• The Journal of the Acoustical Society of Korea
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• v.21 no.7
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• pp.614-623
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• 2002

In this paper, it was manufactured an interferometric optical fiber sensor and measured partial discharge acoustic signal caused by defect of power facilities such as power cables, transformers and gas insulation. Acrylic and aluminium mandrels wound with fiber-optic were chosen as optical fiber sensor, Sagnac and Mach-Zehnder interferometers were chosen to detect discharge acoustic signals. The two fiber optic interferometers were identified by using the PZT. Discharge experimentation set in the discharge imitation cell in oil tank and the discharge phenomena was generated. Based on the experimental result, to detect the discharge acoustic signal, Sagnac interferometer can detect stably the acoustic signal than the Mach-Zehnder interferometer. It is shown that Sagnac optical fiber sensor can detect the discharge acoustic signals effectively.

• Proceedings of the Acoustical Society of Korea Conference
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• 1998.06d
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• pp.5-8
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• 1998

본 논문에서는 지향성이 좋고, 대역폭이 넓은 초음파 스피커를 설계, 제작하는 것을 목표로 하였다. 이를 구현하기 위하여 초음파를 발생시키는데 널리 이용되고 있는 압전 세라믹인 PZT를 사용하였다. 먼저 스피커 제작을 위하여 금속진동판의 종류와 크기, 감도, 대역폭등의 최적값을 도출하여 주변고정, 마디지지, 주변지지의 형태로 스피커를 1차로 제작하여 음압을 측정하였고, 큰 음압을 구현하기 위해 동일한 성능을 가지는 마디지지의 스피커를 60개 배열하여 스피커로서 사용을 검증하였다.

• The Journal of the Acoustical Society of Korea
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• v.6 no.2
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• pp.54-61
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• 1987

This paper is to suggest the test method of sound attenuation caused by absorptive duct silencer using sound intensity method in field. In order to estimate sound attenuation, sound power being radiated from sound power source and duct exhaust terminal was measured by the sound pressure method and sound intensity method in semianechoic and common room. The results of the measured sound attenuation values by sound intensity method are more similar to those of theoretical calculation than those by the sound pressure method. In addition, sound intensity method is much less influenced by sound field condition or continuous background noise than the sound pressure method.

• The Journal of the Acoustical Society of Korea
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• v.24 no.4
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• pp.194-201
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• 2005

Since the necessity for the accurate measurement in the field of acoustics, vibration, and ultrasound was internationally increased, CCAUV (Consultative Committee for Acoustics , Ultrasound and Vibration) was created by the CIPM (International Committee for Weights and Measures) in 1998. One of the first activities of CCAUV is the key comparison on 1' standard microphones. The key comparison was done from April. 1999 to April. 2001 and 12 NMIs(National Metrology Institutes) including KRISS (Korea Research Institute of Standards and Science) were participated. The pilot laboratory was the National Physical Laboratory(NPL). The traveling standards were two LSIP(Laboratory Standard 1' Pressure Type) microphones specified in IEC 61094-1 and the calibration frequency ranges covers from 63Hz to 8kHz. In this paper, the analyzed results in the final report were summarized.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2013.06a
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• pp.8-11
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• 2013

스테레오-멀티채널 업믹스(Stereo-to-Multichannel Upmix)기술은 시장의 대부분을 차지하는 스테레오 음원을 홈시어터와 같은 멀티채널 스피커 재생 환경에서 효과적으로 재생하기 위한 채널 포맷 변환 기술을 말한다. 수평적인 공간감뿐만 아니라 수직적인 공간감을 재현하기 위하여 10.2, 22.2채널 환경의 경우 고도 채널이 추가되었다. 본 논문에서는 이러한 채널 환경에서 수직, 수평적인 공간감을 재현하기 위하여 새로운 초기 반사음을 생성하는 알고리즘을 제안하였다. 제안된 알고리즘은 진폭 패닝방법을 이용하여 전방의 가상 음원들에 의하여 발생되는 리시버 위치에서의 음압을 일치시킴으로써 기존 알고리즘이 가지지 못했던 이론적인 배경을 갖는다. 청취 평가 실험을 통하여 제안된 알고리즘은 음장의 수직, 수평적인 폭을 증가시키며, 좀 더 안정적인 음상 정위 성능을 가지는 것을 확인하였다.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 2001.11a
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• pp.1-4
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• 2001

본 연구에서는 실크 직물 7종의 마찰음을 녹음한 후, 색채 변환시켜 소리와 변환색채에 e한 감성을 평가함으로써 시각과 청각을 만족시킬 수 있는 의류소재 개발에 대한 기초자료를 제공하고자 하였다. 피험자 30명을 대상으로 소리와 변환색채를 차례로 제공한 후 감성을 평가하도록 하였다. 물리량은 소리의 경우 LPT, $\Delta$L, $\Delta$f, ARC를 색채의 경우 RP, GP, BP, CC를 계산하여 감성과의 관계를 조사하였다. 소리와 색채에 대한 감성차원으로는 '우아함', '활동감', '터프함'의 세요인이 도출되었다. 각 감성차원에 대한 소리와 색채 물리량과의 관계를 살펴보면, LPT와 $\Delta$L이 작을수록, 홍색비율이 크고 색채빈도수가 적을수록 우아함차원으로 평가하였으며, LPT와 $\Delta$L의 값이 클수록, 녹색비율이 크고 색채빈도수가 많을수록 활동감차원으로 평가하였다. 또한 ARC값이 작을수록, 홍색비율이 클수록 터프함차원으로 나타났다. 직물별 소리와 색채에 대한 선호도는 전통적인 수자직 직물이 가장 높게 나타났다.

• The Journal of the Acoustical Society of Korea
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• v.15 no.4
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• pp.77-82
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• 1996

In this paper an identification method is presented to obtain the equivalent electric model of a sandwitch type piezoelectric transducer. Unknown parameters related to the equivalent circuit are identified by solving a nonlinear optimization problem which can minimize an error between the experimental and analytical admittances in air. The proposed method is applied to an example transducer. The validity of equivalent circuit model is demonstrated by the comparison between the experimental measurements and analytical calculations of transmitting voltage response(TVR) and receiving voltage response(RVS).

• The Journal of the Korea Contents Association
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• v.2 no.1
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• pp.32-38
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• 2002

In the AV system, stereophonic system has been studied to produce a realistic sound effect. The width of stereo AV system speakers is narrow, to have the spatial impression of sound effect, widening the sound image is necessary. The direction of sound image depends on the phase delay and the sound pressure level difference between two channels. In this paper, we analyze the relationship between the phase delay and the direction of the sound image relating to the frequency of sound source. Also we experimented to directionally localize the sound image of the pure tone with shifting phases and controling sound pressure love between two channels when the sound is reproduced by two speakers to make a spatial impression of sound effect.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.7
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• pp.626-633
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• 2012

In this paper, sound pressure sensitivity of the fiber optic acoustic sensor according to sensor direction and mandrel material were investigated experimentally. Three different directions were selected as stand, lay, and hole. Hollow cylinder type mandrel dimension is 30 mm in outer diameter, 45 mm in length, and 2 mm in thickness, and about 50 m optical fibers were wounded on the surface of the mandrel. Non-directional sound speaker was used as a sound source. Sagnac interferometer and single mode fiber, a laser with 1,550 nm in wavelength, $2{\times}2$ coupler were used. Based on the experimental results, lay direction's sensitivity is the highest in the frequency range of 2 kHz~4 kHz. 'PTFE+carbon' material is more sensitive than PTFE in the frequency range of 5 kHz~20 kHz. Sound pressure detection sensitivity depends on the mandrel direction and material under certain frequency.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.4
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• pp.811-818
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• 1992

The sensor technology has becoming emerging area as the automation process in industry requires higher productivity, better quality, and the reliability. In this research, the dynamic measuring sensor such as piezoelectric accelerometers has been developed. Especially, the research concentrates on a design methodology, an analysis of the structural characteristics, and a method of the performance evaluation. The fabricated piezoelectric accelerometers show that the performance characteristics is better than commercial products available in the current market.