• Journal of Satellite, Information and Communications
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• v.8 no.4
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• pp.43-46
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• 2013

Active use of images in the same place as the religion according to the height of the screen is determined by the height of the main speakers. This causes the 'sound image mismatch' and 'bass boost' sound like a failure occurs. Front seats are good seats in visual acoustics is a bad place. To minimize these obstacles acoustical speakers to actively apply the front fill needed. Higher sound pressure difference between the main speaker and the distance must be determined in accordance with the appropriate capacity. Actively using the front speakers to the sound image field by implementing the agreement to increase the concentration of sound. The relatively high inflow enhance alto lacking the front seat can be implemented evenly in the frequency response. Column in front of the main seat of the main speakers to supplement the deficiencies can be implemented more comfortable acoustic environment. Front fill speaker needs to be actively introduced, thereby presenting a detailed estimate, is needed.

• Journal of Korea Multimedia Society
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• v.13 no.11
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• pp.1728-1738
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• 2010

Pyeon-gyeong, similar to Chinese Bianqing, is a Korean traditional lithophone with multiple stone chimes. Due to the temperature- and humidity-insensitive characteristics of its material, pumice stone, the instrument provides highly stable pitch and therefore has played a key role in Korean traditional court music. By reason of having absolute pitch, it is an important part of the research on the standard pitch and scale system of korean traditional music, but as an instrument, the study on the sound characteristics and worth is not making satisfactory progress, to date. This research is an analysis paper for physical modeling synthesis of pyeongyeong. Through this study, we will determine the original characteristics of the timbre of pyeongyeong as a unique korean traditional percussion, and investigate these characteristics objectively, based on the music acoustics by scientific analysis. Furthermore, this study will be used as an important basic material for physical modeling synthesis of pyeongyeong, and also make a huge contribution to the cultural applicability by the vitalization of graft onto the various artistic creation field, through the comprehension of the timbre of pyeongyeong as an instrument.

• The Journal of the Korea Contents Association
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• v.10 no.6
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• pp.373-377
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• 2010

Numerous quantitative and qualitative studies have already been published related to English vowels. However, only minimal amounts of studies based on the acoustic analysis of Korean vowels have been accomplished. The purpose of this study is to obtain sufficient quantitative data based on the acoustic aspects of Korean vowels produced by males between the ages of 20s and 30s. A total of 31 males in their 20s and 30s produced the five fundamental vowels /a, e, i, o, u/ by repeating each of them three times in the standard Korean dialect. Such speech productions were recorded with 'Cool edit' and F1, F2, F3, F4 were extracted through the MATLAB acoustic analysis program. Results indicated that the overall patterns of formants were similar to previous studies, except that the formant levels of F1 and F2 of the vowels produced in this study were generally lower than that in previous studies. Future studies need to focus on obtaining vowel data by considering other factors such as age and other speech materials.

• Journal of Satellite, Information and Communications
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• v.11 no.4
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• pp.102-106
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• 2016

With the popularity of smart phones and the help of high-speed wireless communication technology, high-quality multimedia contents have become common in mobile devices. Especially, the release of Oculus Rift opens a new era of virtual reality technology in consumer market. At the same time, 3D audio technology which is currently used to make computer games more realistic will soon be applied to the next generation of mobile phone and expected to offer a more expansive experience than its visual counterpart. This paper surveys concepts, algorithms, and systems for modeling 3D sound virtual environment applications. To do this, we first introduce an important design principle for audio rendering based on physics-based geometric algorithms and multichannel technologies, and introduce an audio rendering pipeline to a scene graph-based virtual reality system and a hardware architecture to model sound propagation.

• Korean Journal of Materials Research
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• v.5 no.1
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• pp.12-21
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• 1995

The study was performed to study the effects of strain rate on acoustics emission( AE) during bulging test in corrosive environmentsynthetic sea water. The strain rates used were in the range $4 \times 10^{-6}S^{-1}$ to $1 \times 10^{-4} \times S^{-1}$ and the parameters used to evaluate AE signal characteristics were AE hit and amplitude. It can be observed that the cumulative AE hit and average amplitude during fracture process increase highly at decreasing strain rates while the equivalent fracture strain and the crack length of circumferencial direction become decrease. The peak point of AE signal characteristic parameters approach to the first half of test. When the average amplitude per unit equivalent fracture strain was above 20dB, it was definitly observed stress corrosion cracking phenomena. Additional, we knew that the AE test had the possibility to evaluate SCC susceptibility with various strain rates.

• The Journal of the Acoustical Society of Korea
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• v.22 no.7
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• pp.562-572
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• 2003

A matched-target model inversion method was developed for a passive sonar to estimate the position of moving targets. Based on the well known matched-field processing in underwater acoustics, the method finds target position by matching the measured target directions and frequencies with the corresponding values of the proposed target model. For the efficient and accurate estimations, the parameter searching was accomplished using a hybrid optimizing method, which first starts with a global optimization such as generic algorithm or simulated annealing then applies a local optimization of a simple down hill algorithm. The suggested method was testified using simulations for three different moving scenarios. The simulation results showed that the method is robust in convergence, even under the situation of over 5 times standard deviation of Gaussian distribution of measured error, and is practical in calculation time as well.

• The Journal of the Acoustical Society of Korea
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• v.25 no.3E
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• pp.101-109
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• 2006

Besides dorsal-aspect target strength (TS) of the fish, side-aspect TS information is also acoustically important parameter in fisheries acoustics. In this study, the side-aspect TS of 11 black sea bream (Acanthopagurus schlegeli) were measured using a split beam echosounder of 120, 200, and 420 kHz; total length of the fish ranged from 12.4 to 23.7 cm, and wet weight from 27.5 to 229.8g. For the precise TS measurement with side-aspect angle, we used anesthetized and tethered specimens of known size while being rotated through $360^{\circ}C$ by means of a carousel structure. The side-aspect TS measurements of the fish were conducted by rotating the fish in the horizontal plane at 50 interval. The ping interval was 0.2 second and elapsed time at each angle was 30-60 second. As a result, the measured side-aspect TS data were fitted by sinusoidal function. The relationships between fish length and near full side-aspect TS were as follows: $TS_{120kHz}= 21.46 log (TL)-67.5 (r = 0.70), \;TS_{200 kHz}= 31.03 log (TL)-76.9 (r=0.83),\;TS_{420 kHz}= 30.79 log (TL)-72.2 (r = 0.77)$. For comparison, theoretically estimated side-aspect TS from the Kirchhoff ray mode (KRM) model, which based on swimbladder and body morphology, were compared with the measured TS.

• The Journal of the Acoustical Society of Korea
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• v.34 no.6
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• pp.432-443
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• 2015

Coherence describing the similarity between physical quantities of two signals is a very useful tool to investigate the temporal and spatial characteristics of signals propagating in underwater acoustic waveguide. Ambient noise measurements were made by the vertical received array consisting of three hydrophones as part of the KIOST-HYU joint acoustics experiment, and the coherence for the underwater ambient noise was analyzed. In this paper, the coherence results in cases that the generator in the research vessel was off and turned on are presented. The coherence estimated in the case of the generator operation mode are compared to the predictions obtained using the theoretical model with the directional density function dominated by vertical components propagating downward from the ship. In the case of the generator switch-off, the results are compared to the model predictions with directional density function including the effects of sea surface noise and long-distance shipping noise.

• The Journal of the Acoustical Society of Korea
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• v.34 no.6
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• pp.444-454
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• 2015

Measurements of bottom backscattering strengths in a frequency range of 6-14 kHz were made on the shallow water off the southern Gyeonggi Bay in Yellow Sea in May 2013, as part of the KIOST-HYU joint acoustics experiment. Geological surveys for the experimental area were performed using multi-beam echo sounder, sparker system, and grab sampling to investigate the bottom topography, sub-bottom profile and composition of surficial sediment, respectively. In this paper, the backscattering strengths as a function of grazing angle (in range of $28^{\circ}{\sim}69^{\circ}$) were estimated and compared to the predictions obtained by Lambert's law and APL-UW scattering model. Finally, the effects of geoacoustic parameters corresponding to the experimental area on the backscattering strengths are discussed.

• Speech Sciences
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• v.15 no.3
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• pp.203-217
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• 2008

The number of Asian women immigrants in Korea is getting bigger and it's important to note that their communication problem in Korean causes not only the difficulty of adapting to Korean society but their children's speech-language disorder. To date there is little research on their acoustics characters and articulatory errors. Therefore, this study focuses on acoustic characters and articulatory error patterns of the women immigrants from Japan and Philippine based on the theory of "contrastive analysis". The subjects were 16 Japanese women immigrants(age: 42.5$\pm$4.4) and 14 Philippine women immigrants(age: 31.64$\pm$6.7) and control group consisted of 10 Korean women(age: 28.3$\pm$1.2). Speech and hearing of all subjects and control group were within normal limits. Speech samples were analyzed in a computer using CSL and data analysis was done on FFT widow for F1, F2, F3 of vowels and on wideband spectrogram for VOT of plosives and africatives. The results of this study were like this; For Japanese women immigrants, they had different articulatory patterns of /e/, /a/, /u/, /o/, /$\varepsilon$/, /m/ from those of Koreans and showed articulatory errors on the fortis and aspirated sounds. The reason is Japanese has only two distinctive characters for plosives and affricates; voicing and voiceless. The Philippine women immigrants also showed the same error patterns as the Japanese women immigrants. Especially the errors on aspirated sounds were prominent because their mother tongue has no distinctive characters about aspirated sounds. For vowels, they showed errors of /a/, /o/, /c/.