• IEIE Transactions on Smart Processing and Computing
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• 제5권6호
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• pp.440-444
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• 2016

In this paper, an equivalent circuit model for near-field noise emission is proposed to implement a multimedia operation-monitoring system for mobile devices. The proposed model includes a magnetic field probe that captures noise emissions from multimedia components, and a transfer function for near-field noise coupling from a transmission line source to a magnetic field probe. The proposed model was empirically verified with transfer function measurements of near-field noise emissions from 10 kHz to 500 MHz. With the proposed model, a magnetic field probe was optimally designed for noise measurement on a camera module and an audio codec in a mobile device. It was demonstrated that the probe successfully captured the near-field noise emissions, depending on the operating conditions of the multimedia components, with enhanced sensitivity from a conventional reference probe.

• 한국소음진동공학회논문집
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• 제17권3호
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• pp.226-234
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• 2007

This study aims to evaluate noise emission from water supply and drain installations in apartment bathroom. These noise were one of the most annoying noise sources in apartment houses. Especially, drain plumbing system have used bellow bathroom ceiling, it was very discomfort to hear the noise in bellow apartment. Noise of closets and faucets were measured which were main noise source, then these noise were evaluate and analyzed the emitting characteristics varying the supplying water pressure. As increasing the water pressure, also total noise level of the water supplying stool noise and faucet noise were increased. Especially the water closet showed remarkably the increasing noise level in middle and high frequency bandwidth, while the noise level of faucets increased in $50\;Hz{\sim}250\;Hz$ of low frequency bandwidth. Vortex closet were favorable to syphon closet, and lever faucet were favorable to conventional lavatory faucet on reducing the noise. Above these results could be used in basic data establishing KS (Korean Standard) for evaluation and rating procedure and measures reducing these noise.

• 콘크리트학회논문집
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• 제15권3호
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• pp.504-511
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• 2003

Environmental noise at high intensities directly affects human health by causing hearing loss. Although scientific evidence currently is not conclusive, noise is suspected of causing or aggravating other diseases. Environmental noise indirectly affects human welfare by interfering with sleep, thought, and conversation. Noise emission from motorized vehicle includes power unit noise, tire/pavement noise and aerodynamic noise. Among them, tire/pavement noise is noise emission from interaction of the tire and road surface when the vehicle cruises over the surface of pavement. In general, portland cement concrete(PCC) pavement is known to create more noise than asphaltic surfaces though it has the advantage of durability and superior surface friction. However, the results of preliminary laboratory test showed exposed aggregate concrete(EAC) has and effect on reducing tire/pavement noise. Based on the laboratory test. pilot construction of exposed aggregate concrete pavement was completed and series of in-situ measurements were conducted for noise analysis including the pass-by noise measurement and the close-proximity method. Conclusively, it is expected that tire/pavement noise represent significant portion of noise levels at higher frequencies and it would be reduced on special textures of pavement such as exposed aggregate concrete.

• JSTS:Journal of Semiconductor Technology and Science
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• 제17권2호
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• pp.252-259
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• 2017

In this paper, we propose a novel method for extracting an accurate depth of a trap that causes RTS(Random Telegraph Signal) noise. The error rates of the trap depth rely on the mean time constants and its ratio. Here, we determined how many data of the capture and emission time constant are necessary in order to reduce the trap depth error caused by an inaccurate mean time constant. We measured the capture and emission time constants up to 100,000 times in order to ensure that the samples had statistical meaning. As a result, we demonstrated that at least 1,000 samples are necessary to satisfy less than 10% error for trap depth. This result could be used to improve the accuracy of RTS noise analysis.

• 동력기계공학회지
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• 제11권1호
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• pp.45-50
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• 2007

Acoustic emission technology is applied to diagnosis the internal leak and operating conditions of the major valves at nuclear power plants. The purpose of this study is to verify availability of the acoustic emission as in-situ diagnosis method. In this study, acoustic emission tests are performed when the pressurized high temperature steam flowed through gate valve(1st stage reheater valve) and glove valve(main steam dump valve) on the normal size of 4 and 8". The valve internal leak diagnosis system for practical field was designed. The acoustic emission method was applied to the valves at the site, and the background noise was measured for the abnormal plant condition. To improve the reliability, a judgment of leak on the system was used various factors which are AE parameters, trend analysis, signal level analysis and RMS(root mean square) analysis of acoustic signal emitted from the valve operating condition internal leak.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 추계학술대회논문집
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• pp.679-682
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• 2007

This study aims to select the proper vocabularies for evaluation about the noise emission from water supply and drain installations in apartment bathroom. As a result of surveying overlapping vocabularies and scores of them for each sound sources, 'annoying', 'noisy', 'dynamic' and 'strident' are main unpleasant vocabularies to the noise from water supply and drain installations in apartment bathroom. And vocabularies such as 'dynamic', 'sudden', 'loudness', 'noisy' are classified into the first factor by analysis.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 추계학술대회논문집
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• pp.1482-1489
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• 2007

In this paper, characteristics of infrasound and low-frequency noise emission from large modern wind turbines are experimentally investigated. The sound measurement procedures of IEC 61400-11 and ISO 7196 are utilized to field test and evaluation of noise emission from each of 1.5 MW and 660 kW wind turbines using the stall regulation and the pitch control for the power regulation, respectively. It was found that the G-weighted SPLs of low-frequency noise including infrasound shows positive correlation with the wind speeds, irrespective of methods of power regulation. This highlights the potential complaint of local community against the infrasound and low-frequency noise of wind turbines. The comparison of measured data with the existing hearing thresholds and criteria curves shows that it is highly probable that the low-frequency noise from the 1.5 MW and 660 kW wind turbines in the frequency range over 30 Hz leads to the psychological complaint of ordinary adults, and that the infrasound in the frequency range from 5 Hz to 8 Hz causes the complaint by rattling the house fitting such as doors and windows.

• 천문학회보
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• 제36권2호
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• pp.59.1-59.1
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• 2011

I present an analysis of the long-term evolution of the fluxes of six active galactic nuclei (AGN) - 0923+392, 3C 111, 3C 273, 3C 345, 3C 454.3, and 3C 84 - in the frequency range 80 - 267 GHz using archival calibration data of the IRAM Plateau de Bure Interferometer. Our dataset spans a long timeline of ~14 years with 974 - 3027 flux measurements per source. We find strong (factors ~2-8) flux variability on timescales of years for all sources. The flux density distributions of five out of six sources show clear signatures of bi- or even multimodality. Our sources show mostly steep (alpha~0.5-1), variable spectral indices that indicate outflow dominated emission; the variability is most probably due to optical depth variations. The power spectra globally correspond to red-noise spectra with five sources being located between the cases of white and flicker noise and one source (3C 111) being closer to the case of random walk noise. For three sources the low-frequency ends of their power spectra appear to be upscaled in spectral power by factors ~2-3 with respect to the overall powerlaws. We conclude that the source emission cannot be described by uniform stochastic emission processes; instead, a distinction of "quiescent" and (maybe multiple) "flare" states of the source emission appears to be necessary.

• 한국전자파학회논문지
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• 제22권1호
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• pp.67-75
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• 2011

본 논문은 능동 소자의 스위칭 잡음이 함체 내부에 위치한 PCB에 인가될 때, 함체의 개구 방사에 미치는 영향을 분석한 연구이다. 이상적인 주기 펄스 입력 신호가 PCB에 인가된 경우의 개구 방사와 스위칭 잡음을 포함한 주기 입력 신호가 인가된 경우의 개구 방사를 비교하였다. DC-DC 컨버터의 등가회로를 이용해 능동 소자의 스위칭 잡음을 구현하였으며, 방사 전계 시뮬레이션을 위해 회로 시뮬레이터와 전자기장 시뮬레이터를 연동시켜 해석을 수행하였다. 또한, 측정 결과와 시뮬레이션 결과를 비교하였다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 춘계학술대회논문집
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• pp.104-108
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• 2005

With the improvement of living quality, people's desire for quiet living environment keeps increasing. In particular, complaints about the noise emission by constrcution equipments around residential areas take most part of the noise related complaints. In this study, based on the European Directive/20n/14/EC, noise marking obligation system for the high noise construction equipment of Europe has been reviewed to implement the similar system in Korea.