• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제52권11호
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• pp.548-556
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• 2003

Switched reluctance motor(SRM) has simple magnetic structure, and needs simple power electronic driving circuit. It is very useful for wide range adjustable speed drive system. But, SRM drive generates large vibration and acoustic noise because it is commutated individually by step pulse m.m.f of each phase. In the vibration and acoustic noise characteristics. the considerable vibration and noise is induced by radial deforming of stator, so the frequency of dominant vibration and noise is coincident with the frequency of natural frequency of mechanical structure. This radial vibration force is generated by abrupt change of radial magnetic force in the phase commutation region. This paper studied about simple electromagnetic structure of SRM using auxiliary compensating winding for the reduction of noise and vibration. This auxiliary winding is coupled with all phase windings electromagnetically and absorb and transfer magnetic energy variation from phase to other phase. By this interaction of phase windings and compensating winding can reduce abrupt radial force change and vibration and acoustic noise. In this paper the improvement effect is examined by the test of prototype machine.

• 환경영향평가
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• 제20권2호
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• pp.123-131
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• 2011

The objective of this study is to prepare the effective management plan of environmental noise with a noise map, and the guideline on the management plan of environmental noise was suggested through the review of existing application examples. The management plan of environmental noise with a noise map includes the practical contents in the stages of subdivision of management areas, establishment of reduction measures, opinion collection, post investigation, and reformulation of management plan. First, the classification of management regions is performed considering the excess degree of noise standard and the facility type in the phase of subdivision of management areas. Second, the optimal management plan is established through the investigation of regional characteristics and various noise reduction measures in the phase of establishment of reduction measures, which includes the examination of noise reduction effects with a noise map and the budget planning with the costing of noise reduction measures. Third, the opinion survey with a local resident and a expert is carried out in order to prove the validity of the management plan in the phase of opinion collection, and the management plan is modified with gathered opinions. Fourth, the post examination plan with noise measurement is performed in order to verify the real effect of noise reduction measures according to the management plan in the phase of post investigation. Finally, the amendment of the management plan as well as the improvement of a noise map is carried out at a regular cycle in the phase of reformulation of management plan.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제49권9호
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• pp.565-571
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• 2000

SRM has been applied to many commercial applications that require economical advantages and high performance abilities. But it has some drawbacks such as acoustic noise due to the abrupt change of mmf level when commutation. The abrupt change of a phase excitation produces mechanical stresses and it results in torque ripple and noise. This paper deals with an analysis of vibration and noise in SRM drive. Several types of excitation method are taken into account. The 1-phase and 2-phase excitation technique of short-pitch winding 2-phase excitation technique of full-pitch winding are tested. The acoustic noise is reduced remarkably through the sequential phase excitation in the 2-phase excitation. It is because that the scheme reduces abrupt change of excitation level by distributed balanced excitation with free-wheeling during commutation.

• Journal of electromagnetic engineering and science
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• 제5권4호
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• pp.204-207
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• 2005

In this paper, PBG structure and feedforward circuit has been used to suppress the phase noise of the oscillator. Microstrip line resonator have low Q, but we can obtain high LO power by feedforward circuit and improve the resonator Q by the PBG, simultaneously. The proposed oscillator which uses PBG and feedforward circuit shows 0${\~}$20 dB phase noise reduction compared to the conventional oscillator. We have obtained -115.8 dBc of phase noise at 100 kHz offset from 2.4 GHz center.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 I
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• pp.358-361
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• 2003

In this paper, a new technique to reduce the phase noise in microwave oscillators is proposed using the resonant characteristics of the Photonic Bandgap(PBG). Microstrip line resonator has the low Q(Qaulity factor). Therefore, as PBG structure was applied, we examined that the phase noise of the oscillator has been reduced.

• 한국정보통신학회논문지
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• 제10권2호
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• pp.298-302
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• 2006

전원 잡음에 의한 링발진기의 위상잡음과 jitter의 모델을 제시하고 시뮬레이션을 수행하여 모델의 타당성을 확인하였다. 링발진기의 전원 잡음은 협대역 위상변조에 의해 중심 주파수 양측면에 잡음 주파수만큼 간격을 두고 출력 잡음 신호가 나타나는 위상잡음으로 나타났다. 또한 전원 잡음에 의한 jitter의 선형 모델을 제시하였고, 시뮬레이션에 의해 jitter가 잡음 진폭의 크기에 비례하여 발생하는 것을 확인하였다.

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

• 한국전자파학회논문지
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• 제13권7호
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• pp.649-656
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• 2002

본 논문에서는 고속 주파수 스위칭 특성을 갖는 디지탈 하이브리드 위상고정루프(DH-PLL: Digital Hybrid Phase-Locked Loops)의 위상잡음을 분석하였다. 기존 위상고정루프에 비하여, 디지탈 하이브리드 위상고정루프는 D/A 변환기에서 발생하는 잡음이 전체 출력위상잡음에 추가되므로 위상잡음이 증가되는 문제점이 있다. 입력기준신호, D/A 변환기, 그리고 전압제어발진기(VCO: Voltage Controlled Oscillator)를 주요 잡음원으로 고려하여, 이것에 의한 위상잡음을 해석적으로 분석하였다. 또한 폐루프 대역과 주파수 합성 분주비(hi)에 따른 위상잡음의 변화를 연구하여 디지탈 하이브리드 위상고정루프의 위상잡음을 최소화하는 최적 폐루프 대역을 결정할 수 있다. 또한, 해석적 방법에 의한 분석 결과와 회로 시뮬레이션에 의한 결과가 동일함을 확인하였다.

• 한국산업정보학회논문지
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• 제20권1호
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• pp.49-55
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• 2015

This paper proposes a 2.4 GHz RF oscillator with a very low close-in phase noise performance. This is composed of a low frequency crystal oscillator and three frequency multipliers such as two doubler (X2) and one tripler (X3). The proposed oscillator is implemented as a hybrid type circuit design using a discrete silicon bipolar transistor. The measurement results of the proposed oscillator structure show -115 dBc/Hz close-in phase noise at 10 kHz offset frequency, while only dissipating 5 mW from a 1-V supply. Its close-in phase noise level is very close to that of a low frequency crystal oscillator with little degradation of noise performance. The proposed structure which is consisted of a low frequency crystal oscillator and a frequency multiplier provides new method to implement a low power low close-in phase noise RF local oscillator.

• 한국군사과학기술학회지
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• 제16권3호
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• pp.373-381
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• 2013

In this paper, the effects of phase noise on the radar system were analyzed in terms of 3 point of view. The impact(s) on the compressed pulse waveform, the FMICW(Frequency Modulated Interrupted Continuous Wave) radar performance and the receiver sensitivity were investigated. From the investigation, it was indicated that the phase noise over 10 kHz offset frequency makes the side lobe level of compressed pulse worse. Also it was founded that the FMICW radar performance, especially at the noise level of range profile, is related to the phase noise. Finally, the investigation showed that the phase noise at local oscillator affects the receiver sensitivity.