• 한국음향학회지
• /
• 제30권5호
• /
• pp.281-294
• /
• 2011

물리적 모델링 기반 음 합성 알고리즘은 음 합성 시 많은 연산량을 요구하며 이는 실시간 음 합성을 저해한다. 이러한 문제를 해결하기 위해 본 논문에서는 물리적 모델링 기반 현악기 사운드 엔진을 멀티코어 프로세서에 구현하고, 사운드 엔진을 위한 최적의 멀티코어 프로세서 구조를 제안한다. 대상 현악기의 단위음을 합성하기 위해 각 프로세싱 엘리먼트 (processing element, PE)당 합성하는 샘플 (sample-per-processing element, SPE) 수를 변화시키는 실험을 통해 시스템의 성능 (system performance), 시스템 면적 효율 (area efficiency), 에너지 효율 (energy efficiency)을 각각 측정하고, 측정된 결과를 바탕으로 최적의 멀티코어 프로세서 구조를 선택하였다. 모의실험 결과, 어쿠스틱 기타는 SPE가 5,513과 2,756일 때 가장 높은 시스템 면적 효율과 에너지 효율을 보였으며, 클래식 기타는 SPE가 22,050과 5,513일 때 시스템 면적 효율과 에너지 효율이 가장 높았다. 또한 이를 이용하여 44.1 kHz의 샘플링율을 갖도록 대상 악기의 단위음을 합성한 결과 원음과 스펙트럼에서 매우 유사함을 확인할 수 있었고, 울산대학교 대학원생 및 교수 10명을 대상으로 실시한 MUSHRA 주관 청취 테스트에서도 좋은 결과를 얻었다.

• 한국소음진동공학회논문집
• /
• 제20권5호
• /
• pp.502-509
• /
• 2010

A test facility which can simultaneously measure turbocharger operating condition variables and vibro-acoustic emission in the situations that are quite similar to real internal combustion engine operating conditions has been introduced. Using this facility, a new method sweeping from full open throttle to deep surge region along constant speed curves can be utilized instead of the stationary method that has been traditionally used to obtain turbocharger compressor maps. Data covering an extensive range of the compressor performance map have been collected and analyzed. An experimental study is performed to define a noise diagram that correlates vibro-acoustic measurements to aerothermodynamic operating conditions. An instrumentation set in the facility allows the automatic definition of the operating point on the turbine and compressor map of the turbocharger. Also, radiated sound pressure and casing vibration data corresponding to the point are obtained by a microphone in the vicinity of the compressor casing and an accelerometer on the casing. The major source(s) of noise at specific operating point on the map can be easily identified with these maps. Also, acoustic characteristics of a given turbocharger at the vicinity of the surge as well as in the surge are also defined. Finally, the possibility to define mild surge region of a turbocharger using vibro-acoustic measurements is studied.

• 소음진동
• /
• 제11권3호
• /
• pp.401-409
• /
• 2001

Passive type mufflers installed on every car haute inherent problem of lowering engine power and fuel efficiency caused by backpressure which is byproduct of complex internal structure. Recent improvements like installing a calve to change exhaust gas path depending on power requirement and rpm have only marginally improved performance. Tremendous amount of recent research works on active exhaust noise control have failed to commercialize because of numerous physical and economical reasons. In this paper, a unique seal-active muffler using difference of transmission paths is presented. In this system exhaust pipe is divided into two and joined again downstream. Exhaust noise is reduced by destructive interference when two-divided noise join again with transmission paths'difference which is half of the wavelength of a main noise frequency. One divided path has a sliding mechanism to change length thereby transmission path length difference is adjusted to entwine rpm change. The proposed system has minimal backpressure and does not need a secondary sound source like a speaker so it can overcome many problems of failed active noise control methods. We have verified proposed system's superior performance by simulation and comparison experiment with passive mufflers.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2006년도 추계학술대회논문집
• /
• pp.680-685
• /
• 2006

The latest trend in the automotive industry demands the development of high stiffness car bodies and the securement of inter-system performance for low vibration and noise vehicles. This demand, however, conflicts with need for light weight design and greater fuel efficiency, thus raising the importance of optimization design to satisfy both developmental goals. We chose two European medium sedans, which has gasoline engine and diesel one, to elucidate the noise characteristics of diesel passenger cars, whose sales have been increasing in both Korea and Europe. In the present study a systematic experiment was conducted to analyze the noise characteristics in diesel cars. we made it possible for differentiating car management according to customer demand while allowing for improved commercial feasibility. it was possible to improve interior noise by 2 dB(A) on average sound pressure level. As a result, by 4% higher on articulation index(AI).

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2007년도 춘계학술대회논문집
• /
• pp.51-55
• /
• 2007

In this paper Statistical Energy Analysis has been considered to predict high frequency air borne interior noise. Dash panel Insulation is major part to reduce engine excitation noise. Transmission loss and absorption coefficient are considered to predict dash insulation performance. Transmission lose is derived from coupling loss factor and absorption coefficient is derived from internal damping loss factor. Material Biot properties were used to calculate each loss factors. Insulation geometry thickness distribution was hard to measure, so FeGate software was used to calculate thickness map from CAD drawing. Each predicted transmission losses between conventional insulation and light weight insulation were compared with SEA. Transmission loss measurement was performed to validate each prediction result, and it showed good correlation between prediction and measurement. Finally interior noise prediction was performed and result showed light weight insulation system can reduce 40% weight to keep similar performance with conventional insulation system, even though light weigh insulation system has lower sound transmission loss and higher absorption coefficient than conventional system.

• 한국에너지공학회:학술대회논문집
• /
• 한국에너지공학회 2010년도 춘계학술 발표회
• /
• pp.175-175
• /
• 2010

지능화, 고도화되어 제조되는 유사연료유는 차량 안전과 건전한 에너지 산업 육성을 저해시키고 있다는 점에서 문제가 되고 있다. 대표적인 유사경유 유형 중용제혼입의 경우는 적출과정에서 원료와 일반경유와의 혼입율을 조제시험을 통해 확인하고 있는데, 원료확보와 분석에 많은 시간과 노력이 소요되고 있다. 본 연구에서는 예상 유사경유원료를 조사하고 주요 물성에 대한 분석을 근거로 관계식을 도출하였으며, 실제 분석을 대체할 수 있는 예측 프로그램을 제작하였다.

• 한국추진공학회:학술대회논문집
• /
• 한국추진공학회 2008년도 제30회 춘계학술대회논문집
• /
• pp.36-39
• /
• 2008

연소 불안정 현상은 액체로켓엔진 개발과정에 있어서 반드시 해결해야 하는 문제이다. 이것을 억제하기 위한 도구 중의 하나인 음향공의 오리피스 길이 변화에 의한 감쇠 효과를 선형 음향 해석과 실험을 통하여 연구하였다. 오리피스의 길이가 짧아질수록 감쇠효과가 증가하는 것을 확인하였으며 실험과 선형 음향 해석 결과가 서로 동일한 경향을 보이는 것을 확인 하였다. 또한, 가진 음원의 크기에 따른 실험을 수행하였는데 그 결과 오리피스 길이와 단면적이 작아질수록 가진 음원의 크기 증가의 따른 비선형성이 증가하는 것을 확인하였다.

• 말소리와 음성과학
• /
• 제7권4호
• /
• pp.27-33
• /
• 2015

This paper proposes an audio event classification method using Deep Neural Networks (DNN). The proposed method applies Feed Forward Neural Network (FFNN) to generate event probabilities of ten audio events (dog barks, engine idling, and so on) for each frame. For each frame, mel scale filter bank features of its consecutive frames are used as the input vector of the FFNN. These event probabilities are accumulated for the events and the classification result is determined as the event with the highest accumulated probability. For the same dataset, the best accuracy of previous studies was reported as about 70% when the Support Vector Machine (SVM) was applied. The best accuracy of the proposed method achieves as 79.23% for the UrbanSound8K dataset when 80 mel scale filter bank features each from 7 consecutive frames (in total 560) were implemented as the input vector for the FFNN with two hidden layers and 2,000 neurons per hidden layer. In this configuration, the rectified linear unit was suggested as its activation function.

• Computers and Concrete
• /
• 제1권3호
• /
• pp.303-324
• /
• 2004

The Component-Based Software Development (CBSD) has established itself as a sound paradigm in the software engineering discipline and has gained wide spread acceptance in the industry. The CBSD relies on the availability of standard software components for encapsulation of specific functionality. This paper presents the framework for the development of a software component for the design of general member cross-sections. The proposed component can be used in component-based structural engineering software or as a stand-alone program developed around the component. This paper describes the use-case scenarios for the component, its design patterns, object models, class hierarchy, the integrated and unified handling of cross-section behavior and implementation issue. It is expected that a component developed using the proposed patterns and model can be used in analysis, design and detailing packages to handle reinforced concrete, partially prestressed concrete, steel-concrete composite and steel sections. The component can provide the entire response parameters of the cross section including determination of geometric properties, elastic stresses, flexural capacity, moment-curvature, and ductility ratios. The component can also be used as the main computational engine for stand-alone section design software. The component can be further extended to handle the retrofitting and strengthening of cross-sections, shear and torsional response, determination of fire-damage parameters, etc.

• 한국전산구조공학회:학술대회논문집
• /
• 한국전산구조공학회 2006년도 정기 학술대회 논문집
• /
• pp.772-777
• /
• 2006

An acoustic finite element model of a bridge is developed to evaluate the noise generated by the traffic-induced vibration of the bridge. The dynamic response of a multi-girder bridge, modeled by a 3-dimensional frame element model, is analyzed with a 3-axle(8DOF) truck model and a 5-axle(l3DOF) semi-trailer. The flat plate element is used to analyze the acoustic pressure due to the fluid-structure interactions between the vibrating surface and contiguous acoustic fluid medium. The radiation fields of noise with a specified distribution of vibrating velocity and pressure on the structural surface are also computed using the Kirchhoff-Helmholtz integral. In an attempt to illustrate the influence of the structural vibration noise of a bridge to total noise level around the bridge, the random function is used to generate the vehicle noise source including the engine noise and the rolling noise interacting between the road and tire. Among the diverse parameters affecting the dynamic response of bridge, the vehicle velocity, the vehicle weight, the spatial distribution of the road surface roughness, the stiffness degradation of the bridge and the variation of the air temperature changing the air density are found to be the main factors that increase the level of vibration noise. Consequently, The amplification rate of noise increases with the traveling speed and the vehicle weight.