• Proceedings of KOSOMES biannual meeting
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• 2003.11a
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• pp.45-51
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• 2003

The ship's signal sound dispersed by air, obstacles, and noises due to absorption, reflection, and disturbances, respectively. It is one of the factors of marine casualties by misjudgment if receiving direction The last target of this study is to prevent inherent marine casualty using the analysis-evaluation techniques if the interferences of ship's signal sound. In this work, three-dimensional sound field control model is proposed to simulate various sound transmitting characteristics according to sea environments at sea The efficiency test of the model was carried out using VR-based ship simulator.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.4 s.109
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• pp.428-436
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• 2006

The assessment of an urban site depends on the way whether it responds to multiple needs such as functionality, aesthetic and complex comfort of acoustic, thermal, lighting and air quality etc. This study aims to investigate the assessment of various urban soundscapes in the sense of acoustic amenity by the questionnaires. As a result, acoustic amenity assessment was influenced by the non-acoustic factors such as environment assessment of visual, thermal, air quality etc. In the sense of sound quality, urban environmental sound was interpreted as 3 factors of strength, evolution of time, spacial localization. So these factors would be considered in the new assessment method for acoustic amenity. And it was shown that the subjects tend to perceive the noise level less than $3{\sim}5dB\;L_{eqA}$ according to the urban landscapes under the similar noise exposure level.

• International Journal of Highway Engineering
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• v.15 no.6
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• pp.61-68
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• 2013

PURPOSES : The purpose of this study is to study the noise reducing effect of Micro Surfacing by comparing general asphalt, longitudinal tining and Slurry Seal. METHODS : This study measures vehicles' noise of each section by the NCPX method that can measure noise between the road surface and the tire at the field. Total sound pressure and sound pressure level by the 1/3 octave band frequency are calculated through the field data of each section. Total sound pressure level is compared by ANOVA test statistically. After ANOVA test, post-hoc test is conducted to know mean difference of surface type by Tukey. RESULTS : As the result of CPB analysis to confirm sound pressure levels by frequency, it was shown that sound pressure levels by frequency are totally similar except for those of frequency bands between 100Hz and 500Hz. The result of ANOVA test and post-hoc test, it was shown that sections of surface type have a difference. The result of Micro Surfacing was lower 2~5dB(A) than other surface type. CONCLUSIONS : It is found that the noise reduction performance of Micro Surfacing was better than other surface type.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.97-100
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• 2007

This study deals with the sound insulation performance of the damping sheet, which is widely used in a train. The wall of train is assumed to be a plate made of steel and two damping sheets. In case of damping sheet only, the sound transmission loss follows the mass law. If a steel plate is attached to damping sheet, the transmission loss is found to be higher than single of only steel plate, as we can anticipated, about $3{\sim}5$ dB. This is very well known consequence that is because the density of area increases. However, the increase of the transmission loss is not higher than what we can expect by the mass law. That's because the steel is perfectly blocked from the transmission of the air ; There is no defect in that material.

• Proceedings of the KIEE Conference
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• 2001.11c
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• pp.111-114
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• 2001

In this paper, we supposed teller following algorithm that using sound localization for developing dialog type humanoid robot. A sound localization is studied for develop the techniques of an efficient 3-D sound system based on the psychoacoustics of spatial hearing with multimedia or virtual reality. When a robot talk with human, it is necessary that robot follow human for improved human interface and adaptive noise canceling. We apply this algorithm to robot system.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2010.05a
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• pp.760-761
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• 2010

As is widely known, SPL measurement using sound level meter (SLM) is limited to higher than 30 dBA, because of the self-noise n(x) of condenser microphone (CM). The authors confirmed n(x) is composed of 3 kinds, each of which is stable enough under the condition -20 ~ +50 deg C to eliminate the influence of n(x) by subtracting its energy from the squared input signal in the integration process, as well as to develop new type of SLM with ultra-low SPL measuring function. This is so-called "0-dB SLM" since it enables to measure SPL down to around 0 dB-SPL. The RMS of n(x) is acquired and stored in ROM in advance, by placing CM in the supersilent space or by using dummy microphone with equivalent capacitance before the actual measurements.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.8 s.113
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• pp.797-805
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• 2006

The sound quality characteristics of refrigerator noise in an anechoic chamber and in a real living environment for 30 models of refrigerators were investigated. Subjective evaluation experiments were conducted to determine subjective tolerance level for refrigerator noise. Refrigerator noise was played from a loudspeaker at the position normally occupied by a refrigerator in a real living environment. A nine-point scale was used to measure subjective satisfaction of the sound pressure levels for refrigerator noise. Point 3 on the scale corresponded to a sound pressure level of about 30 dB(A). Seventy percent of the participants were satisfied with this level of refrigerator noise. A semantic differential test was also conducted to evaluate the sound quality of refrigerator noise. From the results of correlation and multiple regression analyses on the psychoacoustical parameters and subjective evaluations of 30 refrigerators, sound quality indices which predict the subjective rating score were proposed.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.10a
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• pp.463-468
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• 2011

According to a quantum leap of the performances of automobile, environmental factors are important as functional factors, especially noise. BLDC motor, one of the part of automobile, is also no exception. In this paper, investigation of the sound sources of outer rotor type BLDC motor is performed. In order to reduce noise, it must be necessary knowing sound source. To this end, this paper is analyzed two viewpoints, structural and electromagnetic causes. For structural analysis, modal experiment and 3D mode analysis are performed. On behalf of electromagnetic analysis, 2D finite element method is carried out. Finally, coupling analysis is performed in order to know about influence between two factors.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 1999.03a
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• pp.177-181
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• 1999

최근 PC의 멀티미디어 성능이 향상되고 디지털 신호처리 기술이 발달함에 따라 복잡한 수식과 방대한 정보처리가 요구되는 입체음향(3D Sound) 처리를 PC상에서도 구현하는 것이 가능하게 되면서, 입체음향에 대한 사용자의 관심이 고조되고 있다. 입체음향을 이용한 청각효과는 3D 영상의 시각효과에 못지 않은 강한 인상을 줄 수 있는 수단으로써 인정받고 있어 게임, 가상현실, 멀티미디어 컨텐트 등에서 사용자의 몰입감과 체험 효과를 최대한을 증대시킬 수 있는 새로운 수단으로 활용되고 있고, 이와 관련하여 입체 음향에 대한 연구와 개발이 국내외에서 활발히 진행중에 있다. 본 논문에서는 2채널 방식의 입체음향 기반기술과 최근의 입체음향 기술개발 동향을 살펴본다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11b
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• pp.1215-1220
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• 2001

Wind tunnel test of a new pantograph, that is developed through the KHST project, was performed in RTRI wind tunnel test center of Japan end of last June. This paper indtroduces the measurement results and analysis of noise measurement part that is achieved during the wind tunnel test. The maximum measured sound pressure level at 5m shows 102.3dB(A) at 350km/h and it leads to 88.3dB(A) of predicted sound pressure at 25m that satisfy 91dB(A) of evaluation criteria. Major noise sources of the pantograph was identified as a link between upper and lower arm, panhead contact strips and shunt wires.