• The Transactions of the Korean Institute of Electrical Engineers P
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• v.63 no.4
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• pp.241-247
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• 2014

This paper propose a variable parameter estimations of five-phase squirrel-cage induction motor(IM) for speed control system. In order to high performance control of AC motor using a field oriented control(FOC) and direct torque control(DTC) algorithm, there are required precise motor parameters for slip calculation, flux observer, controller gain, rotor position, speed estimation, and so on. We are suggest a analyzed estimation results of the motor parameters that developing five-phase squirrel-cage IM have a stator of concentrated winding for experimental of variable input power frequency. There are results of stator winding test, no-load test, locked-rotor test, variable actual load test, and estimated parameters of equivalent circuits using manufactured experimental apparatus by IEEE Standard Test Procedure for Polyphase Induction Motors and Generators 112-2004.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.5
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• pp.106-113
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• 2014

Recently, to reduce test cost by efficiently compressing test patterns for SOCs(System-on-a-chip), different compression techniques have been proposed including the FDR(Frequency-directed run-length) algorithm. FDR is extended to EFDR(Extended-FDR), SAFDR(Shifted-Alternate-FDR) and VPDFDR(Variable Prefix Dual-FDR) to improve the compression ratio. In this paper, a frequency-ordered modification is proposed to further augment the compression ratios of FDR, EFDR, SAFRD and VPDFDR. The compression ratio can be maximized by using frequency-ordered method and consequently the overall manufacturing test cost and time can be reduced significantly.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.53 no.5
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• pp.253-257
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• 2004

In order to analyze the frequency dependance of ground impedance in grounding grids for lightning and surge protection, a novel method for measuring the ground impedance as a function of frequency were experimentally investigated. The experiments were carried out in rectangular grounding grids with $6{\times}8$ conductors of 22 $mm^2$ buried at a depth of 0.5 m. The test current was injected by the variable frequency inverter whose frequency is linearly controlled for the established period in the range of 5∼500 KHz. The amplitude and phase of ground impedance were calculated from the waveforms of the test current and ground potential rise measured by the band-pass filter tuned in a specific frequency. The frequency dependence of ground impedance was mainly caused by the inductive current flowing through grounding conductors over the frequency of 100 KHz. The proposed measurement method of ground impedance would be applicable to evaluate the transient response characteristics in lightning protection grounding systems.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.7
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• pp.38-46
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• 2015

This paper propose a variable parameter estimations for variable over current load of five-phase squirrel-cage induction motor(IM) to servo control system. In order to high performance control of AC motor using a field oriented control(FOC) and direct torque control(DTC) algorithm, there are required precise motor parameters for slip calculation, flux observer, controller gain, torque command of current components, rotor position, speed estimation, and so on. We are suggest a analyzed estimation results of the motor parameters that developing five-phase squirrel-cage IM have a stator of concentrated winding for experimental within variable over current load at rated input frequency. There are results of stator winding measurement, no-load test, locked-rotor test, variable over current load test, and estimated parameters of equivalent circuits using manufactured experimental apparatus by IEEE Standard Test Procedure for Polyphase Induction Motors and Generators 112-2004.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.23 no.4
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• pp.301-307
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• 2013

MRU(motor reduction unit) for KTX is a assembled complex structure that is equipped with a lot of parts at the express train KTX and that is the core power source operating variable speeds. This study is recorded the dynamic characteristics analysis results tested by EMA which is done through the parts and assembly test, transient analysis and stoped train test in order to design the online monitoring system for KTX MRU. And the mode shapes result from critical vibration frequency explain the relation with variable speeds of express train over 250 km/hr. Also these variable speeds make variable operational frequencies at pinion, axle gear mesh frequency and normal bearing fault frequencies. As the specified speed can make resonance with natural frequencies of the MRU, for the train operating stability, this study also presents the MRU's critical speeds calculated by the each train speed.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.8
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• pp.1146-1151
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• 2014

The equipment in ships and railway vehicles are continuously exposed to vibration, and its durability is very important. Therefore, consumers require the verification of the performance of equipment via standardized tests under the given environments to improve and stabilize the performance. In this study, a durability improvement and stabilization plan was proposed, which included the exploratory vibration test, variable frequency test and endurance test for the electrical equipment according to the vibration environment. It is expected that this study results will improve the technological competitive power of the ship and railway-related manufacturers and contribute to the equipment development and export.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2003.11a
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• pp.373-376
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• 2003

A new method measuring soil resistivity in frequency range of 5-500[KHz] using variable frequency inverter was presented, and soil resistivity was analysed by resistive and reactive components on the basis of magnitude and phase of measured ground impedance. The test lead arrangement was proposed to reduce the inductive coupling in test circuit for measuring the soil resistivity. The frequency dependence of soil resistivity was mainly caused by the inductive current flowing through grounding conductors over the frequency of 70[KHz].

• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.3
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• pp.40-49
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• 1989

A variable-state block interference channel model is presented which matches asynchronous multiple-access slow frequency-hopped spread-spectrum systems which suffer from bursts of interference of variable duration. For variable-state block interference channels test pattern techniques combined with interleaving are presented from which the decoder obtain side information about channel states. By examining test patterns the decoder estimates which parts of data blocks are affected by interference and regards the parts of blocks affected by interference as erasures. Since the presence of test patterns reduces the number of bits for data transmission, test patterns are not useful for variable-state block interference channels for small hit probability, It is shown that test patterns increase the capacities of variable-state block interference channels for large hit probability. It is also shown that test patterns provide a almost full side information about channel states for certain values of parameters.

• Wind and Structures
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• v.20 no.6
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• pp.793-810
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• 2015

Tests were conducted at the Florida International University (FIU) Wall of Wind (WOW) to investigate the susceptibility of Variable Message Signs (VMS) to wind induced vibrations due to vortex shedding and galloping instability. Large scale VMS models were tested in turbulence representative of the high frequency end of the spectrum in a simulated suburban atmospheric boundary layer. Data was measured for the $0^{\circ}$ and $45^{\circ}$ horizontal wind approach directions and vertical attack angles ranging from $-4.5^{\circ}$ to $+4.5^{\circ}$. Analysis of the power spectrum of the fluctuating lift indicated that vertical vortex oscillations could be significant for VMS with a large depth ratio attached to a structure with a low natural frequency. Analysis of the galloping test data indicated that VMS with large depth ratios, greater than about 0.5, and low natural frequency could also be subject to galloping instability.

• Proceedings of the Korea Concrete Institute Conference
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• 1993.10a
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• pp.179-183
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• 1993

Loads acting on concrete structures are completely random in nature with respect to frequency, magnitude and order of loading, and are essentially distinct from the loads in two-stage and variable load fatigue test. Thus, this study proposes the fatigue test method generating random loads based on the analyzed result.