• 한국정보디스플레이학회:학술대회논문집
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• 2007.08b
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• pp.1661-1663
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• 2007

The contrast of display is one of the important specifications. Even if the contrast indicates luminance range which is a capability of the display and is greater in lower luminance or higher luminance, we consider that the greater contrast gets not the better performance. It is not the same value in human visual system. In practice, it is difficult to achieve the full dynamic range seen by human beings using electronic equipment. Therefore, we consider ambient condition and human perception to calculate perceptual contrast using the CIECAM02. In this paper, we propose perceptual contrast that is calculated using the brightness of CIECAM02.

• Journal of Broadcast Engineering
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• v.19 no.4
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• pp.468-477
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• 2014

This paper proposes a novel perceptual quality-based (PQ-based) video coding method with foveated contrast sensitivity (FCS). Conventional methods on PQ-based video coding with FCS achieve minimum loss on perceptual quality of compressed video by exploiting the property of human visual system (HVS), that is, its sensitivity differs by the spatial frequency of visual stimuli. On the other hand, PQ-based video coding with foveated masking (FM) exploits the difference of the sensitivity of the HVS between the central vision and the peripheral vision. In this study, a novel FCS model is proposed which considers both the conventional DCT-based JND model and the FM model. Psychological study is conducted to construct the proposed FCS model, and the proposed model is applied to PQ-based video coding algorithm implemented on HM10.0 reference software. Experimental results show that the proposed method decreases bitrate by the average of 10% without loss on the perceptual quality.

• Phonetics and Speech Sciences
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• v.12 no.1
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• pp.1-9
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• 2020

The perceptual assimilation of a nonnative phonological contrast can change with linguistic experience, resulting in naïve listeners and novice second language (L2) learners potentially assimilating the members of a nonnative contrast to different native (L1) categories. While it has been shown that this sort of change can affect the discrimination of the nonnative contrast, it has not been tested whether such a change could have consequences for the production of the contrast. In this study, L1 speakers of Mandarin Chinese who were (1) naïve to Korean, (2) novice L2 learners, or (3) advanced L2 learners participated in a Korean non-word repetition task using word-initial sibilants. The initial CVs of their repetitions were then played to L1 Korean listeners who categorized the initial consonant. The naïve talkers were more likely to repeat an initial /s^ha/ as an affricate, whereas the L2 learners repeated it as a fricative, in line with how these listeners have been shown to assimilate Korean sibilants to Mandarin categories. This result suggests that errors in the production of new words presented auditorily to nonnative listeners may be driven by how they perceptually assimilate the nonnative sounds, emphasizing the need to better understand what drives changes in perceptual assimilation that accompany increased linguistic experience.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.2
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• pp.141-147
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• 2015

The contrast of a display is generally evaluated by using the ratio of the minimum luminance to the maximum luminance of the display. However, this contrast ratio is not matched with perceived contrast because it uses only physical characteristic of display without considering human perceptual characteristics. In this paper, the proposed contrast measure that considers perceptually discriminable brightness within the range of display brightness is suggested. First, the range between the minimum and maximum brightness of display in CIECAM02 color space is calculated to measure the length of perceived brightness for the display. Next, brightness ranges which are perceptually same at each brightness level are determined by applying Weber-Fechner ratio and then, the number of brightness values within each brightness range is counted. Finally, perceptually discriminable brightness is defined as the sum of ratio between the number of brightness values in each brightness range and the perceptual contrast length of the display. In the experiments, preference test using various displays with random brightness patches is performed to evaluate perceived contrast. As a result, the proposed measure is more consistent with human perception than the previous contrast measures.

• Speech Sciences
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• v.9 no.4
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• pp.131-142
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• 2002

Place assimilation in Korean has been argued to reflect the consonantal strength hierarchy in which velar is stronger than labial which is in turn stronger than coronal. The strength relationship has been manifested in two ways in literature. One is through phonological representation as shown in Iverson and Lee (1994). The other is through perceptual salience ranking as suggested by Jun (1995). The goal of this study is to examine the perceptual salience of placed consonants through an identification experiment. The experiment conducted in this study reveals four facts. First, place identification of a prevocalic consonant is higher than that of a postvocalic one. Second, place identification of a stop in coda is more confusable than that of a nasal counterpart in Korean contrary to other previous studies. Third, velar is most confusable in place identification in contrast to Jun (1995) and Hume et al. (1999). Finally, place perception of consonants can vary depending on adjacent vocalic context. These results suggest that perceptual salience is one of the possibly several factors affecting a phonological process.

• Journal of Korea Multimedia Society
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• v.22 no.8
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• pp.860-873
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• 2019

LCD backlight boosting and the integration of boosting and dimming are proposed based on image analysis to maximize perceptual image qualities and to reduce display system power. Based on the histogram of the image data, methods for selecting an image suitable for boosting and for adjusting the optimum backlight brightness are proposed. A comprehensive combined optimization method of LCD backlight boosting, dimming and bypass based on image characteristics is also described. Perceptual image quality enhancement and power consumption are evaluated based on well known image databases. Average subjective image quality is improved by 24.8%, RMS contrast is improved more than 20%, and average power consumption is reduced by 15.94% compared to conventional uniform boosting.

• Phonetics and Speech Sciences
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• v.5 no.4
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• pp.137-143
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• 2013

Recent investigation of acoustic correlates of Korean stop manner contrasts has reported a diachronic transition in Korean stops: young Seoul speakers are relatively more dependent on the F0 characteristics of the stops than on the VOT characteristics in aspirated and lenis stop distinction. This finding has been examined against tonal dialects of Korean and the results suggested that the speakers of tonal dialects are not sharing the transition. These results also suggested that F0 function for segmental stop classification interferes with the function for lexical tone classification in their tonal speech. The current study investigated these findings in terms of perception. Perceptual behavior of Seoul and Busan speakers of Korean was examined in a comparative manner through the measurement of perceptual cue weight of F0 and VOT in particular. The results from regression and correlation analyses revealed that Busan speakers are closer to older Seoul speakers than to younger Seoul speakers in that the cue weight for VOT and F0 were comparable in the aspirated-lenis stop distinction. This result was in contrast to the perceptual behavior of younger Seoul speakers who showed clear dominance of F0 over VOT for the same distinction. These findings provided perceptual evidence of the dual function of F0 for segmental and lexical distinctions in tonal dialects of Korean.

• Phonetics and Speech Sciences
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• v.9 no.2
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• pp.53-59
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• 2017

The present study examined if individual listeners' perceptual variations were associated with their cognitive characteristics indexed by the Autistic Spectrum Quotient (AQ). This study first investigated the perception of the lexical pitch accent contrast in the Kyungsang Korean currently undergoing a sound change, and then tested if listeners' perceptual variations were correlated with their AQ scores. Eighteen Kyungsang listeners in their 20s participated in the perception experiment where they identified two contrastive accent words for auditory stimuli systematically varying F0 scaling and timing properties; the participants then completed the AQ questionnaire. In the results, the acoustic parameters reporting reduced phonetic differences across accent contrasts for younger Kyungsang generation played a reliable role in perceiving the HH word from HL, suggesting the discrepancy between the perception and the production in the context of sound change. This study also observed that individuals' perceptual variations were negatively correlated with their AQ sub scores. The present findings suggested that the sound change might appear differently between production and perception with a different time course, and deviant percepts could be explained by individuals' cognitive measure.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2013.11a
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• pp.8-11
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• 2013

We implement the foveation and frequency sensitivity feature of human visual system in discrete cosine transform (DCT) domain. Resolution of human visual perception decays as distance from the eye-focused point, known as foveation property, and the middle frequency components give most pleasant image quality to human than the low and high frequency components, which is the frequency sensitivity property of human visual system. For satisfying the foveation property, we enhanced the local contrast at the focused regions and smoothed local contrast at the non-focused regions in the DCT domain without bringing the blocking and ringing artifacts. Moreover, the energies at each DCT frequency components is modified with various degree to fulfill the frequency sensitivity property. The proposed method is verified by the subjective and objective evaluations that it can the improve the human perceptual visual quality.

• The Journal of the Acoustical Society of Korea
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• v.19 no.8
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• pp.12-21
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• 2000

In this paper, we propose a novel hearing aid algorithm for sensorinural hearing loss restoration with multi-channel(band) dynamic range compression and psychoacoustics. In this way, we can present a normal perception condition to the impaired listener. The proposed algorithm make loudness scaling function achieve proper loudness level, and analysis masking property for the signal will be perceived to impaired listener, and then, restore normal spectral contrast using SMR(signal-to-masking ratio) defined by distance between the level of each frequency and masking threshold.