• 대한전기학회논문지
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• 제41권4호
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• pp.339-345
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• 1992

Estimates of maximum amplitudes of conductor galloping are needed in order to determine appropriate phase-to-phase clearances on the overhead lines. One approach to obtaining these estimates is through the use of mathematical models of conductor galloping. Unfortunately, the models that consider both vertical conductor motion (Den Hartog type) and torsional conductor motion are often too complex for practical use. However, the estimates of maximum amplitude obtained from galloping models that assume only vertical (Den Hartog type) conductor motion tend to be too conservative. This paper presents the DF method to obtain the estimates of the amplitude and the frequency of galloping limit cycle, along with the wind pressure at which they occur, from a nonlinear dynamic model that considers both Den Hartog type and torsional conductor motion. From these results, the useful data for the line design guide and further insight into the mechanism of the conductor galloping are obtained.

• 전자공학회논문지D
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• 제34D권3호
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• pp.123-130
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• 1997

We determine the dispersion profile of a dispersion decreasing fiber(DDF) for optimum pulse compression from a trade-off between high pulse compression and low pedestal power/short DDF length. We find that the optimum vlaue of the exponential dispersion decreasing factor .alpha. is 0.95 and that the corresponding optimum fiber length is 1.5 times of the initial soliton period. Passing through the dDF, ~10 times of pulse comparession ratio can be achieved without significant increase in pedestal power. To compress relatively broad pulses using a given DDF optimized at a specific pulse width, we also detemrine the optimum input pulse amplitude, as a function of input pulse width.

• 동력기계공학회지
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• 제6권2호
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• pp.33-39
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• 2002

Commercial vehicles are mostly subjected to relatively rougher ground environment than passenger vehicles. Many driver's seats of commercial vehicles have suspension system with spring and dampers. Then, impact or vibrative forces transmitted from the vehicle to the driver can be attenuated. This study deals with a ride evaluation method using sky-hook control algorithm for the suspension dampers. Vibration amplitude transmissibilities were compared between passive dampers and semi-active dampers with sky-hook control method.

• 한국통신학회:학술대회논문집
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• 한국통신학회 1984년도 춘계학술발표회논문집
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• pp.37-41
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• 1984

The error rate performance of amplitude phase keying system has been studied in the environment of cochannel interference and impulsive noise. We have derived the error probability equations of amplitude shift keying signal and phase shift keying signal, and combining the results, we have evaluated the circular APK signal which is the one of the several cases of APK arrays. Using the derived equations, the circular APK system has been evaluated in terms of carrier-to-noise power ratio(CNR), carrier-to-interferer power ratio(CIR), and impulsive index. The graphic results show us the best case and worst case of APK system, and good performance compared to the other systems in cochannel interference and impulsive noise.

• 한국컴퓨터정보학회논문지
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• 제5권2호
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• pp.105-114
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• 2000

본 논문에서는 1차원 움직임을 갖는 신호원의 위치를 실시간으로 탐지하기 위해 N개의 안테나를 반원형 구조로 배열하였고, 각각의 수신어레이로부터 수신 전력패턴과 3차 spline 보간법만을 사용하여 신호원의 입사각을 추정하고, 이로부터 신호원의 수평이동 좌표를 화면에 실시간으로 표시하는 시스템을 구현한 논문이다. 본 논문에서 사용한 신호원은 X 대역의 10.52GHz로 10-20dBm 사이의 송신출력으로 하였고, 신호원의 위치를 좌.우 ${\pm}15^{\circ}$ 이내의 임의의 좌표로 수평 이동하면서 제시한 방법의 타당성을 검증하고자 한다.

• Journal of Power Electronics
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• 제6권2호
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• pp.139-145
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• 2006

This paper describes the ultra precise position estimation of a servomotor using a sinusoidal encoder based on Arcsine Interpolation Method for the cost reduction of circuit design. The amplitude and offset errors of the sinusoidal encoder output signals, from the encoder itself and analog signal processing procedures, are effectively compensated and on-line tuned by utilizing a low cost programmable differential amplifier without any special expensive equipment. For a theoretical evaluation of the practical resolution of this system, the relationship between the amplitude of ADC(Analog to Digital Converter) input signal errors and the anticipated resolution is also addressed. The performance of the proposed method is verified by comparing it with speed control characteristics of the servomotor driving system using a digital incremental 50,000ppr encoder in the experiments.

• Journal of Power Electronics
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• 제13권6호
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• pp.928-938
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• 2013

This paper proposes a novel control method for a multi-output switched-resonant converter. Output voltage can be regulated against variations in the supply voltage and load by controlling the voltage of the resonant capacitor (pulse amplitude control). Precise control is possible when pulse amplitude control is combined with pulse number control. The converter is analyzed, and design considerations are explained by using examples. Control implementation is described and load regulation and ripples are analyzed by simulation and hardware results. The topology is modified to obtain an additional negative output without any additional hardware other than a diode. The analysis of such a triple output converter with two positive outputs and one negative output is conducted and confirmed. The topology and control scheme are scalable to any number of outputs.

• International Journal of Advanced Culture Technology
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• 제9권4호
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• pp.307-314
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• 2021

Recently, positively asymmetric binary pulse amplitude modulation (2PAM) has been proposed to improve the bit error rate (BER) performance of the weak channel gain user, with a tolerable BER loss of the strong channel gain user, for non-orthogonal multiple access (NOMA). However, the BER loss of the stronger channel gain user is inevitable in such positively asymmetric 2PAM NOMA scheme. Thus, we propose the negatively asymmetric 2PAM NOMA scheme. First, we derive closed-form expressions for the BERs of the negatively asymmetric 2PAM NOMA. Then, simulations demonstrate that for the stronger channel gain user, the BER of the proposed negatively asymmetric 2PAM NOMA improves, compared to that of the conventional positively asymmetric 2PAM NOMA. Moreover, we also show that for the weaker channel gain user, the BER of the proposed negatively asymmetric 2PAM NOMA is comparable to that of the conventional positively asymmetric 2PAM NOMA, over the power allocation range less than about 10 %.

• 조명전기설비학회논문지
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• 제21권1호
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• pp.118-124
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• 2007

본 논문에서는 임펄스전류의 크기와 인가횟수가 ZnO바리스터의 수명에 미치는 영향에 관한 것으로 뇌임펄스전류가 ZnO바리스터의 성능에 미치는 영향을 분석하기 위하여 $8/20[{\mu}s]$임펄스전류가 인가되기 전후 ZnO바리스터의 상용주파수 교류전압에 대한 저항성 누설전류와 손실전력을 측정하였다. 그 결과 $8/20[{\mu}s]$임펄스전류의 인가횟수가 증가함에 파라 ZnO바리스터에 흐르는 저항성 누설전류는 증가하고 통과시간은 길어졌다. ZnO바리스터의 수명은 뇌임펄스전류의 크기와 인가횟수에 대해서 평가하는 것이 바람직하다.

• 동력기계공학회지
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• 제14권2호
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• pp.60-64
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• 2010

This paper introduces reliability improvement and time saving in eddy current inspection by signal characteristic optimization of multi-coil eddy current array probe. In the past, Multi-coil array probe and single probe were used for the gas turbine rotor surface inspection & defect evaluation. The multi-coil array probe was used for the broad area inspection. But the signal deviations among multi-coil array probe are maximum 28% in commercial probe. This differences were considered to impedance differences among coils, so it is very difficult to evaluate exact defect size. The signal deviations among multi-coil array probe are maximum 28% in commercial probe. So, single coil inspection was used for exact defect sizing. The purpose of this study is to improve signal deviations of multi-coil array probe. The introduced new technology can improves this deviation by adjusting input voltage in each coil. At first, apply same voltage in each coil and collect signal amplitude of each coil. And calculate new input voltage based on signal amplitude of each coil. If the signal amplitude deviation is within 5% among multi-coil array probe, the signal amplitude of multi-coil array probe is reliable. The proposed technology gives 2% signal deviation among multi-coil array probe. The proposed new technology gives reliability improvement and inspection time saving in eddy current inspection.