• 전력전자학회논문지
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• 제27권2호
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• pp.100-105
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• 2022

This paper applies the arc detection algorithm to prevent the false detection in photo voltaic series arc detection circuit, which is required not only to detect the series arc quickly, but also not falsely detect the arc for the non-arc noise. For this purpose, this study proposes a rapid and preventive false detection method of single peak noise and short noise signals. First, to prevent false detection by single peak noise, Discrete wavelet transform (DWT)-based characteristic parameters are applied to determine the shape and the amplitude of the noise. In addition, arc fault detection within a few milliseconds is performed with the DWT iterative algorithm to quickly prevent false detection for short noise signals, considering the continuity of serial arc noise. Thus, the method operates not only to detect series arc, but also to avoid false arc detection for peak and short noises. The proposed algorithm is applied to real-time serial arc detection circuit based on the TMS320F28335 DSP. The serial arc detection and peak noise filtering performances are verified in the built simulated arc test facility. Furthermore, the filtering performance of short noise generated through DC switch operation is confirmed.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2013년도 춘계학술대회 논문집
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• pp.239-240
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• 2013

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 추계학술대회논문집
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• pp.480-485
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• 2002

The overall noise reduction was compared in regard to the vibrational characteristics of floor impact noise in a multi story residential building which has several noise reduction treatments. The vibration through its structural elements such as wall, floor and ceiling and sound emitting were investigated for each insulation treatment. It was found that, in case of heavy-weight impact noise, the vibration energy is emitted mostly from ceiling, but for the light-weight impact noise, most of the energy comes through ceiling and walls. That is, the vibration of a ceiling is the main factor that determines the frequency characteristics of the transmitting noise to lower floors.

• 한국음향학회:학술대회논문집
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• 한국음향학회 1999년도 학술발표대회 논문집 제18권 2호
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• pp.401-406
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• 1999

In relation to a non-destructive evaluation of irradiation damages of micro-structure interstitial, void and dislocation, the changes in the hysteresis loop, Barkhausen noise amplitude and the harmonics frequency due to a neutron irradiation were measured and evaluated. The Mn-Mo-Ni low alloy steel of RPV was irradiated to a neutron fluence of $2.3\times10^{19}\;n/cm^2\;(E\geq1\;MeV)\;at\;288^{\circ}C$. The saturation magnetization of neutron irradiated metal did not change. The neutron irradiation caused the coercivity to increase, whereas susceptibility to decrease. The amplitude of Barkhausen noise parameters associated with the domain wall motion were decreased by a neutron irradiation. The spectrum of Barkhausen noise is analysed with an applied frequency of 4 Hz and 8 Hz, sampling time of $50\;{\mu}sec\;and\;20\;{\mu}sec$. The harmonic frequency shows 4 Hz, 8 Hz, 12 Hz; and 16 Hz reflected from an unirradiated specimen. On the contrary, the harmonic frequency disappeared on the irradiated specimen.

• The Journal of the Acoustical Society of Korea
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• 제18권1E호
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• pp.7-12
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• 1999

In relation to a non-destructive evaluation of irradiation damages, the changes in the hysteresis loop and Barkhausen noise amplitude and the harmonics frequency due to a neutron irradiation were measured and evaluated. The Mn-Mo-Ni low alloy steel of RPV was irradiated to a neutron fluence of 2.3 ×10/sup 19/ n/㎠ (E ≥1 MeV) at 288℃. The saturation magnetization of neutron irradiated metal did not change. The neutron irradiation caused the coercivity to increase, whereas susceptibility to decrease. The amplitude of Barkhausen noise parameters associated with the domain wall motion were decreased by a neutron irradiation. The spectrum of Barkhausen noise is analysed with an applied frequency of 4 Hz and 8 Hz, sampling time of 50 μ sec and 20 μ sec. The harmonic frequency shows 4 Hz, 8 Hz, 12 Hz and 16 Hz reflected from an unirradiated specimen. On the contrary, the harmonic frequency disappeared on the irradiated specimen. In addition to the amplitude, the harmonic frequency of Barkhausen noise is taken into accounts as a promising tool for monitoring the irradiation induced degradation of the reactor materials such as a SA508 of PWR-RPV steel and a Zr₄ of HANARO-CNH.

• 한국통신학회논문지
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• 제33권11A호
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• pp.1105-1116
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• 2008

Cognitive Radio(CR)는 실제로 사용하지 않는 주파수 대역을 스스로 찾아서 이용함으로써 스펙트럼 효율을 향상시킬 수 있는 기술이다. 현재 사용되지 않는 스펙트럼 대역과 우선사용자(primary user)에 의해 점유되는 대역들을 찾기 위한 스펙트럼 센싱(spectrum sensing)은 CR 시스템에서 중요한 기술의 하나라고 말할 수 있다. 지금가지 연구된 스펙트럼 센싱 방법 중 에너지 검출 방식은 계산의 복잡도가 낮고 비교적 쉽게 구현 할 수 있어서 일반적으로 널리 사용되는 방식이지만 몇 가지 문제점들을 가지고 있다. 특히 불확실한 잡음 전력이 존재하는 환경에서는 에너지 검출기의 성능이 감쇠되기 때문에 이를 해결하기 위해 슬라이딩 윈도우 기반 에너지 검출 기법을 제안하였다. 이 방식은 슬라이딩 윈도우를 이용하여 관심대역에서 신호와 잡음이 가진 에너지를 분리하고 잡음을 제외한 신호의 에너지를 계산해서 우선사용자 신호의 존재 여부를 판단한다. 컴퓨터 시뮬레이션 결과를 통해 제안하는 에너지 검출 기법이 기존의 에너지 검출 방식 보다 우수한 성능을 지닌 다는 것을 확인하였다.

• 한국소음진동공학회논문집
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• 제16권5호
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• pp.503-513
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• 2006

The duration time of aircraft noise event is also an important factor for the evaluation of civil aircraft noise, which is considered as a notable characteristic of military aircraft noise. SEL is proved as a suitable noise metric for the measuring military aircraft noise of various flight pattern considering the duration time of noise event. This study reviews whether SEL is a suitable for measuring civil aircraft noise and study shows SEL is fairly compensating the duration time of civil aircraft noise event for the evaluation of aircraft noise. Noise metric for the evaluation aircraft noise based on SEL is more appropriate than based on $L_{MAX}$ for compensating duration time of noise event either military aircraft or civil aircraft. In this reason, current formula of WECPNL based on energy average of measured $L_{MAX}$ for the evaluation of aircraft noise impact in 'Test Method of Noise and Vibration of Korea' is recommended to be amended to formula of WECPNL based on energy average of measured SEL considering compensation of noise event duration time, if WECPNL is not based on measured EPNL, a metric compensating duration time.

• 디지털융복합연구
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• 제13권10호
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• pp.313-318
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• 2015

전통적인 음성 향상 방법은 잘못된 잡음의 추정에 따라 남아있는 잡음이 발생하여 음성 스펙트럼을 왜곡하거나 음성 프레임을 찾지 못하여 음성 인식 성능을 저하시키는 문제가 발생된다. 본 논문에서는 음성 에너지 분포 처리와 음성 에너지 파라미터를 융합한 음성 검출 방법을 제안하였다. 제안한 방법은 음성 에너지를 최대화시켜 잡음의 영향을 적게 받는 특성을 이용하였다. 또한, 음성 신호의 특징 파라미터 중에서 작은 값을 가지는 로그에너지 특징의 구간에서는 큰 에너지를 가지는 구간에 비해 상대적으로 로그에너지 값을 더 많이 키워서 잡음이 포함한 음성신호의 로그에너지 특징의 크기와 비슷하게 하여 훈련과 인식 환경의 불일치를 융합으로 인해 줄여준다. 인식 실험 결과 기존 방법에 비해 향상된 인식 성능을 확인할 수 있었으며, car 잡음 환경의 음성 구간 적중률은 낮은 SNR구간인 0dB과 5dB에서는 97.1%와 97.3%의 정확도를 보였으며, 높은 SNR구간인 10dB와 15dB에서는 98.3%, 98.6%의 정확도를 보였다.

• 한국소음진동공학회논문집
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• 제18권4호
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• pp.400-410
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• 2008

Reduction of structure-borne noise in the compartment of a car is an important task in automotive engineering. Many methods which analyze noise transfer path have been generally used for structure-borne noise. These methods are useful in solving particular problem but do not quantify the effectiveness of vibration isolation for each isolator of a vehicle. To quantify the effectiveness of vibration isolation, the vibrational power flow measurement has been used for a simple isolation system or a laboratory based isolation system. This paper identifies the transfer path of booming noise in a SUV. The powertrain used for test has a in-line 4cylinder engine and 5-shift auto-transmission. This powertrain is transversely supported by four isolators. We calculated the energy flow throughout four isolator by the measurement of power flow and the contribution of energy flow at each isolator.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2011년도 춘계학술대회 논문집
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• pp.122-127
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• 2011

Recently eco friendly energy is the most interested field and has been research actively. MCFC is a representative technology of eco friendly energy. Eco friendly energy shouldn't cause environmental problems like noise and vibration because that is the technology to solve environmental problems. The major noise and vibration source of MCFC is blowers. this project designed sound enclosure and isolator as the best way for blowers.