• 한국정보통신학회:학술대회논문집
• /
• 한국해양정보통신학회 2011년도 춘계학술대회
• /
• pp.499-501
• /
• 2011

본 논문에서는 천리안 위성의 통신 탑재체의 위상잡음 스펙트럼 특성을 측정 분석하며, 전송 방식에 따른 위상잡음 영향을 평가한다. 천리안 위성의 탑재체는 Ka 대역을 사용하며, 고주파수 사용으로 상대적으로 위상잡음 특성이 증가할 수 있다. 아울러 고차모드 위성 전송시 위상잡음에 영향이 증가하여 전송 선능의 열화를 가져올 수 있다. 본 논문에서는 MSM 기능을 갖는 통신 탑재체의 위상잡음 특성을 측정 평가하며 고차모드 전송에 요구되는 위상잡음을 아울러 평가한다.

• 한국소음진동공학회논문집
• /
• 제23권7호
• /
• pp.617-623
• /
• 2013

Accurate prediction of the radiated noise is important to reduce the noise of the washing machine. It is also necessary to predict the excitation force accurately because excitation force can induce noise. In order to predict the excitation force acting on the washing machine, this paper conducts source identification method by use of phase reference spectrum. In this method, the transfer function between the cabinet and the motor through FEM and the measured response from the surface of the cabinet is used. The analysis of the radiation noise from the identified exciting force has been investigated. The comparison between the predicted SPL and the measured SPL at 1m apart from the front side of the washing machine showed good tendency.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2004년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
• /
• pp.109-113
• /
• 2004

In case while modulation index (M) is more than 0.7, the spectrum of motor voltage and current of a conventional two-phase SRP scheme are not reduced considerably. To solve the problems of a conventional two-phase SRP, this paper proposes a two-phase SRP(DZSRP) with double zero vector mode which zero vector is selected as V(111) in case of M $\geq$ 0.7, and zero vector is selected as V(000) if M < 0.7. For the validity of the proposed method, a 16 bit micro-controller C167 was used and the experiments were conducted with the 1.5kw induction motor under load condition. And the experimental results show that the switching noise spectrum for all the M are spread to a wide band area. Also the switching noise and conducted noise are discussed.

• Journal of information and communication convergence engineering
• /
• 제3권4호
• /
• pp.184-186
• /
• 2005

The effect of power supply noise on the phase noise of a ring oscillator is studied. The power supply noise source in series with DC power supply voltage is applied to a 3 stage CMOS ring oscillator. The phase noise due to the power supply noise is modeled by the narrow band phase modulation. The model is verified by the fact that the spectrum of output of ring oscillator has two side bands at the frequencies offset from the frequency of the ring oscillator by the frequency of the power supply noise source. Simulations at several different frequency of the power supply noise reveals that the ring oscillator acts as a low pass filter to the power supply noise. This study, as a result, shows that the phase noise generated by the power supply noise is inversely proportional to the frequency offset from the carrier frequency.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 2005년도 ICCAS
• /
• pp.233-236
• /
• 2005

Phase noise in a phase-locked-loop (PLL) is unwanted and unavoidable. It is a main concern in oscillation system especially PLL. The phase noise is derived in term of power spectrum density by using a reliable phase noise model. There are four noise sources being considered in this paper, which are generated by reference oscillator, voltage controlled oscillator, filter, and main divider. The major concern for this paper is the noise from the filter. Two types of second order low pass filter are used in the PLL system. Applying the mathematical phase noise model, the output noises are compared. The total noise from the passive filter is lower than the active filter at the offset frequency range between 1 Hz to 33 kHz.

• 전력전자학회논문지
• /
• 제9권2호
• /
• pp.178-186
• /
• 2004

본 연구에서는 3상 RCD(Random Pulse Centered Displacement) PWM기법에 비하여 구현이 용이하고 스위칭 주파수의 정수배 스펙트럼의 광대역화와 선형화의 효과가 우수한, 2상 RCD-PWM을 제안하였으며, 그 파워 스펙트럼을 비교하고 있다 종전의 3상 RCD-PWM과 제안된 2상 RCD-PWM을 구현하기 위하여, 16비트 고성능 마이크로 컨트롤러 SAB-Cl67이 사용되었다 SAB-C167에 의하여 각 변조 구간에서의 듀티비를 구한 후, 선형 랜덤 발생기를 이용하여 균일한 확률 분포로 각 상의 펄스의 위치를 재배치하였다. 제안된 2상 RCD-PWM에 의한 모터전압과 전류 그리고 직류링크 전류의 파워 스펙트럼 및 모터의 가청 스위칭 소음 효과를 종전의 3상 RCD-PWM과 비교 검토하였다

• 한국정보통신학회논문지
• /
• 제13권4호
• /
• pp.652-657
• /
• 2009

본 논문에서는 다양한 배경 잡음에 의해 열화된 음성을 강조하기 위하여 청각모델에 기초로 한 잡음환경에 적응된 잡음억제 시스템을 제안한다. 제안한 시스템은 먼저 유성음, 무성음 및 묵음의 구간을 검출한 후, 각 입력 프레임에서 적응적인 청각기강의 처리를 한다. 마지막으로 진폭성분과 위상성분이 포함된 신경회로망을 사용하여 잡음신호를 제거 한 후에 음성을 강조하는 처리를 한다. 본 시스템은 신호대잡음비의 평가방법을 통하여 다양한 잡음에 의해서 열화 된 음성신호에 대해서 유효하다는 것을 실험으로 확인한다.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 2004년도 전력전자학술대회 논문집(1)
• /
• pp.283-288
• /
• 2004

In case while modulation index (M) is more than 0.7, the spectrum of motor voltage and current of a conventional two-phase SRP scheme are not reduced considerably. To solve the problems of a conventional two-phase SRP, this paper proposes a two-phase SRP(DZSRP) with double zero vector mode which zero vector is selected as V(111) in case of $M\;\geqq\;0.7$, and zero vector is selected as V(000) if M < 0.7. For the validity of the proposed method, a 16 bit micro-controller C167 was used and the experiments were conducted with the 1.5kw induction motor under load condition. And the experimental results show that the switching noise spectrum for all the M are spread to a wide band area.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2006년도 학술대회 논문집 전문대학교육위원
• /
• pp.154-158
• /
• 2006

The switching-mode power converter has been widely used because of its features of high efficiency and small weight and size. These features are brought by the ON-OFF operation of semiconductor switching devices. However, this switching operation causes the surge and EMI(Electromagnetic Interference) which deteriorate the reliability of the converter themselves and entire electronic systems. This problem on the surge and noise is one of the most serious difficulties in AC-to-DC converter. Random Pulse Width Modulation (RPWM) is peformed by adding a random perturbation to switching instant while output-voltage regulation of converter is performed. RPWM method for reducing conducted EMI in single switch three phase discontinuous conduction mode boost converter is presented. The more white noise is injected, the more conducted EMI is reduced. But output-voltage is not sufficiently regulated. This is the reason why carrier frequency selection topology is proposed. In the case of carrier frequency selection, output-voltage of steady state and transient state is fully regulated. A RPWM control method was proposed in order to smooth the switching noise spectrum and reduce it's level. Experimental results are verified by converter operating at 300v/1kW with $5%{\sim}30%$ white noise input. Spectrum analysis is performed on the Phase current and the CM noise voltage. The former is measured with Current Probe and the latter is achieved with LISN, which are connected to the spectrum analyzer respectively.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2008년도 춘계학술대회논문집
• /
• pp.185-188
• /
• 2008

This paper introduces the Bootstrap method for statistical analysis of noise and vibration spectrum in aeronautic and space fields. Generally, all components of a launch vehicle and its payloads are subjected to high intensive noise and vibration environment during the lift-off phase and the ascent phase through Mach =1 and Max Q. In order to verify their survivabilities against these severe vibroacoustic environments during qualification tests and acceptance tests, it is most important to estimate the proper upper limits of the environmental condition. Although NASA has typically utilized the Normal Tolerance Limit method in deriving these levels, the reference[1] says that the Bootstrap can be also an alternative method to estimate the maximum expected environments. In this paper, a general procedure of the Bootstrap method is summarized, and it is applied to analyze acceleration power spectral density functions, which were measured during acoustic test on the upper stage of KSLV-I.