• Proceedings of the Korea Information Processing Society Conference
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• 2017.11a
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• pp.909-912
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• 2017

In implementing a computerized virtual training system, the auditory element is responsible for the human cognitive ability following visual elements. Especially, the improvement of hearing ability is closely related to the performance of the training, and it contributes to improvement of the training effect. In this paper, we propose a sound system that is necessary for constructing such a virtual training system as a test system that can use a sound source using a head related transfer function (HRTF). Functional and auditory tests were performed to evaluate system performance.

• KIEAE Journal
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• v.10 no.5
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• pp.109-114
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• 2010

There are many business in complex building, and recently noise claims have increased in those buildings. It is one of the most desirable methods reducing the noise level to establish the noise criteria considering the admittable noise level between the source and receiving room, which are to be derived from the subjective response in the real conditions. Because the degree of annoyance and loudness for the intruding noises in complex building could be changed with background noise level, it is suggested to be researched the relationship between the noise levels and subjective response. In this study, the subjective response for three different background levels in receiving business or rooms were investigated for the typical eight business noise source including aerobic music. The results can be summarized as follows. In conditions of low background noise level(40 dB(A)), there is a tendency of intentionally attention situation (listening) in a subjective test. The other hand in conditions of relatively high background noise level(50 dB(A)), there is a unconscious situation (heraing). As the degree of moderately heard or annoyed in SD rating scale means that the noise is easily recognized in neighboring shops, usually the limit of noise criteria were decided on this rating point, so it will be reasonable to be adopted the criteria rating scale as slight heard or annoyed degree (SD criteria 3).

• Journal of the Korean Institute of Intelligent Systems
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• v.18 no.3
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• pp.381-386
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• 2008

Virtual 3D audio methods that create 3D sound effects are researched highly for multimedia devices using 2 speakers or headphone. The most typical method to create 3D effects is a technology through use of head related transfer function (HRTF) which contains the information that sound arrives from a sound source to the ears of the listener. But it can decline some 3D effects by cone of confusion between front and back directions due to the non-individual HRTF depending on each listener. In this paper, we propose a new method to use psychoacoustic theory that creates realistic 3D audio. In order to improve 3D sound, we calculate the excitation energy of each symmetric HRTF and extract the ratio of energy of each bark range. Informal listening tests show that the proposed method improves the front-bach sound localization characteristics much better than the conventional methods.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.20 no.6
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• pp.400-408
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• 2008

Multipurpose Dam, it produces electric energy by converting the potential energy into kinetic energy utilizing its head and quantity of the water. However, in this process, since during the time when the turbine connected to the hydraulic turbine generator revolves, there occurs a ceaseless loud noise, and due to this condition, it is true state that those people who work at inside of the power plant are damaging as hard as they are unable to concentrate on their work. Not only this, because the hydro-electric power generator room that locates at middle section between the hydraulic turbine room and the office is very large space volume, also since it was constructed chiefly by the reflecting material, it is functioning of amplify the noise when operating the generator, the soundproof measure against this condition is necessitated. On such viewpoint, I have presented the problem point of the relevant Hydraulic turbine dynamo and Hydraulic turbine dynamo room, and after improve such problem point, this study has ever investigated the satisfying degree about the noise-reduction at before and after of the improvement of soundproof measure, using the Auralizational technique that can experience virtual acoustic field. It is considering that such result could be utilized usefully as the fundamental material hereafter for the acoustic performance of the hydro-electric power generator room in dam and when its construction.

• The Journal of the Acoustical Society of Korea
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• v.28 no.6
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• pp.557-565
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• 2009

To perceive the direction and the distance of a sound, we always use a couple of information. Head Related Transfer Function (HRTF) contains the information that sound arrives from a sound source to the ears of the listener, like differences of level, phase and frequency spectrum. For a reproduction system using 2 channels, we apply HRTF to many algorithms which make 3d sound. But it causes a problem to localize a sound source around a certain places which is called the cone-of-confusion. In this paper, we proposed the new algorithm to reduce the confusion of sound image localization. The difference of frequency spectrum and psychoacoustics theory are used to boost the spectral cue among each directions. To confirm the performance of the algorithm, informal listening tests are carried out. As a result, we can make the improved 3d sound in 2 channel system based on a headphone. Also sound quality of improved 3d sound is much better than conventional methods.

• The Journal of the Acoustical Society of Korea
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• v.27 no.6
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• pp.296-302
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• 2008

This study investigated that the preference model of soloist performers for both vocal and instrumental types in terms of a stage support parameter, ST1. The test was carried out on a stage of a fan-shaped multi-purpose hall with orchestra shell. Objective measurements were carried out at 15 positions on the stage to evaluate various stage condition. The results showed that ST1 varies between -19.9 and -11.3 dB. Vocal and instrumental players participated in performance evaluation test as they played at 5 selected positions according to ST1 values. Players' preference was evaluated by 5-point rating and rank ordering method. As a result, it was found that the preference model of vocalist is different from that of instrumentalist. It was also found that the ST1 does not correlate well with the performer's preference.

• The Journal of the Acoustical Society of Korea
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• v.30 no.4
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• pp.181-189
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• 2011

According to developments of digital signal processing, 3D sound come into focus on multimedia systems. Many studies on 3d sound have proposed lots of clues to create realistic sounds. But these clues are only focused on binaural systems which two ears are normal. If we make the 3d sound using those clues at monaural systems, the performance goes down dramatically. In order to use the clues for monaural systems, we have studies algorithms such as duplex theory. In duplex theory, the sounds that we listen are affected by human's body, pinna and shoulder. So, we can enhance sound localization performances using its characteristics. In this paper, we propose a new method to use psychoacoustic theory that creates realistic 3D audio at monaural systems. To improve 3d sound, we calculate the excitation energy rates of each symmetric HRTF and extract the weights in each bark range. Finally, they are applied to emphasize the characteristics related to each direction. Informal listening tests show that the proposed method improves sound localization performances much better than the conventional methods.

• Science of Emotion and Sensibility
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• v.20 no.2
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• pp.171-178
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• 2017

'Smart Sensibility Mat (SSM)' was developed and manufactured for positive sensibility of newborn with fiber, digital, and sensibility technology to reflect features and advantages of kangaroo care. For tactile stimuli, the tube of the silicon material to provide a constant temperature of $32^{\circ}C$ was inserted into the mat and connected to the water-thermostat. To provide a uniform temperature throughout the mat, the fabric by the inserting conductive yarn was attached to the mat surface. After wrapping the mat with cotton pad, the polyurethane foam used as medicine in order to similar to the human skin was bonded to the surface of the mat. To provide the auditory stimuli of a level of 30dB with mother's heartbeat sounds and voice recorded in advance, the Bluetooth speaker was inserted into the mat. To investigate the effects of SSM, 10 newborns who born within two weeks were involved in this experiment. While the baby was lying on each of the general mat (GM) and SSM, the baby's physiological signals-heart rate, breathing rate, temperature- were measured and then, those were conducted t-test to examine the difference between the signals of SSM and GM. The results were as follows: heart rate (t=8.131, p<.001) and respiratory rate (t=7.227, p<.001) among the physiological signals of SSM decreased significantly than GM within the normal range. Temperature (t=1.062, p=0.292) at SSM showed a tendency to decrease than GM within the normal range. This means the tactile stimuli and the auditory stimuli providing from SSM give stable physiological responses. Thus, SSM leads to have psychological comfort and stability of newborns.

• The Journal of the Acoustical Society of Korea
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• v.30 no.8
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• pp.410-420
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• 2011

The present study aims to investigate the soundscapes of Jeju olle route through the soundwalking. In order to do this, sound measurements and sound recording were undertaken at 10 points along Jeju olle route. Also, loudness of background sound and figure sound were examined. Subjective surveys were carried out using questionnaire and interviews with 32 tourists and 5 acoustical specialists in order to investigate the loudest sound, most pleasant and unpleasant sound, and impressive sound among 17 natural and artificial sounds. Additionally, laboratory experiments were achieved to evaluates sound that have been recorded at the field using same questionnaire and the results were compared with those of field experiments. As a result, the sound heard most in Jeju olle route is the sea wave sound, wind sound, automobile noise, and human voice. It was revealed that the most pleasant sound consisted of nature sound among them, and that unpleasant sounds are artificial sounds. The results of subjective test denote that unpleasant sound is affected by ratio of artificial sound and nature sound. And this also affects the assessment about the loudness of the sound. Also, it was found that the results of both field test and laboratory test are closely correlated in the evaluation of loudness of sound and unpleasant feeling.

• Journal of the Korean Institute of Intelligent Systems
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• v.15 no.2
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• pp.230-235
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• 2005

In this paper, we propose an algorithm that improves a tone quality of a noisy audio signal in order to enhance a performance of perceptual filter using intelligent estimation of noise pattern from a band degraded by additive noise. The proposed method doesn't use the estimated noise which is obtained from silent range. Instead new estimated noise according to the power of signal and effect of noise variation is considered for each frame. So the noisy audio signal is enhanced by the method which controls a estimation of noise Pattern effectively in a noise corruption band. To show the performance of the proposed algorithm, various input signals which had a different signal-to-noise ratio(SNR) such as $5\cal{dB},\;10\cal{dB},\;15\cal{dB}\;and\;20\cal{dB}$ were used to test the proposed algorithm. we carry out SSNR and NMR of objective measurement and MOS test of subjective measurement. An approximate improvement of $7.4\cal{dB},\;6.8\cal{dB},\;5.7\cal{dB},\;5.1\cal{dB}$ in SSNR and $15.7\cal{dB},\;15.5\cal{dB},\;15.2\cal{dB},\;14.8\cal{dB}$ in NMR is achieved with the input signals, respectively. And we confirm the enhancement of tone quality in terms of mean opinion score(MOS) test which is result of subjective measurement.