• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1997.10a
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• pp.286-292
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• 1997

Sound quality is becoming the major concern in passenger vehicle. The study on it has been done recently but it is not good enough. In order to improve the sound quality in passenger vehicle, so many noise sources must be considered and human feeling to the noise also be taken into account. In this paper, the sound quality was analyzed by vehicle road test which was carried out with varying the traveling speed. As basic factors for sound quality, only objective factors are considered such as loudness, sharpness, speech intelligibility, sound pressure level ... etc. The relations between sound pressure level and other factors are discussed from a point of view of traveling speed dependency. The frequency dependency of sound quality factor is also analyzed by frequency analysis.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2019.06a
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• pp.153-155
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• 2019

본 논문에서는 컨볼루션 신경망을 이용하여 예측 된 공간 오디오 큐를 이용한 오디오 채널 확장 기술을 소개한다. 오디오 채널 확장 기술은 일반적인 스테레오 신호에 적용되어 5.1 레이아웃과 같은 고차원 오디오 신호를 생성하는 기술이다. 스테레오 신호에서 채널을 확장하기 위해 스테레오 신호에서 공간 큐를 예측하고 예측 공간 큐의 방향에 따라 5.1 채널 신호의 스펙트럼 구성 요소를 할당하여 다중 채널 신호를 합성한다. 제안된 방식으로 생성된 5.1 채널 신호는 원 5.1 채널과 유사한 공간 정보 합성 능력과 스테레오 대비 주관적 선호도가 개선된 음질을 제공한다.

• The Journal of the Acoustical Society of Korea
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• v.33 no.1
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• pp.75-80
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• 2014

The quality of real-time Voice over Internet Protocol (VoIP) network is affected by network impariments such as delays, jitters, and packet loss. This paper proposes a packet loss concealment algorithm based on voice classification for enhancing VoIP speech quality. In the proposed method, arriving packets are classified by an adaptive thresholding approach based on the analysis of multiple features of short signal segments. The excellent classification results are used in the packet loss concealment. Additionally, linear prediction-based packet loss concealment delivers high voice quality by alleviating the metallic artifacts due to concealing consecutive packet loss or recovering lost packet.

• 한국HCI학회:학술대회논문집
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• 2008.02a
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• pp.643-647
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• 2008

ACE (Advanced Collaboration Environment) [1] aims to provide people to have remote collaboration as they are in the same Space. To provide tele-presence in remote collaboration, quality of audio and sharing of view which can show overall environment. Visual Sharing focuses on providing interactive view sharing among remote participants. A user can see remote collaboration space from any direction and can share his working screen view with others. In this paper, we summarize the development plan of Visual Sharing and relevant elementary techniques for developing Visual Sharing.

• Transactions of the Korean Society of Automotive Engineers
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• v.18 no.5
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• pp.37-44
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• 2010

Impact noise is induced in a car when it is driven on a harsh road or over some bumps. This noise occurs with the very high level of sound, which affects passengers in some way or other. Although it is impossible to clearly remove such noise, it is necessary to research an improvement in sound quality for impact noise. A new sound metric for impact sound is presented. This metric is verified by comparison between mean subjective ratings and several sound metrics. In this paper, more objective attributes are considered, which the attributes are expressing the level and modulation of sound. Three sound metrics are employed to get impact sound indexes for each course by the method of multiple linear regressions. The indexes are verified by considering the correlation between the estimated values from the multiple linear regressions and the mean subjective ratings by evaluators. Also, the subjective ratings on the indexes are estimated for the case in which some parts of suspension system are changed. The estimated ratings represent more reasonable or acceptable ratings. Thus, such indexes can be used for modification of the parts of suspension system under considering a good sound quality.

• Journal of the Korean Institute of Intelligent Systems
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• v.20 no.2
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• pp.208-213
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• 2010

Generally, the mal factor for speech recognition is the background noise in speech recognition. The noise is the reason to reduce the speech recognition performance. Owing to the fact, the place to recognize is very important. To improve the recognition performance from the sound having noise, we implemented the noise filtered Wiener filter at the signal process step which adopted the FIR filter. In FIR filter, it deal with the filtered speech signal which is appropriate frequency range of human speech frequency range. Therefore, we make the recognition system distinguish between noise and speech sound from the incoming speech signal.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.10B
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• pp.916-926
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• 2003

The encryption of packets increases delay and delay jitter that may degrade the quality of service (QoS) in real-time communications. So, we analyzed the delay jitter, delay, and interval delay between consecutive packets which were encrypted by the DES, 3DES, SEED and AES algorithms in this study. The interval delay and jitter of three algorithms such as the DES, SEED, AES were similar to the results of no encryption. But in the case of 3DES, the encryption of packets increases the variance of interval delay and jitter in comparison with other algorithms. we also analyzed properties of security and an efficiency of RTP security between SRTP and H.235.

• The Journal of the Acoustical Society of Korea
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• v.29 no.6
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• pp.381-387
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• 2010

Both timbral features and spatial features are important in the assessment of multichannel audio coding systems. The prediction model, extending the ITU-R Rec. BS. 1387-1 to multichannel audio coding systems, with the use of spatial features such as ITDDist (Interaural Time Difference Distortion), ILDDist (Interaural Level Difference Distortion), and IACCDist (InterAural Cross-correlation Coefficient Distortion) was proposed by Choi et al. In that model, ITDDistswere only computed for low frequency bands (below 1500Hz), and ILDDists were computed only for high frequency bands (over 2500Hz) according to classical duplex theory. However, in the high frequency range, information in temporal envelope is also important in spatial perception, especially in sound localization. A new model to compute the ITD distortions of temporal envelopes in high frequency components is introduced in this paper to investigate the role of such ITD on spatial perception quantitatively. The computed ITD distortions of temporal envelopes in high frequency components were highly correlated with perceived sound quality of multichannel audio sounds.

• The Journal of the Acoustical Society of Korea
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• v.20 no.3
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• pp.34-41
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• 2001

In an IMBE (Improved Multi-band Excitation) speech coder, initial pitch estimation occupies most of the total computing time for the coder due to complex cost function and exhaustive search over candidate pitches. Future frames in initial pitch estimation cause inevitable time delay. Therefore, it is difficult to implement a real-time coder. Furthermore, unvoiced frames use the unnecessary pitch estimation as in the voiced frames. In this paper, each frame is determined voiced or unvoiced by Dyadic Wavelet Transform (DyWT) and, then, initial pitch estimation is performed only for voiced frame. Therefore different pitch estimation algorithms are employed between voiced and unvoiced frames incurring reduced time delay at transmitter and receiver. Simulation result show that the relative complexity of initial pitch estimation is reduced by 23％, and the processing time decreases down to 1/10 ∼ 1/1l of the IMBE coder while speech quality is almost maintained.

• Applied Biological Chemistry
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• v.29 no.3
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• pp.241-247
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• 1986

The relationship between rice and the fluid during cooking was investigated to examine the factors affecting the quality of cooked rice and a new rice cooking method was proposed to improve the unpalatability of aged Milyang 23-long grain rice variety. The changes of heights of rice-bed and the fluid during cooking were measured with a laboratory cooking apparatus made of flat bottomed graduated glass cylinder. Around the boiling, a sudden disappearance of the fluid was observed and then thin film was formed on the rice grains. This film coating was fortified by the addition of 1-2%(w/w) of glutinous rice powder as a film forming agent. The artificial coating on the cooked rice of low quality remarkably improved the gloss, moisture content and shape and the extent of leaching of rice solid into the fluid was reduced with the treatment.