• 전기학회논문지P
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• 제63권4호
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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.

• 전자공학회논문지
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• 제51권5호
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• pp.106-113
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• 2014

최근 반도체 업계에서 주요 관심사로 떠오르고 있는 SOC(System-on-a-chip) 테스트는 비용 및 시간 절감을 위해 여러 종류의 FDR(Frequency-directed run-length) 기술이 제안되었다. 기존의 FDR보다 압축률을 향상시키는 EFDR(Extended-FDR)과 SAFDR(Shifted-Alternate-FDR), VPDFDR(Variable Prefix Dual-FDR)이 있다. 본 논문에서는 제안한 Frequency-ordered 방식은 FDR, EFDR, SAFDR, VPDFDR에 적용시켜 상당한 압축률 개선을 보인다. 본 기술을 사용하면 압축률을 극대화할 수 있고, 결과적으로 전체적인 양산 테스트 비용 및 시간을 크게 절감할 수 있게 한다.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제53권5호
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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.

• 조명전기설비학회논문지
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• 제29권7호
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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.

• 한국소음진동공학회논문집
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• 제23권4호
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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.

• 전기학회논문지
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• 제63권8호
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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.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2003년도 학술대회논문집
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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].

• 대한전자공학회논문지
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• 제26권3호
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• pp.40-49
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• 1989

지속기간이 가변적인 블록간섭이 있는 비동기 다원접속 저속 주파수 도약 확산대역 시스템에 맞는 가변상태 블록 간섭 채널이 제안된다. 가변상태 블록간섭 채널에서 복호기에 부가정보를 주기 위하여 인터리빙과 결합된 테스트 패턴 기법이 제안된다. 복호기는 테스트 패턴을 검사함으로써 간섭의 영향을 받은 데이타 블록의 부분을 추정하고 그 부분을 소거(erasure)로 간주한다. 테스트 패턴의 존재가 데이타 전송에 쓰이는 비트 수를 감소시키므로 테스트 패턴은 다른 사용자에 의한 주파수 충돌확률이 작은 가변상태 블록간섭 채널에 대해서는 유용하지 않다. 주파수 충돌확률이 큰 가변상태 블록간섭 채널에 대하여 테스트 패턴을 사용하면 채널용량이 증가함을 보인다. 또한 채널의 변수가 특정한 법위의 값을 가질 때 테스트 패턴으로부터 채널상태에 대한 거의 완전한 부가정보가 얻어짐을 보인다.

• Wind and Structures
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• 제20권6호
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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.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1993년도 가을 학술발표회 논문집
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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.