• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권12호
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• pp.4476-4491
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• 2021

Video service providers tend to face user network problems in the process of transmitting video streams. They strive to provide user with superior video quality in a limited bitrate environment. It is necessary to accurately determine the target bitrate range of the video under different quality requirements. Recently, several schemes have been proposed to meet this requirement. However, they do not take the impact of visual influence into account. In this paper, we propose a new multi-category model to accurately predict the target bitrate range with target visual quality by machine learning. Firstly, a dataset is constructed to generate multi-category models by machine learning. The quality score ladders and the corresponding bitrate-interval categories are defined in the dataset. Secondly, several types of spatial-temporal features related to VMAF evaluation metrics and visual factors are extracted and processed statistically for classification. Finally, bitrate prediction models trained on the dataset by RandomForest classifier can be used to accurately predict the target bitrate of the input videos with target video quality. The classification prediction accuracy of the model reaches 0.705 and the encoded video which is compressed by the bitrate predicted by the model can achieve the target perceptual quality.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 Ⅳ
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• pp.2232-2235
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• 2003

In speech communication systems where two different speech codecs are interoperated, transcoding algorithm is a good approach because of its low complexity and improved synthesized speech quality. This paper proposes an efficient method to further improve the performance of transcoding algorithms as well as to reduce the complexity. In the conventional transcoding algorithms. a post-filter and a perceptual weighting filter should be operated sequentially because both decoding and encoding processes are needed. This results in the redundancy of the processing in terms of complexity and perceptual quality. Using the fact that their filter structures are similar, we replaced the two filters with one. The proposed algorithm requires 72.8% lower complexity than the conventional transcoding algorithm when we compare only the complexity of the filtering processes. The results of both objective and subjective tests verify that the proposed algorithm has slightly better quality than the conventional one.

• 융합신호처리학회논문지
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• 제3권1호
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• pp.15-20
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• 2002

동영상 부호기에서 화면내 프레임 부호화는 전체 프레임의 화질에 중요한 영향을 미친다. 표준화된 동영상의 부호기는 DCT를 쓰지만, 저 비트율에서의 블록화 현상으로 화질의 열화를 가져올 수 있다. 본 논문에서는 화질의 열화를 감소시키고 인간 시각적인 측면에서의 화질 개선을 위한 비디오 코딩을 제안한다. 제한안 방법에서는 웨이브릿 변환에서 인지적 가중치를 화면내 프레임에 적용하여 SPIHT와 VLC를 이용하여 부호화하였고, 인간 시각 특성을 고려하여 시각적인 노이즈를 제거하여 주관적인 화질을 향상 시켰다.

• IEIE Transactions on Smart Processing and Computing
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• 제4권1호
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• pp.22-27
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• 2015

Transform-domain JND (Just Noticeable Difference)-based for PVC (Perceptual Video Coding) is often performed in quantization processes to effectively remove perceptual redundancy. This study examined the JND-suppression effects on quantized coefficients of transform in HEVC (High Efficiency Video Coding). To reveal the JND-suppression effect in quantization, the properties of the floor functions were used for modeling the quantized coefficients, and a JND-adjustment process in an HEVC-compliant PVC scheme was used to tune the JND values by analyzing the JND suppression effect. In the experimental results, the bitrate reduction decreases slightly, but the PSNR and perceptual quality are improved significantly when the proposed JND adjustment process is applied.

• 한국주거학회논문집
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• 제10권4호
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• pp.161-174
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• 1999

This study tried to search for solutions of present problems in architecture through interdisciplinary study which includes biology, literature, aesthetics, and psychology, and set up two models composed of the nature and the human perception which contemporary architecture has problems on. By nature-oriented approach through biology and romanticist literature, the five types of organic principles which could be obtained from structure and order in natural system and by human perception-oriented approach through aesthetic theory of Harold Osborne and perceptual and cognitive psychology the structure and order of perceptual arousal, perceptual balance, and perceptual order in human cognition based on perceptual appropriateness could be found. The unified and organic framework of architectural composition must be considered through a deductive and inductive study as this study was approached. The results of the present study can be applied to construct human-oriented design principles and factors in architectural space and form, and better environmental quality.

• 전자공학회논문지
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• 제52권5호
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• pp.147-154
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• 2015

본 논문에서는 주변의 밝기에 대한 HVS의 민감도를 모델링한 JND (Just Noticeable Difference)를 비디오 코딩에 적용함으로써, JND 모델에 따른 임계치를 기준으로 현재 코딩 유닛에 적용 가능한 최대 양자화 파라미터를 결정하여 유사한 주관적 화질에서 비트율을 절감시키는 방법을 제안한다. 제안하는 방법은 입력된 현재 코딩 유닛에 대하여 기준이 되는 양자화 파라미터가 적용된 복원 신호 대비 더 높은 양자화 파라미터를 적용한 복원 신호가 JND 관점에서 유사하게 인지되는 경우에 더 높은 양자화 파라미터를 선택함으로써 비트율을 절감시킨다. 제안하는 알고리즘의 성능 검증을 위하여 최신 비디오 압축 표준인 HEVC (High Efficiency Video Coding)의 참조 소프트웨어인 HM16.0에 본 알고리즘을 적용하였으며, HM16.0을 통해 압축된 영상 대비 유사한 화질에서 최대 20.21%, 평균적으로 약 6.18%의 비트율 절감을 달성하였다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 하계종합학술대회 논문집(3)
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• pp.93-96
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• 2000

Currently, the most important technology is the compression methods in the multimedia society. Audio files are rapidly propagated through internet. MP-3 is offered to CD tone quality in 128Kbps, but 64Kbps below tone quality is abruptly down and high bitrate. on the other hand, MPEG-II AAC (Advanced Audio Coding) is not compatible with MPEG-I, but AAC has a high compression ratio 1.4 better than MP-3. Especially, AAC has max. 7.1 channel and 96KHz sampling rate. In this paper, the perceptual model is dealt with 44.1KHz sampling rate for SMR(Signal to Masking Ratio)

• 대한후두음성언어의학회지
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• 제32권3호
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• pp.109-117
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• 2021

The auditory-perceptual evaluation of speech-language pathologists (SLP) in patients with voice disorders is often regarded as a touchstone in the multi-dimensional voice evaluation procedures and provides important information not available in other assessment modalities. Therefore, it is necessary for the SLPs to conduct a comprehensive and in-depth evaluation of not only voice but also the overall speech production mechanism, and they often encounter various difficulties in the evaluation process. In addition, SLPs should strive to avoid bias during the evaluation process and to maintain a wide and constant spectrum of severity for each parameter of voice quality. Lastly, it is very important for the SLPs to perform a team approach by documenting and delivering important information pertaining to auditory-perceptual characteristics in an appropriate and efficient way through close communication with the laryngologists.

• 한국산업정보학회논문지
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• 제21권2호
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• pp.73-91
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• 2016

이 연구는 사용자 관점의 클라우드 품질항목 체계를 도출하고, 각 품질항목별 중요도와 만족도를 조사하며, 사용자-공급자의 인식 차이를 실증 분석함으로써 향후 품질 개선을 위한 정보를 제공한다. 선행 연구 조사와 전문가 포커스 그룹 평가에 의하여 도출된 13개 품질항목은 (1)기능 충분성, (2)이용 편리성, (3)서비스 가용성, (4)반응속도, (5)기술 최신성, (6)서비스 호환성, (7)서비스 맞춤화, (8)서비스 확장성, (9)시스템 보안, (10)고객비밀 보장, (11)계약 신뢰성, (12)고객대응 성실성, (13)인력 전문성이다. 13개 품질항목별 중요도와 만족도를 묻는 설문조사를 사용자 그룹과 공급자 그룹을 대상으로 각각 실시하였다. 통계 분석 결과, 각 품질항목이 얼마나 중요한지에 대하여 사용자와 공급자가 달리 인식하고 있고, 사용자의 만족도가 공급자 만족도보다 낮은 것으로 나타났다. IPA 기법 분석 결과에서도 두 그룹 간 차이가 현저하였다. 13개 품질항목 중 (1)기능 충분성, (10)고객비밀 보장 등 6개 항목의 품질개선이 필요한 것으로 나타났으며, 이러한 개선 필요성은 공급자가 아니라 사용자 관점에서 주로 제시되고 있었다. 연구 본문은 이런 분석 결과가 나타난 원인과 시사하는 바를 조명하고 있다.

• 전자공학회논문지B
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• 제33B권4호
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• pp.156-163
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• 1996

In this paper, we described the implementation and the sound quality assessment of a real-time stereo audio codec using TMS320C40 DSP (digital signal processing) chip for low bitrte and high quality audio. We implemented hardware and software in order to overcome a real-time processing problem of audio compression algorithm that can be produced by largely recursive computing and complexity of the process. We have studied five types of distortion that can be produced by perceptual coding and the codec was evaluated by eight test musics that are selected in SQAM (sound quality assessment material) 422-2-4-2 produced by EBU (european broadcast union). The subjective listening tests were carried out on the codec quality and preformance by double blind method in a listening room with eleven listeners. As a result, 5 grade-impairment scale was scored under minus one and the codec quality was evaluated to be perceptible, but not annoying.