• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.04a
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• pp.163-164
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• 2014

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.04a
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• pp.534-537
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• 2011

This Paper present prediction Vehicle Interior Noise using ATF(Acoustic Transfer Function) and engine radiated sound power. This is useful tool to qualifying the effectiveness of Air-borne noise Path. Furthermore This method provide acoustic package performance of the vehicle and able to prepare frequency band to same segment or benchmarking vehicle.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.11a
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• pp.589-590
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• 2008

Sound absorption characteristics of audience seating is very important when design and simulate room acoustics of concert halls or multi-purpose auditoriums. Sound absorption characteristics of audience seats were measured in reverberation chamber by varying the row to row spacing and number of audiences. By the increment of the row to row spacing, sound absorption characteristics in mid frequency band was increased. Also, sound absorption was proportionated to the number of audience.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1997.10a
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• pp.250-255
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• 1997

The computer simulation and mock-up test are recently applied to the practical design for the room acoustics to predict and evaluate its characteristics. In this paper, the sound field properties predicted and evaluated by the computer simulation were compared to the measured data. Comparison and analysis between simulation data and measured data were performed for the Reverberation Time, Sound Pressure Level at the various measuring positions and frequencies and Definition, Early Decay Time, Speech Transmission Index.

• Journal of the Korean Society for Nondestructive Testing
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• v.23 no.5
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• pp.480-487
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• 2003

To improve environmental control in various plants, signal characteristics of plants have been studied by a nondestructive technique. In this paper, the acoustic emission (AE) from plants was analyzed for water stress dependency. AE signals were taken from gymnosperm and angiosperm. AE sensor detected AE signals from the plant stem underneath the plant surface below the sensor. AE hit-event counts in daytime were more than those in night time, and it was found that the daily hit counts pattern was strongly affected by the water stress in the plant. frequency bands of AE signals from the angiosperm was different from those from the gymnosperm. Frequency bands of AE in outdoor condition were in accord with those in indoor having similar conditions.

• The Journal of the Acoustical Society of Korea
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• v.30 no.8
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• pp.468-473
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• 2011

Speech may not be clearly understandable in the room that is highly reverberant, due to the loss of consonants intelligibility. Therefore, it is very important to obtain a high sound pressure level of direct sound in reverberant room. A properly designed sound reinforcement system can not provide the good speech intelligibility without the absorption treatments of walls. With using the highly directional speaker, we can transmit the sound energy into only the areas where people are sitting. This can be help to improve the speech intelligibility. In this paper, even in reverberant rooms, it will be shown that the good speech intelligibility can be obtained by only the directivity control of speaker without the room treatment. Also, it would be more improved by the properly room tuning using an equalizer.

• The Journal of the Acoustical Society of Korea
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• v.15 no.4
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• pp.105-112
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• 1996

A linear acoustic analysis for baffled rocket combustion chambers has been developed. This study provides the comprehensive theoretical background for the baffle as one of the stabilizing devices in a liquid rocket propulsion system. Several specific effects of baffles are presented as mechanisms by which baffles eliminate instability. Included are longitudinalization of transverse waves inside baffle compartments, severe restriction of velocity fluctuations near the injector face, and decreased normal mode frequency of the chamber.

• Journal of KSNVE
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• v.11 no.2
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• pp.187-195
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• 2001

승용차 실내소음은 소음의 전달 방법에 따라 구조기인소음(structure-borne noise)과 공기기인소음(air-borne noise)으로 구별된다. 구조기인 소음은 차체에 전달된 외력이 차체를 통하여 전달되고 전달된 차체의 진통이 최종적으로 차실을 이루는 패널의 진동을 일으켜 승객에 전달되는 소음이며 공기기인소음은 발생한 소읍이 공기를 타고 전파되어 차실을 투과하여 승객의 귀에 전달되는 소음을 말한다. 구조기인소음을 일으키는 기진력으로 엔진의 관성 및 폭발력, 노면의 입력, 구동계 진동, 풍력 등이 있다. 발생된 기진력은 엔진 마운트, 서스펜션 등을 통하여 차체에 전달되고 최종적으로 대쉬, 루프 등의 패널을 떨게 만들며 이러한 진동은 50∼500Hz 대역에서 차실 공간의 음향 특성에 따라 가감되어 저주파 실내 소음을 발생시킨다. 500Hz 이상 대역의 실내소음은 일반적으로 공기기인 소음이 대부분을 차치하게 된다.(중략)

• Information and Communications Magazine
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• v.32 no.2
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• pp.81-88
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• 2015

본 고에서는 최근 각광받고 있는 실내 위치측위 기술의 연구 동향을 설명하고, 향후 전망에 대해 분석한다. 스마트폰 및 태블릿PC와 같은 상용 단말의 보급과 위치기반서비스 시장의 확대에 따라 일반 사용자가 별도의 장비 없이 개인 단말을 이용하여 사용자 자신의 위치정보를 획득할 수 있는 실내 측위기술에 대해 많은 연구가 진행되고 있다. WiFi 인프라 기반 기술과 단말에 탑재된 관성항법장치 기반 기술에 대한 연구가 중점을 이루고 있으며, 이 외에도 음향신호, 레이저, LED 기반 가시광 통신, Bluetooth 등을 이용한 측위기술이 연구 중에 있다. 미래에는 차세대 이동통신 기술의 도입으로 Heterogeneous 네트워크 환경과 단말 간 직접 통신을 통한 무선애드혹네트워크 환경이 구성될 것으로 전망하며, 이에 따른 미래 실내 측위기술에 대해 간략히 기술한다.

• The Journal of the Acoustical Society of Korea
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• v.31 no.3
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• pp.129-141
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• 2012

The present study aims to investigates the effects of the physical sound clarity (D50, STI) on the subjective speech intelligibility of the both Korean and Chinese languages which can be caused by increase of the sound absorption in classroom. In order to this, sound measurements were undertaken at a classroom with and without absorption materials. Also, speech intelligibility tests were conducted by Korean and Chinese students using their native languages. As the results, it was found that both sound clarity and speech intelligibility were improved with increasing sound absorption. Also, it was revealed that Chinese speech intelligibility was more improved than Korean with same impose of sound absorption. It was considered by the difference of phonetic characteristics of two languages. Analysing correlation of physical sound clarity and subjective speech intelligibility, it was shown that D50 is highly correlated with Korean (0.696) and Chinese (0.707) respectively. Also, STI was highly correlated with Korean (0.651) and Chinese (0.665). Thus, it can be concluded that D50 and STI have significant correlations with the speech intelligibility.