• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2002.05c
• /
• pp.237-241
• /
• 2002

전력선과 조명등을 이용한 음향전달 시스템을 구성하여 어학실습 교육용으로의 활용 가능성을 평가하였다. 음성신호를 변조하여 전력선에 실어 보내는 송신기와 조명등의 빛으로부터 음성신호를 검출하여 이어폰 또는 헤드폰 둥으로 들을 수 있는 수신기로 구성하였다. 제작한 송신기와 수신기의 주파수 특성과 스펙트럼분석을 하였다. 스피커로 출력되는 음질상태는 최적상태는 아니지만 음성이나 노래 등을 이용한 어학실습 교육용으로는 충분한 수준이 었다.

• Annual Conference on Human and Language Technology
• /
• 2022.10a
• /
• pp.109-114
• /
• 2022

질의 생성 모델은 스마트 스피커, 챗봇, QA 시스템, 기계 독해 등 다양한 서비스에 사용되고 있다. 모델을 다양한 서비스에 잘 적용하기 위해서는 사용자들의 실제 질의 특성을 반영한 자연스러운 질의를 만드는 것이 중요하다. 본 논문에서는 사용자 질의 특성을 반영한 간결하고 자연스러운 질의 자동 생성 모델을 소개한다. 제안 모델은 topic 키워드를 통해 모델에게 생성 자유도를 주었으며, 키워드형 질의→자연어 질의→응답으로 연결되는 chain-of-thought 형태의 다중 출력 구조를 통해 인과관계를 고려한 결과를 만들도록 했다. 최종적으로 MRC 필터링과 일관성 필터링을 통해 고품질 질의를 선별했다. 베이스라인 모델과 비교해 제안 모델은 질의의 유효성을 크게 높일 수 있었다.

• The Journal of the Acoustical Society of Korea
• /
• v.22 no.7
• /
• pp.585-591
• /
• 2003

In this paper, fiber optic sensor using Fabry-Perot interferometer which had benefit of minimize and light-weight was used. The sensor head has 1cm in length, total length of fiber is 9.5 chi and the sensor supported at both ends, simply. To analyze the acoustic characteristic non-directional speaker is used as a sound source. Acoustic applied in lateral direction and detected two signals were compared each other. Below 1㎑ fiber optic sensor has more sensitive than microphone, but in 2㎑ fiber optic sensor has less sensitive than microphone. This characteristic varies to the supporting system of fiber optic sensor. It was confirmed that the Fabry-Perot interferometric sensor detected acoustic signal, effectively. This kind of sensor can be applied to the structural health monitoring field of intellectual structure.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.34 no.12
• /
• pp.35-40
• /
• 2006

The combustion instability in a model dump combustor with an exhaust nozzle and the possibility of combustion control using a loudspeaker to these instabilities were studied. By changing inlet velocity, combustor length and equivalence ratio, dynamic pressure signals and flame structures were simultaneously taken. Because inlet velocity and combustor length affect the life time of vortex in the dump combustor, the results showed that as the combustor length increased and the inlet velocity decreased, the instability frequency decreased and the maximum power spectral density of the dynamic pressure generally decreased. Also, instability frequency and maximum power spectral density of the dynamic pressure increased with the increment of equivalence ratio. From the data of close-loop control, the optimum time-delay control using a loudspeaker was confirmed to be able to reduce the vortex shedding induced from the mixed acoustic-convective mode combustion instability.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.18 no.1
• /
• pp.154-160
• /
• 2004

In this paper, implementation of active noise curtains using multiple channel adaptive filters is presented. The same numbers of single channel LMS algorithms as control loudspeakers is used instead of a multi-channel LMS algorithm to reduce the computational burden of adaptive filter algorithms. In general, a multi-channel LMS algorithm is usually used in active noise control system. but this algorithm has much more computational complexity. The single channel control techniques have less amount of DSP calculation, compared to multiple channel control techniques. A stabilizing procedure for adaptive IIR filters is also proposed to improve the stability of recursive LMS algorithms. Both experimental results of two control techniques using TMS320VC33 digital signal processor show the similar noise reduction, but the single channel control techniques are more efficient in practical active noise curtain applications

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.12 no.5
• /
• pp.91-97
• /
• 2012

Recently, the performances of electrical and electronic devices are improving while the sizes are becoming smaller. As sound-generating systems, the two-dimensional speakers have been developed in place of conventional three-dimensional ones. Piezoelectric materials show the mechanical vibrations due to the voltage applied from outside the materials. The early film speakers had a limitations of output power in that it was not easy to make the conducting macromolecular films on the surfaces of the materials due to the internal chemical properties of materials. We have adopted the corona surface treatment in order to improve the output characteristics by increasing the adhesion of the coating material on to the surface of the center material of piezo film. The results showed the improvement of output power in the wider range of operating frequencies.

• Journal of IKEEE
• /
• v.25 no.4
• /
• pp.591-597
• /
• 2021

This paper proposes an EMC-aware PCB design method to reduce electromagnetic emission, where trace length and teturn path of critical signal are shortened by changing chip location and trace layout on the PCB, while additional filters or decoupling capacitors are not required. In the proposed method, signal velocity is calculated for various signals on the PCB. Critical signal with the fastest signal velocity is determined and its return path is shortened as much as possible by placing chip location and trace routing first. Return path of critical signal should be carefully designed not to have discontinuity. Power plane and ground plane should be carefully designed not to be divided, since these planes are the reference of return path. The proposed method was applied to automotive directional Bluetooth speaker which failed to pass CISPR 32 and CISPR 25 EMC tests. Its PCB was redesigned based on the proposed method and it easily passed the EMC tests. The proposed method is useful to EMC-sensitive electronic equipments.

• The Journal of the Acoustical Society of Korea
• /
• v.27 no.4
• /
• pp.207-214
• /
• 2008

To create 3D sound, we usually use two methods which are two channels or multichannel sound systems. Because of cost and space problems, we prefer two channel sound system to multi-channel. Using a headphone or two speakers, the most typical method to create 3D sound effects is a technology of head related transfer function (HRTF) which contains the information that sound arrives from a sound source to the ears of the listener. But it causes a problem to localize a sound source around a certain places which is called cone-of-confusion. In this paper, we proposed the new algorithm to reduce the confusion of sound image localization. HRTF grouping and psychoacoustics theory are used to boost the spectral cue with spectrum difference among each directions. Informal listening tests show that the proposed method improves the front-back sound localization characteristics much better than conventional methods.

• The Journal of the Acoustical Society of Korea
• /
• v.11 no.2
• /
• pp.28-37
• /
• 1992

In the study, the Acoustic transducer of a thin circular disc-type with PZT/Metal was manufactured. The 'tape casting method' was introduced to prepare the thin disc-type of piezoelectric ceramics. The acoustic characteristics of PZT/Metal acoustic transducer for piezoelectric buzzer and piezoelectric speaker etc. have been studied and analyzed. As a result, the sound pressure level (dB), in the range from -6dB to -14dB, increased with increasing the piezoelectric coeffeicient ($d_{31}$) of ceramics. The optimal conditions of the sound pressure characteristics of acoustic transducer were that the radius ratio(${\eta}$) of ceramics and metal plate is 0.7-0.8 and the thickness ratio(${\beta}$) is 1.0, and the value were -15~-165dB.

• Proceedings of the Acoustical Society of Korea Conference
• /
• spring
• /
• pp.241-244
• /
• 2004

전민동 성당은 얕은 팔각뿔대 형상의 지붕을 가진 팔각기둥의 형태로 재설계되었다. 팔각기둥의 형상은 마주보는 4쌍의 벽들로 인하여 공간에서 정상파가 발생하기 쉽고, 지붕 또한 둥근 형태로 음향 초점이 발생할 수 있는 등 여러가지 문제점을 가지고 있다. 이러한 형태의 전민동 성당에 대하여 여러 가지 음향 인자들을 예측하였고, 예측치와 측정치를 비교하였다. 사용된 음장해석 프로그램은 $CATT^{TM}$이고 예측 또는 측정된 음향인자는 RT, D50, C80 등이다. 건축물만의 특성과 전기음향설비가 포함된 음향특성을 비교하기 위하여, 무지향성 스피커를 이용한 측정과 성당에 장착된 전기음향장치를 이용한 측정을 수행하였다. 공연장과 마찬가지로 성당의 신도석에서도 음이 고르게 분포되는 것이 바람직하며, 신도석에서의 음압분포를 예측과 측정을 통하여 비교하여 보았다.