• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.197-201
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• 2000

For building acoustics, the revision and establishment of ISO JIS were carried out actively in the direction of international harmonization recently. In this consideration, the trends of the ISO and JIS were reviewed and the establishment process of KS was introduced. As a result of this consideration, it is thought to be that 'International Harmonization' should be a base for KS and the speciality of domestic characteristics should be attached to annex.

• Proceeding of Spring/Autumn Annual Conference of KHA
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• 2004.11a
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• pp.367-371
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• 2004

The purpose of this research is furnishing of basic material for acoustic planning hereafter, after understanding the acoustic merits and demerits through measuring and analyzing on room acoustic of small performance hall. As the result of the measurement, those physical evaluation indexes such as SPL, RT, EDT, $D_{50}$, $C_{80}$, RASTI have being kept the satisfiable acoustic condition for the service of performance hall. Therefore, as small performance hall is regarded as equipped with sufficient volume of sound, reverberatory feeling and diffusive feeling, it judges as an excellent performance place, also it is considered that it could be utilized as a useful material when design so similar performance hall, hereafter.

• The KSFM Journal of Fluid Machinery
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• v.19 no.2
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• pp.11-15
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• 2016

In this study, the generation of the propeller hub vortex was analyzed and a PBCF(Propeller Boss Cap Fins) was designed to control the propeller hub vortex. A RANS(Reynolds-averaged Navier-stokes) approach is employed to predict the hub vortex characteristics. The hub profile is an important factor but only a small increase (1.9%) of efficiency was obtained with the hub profile modification. The propeller hub vortex was eliminated by installing the PBCF and as a result, the propeller efficiency was increased by 5.6%.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.147-150
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• 2004

The reverberation characteristics of the Korean Traditional buildings aren't well-known, but there could be many particular properties. In this study, we compare the reverberation characteristics of a Korean traditional building of a temple, ‘Magoksa’, with three modern buildings. We use 5 parameters which have been widely studied in architectural acoustics such as reverberation time, early decay time, clarity, initial-time delay gap and R/D ratio.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.244-246
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• 2005

The Tonpiltz transducer is one of the essential elements in sonar application. The characteristics of transducer depend on the piezoelectric ceramics and mechanical elements such as head mass, tail mass, pre-stress rod and so on. One of the important characteristics is stable electric resistance for high power transmitting operation. This paper presents characteristics variation of the underwater acoustic transducer with material variation of electric decoupler.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.04a
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• pp.310-311
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• 2014

• Proceedings of the SAREK Conference
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• 2003.07a
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• pp.202-202
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• 2003

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.10a
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• pp.300-301
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• 2013

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.9 no.1
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• pp.27-31
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• 1998

Nasal sounds include nasalized vowels and consonants. Nasal cavity is important for the acoustics of nasal sounds. Evaluating the effects of site-specific nasal obstruction on nasal sound will help us to understand the importance of nasal geometry for the nasal sound and to foretell voice change after nasal surgery This study was designed to analyze the change of nasality and formant characteristics of nasal sound by obstructing different sites around the ostiomeatal unit(OMU). Ten adult male and female volunteers participated. The nasal formants and bandwidths of nasal consonant /n/ were checked in various conditions of nasal obstruction. The nasalance of rabbit, baby, and mama passages were compared in each conditions. Nasalance of all passages decreased when anterior portion of OMU was obstructed. Center frequency of first nasal formant(NF1) of /n/ has decreased in the order of anterior, inferior obstruction. The bandwidth of NF1 decreased in female with anterior obstruction. Anterior portion of OMU is most critical to the change of nasality and acoustics of nasal consonant. When anterior portion of OMU is obstructed, the shift of NF1 to a lower frequency and the narrowing of NF1 bandwidth are the major acoustic changes of nasal consonant /n/.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.817-820
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• 2006

The Tonpilz transducer is one of the essential elements in active sonar application. The characteristics of transducer depend on the piezoelectric ceramics and mechanical elements such as head mass, tail mass, pre-stress rod and so on. One of the important characteristics is electric and mechanical stability of transducer for long term high power transmitting operation. This parer presents the results about long term endurance tests of the underwater acoustic transducer.