• The Journal of the Acoustical Society of Korea
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• 제24권3E호
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• pp.90-98
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• 2005

Enhanced approach using computational and experimental method is proposed and performed to describe very well the behavior of loudspeaker than conventional method. Proposed procedure is composed of four parts. First, Thiele-Small parameters for test loudspeaker are identified by an electrical impedance method like as a delta mass method. Second part includes the processes to measure physical properties. Physical data like masses and thicknesses of loudspeaker's components are measured by an electrical precision scale and a digital vernier caliper. Third, the identified Thiele-Small parameters are proposed to be used as load boundary conditions for vibration analysis instead of electromagnetic circuit analysis to get a driving force upon bobbin part. Also, these parameters and physical data are used to modify physical properties required for computation to accommodate simulated sound pressure level with measured one for loudspeaker enclosure system. These data like as Young's modulus and thickness for a diaphragm are required for vibration analysis of loudspeaker but not measured accurately. Finally, it was investigated that simulated sound pressure level with full acoustic modeling including an acoustic port for test loudspeaker agreed with experimental result very well in the midrange frequency band(from 100 Hz to 2,000 Hz). In addition, several design parametric study is performed to grasp acoustical behaviors of loudspeaker system due to variations of diaphragm thicknesses and shapes of dust cap.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 추계학술대회논문초록집
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• pp.385.1-385
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• 2002

Operational Modal Analysis also known as Ambient Modal Analysis has an increasing interest in mechanical cngineering. Especially on big structures where the excitation and not less important the determination of the forces is most often a problem. In a structure like a wind turbine wing where the modes occur both close in frequency and bi-directional the Ambient excitation has big advantages. (omitted)

• 대한음성학회지:말소리
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• 제55권
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• pp.119-130
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• 2005

The aim of this paper is to investigate some acoustical characteristics of the voice quality features from the emotional speech database. Six different parameters are measured and compared for 6 different emotions (normal, happiness, sadness, fear, anger, boredom) and from 6 different speakers. Inter-speaker variability and intra-speaker variability are measured. Some intra-speaker consistency of the parameter change across the emotions are observed, but inter-speaker consistency are not observed.

• 한국음향학회:학술대회논문집
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• 한국음향학회 2004년도 추계학술발표대회논문집 제23권 2호
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• pp.511-514
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• 2004

본 연구에서는 스피커 전용 해석 소프트웨어를 이용 하이파이용 우퍼에 대한 해석결과를 기술하였다. 전용 소프트웨어를 사용하는 경우에는 범용 소프트웨어에 비하여 다양한 경계조건을 갖는 경우에는 적용할 수 없다. 해석 대상은 무한배플에 장학된 하이파이용 우퍼로서 다이아프램의 breakup 현상을 예측할 수 있었다. 또한, 다이아프램의 두께 변경과 다양한 재료 및 힘 요소의 크기에 따른 하이파이용 라우드스피커의 음향특성들을 파악할 수가 있었다.

• 한국음향학회:학술대회논문집
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• 한국음향학회 2004년도 추계학술발표대회논문집 제23권 2호
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• pp.495-498
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• 2004

핸드폰등에 사용되고 있는 마이크로스피커를 개발하는 과정에서 마이크로스피커의 진동특성과 음향특성 을 전산해석하였다. 해석과정에서 기초 데이터를 얻기 위하여 하이브리드 방법을 이용하여 각 부품들의 제원 및 마이크로스피커 모델링을 위한 매개변수들을 규명하였다. 전산 해석 결과와 측정한 전기 임피던스 및 음향 응답특성은 잘 일치함을 보였다. 또한, 진동특성을 분석하여 각 주파수에서의 다이아프램의 변위등 진동특성을 분석하여 다이아프램등의 형상에 따른 이상 진동현상 등을 파악할 수 있었다. 전산해석 방법을 이용하면 최적 음향특성을 위한 마이크로스피커의 다이아프램 형상 및 전자기 회로 개선에 사용할 가능성을 알 수 있었다.

• The Journal of the Acoustical Society of Korea
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• 제26권3E호
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• pp.74-79
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• 2007

In this paper, we report our recent work on a indexing and retrieval system of broadcast news using audio content analysis. Key issues addressed in this work are two major parts of the audio indexing system: anchorperson detection based on audio segmentation, and phone-based spoken document retrieval, developed in the framework of the emerging MPEG-7 standard. Experiments are conducted on a database of Britisch broadcast news videos. We discuss the development of the retrieval system, and the evaluation of each part and the retrieval system.

• The Journal of the Acoustical Society of Korea
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• 제15권2E호
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• pp.63-75
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• 1996

The squeal vibration of a drum is the major source of brake noise. In this system the binary flutter model of squeal vibration was employed for the drum brake of a passenger car. The vibration analysis of a drum brake was performed by using normal modes, which are obtained by variational method. An improved method for the estimation of shoe modes is proposed and the results are compared with the exact solutions. Numerical results for the coupled system of drum and shoes good agreement with the results of experimental model analysis and those obtained by FE analysis.

• The Journal of the Acoustical Society of Korea
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• 제15권2E호
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• pp.8-13
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• 1996

The pseudomedian filter was designed to be a computationally effecient alternative to the median filter. However, a thorough analysis ofter pseudomedian filter reveals some important differences between its response and that of the median filter. This paper develops some formal properties of the pseudomedian filter. The root signal analysis demonstrates the close relatonship between the median and pseudomedian filters while pointing out important and useful differences.

• The Journal of the Acoustical Society of Korea
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• 제27권2E호
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• pp.64-68
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• 2008

This paper investigates noise reduction performance and performs convergence analysis of a Variable Error Data Normalized Step-Size Least Mean Square(VEDNSS LMS) algorithm. Adopting VEDNSS LMS results in higher system complexity, but noise is reduced providing fast convergence speed Mathematical analysis demonstrates that tap coefficient misadjustment converges. This is confirmed by computer simulation with the proposed algorithm.

• 한국음향학회:학술대회논문집
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• 한국음향학회 1984년도 추계학술발표회 논문집
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• pp.66-69
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• 1984

This paper is a study on the Endpoint Detection for Korean Speech Recognition. In speech signal process, analysis parameter was classification from Zero Crossing Rate(Z.C.R), Log Energy(L.E), Energy in the predictive error(Ep) and fundamental Korean Speech digits, /영/-/구/ are selected as date for the Recognition of Speech. The main goal of this paper is to develop techniques and system for Speech input ot machine. In order to detect the Endpoint, this paper makes choice of Log Energy(L.E) from various parameters analysis, and the Log Energy is very effective parameter in classifying speech and nonspeech segments. The error rate of 1.43% result from the analysis.