Optimal Channel Adaptation of Scalable Video Over a Multicarrier-Based Multicell Environment

Jincheol Park,Hyungkeuk Lee,Sanghoon Lee,Bovik, A.C. IEEE 2009 IEEE transactions on multimedia Vol.11 No.6

<P>To achieve seamless multimedia streaming services over wireless networks, it is important to overcome inter-cell interference (ICI), particularly in cell border regions. In this regard scalable video coding (SVC) has been actively studied due to its advantage of channel adaptation. We explore an optimal solution for maximizing the expected visual entropy over an orthogonal frequency division multiplexing (OFDM)-based broadband network from the perspective of cross-layer optimization. An optimization problem is parameterized by a set of source and channel parameters that are acquired along the user location over a multicell environment. A suboptimal solution is suggested using a greedy algorithm that allocates the radio resources to the scalable bitstreams as a function of their visual importance. The simulation results show that the greedy algorithm effectively resists ICI in the cell border region, while conventional nonscalable coding suffers severely because of ICI.</P>

3D Visual Discomfort Prediction: Vergence, Foveation, and the Physiological Optics of Accommodation

Jincheol Park,Sanghoon Lee,Bovik, Alan Conrad IEEE 2014 IEEE journal of selected topics in signal processi Vol.8 No.3

<P>To achieve clear binocular vision, neural processes that accomplish accommodation and vergence are performed via two collaborative, cross-coupled processes: accommodation-vergence (AV) and vergence-accommodation (VA). However, when people watch stereo images on stereoscopic displays, normal neural functioning may be disturbed owing to anomalies of the cross-link gains. These anomalies are likely the main cause of visual discomfort experienced when viewing stereo images, and are called Accommodation-Vergence Mismatches (AVM). Moreover, the absence of any useful accommodation depth cues when viewing 3D content on a flat panel (planar) display induces anomalous demands on binocular fusion, resulting in possible additional visual discomfort. Most prior efforts in this direction have focused on predicting anomalies in the AV cross-link using measurements on a computed disparity map. We further these contributions by developing a model that accounts for both accommodation and vergence, resulting in a new visual discomfort prediction algorithm dubbed the 3D-AVM Predictor. The 3D-AVM model and algorithm make use of a new concept we call local 3D bandwidth (BW) which is defined in terms of the physiological optics of binocular vision and foveation. The 3D-AVM Predictor accounts for anomalous motor responses of both accommodation and vergence, yielding predictive power that is statistically superior to prior models that rely on a computed disparity distribution only.</P>

Video Quality Pooling Adaptive to Perceptual Distortion Severity

Jincheol Park,Seshadrinathan, K.,Sanghoon Lee,Bovik, A. C. IEEE 2013 IEEE TRANSACTIONS ON IMAGE PROCESSING - Vol.22 No.2

<P>It is generally recognized that severe video distortions that are transient in space and/or time have a large effect on overall perceived video quality. In order to understand this phenomena, we study the distribution of spatio-temporally local quality scores obtained from several video quality assessment (VQA) algorithms on videos suffering from compression and lossy transmission over communication channels. We propose a content adaptive spatial and temporal pooling strategy based on the observed distribution. Our method adaptively emphasizes “worst” scores along both the spatial and temporal dimensions of a video sequence and also considers the perceptual effect of large-area cohesive motion flow such as egomotion. We demonstrate the efficacy of the method by testing it using three different VQA algorithms on the LIVE Video Quality database and the EPFL-PoliMI video quality database.</P>

STRUCTURAL SIMILARITY BASED PERCEPTUAL VIDEO QUALITY ASSESSMENT

Jincheol Park(박진철),Hyungkeuk Lee(이형극),Sanghoon Lee(이상훈) 한국통신학회 2009 한국통신학회 학술대회논문집 Vol.2009 No.11

A Study on Korean Language Learner Variables based on the Statistical Method

Jincheol Park,Kyung-Mo Min,Seon-Jung Kim 계명대학교 자연과학연구소 2017 Quantitative Bio-Science Vol.36 No.2

Various factors that exert an influence on foreign Korean-language learners’ achievements have long been studied. Recently, to obtain a better understanding of differences in learning achievements, studies have begun comparing learning achievements between learners in the same educational environment. In this study, we examine whether there exists a difference in academic achievements between genders and between Hanja and non-Hanja culture learners. We also investigate whether those who have received Korean language education from basic to intermediate level with identical textbooks and identical curricula have higher academic achievements than those who have not received such education. To this end, using the linear mixed model, we conducted a statistical analysis of Korean-language fulfillment score data collected from a Korean-language institute administrated by K-university. We found that the high-scoring group tended to make slow, constant progress with regard to advancing to Korean-language level, whereas the low-scoring group tended to withdraw after a significant degree of achievement. Additionally, female learners performed much better than male learners in the high-scoring group, but in the low-scoring group, much poorer performance was observed. Finally, we found that it is a better strategy to start learning Korean from the basic level to the intermediate level at the same university.

3D Visual Discomfort Predictor: Analysis of Disparity and Neural Activity Statistics

Jincheol Park,Heeseok Oh,Sanghoon Lee,Bovik, Alan Conrad IEEE 2015 IEEE TRANSACTIONS ON IMAGE PROCESSING - Vol.24 No.3

<P>Being able to predict the degree of visual discomfort that is felt when viewing stereoscopic 3D (S3D) images is an important goal toward ameliorating causative factors, such as excessive horizontal disparity, misalignments or mismatches between the left and right views of stereo pairs, or conflicts between different depth cues. Ideally, such a model should account for such factors as capture and viewing geometries, the distribution of disparities, and the responses of visual neurons. When viewing modern 3D displays, visual discomfort is caused primarily by changes in binocular vergence while accommodation in held fixed at the viewing distance to a flat 3D screen. This results in unnatural mismatches between ocular fixations and ocular focus that does not occur in normal direct 3D viewing. This accommodation vergence conflict can cause adverse effects, such as headaches, fatigue, eye strain, and reduced visual ability. Binocular vision is ultimately realized by means of neural mechanisms that subserve the sensorimotor control of eye movements. Realizing that the neuronal responses are directly implicated in both the control and experience of 3D perception, we have developed a model-based neuronal and statistical framework called the 3D visual discomfort predictor (3D-VDP) that automatically predicts the level of visual discomfort that is experienced when viewing S3D images. 3D-VDP extracts two types of features: 1) coarse features derived from the statistics of binocular disparities and 2) fine features derived by estimating the neural activity associated with the processing of horizontal disparities. In particular, we deploy a model of horizontal disparity processing in the extrastriate middle temporal region of occipital lobe. We compare the performance of 3D-VDP with other recent discomfort prediction algorithms with respect to correlation against recorded subjective visual discomfort scores, and show that 3D-VDP is statistically superior to the other methods.</P>

Review on statistical methods for large spatial Gaussian data

Park, Jincheol The Korean Data and Information Science Society 2015 한국데이터정보과학회지 Vol.26 No.2

The Gaussian geostatistical model has been widely used for modeling spatial data. However, this model suffers from a severe difficulty in computation because inference requires to invert a large covariance matrix in evaluating log-likelihood. In addressing this computational challenge, three strategies have been employed: likelihood approximation, lower dimensional space approximation, and Markov random field approximation. In this paper, we reviewed statistical approaches attacking the computational challenge. As an illustration, we also applied integrated nested Laplace approximation (INLA) technology, one of Markov approximation approach, to real data to provide an example of its use in practice dealing with large spatial data.

Complex System and U Statistic

Park, Jincheol,박철용,하정철,유동현,김태윤 계명대학교 자연과학연구소 2015 Quantitative Bio-Science Vol.34 No.2

Applications of the complex system technique to various social problems have been very limited mainly due to the lack of quantitative definitions. Emergence (or scale free) is one of the most crucial concept of complex system theory and there have been many scientific and philosophical discussions without significant effort to quantify it in a practical way. In this article, quantifying the emergence in a statistical way, we investigate an interdependence amongst observations as a main player behind the emergence.

Performance study of propensity score methods against regression with covariate adjustment

Park, Jincheol The Korean Data and Information Science Society 2015 한국데이터정보과학회지 Vol.26 No.1

In observational study, handling confounders is a primary issue in measuring treatment effect of interest. Historically, a regression with covariate adjustment (covariate-adjusted regression) has been the typical approach to estimate treatment effect incorporating potential confounders into model. However, ever since the introduction of the propensity score, covariate-adjusted regression has been gradually replaced in medical literatures with various balancing methods based on propensity score. On the other hand, there is only a paucity of researches assessing propensity score methods compared with the covariate-adjusted regression. This paper examined the performance of propensity score methods in estimating risk difference and compare their performance with the covariate-adjusted regression by a Monte Carlo study. The study demonstrated in general the covariate-adjusted regression with variable selection procedure outperformed propensity-score-based methods in terms both of bias and MSE, suggesting that the classical regression method needs to be considered, rather than the propensity score methods, if a performance is a primary concern.

A Study on Korean Language Learner Variables based on the Statistical Method

Park, Jincheol,민경모,김선정 계명대학교 자연과학연구소 2017 Quantitative Bio-Science Vol.36 No.2

Various factors that exert an influence on foreign Korean-language learners’ achievements have long been studied. Recently, to obtain a better understanding of differences in learning achievements, studies have begun comparing learning achievements between learners in the same educational environment. In this study, we examine whether there exists a difference in academic achievements between genders and between Hanja and non-Hanja culture learners. We also investigate whether those who have received Korean language education from basic to intermediate level with identical textbooks and identical curricula have higher academic achievements than those who have not received such education. To this end, using the linear mixed model, we conducted a statistical analysis of Korean-language fulfillment score data collected from a Korean-language institute administrated by K-university. We found that the high-scoring group tended to make slow, constant progress with regard to advancing to Korean-language level, whereas the low-scoring group tended to withdraw after a significant degree of achievement. Additionally, female learners performed much better than male learners in the high-scoring group, but in the low-scoring group, much poorer performance was observed. Finally, we found that it is a better strategy to start learning Korean from the basic level to the intermediate level at the same university.