• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.7 no.2
• /
• pp.344-352
• /
• 2003

An effective algorithm for implementation of which detects moving object from image sequences. predicts the direction of it. and drives the camera in real time is proposed. In static camera, for robust motion detection from a dynamic background scene, the proposed algorithm performs statistical modeling of moving objects and background, and trains the statistical modeling of moving objects and background, and trains the statistical feature of background with the initial parts of sequence which have no moving objects. Active camera moving objects are segmented by following procedure, an improved order adaptive lattice structured linear predictor is used. The proposed algorithm shows robust object tracking results in the environment of static or active camera. It can be used for the unmanned surveillance system, traffic monitoring system, and autonomous vehicle.

• Journal of Korean Society of Transportation
• /
• v.20 no.3
• /
• pp.193-207
• /
• 2002

실시간 교통신호 제어시스템은 검지기 체계로부터 교통소통자료를 수집하고, 이를 중앙시스템에서 실시간으로 분석, 처리하여 신호시간을 신호주기별로 산출하는 시스템이다. 신호제어시스템의 운영성과는 시스템의 신호제어기능 또는 제어 알고리즘을 활용할 수 있는 신호제어전략의 효율성 여부에 의하여 크게 좌우된다. 본 연구에서는 신신호 시스템의 기본 제어알고리즘과 개선된 신호제어 알고리즘을 개관하고, 신신호시스템의 운영성과를 현장자료를 토대로 분석하였다. 신신호 시스템의 운영성과는 시스템의 제어기능과 알고리즘을 토대로 비 중요교차로의 패턴 Table을 조정하여 신호제어전략을 수립하고, 이의 적용성을 분석하는 과정을 통하여 분석되었다. 운영성과는 시범지역의 남북 교통축(영동대로)과 동서 교통축(도곡동길)을 대상으로 분석하였다. 분석결과 영동대로는 비 중요 교차로의 패턴 Table을 조정함에 따라 시스템 운영성과가 현저하게 개선되는 것을 확인할 수 있었으며, 도곡동길은 현재의 신호운영 전략과 검토대안이 비슷한 수준의 운영성과를 도출하는 것으로 분석되었다. 시범 운영지역의 교통축은 1개의 중요 교차로와 5-6개의 비 중요 교차로로 구성된다. 영동대로의 운영성과 분석결과, 교통축의 운영효과는 중요교차로의 교통대응 제어기능과 동시에 비 중요 교차로의 패턴 제어기능이 적절하게 연계 운영될 때 운영효율성을 높일 수 있음을 확인하였다. 따라서 향후 신호운영의 효율성을 높이기 위해서는 중요교차로의 교통대응 제어기능의 개선과 동시에 비중요교차로의 패턴 Table의 개선이 필수적인 것으로 판단된다.

• Journal of Computing Science and Engineering
• /
• v.7 no.3
• /
• pp.168-176
• /
• 2013

Long-term evolution (LTE) is emerging as a major candidate for 4G cellular networks to satisfy the increasing demands for mobile broadband services, particularly multimedia delivery. Multiple-input multiple-output (MIMO) technology combined with orthogonal frequency division multiple access and more efficient modulation/coding schemes (MCS) are key physical layer technologies in LTE networks. However, in order to fully utilize the benefits of the advances in physical layer technologies, the MIMO configuration and MCS need to be dynamically adjusted to derive the promised gains of 4G at the application level. This paper provides a performance evaluation of video traffic with variations in the physical layer transmission parameters to suit the varying channel conditions. A quantitative analysis is provided using the perceived video quality as a video quality measure (evaluated using no-reference blocking and blurring metrics), as well as transmission delay. Experiments are performed to measure the performance with changes in modulation and code rates in poor and good channel conditions. We discuss how an adaptive scheme can optimize the performance over a varying channel.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.11 no.3
• /
• pp.1441-1461
• /
• 2017

Nowadays, Dynamic Adaptive Streaming over HTTP (DASH) has become very popular in streaming multimedia contents. In DASH, a client estimates current network bandwidth and then determines an appropriate video quality with bitrate matching the estimated bandwidth. Thus, estimating accurately the available bandwidth is a significant premise in the quality of video streaming, especially when network traffic fluctuates substantially. To cope with this challenge, researchers have presented various filters to estimate network bandwidth adaptively. However, experiment results show that current schemes either adapt slowly to network changes or adapt fast but are very sensitive to delay jitter and produce sharply changed estimation. This paper presents a novel bandwidth estimation scheme based on Moving Average Convergence Divergence (MACD). We applied an MACD indicator and its two thresholds to classifying network states into stable state and agile state, based on the network state different filters are applied to estimate network bandwidth. In the paper, we studied the performance of various MACD indicators and the threshold values on bandwidth estimation. Then we used a DASH proxy-based environment to compare the performance of the presented scheme with current well-known schemes. The simulation results illustrate that the MACD-based bandwidth estimation scheme performs superior to existing schemes both in the speed of adaptively to network changes and in stability in bandwidth estimation.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.13 no.2
• /
• pp.355-361
• /
• 2009

This paper proposes a new basic unit level rate control algorithm which generates the output bits corresponding to the target bits. The H.264 standard uses various coding modes and optimization methods to improve the compression performance, which makes it difficult to control the generated traffic accurately. In the proposed scheme, the allocated bits to a frame are distributed to all basic units properly to encode each basic unit according to the bit budget. After encoding the frame, the encoding parameters are adjusted according to the difference between the target and the resulting values. It is shown by experimental results that the new algorithm can generate output bit rates accurately corresponding to the target bit rates with the PSNR performance better than that of the existing rate control algorithm.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.29 no.4B
• /
• pp.435-443
• /
• 2004

Although RSVP is a strong signaling protocol in providing QoS support, it is not scalable. Thus, the IETF introduced the concept of aggregation into RSVP However, the specification for the aggregation of RSVP does not specify how to compute the size of aggregate reservation for a path, but only describes how the resources are reserved and released with a given size. This paper proposes the method of properly determining the size of aggregate reservation on the path condition, when aggregate reservation is performed through RSVP for guaranteeing QoS of multimedia traffic. Simulation results show that the proposed method improves efficiency of the aggregation of RSVP.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.38B no.12
• /
• pp.962-966
• /
• 2013

The internet will should require the QoS(quality of service) guarantees that the real-time traffic like as audio and video data will be operated well in the future. We had designed Q-MOTP which transfer multimedia object data and proved excellent performance. This paper describes an adaptive QoS management architecture and mechanism based on the information of system resources. Resource manager reports the system resource information periodically or when resources are in the overload state, or on demand by the QoS manager. By using this information, the QoS manager can predict QoS degradation and perform CAC.

• The Journal of Korean Association of Computer Education
• /
• v.11 no.2
• /
• pp.99-106
• /
• 2008

In this paper, we have proposed a novel re-marking strategy at tbe ingressive edge router to improve TCP fairness of DiffServ Assured Services. Our re-marking strategy introduces a configuration method of the Temporary Permitted Rate (TPR). By using this new configuration method of TPR, IN packets of greedy TCP flows are re-marked to OUT packets pertinently and constantly whenever the network traffic changes. Simulation Results show that this novel re-marking strategy can regulate the packet transmission rate of each TCP flow to the contract rate without a decrease in the link utilization.

• Journal of Korean Institute of Industrial Engineers
• /
• v.33 no.2
• /
• pp.191-200
• /
• 2007

We propose the QoS (Quality of Service) assurance model for AMR (Adaptive MultiRate) voice users considering the capacity and service quality jointly in downlink WCDMA system. For this purpose, we introduce a new system performance measure and the number-based AMR mode allocation scheme. The proposed number-based AMR mode allocation can be operated only with the information of total number of ongoing users. Therefore, it can be more simply implemented than the existing power-based allocation. The proposed system performance measure considers the stochastic variations of AMR modes of ongoing users and can be analytically obtained using CTMC (Continuous Time Markov Chain) modeling. In order to validate the proposed analytical model, a discrete event-based simulation model is also developed. The performance measure obtained from the analytical model is in agreement with the simulation results and is expected to be useful for parameter optimization.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.13 no.12
• /
• pp.6243-6259
• /
• 2019

As a foundation of next-generation air transportation systems, automatic dependent surveillance-broadcast (ADS-B) helps pilots and air traffic controllers create a safer and more efficient national airspace system. Owing to the open communication environment, it is easy to insert fake aircraft into the system via spoofing or the insertion of false messages. Efforts have thus been made in academic research and practice in the aviation industry to ensure the security of transmission of messages of the ADS-B system. An identity-based batch verification (IBV) scheme was recently proposed to enhance the security and efficiency of the ADS-B system, but current IBV schemes are often too resource intensive because of the application of complex hash-to-point operations or bilinear pairing operations. In this paper, we propose a lightweight IBV signature scheme for the ADS-B system that is robust against adaptive chosen message attacks in the random oracle model, and ensures the security of batch message verification and against the replaying attack. The proposed IBV scheme needs only a small and constant number of point multiplication and point addition computations instead of hash-to-point or pairing operations. Detailed performance analyses were conducted to show that the proposed IBV scheme has clear advantages over prevalent schemes in terms of computational cost and transmission overhead.