• 한국전자통신학회논문지
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• 제7권4호
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• pp.855-859
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• 2012

본 연구에서는 선형시변 발진기 위상잡음 이론에 있어서 전력 스펙트럼 밀도식의 일반화된 형태를 유도한다. 유도된 전력 스펙트럼 밀도식을 바탕으로 선형시변 발진기 위상잡음 이론은 발진 신호의 전력 보존성을 예측할 수 있음을 본 연구에서 증명한다. 게다가, 유도된 전력 스펙트럼 밀도식은 선형시변 발진기 위상잡음 이론이 기본 주파수와 그 하모닉을 포함하는 전 주파수 영역에 걸친 전력 스펙트럼의 특성을 설명 할 수 있게 한다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1991년도 하계학술대회 논문집
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• pp.730-733
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• 1991

The inspection for steam generator tubes of nuclear power plants is performed by eddy current test method. In the current, human experts should check enormous amounts of eddy current(EC) signals to find abnormal ones on the computer screen. This method could cause a few problems. The purpose of this paper is to develop an expert system which can automatically evaluate EC signals of steam generator tubes. Since this expert system can replace or help human experts, the reliability in EC signal evaluation can be improved, and the required man-power can be reduced. Additionally, application of this system can shorten the overhaul period, contribute to a safe operation of the nuclear power plant.

• 전자공학회논문지D
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• 제35D권8호
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• pp.69-75
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• 1998

We demonstrate wavelength conversion of 2.5Gb/s optical signals by four-wave mixing (FWM) in a semiconductor optical amplifier (SOA). We investigate the effect of input pump and signal powers on the coversion efficiency, optical signal-to-noise ratio (OSNR) and extinction ratio to be a measure of performance in a wavelength converter. As a result, we show that the maximum bit error rate (BER) performance can be obtained by co promising among high-vonversion efficiency (minimum Pprobe), high-OSNR (maximum Pprobe) and low-cross-gain saturation effects (Pprobe kept at least 6dB weaker than Ppump). In our experiment, we obtain optimum performance at +3 dBm pump power and -6dBm signal power. The power penalty incurred in the wavelength conversion can be minimized by careful selection of the input pump and signal powers. We show that about 0.5dB power penalty for 3.2nm wavelength coversion at 10-10 BER is achievable.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2009년도 정기총회 및 추계학술대회 논문집
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• pp.185-187
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• 2009

This paper describes development of a hardware simulator for the PMSG wind power system. The simulator consists of a realistic wind turbine model using anemometer, vector drive, induction motor. The turbine model generates torque and speed signals for a specific wind turbine with real wind speed. The torque and speed signals are scaled down to fit for the input power of 3kW PMSG. The hardware simulator was developed through computer simulations, and the operation was confirmed by experimental works.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 B
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• pp.729-732
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• 2001

Digital signal processors(DSP) are widely used in modern power conversion devices, ac motor drives. However, generating pulse-width modulation(PWM) gating signals requires so high sampling rates that most computation resources of the DSP must be devoted to generating them. This paper presents an ASIC realization of 2 channel space-vector PWM(SVPWM). The developed DSP(ECLDSP) board can transmit gating signals to 2 converter/inverter and control them. ECLDSP board is used for control the various kinds of power-quality improvement systems.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권4호
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• pp.1889-1910
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• 2017

This paper investigates a protocol so-called Adaptive Harvest Then Transmit (AHTT) for wireless powered communication networks (WPCNs) in multiple-input single-output (MISO) downlink systems, which assists in transmitting signals from a multi-antenna transmitter to a single-antenna receiver. Particularly, the power constrained relay is supplied with power by utilizing radio frequency (RF) signals from the source. In order to take advantage of multiple antennas, two different linear processing schemes, including Maximum Ratio Combining (MRC) and Selection Combination (SC) are studied. The system outage capacity and ergodic capacity are evaluated for performance analysis. Furthermore, the optimal power allocation is also considered. Our numerical and simulation results prove that the implementation of multiple antennas helps boost the energy harvesting capability. Therefore, this paper puts forward a new way to the energy efficiency (EE) enhancement, which contributes to better system performance.

• 전기학회논문지
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• 제57권5호
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• pp.881-888
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• 2008

We present a novel fault diagnosis methodology using acoustic sensor systems and neural independent component analysis for large-scaled power machines. Acoustic sensors are carried out to measure sounds generated from power machines whose signal is used to determine whether fault is occurred or not. Acoustic measurements are independently mixed and deteriorated from original source signals. We propose a demixing algorithm against such mixed signals by means of independent component analysis which is achieved based on information theory and higher-order statistics to derive learning mechanism.

• E2M - 전기 전자와 첨단 소재
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• 제7권1호
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• pp.42-48
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• 1994

The preventive diagnosis technique for power system is being highlighted as a research area for deterioration of insulation in machinery because of high-voltage power system. We make efforts to develop not only diagnosis of aging state but also detection of defects in the initial stage from preventive diagnosis technique. Especially, partial discharge is actively studied as a non-destructive diagnosis technique and very useful because partial discharge measurement reduces damage than conventional diagnosis technique. The loaded stress during this test is smaller than that of other diagnosis techniques. But the continuous research for various complicated analysis method is required because partial discharge has very small signals and its signals have complex forms. In this paper, the measurement of partial discharge was investigated and studied on many specimens with void. We made samples having artificial voids and measured partial discharge. In order to use as a practical diagnosis technique, we studied ways of measurement, measured illustrations and types of partial discharge which could be used in order to diagnose defects of power machinery.

• Communications for Statistical Applications and Methods
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• 제3권1호
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• pp.243-255
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• 1996

The number of neutron signals from a neutral particle beam(NPB) at the detector, without any errors, obeys Poisson distribution, Under two assumptions that NPB scattering distribution and aiming errors have a circular Gaussian distribution respectively, an exact probability distribution of signals becomes a Poisson-power function distribution. In this paper, we show that the error rate in simple hypothesis testing for the limiting Poisson-power function distribution is not zero. That is, the limit of ${\alpha}+{\beta}$ is zero when Poisson parameter$\kappa\rightarro\infty$, but this limit is not zero (i.e., $\rho\ell$>0)for the Poisson-power function distribution. We also give optimal decision algorithms for a specified error rate.

• 대한의용생체공학회:의공학회지
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• 제6권1호
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• pp.19-30
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• 1985

This paper describes the EMG signals in frequency domain using power spectral density, The changes in the moan frequency can represent the energy distribution which results from changing in load before and during fatigue. Most of EMG signal power spectrum is located between 10 and 200Hz. Shifts of the high-energy regions of the power spectra can be inferred from the changes in the mean frequency. If the load is increased without fatigue-ocurring, the high frequency regions have more energy than the low frequency regions. And if load is increased during fatigue, the low frequency regions have more energy than the high frequency regions.