• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2010년도 추계학술대회 논문집
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• pp.297-297
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• 2010

이 논문에서는 음향 임피던스를 제어하는 능동형 소음 제어 방법을 연구하였다. 음향 임피던스 제어는 기존의 적응 제어 알고리즘 대신 임피던스의 크기 및 위상 최적화를 통하여 닫힌 관의 끝단에 음파의 반사를 최소화 하는 임피던스를 계산하고 제어함으로써 소음을 저감시킨다. 그리고 음향 임피던스 제어 방법을 끝단이 개방되어 있고, 중앙에 스피커가 있는 관에 적용시킨다. 이 경우에는 개방된 음장에서 음향 전달이 최소화하기 위한 임피던스를 계산하고, 음향 임피던스 제어를 통한 소음 저감을 확인한다. 이를 위해 스피커, 마이크로폰, 진동측정용 레이저 바이브로미터, 그리고 능동 소음 제어 하드웨어로 구성된 시스템을 구축하고 검증하였다.

• 비파괴검사학회지
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• 제13권1호
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• pp.21-28
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• 1993

If the infinitesimal delamination exists and the two waves can hardly be distinguished from each other on account of being much closer, we cannot measure the thickness of delamination by the time difference method. On this study, we calculated the thickness of infinitesimal delamination model by means of measuring echo height due to the deflection of material particles and utilized Newton Ring for optical measurement as a delamination model. From the result of Newton Ring expressed in the delamination model, we can calculate the infinitesimal delamination thickness up to $0.2{\sim}0.3{\mu}m$ due to the difference of acoustic impedance by the ratio of the echo height to the total reflection.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 추계학술대회논문집
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• pp.23-27
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• 2007

Many trials have been used to model room impulse responses, all attempting to provide efficient representations of room acoustics. The traditional model designs for room impulse response seem to fail in accuracy, controllability, or computational efficiency. In time domain, a room impulse response is generally considered as the combination of three parts having different acoustic characteristics, initial time delay, early reflection, and late reverberation. This paper introduces new learning hybrid model for the room impulse response. In this proposed model, those three parts are modeled using different models with learning algorithms that determine the length or boundary of each model in the hybrid model. By the simulation with measured room impulse responses, it was examined that the performance of proposed model shows the best efficiency in views of both the parameter numbers and modeling error.

• 한국소음진동공학회논문집
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• 제18권3호
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• pp.361-367
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• 2008

Many trials have been used to model room impulse responses, all attempting to provide efficient representations of room acoustics. The traditional model designs for room impulse response seem to fail in accuracy, controllability, or computational efficiency. In the time domain, room impulse responses are generally considered as combination of the three Parts having different acoustic characteristics, initial time delay, early reflection, and late reverberation. This paper introduces new learning hybrid model for room impulse responses. In this proposed model, those three parts are modeled using different models with learning algorithms that determine the boundary of each model in the hybrid model. By the simulation with measured room impulse responses, the performance of proposed model shows the best efficiency in views of computational burden and modeling error.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.1515_1516
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• 2009

A 440MHz wireless and passive surface acoustic wave (SAW) based micro-sensor was developed for simultaneous measurement of temperature and humidity. The developed sensor is composed of a SAW reflective delay lines structured by an IDT (Inter-Digital Transducer), four reflectors and humidity sensitive film (polyimide). Polyimide was dry-ecthed by RIE (Reactive Ion Etching) to obtain high roughness, which gives the large reaction area resulting in high sensitivity. In wireless testing using a network analyzer, sharp reflection peaks with high S/N ratio, small signal attenuation, and few spurious peaks were observed in the time domain. High sensitivity towards the temperature and humidiy were also observed in the large concentration range. The obtained sensitivity was $16.8^{\circ}/^{\circ}C$ for temperature sensor and $15.8^{\circ}$/%RH for humidity sensor.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1993년도 춘계학술대회 논문집
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• pp.198-203
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• 1993

In this study, byusing EMAT(Electro Magnetic Acoustic Transducer) the artificial slit is installed on 12B-SUS pipe test piece. By mading 4 cycle SH-bust wave (EMA) incidence to 45 .deg. angle, the signaldata of pulse, which is recevied from EMAT translated intodigital-signal-processing-method SSP and Deconvolution method by using FACOM. Results of these indicated that (1) this method of this study shows exellent result more than Ultrasonic testing method; (2) noise is well removed by SSP using signal dataa and resolving power and S/N ratio are advanced; (3) regradless of Ultrasonic wave, whichhas properties of generalstainless steel is generated into multiscattering and reflection phenomena, the resolving power of more than two times is progressed by being translated into Decon-volution method; and (4) as addition-averaging-processing number is increaing, the resolving power and S/N ratio are improved and the satisfactory signal is obtained.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 춘계학술대회 논문집
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• pp.680-681
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• 2009

On the basis of seismic interpretation, seismic indicators of gas hydrate and associated gas such as bottom simulating reflector (BSR), acoustic blanking, column structure, gas seepage, enhanced reflection were identified in the Ulleung Basin. Fractures, faults, sandy layer could be the migration pathways transporting fluid and gas to stability zone. The formation of gas hydrate in the Ulleung Basin include: (1) nodules, veins, layers in muddy sediments and disseminated forms in sandy layer within localized column structure, (2) disseminated forms in sandy layer, and (3) disseminated forms in sandy layer just above BSR.

• Interaction and multiscale mechanics
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• 제1권1호
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• pp.53-81
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• 2008

The theory of microlocal analysis of hyperbolic partial differential equations shows that the energy density associated to their high-frequency solutions satisfies transport equations, or radiative transfer equations for randomly heterogeneous materials with correlation lengths comparable to the (small) wavelength. The main limitation to the existing developments is the consideration of boundary or interface conditions for the energy and power flow densities. This paper deals with the high-frequency transport regime in coupled heterogeneous structures. An analytical model for the derivation of high-frequency power flow reflection/transmission coefficients at a beam or a plate junction is proposed. These results may be used in subsequent computations to solve numerically the transport equations for coupled systems, including interface conditions. Applications of this research concern the prediction of the transient response of slender structures impacted by acoustic or mechanical shocks.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 춘계학술대회논문집
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• pp.109-114
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• 2004

Measurement of noise is not only to know the information of acoustic pressure but to assess human response for noise. Provided that want to find human response for transportation noise, we will have to reproduce the measured noise. The method of reproduction is largely divided into monaural and binaural reproduction techniques. Human fundamentally hears sound through both ears, which is binaural hearing. And binaural technique includes the more information of physical phenomena like acoustical reflection and deflection. So, binaural reproduction is more suitable for assessment of the psychoacoustical and physiological response for transportation noise exposures.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2010년도 춘계학술대회 논문집
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• pp.537-537
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• 2010

이 논문에서는 음향 임피던스를 제어하는 능동형 소음 제어 방법을 연구하였다. 관의 끝단에 스피커를 이용하여 음향 임피던스를 제어하게 된다. 음향 임피던스 제어는 음향의 반사를 최소화 하는 제어 방법을 이용하는 것으로, 닫힌 관의 끝단에 음파의 흡수와 반사를 제어한다. 나아가 음향 임피던스 제어 방법은 관의 중앙에 설치되어 적용된다. 이 경우에는 음향의 반사, 흡수 및 전달이 측정되고, 최소화하기 위한 임피던스가 계산된다. 이를 위해 가진기, 마이크로폰, 진동측정용 레이저 바이브로미터, 그리고 능동 소음 제어 하드웨어로 구성된 시스템을 구축하고 검증하였다.