• Journal of Communications and Networks
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• 제13권3호
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• pp.277-285
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• 2011

Real-time multimedia streaming over the Internet is rapidly increasing with the popularity of user-created contents, Web 2.0 trends, and P2P (peer-to-peer) delivery support. While many homes today are broadband-enabled, the quality of experience (QoE) of a user is still limited due to frequent interruption of media playout. The vulnerability of TCP (transmission control protocol), the popular transport-layer protocol for streaming in practice, to the packet losses, retransmissions, and timeouts makes it hard to deliver a timely and persistent flow of packets for online multimedia contents. This paper presents TCP-real-time online multimedia environment (ROME), a novel transport-layer framework that allows the establishment and coordination of multiple many-to-one TCP connections. Between one client with multiple home addresses and multiple co-located or distributed servers, TCP-ROME increases the total throughput by aggregating the resources of multiple TCP connections. It also overcomes the bandwidth fluctuations of network bottlenecks by dynamically coordinating the streams of contents from multiple servers and by adapting the streaming rate of all connections to match the bandwidth requirement of the target video.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권8호
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• pp.3121-3135
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• 2015

Owing to the increase in consumption of multimedia content and the improvement of device capacity, user demand for high-quality content has increased. However, it is difficult to transport such large amounts of content over the existing broadcasting network with limited bandwidth. To provide high-definition broadcasting, some studies suggest methods of transporting multimedia over heterogeneous networks after encoding content hierarchically. MPEG Media Transport (MMT), standardized by Moving Picture Experts Group (MPEG), is a solution that enables large-volume media transport over heterogeneous networks such as digital broadcasting networks and packet-switched networks. In the case of delivering a scalable encoded video over different networks, synchronization of each stream is an important issue. MMT defines a synchronization scheme, but does not contain sufficient functions to implement it. In this paper, we propose a synchronization scheme for media streams that are encoded hierarchically, divided into layers, and transported over heterogeneous networks. We implement our scheme using MMT and HTTP, and experimented using three encapsulated video streams with different durations. As a result, we show that the proposed scheme can reduce the waiting time to display high-quality video, relative to Dynamic Adaptive Streaming over HTTP-Scalable Video Coding (DASH-SVC) by requesting segments of enhanced layers after calculating the transmission time. Additionally, we find out that the selection of durations have a relation to the characteristics of the video.

• 융합신호처리학회논문지
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• 제14권1호
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• pp.62-69
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• 2013

본 논문은 멀티미디어 광 네트워크인 MOST를 통해 차량의 카메라에서 입력된 영상을 실시간으로 전송하여 디스플레이 할 수 있는 MOST 기반 영상 송 수신 시스템을 제안하였다. 기존의 차량에서는 카메라를 아날로그 형태로 연결하여 영상을 전송하였으나, 차량에 장착되는 카메라의 수가 점점 증가함에 따라 네트워크로 연결하여 영상을 전송하는 것을 요구하게 되었다. 본 논문에서는 실시간 영상 전송을 위해 DSP를 이용하여 MPEG 인코딩과 디코딩을 하였다. 그리고 DSP와 MOST 네트워크 컨트롤러 사이의 스트림 데이터 전송은 MediaLB를 이용하였다. 이때 DSP가 MediaLB와의 연결을 지원하지 않기 때문에 스트림 데이터를 직접 주고 받을 수 없다. 따라서 FPGA를 사용하여 MediaLB를 통해 전송되는 스트림 데이터를 DSP에 전달하도록 하였다. MediaLB는 MOST 네트워크에 대한 하드웨어 및 소프트웨어 응용 프로그램 개발을 쉽게 할 수 있도록 해주고 모든 MOST 네트워크의 데이터 전송방법을 지원한다 본 논문에서 제안된 시스템으로 실시간 영상 전송을 테스트 한 결과 정상적으로 동작하는 것을 확인하였다.

• 한국농공학회논문집
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• 제50권2호
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• pp.45-52
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• 2008

Contaminant transport has been widely studied in rigid porous media, but there are some cases where a large volumetric stain occurs such as dewatering of dredged contaminated sediment, landfill liner, and in-situ capping. This paper presents a numerical investigation of contaminant transport coupled with large strain consolidation. Consolidation test was performed with contaminated sediments collected in Gary, Indiana, U.S. to obtain constitutive relationships, which are required for numerical simulations. Numerical results using CST2 show an excellent agreement with measured settlement and excess pore pressure. CST2 is then used to simulate contaminant transport during and after in-situ capping. Numerical simulations provide that transient advective flows caused by consolidation significantly increase the contaminant transport rate. In addition, the numerical simulations revealed that active capping with Reactive Core Mat (RCM) significantly decelerates consolidation-induced contaminant transport.

• Advances in environmental research
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• 제5권4호
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• pp.263-282
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• 2016

Contaminant transport in groundwater induces major threat and harmful effect on the environment; hence, the fate of the contaminant migration in groundwater is seeking a lot of attention. In this paper a two dimensional numerical flow and transport model through saturated layered soil is developed. Groundwater flow and solute transport has been simulated numerically using proposed model. The model implements the finite volume time splitting method to discretize the main equations. The performance, accuracy and efficiency of the out coming numerical models have been successfully examined by two test cases. The verification test cases consist of two-dimensional, groundwater flow and solute transport. The final purpose of this paper is to discuss and compare the shape of contaminant plume in homogeneous and heterogeneous media with different soil properties and control of solute transport using a zone for minimizing the potential of groundwater contamination; furthermore, this model leads to select the effective and optimum remedial strategies for cleaning the contaminated aquifers.

• 방송공학회논문지
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• 제23권2호
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• pp.261-273
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• 2018

영상 처리, 컴퓨터 비전 및 영상 디스플레이와 같은 기술의 발전으로 다양한 미디어의 생성 및 소비 방식에 대한 시장이 관심이 증대됨에 따라, Ultra Wide Viewing(UWV) 미디어에 관한 관심 또한 높아지고 있다. 이와 같은 UWV 미디어의 소비에 있어, 서버의 부하 및 단말의 자원을 효율적으로 관리하고 사용자의 자유도 높은 서비스를 제공하기 위하여, 사용자가 관심 영역을 선택 및 소비할 수 있게 하는 기술이 필요하다. 이에 본 논문에서는 MPEG-CI 및 Layout 시그널링을 이용하고 확장하여 UWV 미디어를 구성하는 다양한 미디어 간 공간적 위치정보를 기술하고 이를 전송하는 방안을 통해 사용자로 하여금 선택적 소비를 가능케하는 방안을 제안하였다.

• ETRI Journal
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• 제26권3호
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• pp.203-217
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• 2004

This paper presents a method and architecture to analyze streaming media and multimedia conferencing traffic. Our method is based on detecting the transport protocol and port numbers that are dynamically assigned during the setup between communicating parties. We then apply such information to analyze traffic generated by the most popular streaming media and multimedia conferencing applications, namely, Windows Media, Real Networks, QuickTime, SIP and H.323. We also describe a prototype implementation of a traffic monitoring and analysis system that uses our method and architecture.

• Geomechanics and Engineering
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• 제2권2호
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• pp.141-156
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• 2010

In the framework of meshfree methods, a new methodology is developed based on radial point interpolation method (RPIM). This methodology is applied to a one-dimensional contaminant transport modelling in the saturated porous media. The one-dimensional form of advection-dispersion equation involving reactive contaminant is considered in the analysis. The Galerkin weak form of the governing equation is formulated using 1D meshfree shape functions constructed using thin plate spline radial basis functions. MATLAB code is developed to obtain the numerical solution. Numerical examples representing various phenomena, which occur during migration of contaminants, are presented to illustrate the applicability of the proposed method and the results are compared with those obtained from the analytical and finite element solutions. The proposed RPIM has generated results with no oscillations and they are insensitive to Peclet constraints. In order to test the practical applicability and performance of the RPIM, three case studies of contaminant transport through the landfill liners are presented. A good agreement is obtained between the results of the RPIM and the field investigation data.

• 한국막학회:학술대회논문집
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• 한국막학회 2004년도 Proceedings of the second conference of aseanian membrane society
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• pp.132-135
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• 2004

It has been known that transport characteristics of ions are very complicated in CEDI system due to the inter-relations between ion exchange media and solution. Thus, this study sought to determine the ionic mobility of cobalt ion through cation exchange textile under electroregeneration and consequently verify the transport mechanisms of cobalt ion in a CEDI system.(omitted)

• Computers and Concrete
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• 제31권6호
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• pp.485-499
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• 2023

Both damage and unsaturated conditions accelerate the transport of erosive media inside concrete. However, their combined effects have not been fully investigated. A multiscale mortar model using representative volume elements is developed, capturing the number and distribution in each phase. Afterwards, mortar damage microstructure evolution is simulated in the tensile process. Finally, the unsaturated mortar transport is predicted and analysed. The results indicate that damage significantly affects the diffusion process in the early stage, while the transport performance is weakened due to the obstruction of the nontransport phase in the later stage. The higher the saturation and the more connected pores, the faster the diffusion rate of chloride ions. Chloride ions spread around the cracks in a tree-like manner along. The model can very well predict the chloride ion transport performance of unsaturated and damaged mortar.