• 한국음향학회지
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• 제28권4호
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• pp.299-307
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• 2009

본 연구에서는 마이크로스피커에서 진동판의 패턴에 따른 음향특성의 변화를 연구하였다. 진동판을 에지부와 돔부로 크게 나누고, 이들 각각에 대한 패턴형태의 변화는 진동판의 인장강도에 영향을 주는 것으로 나타났고, 그 결과로써 마이크로스피커의 공명진동수가 변하였다. 에지부에서 패턴의 수가 증가하면, 공명진동수가 증가하여 최대가 된 후에 다시 지수함수적으로 감소하였다. 에지부에서 "U"형 드릴의 사용, 회오리형 패턴과 "V"형 드릴의 각도를 감소시키거나 또는 돔부에서 방사형 패턴의 수와 돔 높이의 감소와 곡률반경의 증가는 진동판의 인장강도를 증가시켜 공명진동수를 높였다. 그러나 에지부에서 "V"형 드릴의 사용, 방사형 패턴과 "V"형 드릴각도의 증가와 돔부에서 방사형 패턴의 수와 돔의 높이를 증가시키거나 곡률반경을 감소시키면 진동판의 인장강도가 감소하여 공명진동수가 감소하였다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2005년도 추계종합학술대회
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• pp.411-414
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• 2005

The most recent trend on digital hearing aid is to increase the ratio of signal to noise by directivity or to develop noise reduction algorithm inside DSP IC chip. This paper designed, fabricated and tested a digital hearing aid directivity testing device in which a micro-mouse-like the stepping motor with a speaker rotates around an examinant. Both ears of the examinant were fixed with ITE hearing aids in order to response to receiving sound. The diameter of the directivity testing device was 2 [m] and the micro-mouse was precisely controlled by PICBASIC micro processor.

• 전기학회논문지
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• 제67권3호
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• pp.383-390
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• 2018

Piezoelectric micro-machined ultrasonic transducers for highly directional speaker need DC bias voltage. Most existing power amplifiers are not suitable for use in highly directional transducers because they are based on AC. In addition, since the piezoelectric micro-machined ultrasonic transducer has a large capacitive reactance, the power efficiency of the power amplifier is very low. Thus this paper proposes a new high efficiency power amplifier with DC bias voltage. In addition, by designing a matching circuit to compensate the capacitive reactance of the micro-machined ultrasonic transducer, the power efficiency of the power amplifier increases. The operating characteristics of the proposed power amplifier was verified by an experimental prototype. The proposed power amplifier is expected to be widely used in designing and implementing other related power amplifiers.

• 한국소음진동공학회논문집
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• 제16권1호
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• pp.81-88
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• 2006

The most recent trend on digital hearing aid is to increase the ratio of signal to noise by directivity or to develop noise reduction algorithm inside DSP IC chip. This paper designed, fabricated and tested a digital hearing aid directivity testing device in which a micro-mouse-like the stepping motor with a speaker rotates around an examinant. Both ears of the examinant were fixed with ITE hearing aids in order to respond to receiving sound. The experimental results were compared with those of a boundary element method program for verification. The diameter of the directivity testing device was 2 m and the micro-mouse was precisely controlled by PICBASIC micro processor.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 추계학술대회논문집
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• pp.469-474
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• 2005

The most recent trend on digital hearing aid is to increase the ratio of signal to noise by directivity or to develop noise reduction algorithm inside DSP IC chip. This paper designed, fabricated and tested a digital hearing aid directivity testing device in which a micro-mouse-1ike the stepping motor with a speaker rotates around an examinant. Both ears of the examinant were fixed with ITE hearing aids in order to response to receiving sound. The experimental results were compared with a boundary element method program for verification. The diameter of the directivity testing device was 2 [m] and the micro-mouse was precisely controlled by PICBASIC micro processor.

• 한국음향학회:학술대회논문집
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• 한국음향학회 2004년도 추계학술발표대회논문집 제23권 2호
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• pp.499-500
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• 2004

일반적으로 진동판의 크기와 형태는 스피커의 음파 방출 효율과 재생대역 및 왜곡특성을 결정하는 중요한 요인이다. 지금까지 대부분의 연구결과들은 직경 25mm 이상, 두께 0.1mm 이상의 다양한 소재의 진동판으로 이루어진 스피커들을 대상으로 하였다. 그러나 현재 수요가 급증하고 있는 마이크로스피커에 사용되는 진동판들은 직경이 20mm 이하이고, 그 두께는 수십 ${\mu}m$ 필름 소재를 사용하고 있다. 이러한 이유로 마이크로스피커의 동작특성은 일반적인 스피커에 비해 재생대역이 좁고, 고조파 왜가 크게 나타난다. 본 논문은 수 십 ${\mu}m$ 두께의 필름 진동판을 사용하는 마이크스피커의 설계 시, 기본적인 특성을 예측할 수 있도록 하기 위해 진동판의 두께 변화, 단면의 곡률변화에 따른 스피커의 특성 변화를 조사하였다.

• 음성과학
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• 제7권1호
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• pp.217-232
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• 2000

In this study, I investigate the role of post-consonantal fundamental frequency (F0) as a cue for automatic distinction of types of Korean stops and affricates. Rather than examining data obtained by restricting contexts to a minimum to prevent the interference of irrelevant factors, a relatively natural speaker independent speech corpus is analysed. Automatic and statistical approaches are adopted to annotate data, to minimise speaker variability, and to evaluate the results. In spite of possible loss of information during those automatic analyses, statistics obtained suggest that vowel F0 is a useful cue for distinguishing manners of articulation of Korean non-continuant obstruents having the same place of articulation, especially of lax and aspirated stops and affricates. On the basis of the statistics, automatic classification is attempted over the relevant consonants in a specific context where the micro-prosodic effects appear to be maximised. The results confirm the usefulness of this effect in application for Korean phone recognition.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 하계종합학술대회 논문집(5)
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• pp.155-158
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• 2000

In this paper, For operator's conveniency of the mobile robot, achieved the system which control the robot by adopting the speaker independently isolated word recognition and by implementing the real time with TMS320C31. and This paper using the Tri-ultrasonics range finder to detect obstacles and implements the mobile robot. In this paper, DSP processor (TMS320C31) is used signal processing for speech recognition in the real time and Micro processor(80C196KC) is controling the ultrasonics range finders.

• 소성∙가공
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• 제23권1호
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• pp.10-15
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• 2014

Recently, micro-speakers have attracted much attention due to their increasing demand in mobile devices. Micro-speakers use polymer diaphragms, which are manufactured from thin polymer film by the thermoforming process. The diaphragm is generally designed to be a circular membrane with a cross section consisting of a double dome structure, and a number of corrugations are located in the outer region to produce better sound quality. In the current study, a finite element (FE) analysis is performed for thermoforming, and the resulting thickness reduction in the corrugation regions is estimated. The estimated thickness distribution is used in further structural and modal FE analyses, from which the effects of local thickness reduction on the stiffness and vibration characteristics are determined.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 추계학술대회논문집 II
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• pp.1335-1340
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• 2001

The information technology brought us many kinds of conveniences to our life, but it also caused social problems such as privacy interference, unexpected personal information leaks, and nose generation by telephonic talks, etc. In this paper, the microphone system of the cellular phone is developed to prevent these problems caused by progress of information technology. The developed system was designed to detect only acoustic signals from a human being in the presence of various kinds of background noises. A windscreen was designed by use of micro-channels to eliminate the popping noise by the wind from the mouth of a speaker and four microphone array and signal processing techniques are applied to reduce background noise. The impact of the developed system was evaluated by experimental tests. The results show that the system can improve the required functions considerably.