• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.8
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• pp.1684-1690
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• 2003

In this paper, we proposed a fuzzy controller for the evaluation of the quantization Parameters in the H.263 coder to optimize the subjective quality of each coded frame, keeping the transmission rate constant. We adopted the Mamdani method for fuzzification and the centroid method for defuzzification. The energy and entropy are correlated to features of the HVS in spatial domain, while motion vectors are used to estimate the temporal characteristics of the signal. And then, the fuzzy inputs adapted the variance and the entropy in spatial domain, and the motion vector in temporal domain. We induced the fuzzy membership function and decided the fuzzy relevance to be compatible in visual characteristics. And then, we designed FAM banks. The fuzzy technology has been applied to a practical video compression. This results is obtained an effective rate control technique, an optimum bit allocation and a high subjective quality using fuzzy quantization.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.23 no.8
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• pp.2025-2031
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• 1998

In moving picture coding standard MPEG2, a bit rate control system plays a key role for the compressing ratio and picture quality. We proposed a bit rate control scheme which assigns more bits to I, P frames and uses the average MQUANT of previous mackoblocks. The proposed scheme showed about 0.9dB improvement of image quality when compared to bit rate control method of MPEG2 Test-Model5.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.1033-1037
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• 2010

Railway signal facilities are very important because they are directly related to safe train operation. By the result of the unification of signal and station control, station control staffs have been having a hard time to grasp the knowledge about signal facilities and the fault restoration ability in a short term since the existing manuals were only made with text materials. To meet the growing demand to educate the maintenance work in actual and effective way, the maintenance manuals and periodic procedures was developed in the forms of video clips and animations with quality contents onto a DVD enabling not only to improve the maintenance works for signal facilities but to contribute budget saving and profit generating.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.8A
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• pp.879-888
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• 2004

In this paper, we propose a real time QoS(Quality of Service) guaranteed transmission mechanism for MPEG video traffic at the congested node in IP based networks. Recent spread of the Internet has increased the demands of a real time multimedia service of the quality, Because the type of Internet services can, however, offer the best effort delivery strategies, it is difficult to treat all the types of traffic with differential COS (Class of Service). Most of all, the hierarchical coding method of MPEG data utilizes the reference frame for the motion prediction. The loss of the reference frames makes QoS of the video traffic degraded because the reference frame bit error causes the consecutive packet loss. Therefore we have studied the real time QoS guaranteed mechanism for video traffic by analyzing the previous methods. Computer simulation results show that the proposed scheme has better performance than the previous one.

• Journal of Broadcast Engineering
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• v.10 no.4 s.29
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• pp.488-504
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• 2005

In this paper, we propose a new bitrate control scheme to improve the quality of image encoded by SVC and to resolve the problems of conventional scheme. In JSVM2.0, bitrate of a frame is controlled by an initial quantization parameter and scaling factor that it hasdifferent value according to frame. Itis difficult to get the best of video quality at arbitrary bitrate because the conventional scheme has two defects. One is that we have to know proper initial QP's fur all sequences. Another is that QP's control skill for macroblocks is very inefficient. In this paper, we propose an efficient bit allocation algorithm to reduce the effect of the initial QP and to increase the efficiency of bit allocation by using proper QP's for macroblocks. In simulation results, it can be seen that using the proposed scheme enables the SVC encoder to control the bitrate by the macroblock unit and outperforms the conventional schemes in the respect of rate-distortion.

• Journal of Korea Multimedia Society
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• v.14 no.1
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• pp.44-53
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• 2011

H.264/SVC provides scalable video streams which consist of a base layer and one or more enhancement layers. Thus, it can efficiently adapt encoded streams to individual network conditions by dropping some layers of bit streams. However, on a dynamic environment such as the Internet, random packet losses due to network congestion can cause drastic effect on SVC quality. To avoid network congestion, the rate of video streams should be adjusted by carefully selecting a layer of each stream. In this paper, we propose three layer selection algorithms which can avoid network congestion by using the rate-distortion characteristics of streams. Simulation results show that FS(Far-Sighted) algorithm can maximize the overall PSNR value of streams by efficiently using the characteristics of video streams.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.06a
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• pp.175-178
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• 2007

According to recently presented QoS architecture by 3GPP, a traffic conditioner may be deployed to provide conformance of the negotiated QoS. A real-time frame-layer rate control method which can be applied to the traffic conditioner is proposed. The proposed rate control method uses a non-iterative optimization method for low computational complexity, and performs bit allocation at the frame level to minimize the average distortion over an entire sequence as well as variations in distortion between frames. The proposed algorithm does not produce time delay from encoding, and is suitable for real-time low-complexity video encoder.

• The Journal of Korean Physical Therapy
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• v.28 no.6
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• pp.355-363
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• 2016

Purpose: In this study, we investigated the effectiveness of a 12-week virtual reality exercise program using the Nintendo Wii console (Wii) in improving balance, emotion, and quality of life among patients with cognitive decline. Methods: The study included 30 patients with cognitive decline (12 female, 18 male) who were randomly assigned to an experimental (n=15) and control groups (n=15). All subjects performed a traditional cognitive rehabilitation program and the experimental group performed additional three 40-minute virtual reality based video game (Wii) sessions per week for 12 weeks. The berg balance scale (BBS) was used to assess balance abilities. The short form geriatric depression scale-Korean (GDS-K) and the Korean version of quality of life-Alzheimer's disease (KQOL-AD) scale were both used to assess life quality in patients. Statistical significance was tested within and between groups before and after treatment, using Wilcoxon signed rank and Mann-Whitney u-tests. Results: After 36 training sessions, there were significant beneficial effects of the virtual reality game exercise on balance (BBS), GDS-K, and KQOL-AD in the experimental group when compared to the control group. No significant difference was observed within the control group. Conclusion: These findings demonstrate that a virtual reality-training program could improve the outcomes in terms of balance, depression, and quality of life in patients with cognitive decline. Long-term follow-ups and further studies of more efficient virtual reality training programs are needed.

• Journal of Broadcast Engineering
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• v.15 no.3
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• pp.321-331
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• 2010

Most of multimedia video coding algorithms are lossy schemes and several kinds of spatial and temporal artifacts are inevitable. Flickering, which is the most typical coding artifact in time domain, is mainly due to fact that the quality of coded sequence fluctuates as the quantization parameter is adjusted for rate control. In this paper, we analyzed the effect of quality variation according to the characteristics of video sequence when the I-frames are periodically inserted. And we proposed the FR(Full Reference)-based assessment algorithm to measure the amount of flickering artifacts in the coded video. It is discovered that the flickering becomes critical when the level of quality is intermediate and is affected by the amount of detail or movement, the size of object, and camera parameters. The proposed measurement algorithm shows is well consistent with HVS(Human Visual System).

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.9C
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• pp.849-860
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• 2007

Because the H.264/AVC standard adopts the variable length coding algorithm, the rate of encoded video bitstream fluctuates a lot as time flows, though its compression efficiency is superior to that of existing standards. When a video is transmitted in real-time over networks with fixed low-bandwidth, it is necessary to control the bit rate which is generated from encoder. Many existing rate control algorithms have been adopting the quadratic rate-distortion model which determines the target bits for each frame. We propose a new rate control algorithm for H.264/AVC video transmission over networks with fixed bandwidth. The proposed algorithm predicts quantization parameter adaptively to reduce video distortion using the quadratic rate-distortion model, which uses the target bit rate and the mean absolute difference for current frame considering pixel difference between macroblocks in the previous and the current frame. On video samples with high motion and scene change cases, experimental results show that (1) the proposed algorithm adapts the encoded bitstream to limited channel capacity, while existing algorithms abruptly excess the limit bit rate; (2) the proposed algorithm improves picture quality with $0.4{\sim}0.9dB$ in average.