• 한국HCI학회:학술대회논문집
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• 2008.02a
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• pp.135-140
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• 2008

최근 관련 기술의 발전과 디지털 컨버전스의 가속화로 모바일 제품이 소형화, 다기능화 되어 가고 있다. 이러한 경향에 따라, 다양한 기능을 지원하기 위한 높은 사양의 디스플레이가 요구되고 있으며, 많은 업체들이 고화질, 고해상도 디스플레이의 개발에 경쟁적으로 매진하고 있다. 그러나 사용자의 인지적 특성을 고려하지 않은 고해상도 경쟁은 생산비용만 높이는 결과를 초래할 수 있다. 본 연구는 디스플레이의 설계 요소별 선호도를 분석하고, 사람이 탐지할 수 있는 두 자극 간의 최소한의 차이역(difference threshold)인 JND(Just Noticeable Difference)을 활용하여, 설계 요소의 인지적 특성을 파악하는 것을 목적으로 한다. 이를 위하여 모바일 제품에 주로 사용되는 TFT-LCD 를 평가 대상으로, 30 명의 피실험자를 대상으로 JND 측정실험을 수행하였으며, 실험결과를 바탕으로 디스플레이에 대한 주요 설계변수들의 특성을 파악하였다. 이 연구결과는 사용자의 선호도를 고려한 모바일 제품의 디스플레이 설계지침으로 활용될 수 있을 것이다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.18 no.2
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• pp.438-455
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• 2024

Recently, many unsupervised learning-based models have emerged for Just Noticeable Difference (JND) estimation, demonstrating remarkable improvements in accuracy. However, these models suffer from a significant drawback is that their heavy reliance on handcrafted priors for guidance. This restricts the information for estimating JND simply extracted from regions that are highly related to handcrafted priors, while information from the rest of the regions is disregarded, thus limiting the accuracy of JND estimation. To address such issue, on the one hand, we extract the information for estimating JND in an Adversarial Complementary Learning (ACoL) way and propose an ACoL-JND network to estimate the JND by comprehensively considering the handcrafted priors-related regions and non-related regions. On the other hand, to make the handcrafted priors richer, we take two additional priors that are highly related to JND modeling into account, i.e., Patterned Masking (PM) and Contrast Masking (CM). Experimental results demonstrate that our proposed model outperforms the existing JND models and achieves state-of-the-art performance in both subjective viewing tests and objective metrics assessments.

• Journal of Korean Institute of Industrial Engineers
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• v.30 no.1
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• pp.27-35
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• 2004

A study was conducted to investigate an optimal vibration frequency for mobile phones with just noticeable difference(JND). The just noticeable difference, Weber's law, is the minimum amount by which stimulus intensity must be changed in order to produce a noticeable variation in sensory experience. In order to find the optimal vibration frequency, sixteen frequencies ranged from 24Hz to 603Hz were selected. Subjects then wereasked to differentiate a pair of vibration frequencies. For the analysis, the psychometric function to determine the optimal vibration frequency and the logistic regression to validate the determined frequency were used. The results show that the 2nd order polynomial equations were best fitted for the JND psychometric function and the optimal mobile phone vibrations were determined at 140Hz, 151 Hz, and 160Hz. With the ogive-shaped psychometric function developed by the logistic regression, the results of this study was validated that the determined vibration frequencies (140Hz, 151 Hz, and 160Hz) were optimal mobile phone vibration frequencies.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.39 no.5
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• pp.513-521
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• 2002

This paper proposes a gamut mapping algorithm based on color space division for cross media color reproduction. As each color device has a limited range of producible colors, reproduced colors on a destination device are different from those of the original device. In order to reduce the color difference, the proposed method divides the whole gamut into parabolic shapes based on intersecting lightness by the just noticeable difference (JND) and the original device gamut boundary. Dividing the gamut with parabolic shapes and piecewise mapping of each region not only considers gamut characteristics but also provides for mapping uniformity. Also the lightness variations are more sensitive to the human visual system and by using lightness JND it can restrict lightness mapping variations that are unperceivable to enhance lightness contrast and chrominance. As a result, the proposed algorithm is able to reproduce high quality images using low-cost color devices.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.8
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• pp.3935-3949
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• 2017

In this paper, a novel multiple description image coding (MDC) scheme is proposed, which is based on the characteristics of the human visual model. Due to the inherent characteristics of human vision, the human eye can only perceive the change of the specific thresholds, that is, the just noticeable difference (JND) thresholds. Therefore, JND model is applied to improve MDC syetem. This paper calculates the DCT coefficients firstly, and then they are compared with the JND thresholds. The data that is less than the JND thresholds can be neglected, which will improve the coding efficiency. Compared with other existing methods, the experimental results of the proposed method are superior.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2016.06a
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• pp.215-219
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• 2016

본 논문에서는 인간의 시각적 특성을 반영한 Just Noticeable Difference (JND) 모델을 사용한 움직임 예측을 통한 프레임율 향상 기법을 제안한다. 기존의 다중 프레임 기반 움직임 예측을 통한 프레임율 향상 기법은 움직임 벡터의 정확성을 높이기 위해 다중 프레임을 사용하며, 전체 영역에 대해 같은 블록 크기와 탐색 영역으로 움직임 예측을 수행함으로써 불필요한 계산량이 많아지고 움직임 벡터의 부정확한 예측이 수행된다는 단점이 있다. 제안하는 알고리듬은 인간의 시각적 특성을 고려한 Free Energy-based Just Noticeable Difference (FEJND) 모델을 사용하여 이전 프레임과 현재 프레임만을 사용하여 영역 특성에 따른 적응적 움직임 예측을 수행하여 정확성을 높인다. 실험 결과에 따라 제안하는 알고리듬의 성능이 향상되었음을 알 수 있다.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.5
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• pp.147-154
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• 2015

In this paper, we employed a model which defines the sensitivity according to the background luminance, so called JND (Just Noticeable Difference), and applied to the video coding. The proposed method finds out the maximum possible quantization parameter for the current unit based on the threshold of JND model and reduce the bitrate with similar perceptual quality. It selects the higher quantization parameter and reduce the bitrate when the reconstructed signal which is coded with higher quantization parameter is in a range of allowance based on the JND threshold, i.e. the signal has the similar perceptual quality compared to that is coded with the initial quantization parameter. The proposed algorithm was implemented on HM16.0, which is a reference software of the latest video coding standard HEVC (High Efficiency Video Coding) and the coding performance was evaluated. Compared to HM16.0, the proposed algorithm achieved maximum 20.21% and 6.18% of average bitrate reduction with the similar perceptual quality.

• Phonetics and Speech Sciences
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• v.4 no.4
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• pp.19-27
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• 2012

When two speakers read a text together, the produced speech has been shown to reduce a high degree of variability (e.g., pause duration and placement, and speech rate). This paper provides a quantitative analysis of speech rate variation exhibited in synchronous speech by examining the global and local patterns in two dialects of Mandarin Chinese (Taiwan and Shanghai). We analyzed the speech data in terms of mean speech rate and the reference of "Just Noticeable difference (JND)" within a subject and across subjects. Our findings show that speakers show lower and less variable speech rates when they read a text synchronously than when they read alone. This global pattern is observed consistently across speakers and dialects maintaining the unique local variation patterns of speech rate for each dialect. We conclude that paired speakers lower their speech rates and decrease the variability in order to ensure the synchrony of their speech.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.1442-1445
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• 2007

Just noticeable differences (jnds) of autocorrelation function (ACF) parameters - Phi (0), Tau 1 and Phi 1 - of household refrigerator noise were investigated by psychoacoustical analyses. Phi (0) of five refrigerators' noise was changed with equal (${\pm}$) interval level of 0.5-1.0 dB up to five intervals by manipulating sound pressure level of the noise. Tau 1 and Phi 1 were varied with equal (${\pm}$) interval of around 0.10 ms and 0.02, respectively. Pitch shifting and strengthen methods were applied for the Tau 1 and Phi 1 variations. As results of subjective evaluations, about 2.0 dB was shown as jnd of Phi (0). The values of 0.30 ms and 0.06 were found as jnds of Tau 1 and Phi 1, respectively. The jnd results of each ACF parameter can be applied to explain substantial amount of sound quality (SQ) enhancement in the SQ prediction indices which were proposed in the authors' previous study [Sato et al. (2007) J. Acoust. Soc. Am.].

• IEIE Transactions on Smart Processing and Computing
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• v.4 no.1
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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.