• Journal of KSNVE
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• v.8 no.6
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• pp.1086-1092
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• 1998

This paper presents a general analytical method for analyzing the instability of unbalanced electromagnetic forces produced in induction motors with an eccentric rotor. The equations to be solved are a set of second order differential equations which give matrices with periodic coefficients that are a function of time due to the unbalanced electromagnetic force. The method is based on an extension of the Floquet theory. A transfer matrix over one period of the motion is obtained. and the stability of the system can be determined with the eigenvalues of the matrix. The analysis results of instability zone were coincided upon comparing that of transfer matrix method with that of rotating frame. Two examples are given. including an industrial application. The results show that the method proposed is satisfactory.

• Journal of electromagnetic engineering and science
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• v.16 no.4
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• pp.225-228
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• 2016

KRISS-V, a V-band millimeter-wave source module for a primary RF power standard and calibration system developed by the Korea Research Institute of Standards and Science is here presented. The output power of KRISS-V is several times higher than that of commercial amplifier/multiplier chains and is highly stable (the standard deviations of output power are less than 0.01% in the worst case). The spectral purity of KRISS-V is high enough to consider it a single-tone signal generator. We also added programmable attenuation capability to KRISS-V for remote power control. Moreover, the in-house source module is cost-effective and adaptable to various measurement schemes. The structure of the model as well as detailed component information are introduced so that it can be reproduced.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.1089-1092
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• 1995

A planar vibratory gyroscope using electrostatic actuation and electromagnetic detection is proposed. The gyroscope has large sensitivity and can be fabricated by using surface micrimachining, bulk micromachining and conventional machining technology. In this paper, the gyroscope and the electromagnetic detecting system equations are derived to determine the output characteristics for the planar vibratory gyroscope using electrostatic acturation and electromagnetic detection. The maximum output is obtained when the driving frequencyequals to the detecting frequency. The resonant frequencies of the resonator are determined by the beam stiffness, i.e. the material constants and spring dimensions. The dimensions of the beams are determined using the analytic vibration modelling. The expected resonant frequencies are 200Hz both and the sensitivity is 62mV/deg/sec with 4000 electronic circuit amplifying coefficient for an AC drive voltage of 3V bias voltage of 15V and DC field current of 50 mA.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.53 no.1
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• pp.38-42
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• 2004

In this paper we analyzed the electromagnetic behavior of a superconducting fault current limiter (SFCL) under the quench state using FEM. The analysis model used in this work is 5.5 KVA meander-line type SFCLs which are currently developed by Superconductor Power System Lab in Korea Electric Power Research Institute. Meshes of 3,650 triangular elements were used in the analysis of this SFCL. Analysis results showed that the distribution of current density was concentrated to inner curved line in meander-line type SFCL and the maximum current density was 14.61 A/$m^2$ and also the maximum Joule heat was 2,030 W/$m^2$ in this region. We think that the new and the modified structure must be considered for an uniform distribution of the electromagnetic field.

• Progress in Superconductivity and Cryogenics
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• v.15 no.3
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• pp.13-19
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• 2013

Superconducting field coils using a high-temperature superconducting (HTS) wires with high current density generate high magnetic field of 2 to 5 [T] and electromagnetic force (Lorentz force) acting on the superconducting field coils also become a very strong from the point of view of a mechanical characteristics. Because mechanical stress caused by these powerful electromagnetic force is one of the factors which worsens the critical current performance and structural characteristics of HTS wire, the mechanical stress analysis should be performed when designing the superconducting field coils. In this paper, as part of structural design of superconducting field coils for 17 MW class superconducting ship propulsion motor, mechanical stress acting on the superconducting field coils was analyzed and structural safety was also determined by the coupling analysis system that is consists of commercial electromagnetic field analysis program and structural analysis program.

• Journal of the Korea Concrete Institute
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• v.12 no.3
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• pp.115-123
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• 2000

Characterizing the electromagnetic properties of concrete is essential to the enhancement of accuracy and reliability in nondestructive testing of concrete structures using electromagnetic techniques. To establish a data base for the properties of concrete, a measurement technique has been developed and a set of data has been obtained for the frequency range of 1~6 GHz. As moisture content is one of major contributing factors to determine permittivity of dielectric material, moisture content is varied during the measurement. An application of a measurement system which consists of open-ended coaxial probe and automatic network analyzer to concrete and mortar specimens is studied. For this, calibration techniques, size of specimens, and number of measurements necessary to obtain reliable data are investigated. From the measured data, it is shown that moisture content plays an important role to determine the permittivity of specimens. As the moisture content increases. The permittivity of specimens show tendency to approach the permittivity of water.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.1 no.1
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• pp.20-27
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• 1990

This paper presents an efficient method to estimate the induced current by the external electromagnetic wave when the line system is composed of cascaded transmission lines. To solve this phenomena, we apply the state variable method to the nonhomogeneous differential equation. This new method is the way of transferring the sources at a different point by the Ch- aracteristics of the transition matrix. Using this method, we investigate the characteristics of the induced power of the transmission line above the perfectly conducting ground plane.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 1999.11a
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• pp.285-289
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• 1999

Insulation diagnosis techniques of power equipments for the stable power supply and prevention from accidents are of high importance. Diagnosis techniques is able to prevent from large accidents before they happen by finding signs of the accidents. From this point of view, this paper simulated discharge progress and partial discharge using needle-plan electrode system in air, studied the distribution of frequency spectrum of the radiated electromagnetic waves using biconical antenna and spectrum analyzer. From results of this study, the new method was introduced for measurement and analyzation of the radiated electromagnetic waves in accordance with discharge progress in air, Besides, according to the consideration of the mutual relation between frequency spectrum of the radiated electromagnetic waves and discharge progress, it was confirmed that detecting partial discharge and estimating discharge progress were possible.

• Journal of the Korea Institute of Military Science and Technology
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• v.17 no.5
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• pp.569-576
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• 2014

There were overwhelming high-frequency electromagnetic noises in 200kW-class hybrid electric vehicle(HEV) although EMC control strategy had been applied to cope with the electromagnetic noises during the development of HEV. This paper investigates the characteristics of the conducted and radiated emission noises, the source and path of noises, and the effects of EMI on the electronics. Finally the design concept of noise control is proposed.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2016.10a
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• pp.20-21
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• 2016

In this study, the shielding properties of concrete with conductive materials as shielding material for electromagne- tic pulse(EMP) within 10kHz~18GHz were investigated. The shielding effectiveness of specimens were compared with different entrained materials. The shielding effectiveness were determined according to MIL-STD-188-125-1, IEEE-STD-299 at 28 days of concrete curing. The results of shielding effectiveness did not meet the criteria(80dB) severely.