switched reluctance motor for an electric power pallet vehicle. The designed switched reluctance motor is redesigned by using the finite element analysis(FEA) as a variation of the pole-arc angle for the purpose of an electric power pallet vehicle performance. The output power and torque characteristics of a switched reluctance motor are variable by switching angles of the commutator. Therefor this paper is studied about relationship between the output power and torque characteristics of a switched reluctance motor according to switching angles. The output power of the characteristic point of an electric power pallet vehicle has been shown by experiment. The designed motor drive system operates with the low voltage and high current with using the battery. The core and frame temperatures were described. In this paper, the designed motor is shown better drive characteristics than the DC motor from the rated to maximum, which is verified by the finite element analysis and experimental results.

• 한국기계가공학회지
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• 제21권9호
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• pp.50-55
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• 2022

Acceleration performance, maximum velocity, urban driving energy consumption, and high-way driving energy consumption are important characteristics of electric vehicle driving. This study analyzes the effect of a gear ratio on these characteristics for a front wheel drive electric vehicle. The normalized sensitivity metric is used to compare the sensitivity of these scaled characteristics to the changes in the gear ratio. The sensitivity analysis results show that the normalized values are 0.95 for maximum velocity, 0.91 for acceleration performance, 0.51 for urban driving energy consumption, and 0.24 for high-way driving energy consumption. Therefore, the maximum velocity was affected the most by the changes in the gear ratio. These results can be used to determine the gear ratio of a front wheel drive electric vehicle to optimize the driving characteristics simultaneously.

• Journal of Electrical Engineering and Technology
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• 제13권3호
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• pp.1355-1362
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• 2018

In order to obtain a better understanding of the ageing process of the field composite insulators, it is necessary to explore a quantitative-valuation method for the aging state evaluation. And the linear relationship between volume resistivity and temperature is proposed. In this paper, the composite insulators with different lengths of operating lives from two manufacturers were tested. The relationship between trap characteristics and volume resistivity-temperature characteristics were analyzed based on Thermal Stimulated Current (TSC), volume resistivity-temperature test, Scanning Electron Microscope (SEM) and Fourier Transform Infrared Spectroscopy (FTIR). Furthermore, the application of trap characteristics in the quantitative evaluation of aging state of composite insulators was discussed. The results showed that there was a general negative correlation between the relative variation ratio of trap charges and the volume resistivity-temperature characteristics. Meanwhile, the physicochemical properties would change with the aging time, which would result in the increasing of electron traps. Combined with the TSC and volume resistivity test results, the trap characteristic thresholds which indicated the serious age of the composite insulators had been proposed.

• 한국기계가공학회지
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• 제2권3호
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• pp.48-55
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• 2003

This study investigates the effect of temperature and electric field strength on the Bingham characteristics of Electro-Rheological(ER) fluids which change their Yield shear stress and viscosity by temperature and electric field strength. It is found that under constant temperature the Yield sheal stress and viscosity of ER fluids proportionally increase with the applied electric field strength, and under constant applied electric field strength the Yield shear stress and viscosity of ER fluids decrease with the increasing temperature. These results are considered to be applied to the fluid and pneumatic power industry.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2006년도 전력전자학술대회 논문집
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• pp.323-326
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• 2006

This paper shows the comparison of operating characteristics between squirrel cage induction generator and DFIG(Double Fed Induction Generator). Because squirrel cage induction generator consume the reactive power due to magnetizing reactance, the capacitor is need to compensate the reactive power. Otherwise, two back-to-back PWM voltage-fed inverters connected between the stator and the rotor allow sub/super synchronous operation with low distortion currents. In this paper, the response characteristics of squirrel cage induction generator and DFIG, were analyzed and investigated using PSCAD/EMTDC.

• 전기학회논문지
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• 제58권9호
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• pp.1695-1699
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• 2009

This paper analyzed the characteristics of the demand of electric power in Jeju by year, day. For this analysis, this research used the correlation between the changes in the temperature and the demand of electric power in summer, and cleaned the data of the characteristics of the temperatures, using the coefficient of correlation as the standard. And it proposed the algorithm of forecasting the short-term electric power demand in Jeju, Therefore, in the case of summer, the data by each cleaned temperature section were used. Based on the data, this paper forecasted the short-term electric power demand in the exponential smoothing method. Through the forecast of the electric power demand, this paper verified the excellence of the proposed technique by comparing with the monthly report of Jeju power system operation result made by Korea Power Exchange-Jeju.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2008년도 하계종합학술대회
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• pp.483-484
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• 2008

In this paper, we present high-temperature characteristics of tunable all-optic filter using fiber Bragg grating(FBG), including peak reflectivity, FWHM bandwidth, refractive index change along temperature variation. The characteristics of a FBG tunable filter with refractive index change is affected by its thermal stability.

• 전기학회논문지P
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• 제58권1호
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• pp.33-37
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• 2009

In this paper, a printed small Ultra-Wideband (UWB) antenna with directive radiation characteristics based on combination of electric-magnetic radiators is presented. The combinations of the electric and magnetic type antennas result in the directive radiation patterns for all observed UWB frequency band. Simple combination of dipole antenna and loop antenna is also presented to show that proper configuration of electric radiator and magnetic radiator can produces directive radiation characteristics. The target frequency is from 3.1 GHz to 10.6 GHz with size of $15\;mm{\times}31\;mm$. A proto-type of the combined antenna is simulated, fabricated and measured. Simulation and experimental results of input impedance and gain characteristics of the proposed antenna are presented. There are good agreements between the simulated and measured VSWR curves. Also, the results show the directive radiation characteristics with small antenna form factor over the target frequency range.

• Transactions on Electrical and Electronic Materials
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• 제10권6호
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• pp.196-199
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• 2009

The practical applications of piezoelectric ceramics are applied not only under low electric field environment. Therefore, an examination for characteristics of PZT ceramics under the high electric field condition can contribute to reducing the susceptibility of multifarious applications and to facilitating production of control circuits. These contributions can lead to the expansion of industrial applications. In this research, we fabricated disk-type PZT ceramic samples using conventional methods, measured the resonance characteristics of these samples under from low to high voltage conditions and calculated the PZT constants.