• KSII Transactions on Internet and Information Systems (TIIS)
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• 제7권4호
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• pp.800-818
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• 2013

Supporting video streaming over multi-hop wireless networks is particularly challenging due to the time-varying and error-prone characteristics of the wireless channel. In this paper, we propose a joint optimization scheme for video streaming over multi-hop wireless networks. Our coding scheme, called Joint Source/Network Coding (JSNC), combines source coding and network coding to maximize the video quality under the limited wireless resources and coding constraints. JSNC segments the streaming data into generations at the source node and exploits the intra-session coding on both the source and the intermediate nodes. The size of the generation and the level of redundancy influence the streaming performance significantly and need to be determined carefully. We formulate the problem as an optimization problem with the objective of minimizing the end-to-end distortion by jointly considering the generation size and the coding redundancy. The simulation results demonstrate that, with the appropriate generation size and coding redundancy, the JSNC scheme can achieve an optimal performance for video streaming over multi-hop wireless networks.

• 한국정보통신학회논문지
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• 제14권9호
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• pp.2150-2156
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• 2010

본 논문에서는 효율적이고 효과적인 정보 흐름을 가능하게 해주는 네트워크와 네트워크의 잠재력에 집중하고자 한다. 네트워크 중심 환경하에서 운용되는 군 지휘 통제 시스템을 포함하는 모든 네트워크들은 복잡하게 얽혀있다. 따라서 복잡도의 특성을 이해하고, 그에 따른 효과는 무엇이며, 어떻게 측정할 수 있을지에 대해서 알아본다. 우리는 정보의 접근성에 의한 효과와 네트워크화에 기반하는 중복성에 의한 효과에 대해서 결과를 제시하였다.

• 한국통신학회논문지
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• 제38A권8호
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• pp.662-668
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• 2013

무선이동통신 시스템은 무선 채널상황에 맞게 변조 파라미터와 부호율 등을 적응적으로 변화시켜 성능 이득을 얻을 수 있는 다양한 전송기법을 채택해오고 있다. 그 중에서 재전송 기법과 오류정정부호의 패리티 양을 적응적으로 조절하여 전송하는 incremental redundancy hybrid ARQ (IR-HARQ) 방식은 시스템 수율 측면에서 효율적인 것으로 알려져 있으며 다양한 무선이동통신시스템에서 사용되고 있다. 본 논문에서는 이중 대각 패리티 구조를 갖는 블록 LDPC의 IR-HARQ 방식을 제안한다. IR-HARQ 설계 시 모부호에 의해 부호화된 비트의 전송 순서가 성능을 좌우하는 것을 고려하여 전송 우선순위를 정의하고 전송 패킷 구성 규칙을 제안한다. 제안한 방식의 성능 분석을 다양한 변조 파라미터 및 부호율에서 수행하였으며, 다중 안테나 모드에 따른 시스템 수율 성능을 제시한다. 성능 분석 결과를 통해 제안한 방식은 기존의 방식에 비해 성능 이득을 얻음을 확인할 수 있다.

• Journal of Communications and Networks
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• 제14권6호
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• pp.653-661
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• 2012

High-availability seamless redundancy (HSR) is a redundancy protocol for Ethernet networks that provides two frame copies for each frame sent. Each copy will pass through separate physical paths, pursuing zero fault recovery time. This means that even in the case of a node or a link failure, there is no stoppage of network operations whatsoever. HSR is a potential candidate for the communications of a smart grid, but its main drawback is the unnecessary traffic created due to the duplicated copies of each sent frame, which are generated and circulated inside the network. This downside will degrade network performance and might cause network congestion or even stoppage. In this paper, we present two approaches to solve the above-mentioned problem. The first approach is called quick removing (QR), and is suited to ring or connected ring topologies. The idea is to remove the duplicated frame copies from the network when all the nodes have received one copy of the sent frame and begin to receive the second copy. Therefore, the forwarding of those frame copies until they reach the source node, as occurs in standard HSR, is not needed in QR. Our example shows a traffic reduction of 37.5%compared to the standard HSR protocol. The second approach is called the virtual ring (VRing), which divides any closed-loop HSR network into several VRings. Each VRing will circulate the traffic of a corresponding group of nodes within it. Therefore, the traffic in that group will not affect any of the other network links or nodes, which results in an enhancement of traffic performance. For our sample network, the VRing approach shows a network traffic reduction in the range of 67.7 to 48.4%in a healthy network case and 89.7 to 44.8%in a faulty network case, compared to standard HSR.

• 대한전자공학회논문지
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• 제17권2호
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• pp.23-28
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• 1980

C.E.Shannon에 의하여 정보이론의 기초가 확립된 이래 각국언어에 대한 많은 연구가 발표되고 있다. 마찬가지로 한글 element(요소)를 정보공학에 적용하기 위해서는 한글 정보원을 구성하는 모든 element(요소)에 대한 확률이 적용되어야 한다. 본 논문에서는 그간 누락된 Space(공백소)가 포함되었을 때의 엔트로피(entropy)와 리던던시(redundancy)를 고려하였다. 따라서 본 결과는 기존 각종 한글 정보처리장치의 재평가 및 새로운 정보장치의 코-드(code)화에 있어서 수요한 자료로서 사용될 것이다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 추계종합학술대회 논문집(4)
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• pp.267-270
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• 2000

In this paper, we describe implementation of efficient wavelet image compression and decompression system for DVR(Digital Video Recoder). We used various methods to remove time redundancy, spatial redundancy and statistical redundancy of video camera inputs. Motion detection, wavelet transform, RLC(Run Length Coding) and huffman coding techniques are combined for efficient compression / decompression.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2004년도 하계종합학술대회 논문집(2)
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• pp.541-544
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• 2004

This paper presents a new circuit panitioning algorithm using wire redundancy removal. This algorithm consist of the two steps. In the first step. We propose a new IIP(Iterative Improvement Partitioning) technique that selects the method to choice cells according to improvement status using two kinds of bucket structures, the one kept by total gain, and the other by updated gain. In the second step, we select the target wire in the cut-set. We add a alternative wire in the circuit to remove the target wire. For this we use wire redundancy removal and addition method The experimental results on MCNC benchmark circuits show improvement up to $41-50\%$ in cut-size over previous algorithms

• 한국위성정보통신학회논문지
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• 제12권3호
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• pp.103-107
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• 2017

위성탑재컴퓨터(OBC, On-Board Computer)는 인공위성의 자세제어, 임무수행, 지상명령 송수신 및 처리 등 다양한 기능을 수행한다. 위성탑재컴퓨터는 다양한 모듈로 구성되어 있으며, 각 모듈은 매우 중요한 기능을 수행하기 때문에 이중화로 설계되어 있다. 이중화된 모듈은 그 특성에 따라 Hot/Cold Redundancy 정책을 적용하여 운영한다. 각 모듈을 이중화로 설계함으로써 위성의 신뢰성을 높이고, 특정 모듈에 문제가 발생하였을 때 정상적인 모듈로 위성탑재컴퓨터를 재구성을 함으로써 위성의 정상적인 동작을 보장한다. 본 논문에서는 저궤도 위성에서 위성탑재컴퓨터의 재구성 처리방법에 대해 기술하고 해당 기능을 ETB(Electrical Test Bed) 시험환경에서 검증한 내용에 대해 기술한다.

• 제어로봇시스템학회논문지
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• 제10권11호
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• pp.1037-1043
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• 2004

In this paper, a new fault detection and isolation algorithm fur inertial sensor system is proposed. To identify the inertial sensor fault, single antenna GPS receiver is used as an effective redundancy source. To use GPS receiver as redundancy for the inertial sensors, the algorithm to estimate the attitude and acceleration using single antenna GPS receiver is adopted. By using Doppler shift of carrier phase signal and kinetic characteristics of aircraft, attitude information of aircraft can be obtained at the coordinated flight condition. Based on this idea, fault diagnosis algorithm for inertial sensors using single antenna GPS based attitude is proposed. For more effective FDI, decision variables considering the aircraft maneuver are proposed. The effectiveness of the proposed algorithm is verified through the numerical simulations.

• Journal of Information Display
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• 제10권1호
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• pp.6-15
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• 2009

In this paper, a new approach is proposed for the efficient generation of computer-generated holograms (CGHs) using the spatially redundant data on a 3D object and the novel look-up table (N-LUT) method. First, the pre-calculated N-point principle fringe patterns (PFPs) were calculated using the 1-point PFP of the N-LUT. Second, spatially redundant data on a 3D object were extracted and re-grouped into the N-point redundancy map using the run-length encoding (RLE) method. Then CGH patterns were generated using the spatial redundancy map and the N-LUT method. Finally, the generated hologram patterns were reconstructed. In this approach, the object points that were involved in the calculation of the CGH patterns were dramatically reduced, due to which the computational speed was increased. Some experiments with a test 3D object were carried out and the results were compared with those of conventional methods.