• The KIPS Transactions:PartC
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• v.8C no.5
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• pp.647-656
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• 2001

Video delivery from a server to a client across a network system is an important part of many multimedia applications. Usually, the network system has constraint in both the amount of network bandwidth and the buffer size in the client. While delivering a video stream across such a constrained network system, loss of frames may be unavoidable. The system resources consumed by the dropped frames are wasted, and the losses of frames would result in discontinuous display at the client. In this paper, for delivering hierarchically encoded video stream, we introduce the notion of selective layer discard algorithm at the server which not only preemptively discards data at the server but also drops less important part of a frame instead of the entire frame. By the simulation, we compare the proposed selective layer discard algorithm and the existing selective frame discard algorithm. The simulation results show that the proposed algorithm may improve the quality of decoded video, and decrease the replay discontinuity at the client.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37C no.11
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• pp.1084-1093
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• 2012

For large multihop networks, large time synchronization (TS) errors can accumulate with conventional methods, such as TPSN, RBS, and FTSP, since they need a large number of hops to cover the network. In this paper, a method combining Concurrent Cooperative Transmission (CCT) and Semi- Cooperative Spectrum Fusion (SCSF) is proposed to reduce the number of hops to cover the large network. In CCT, cooperating nodes transmit the same digitally encoded message in orthogonal channels simultaneously, so receivers can benefit from array and diversity gains. SCSF is an analog cooperative transmission method where different cooperators transmit correlated information simultaneously. The two methods are combined to create a new distributed method of network TS, called the Cooperative Analog and Digital (CANDI) TS protocol, which promises significantly lower network TS errors in multi-hop networks. CANDI and TPSN are compared in simulation for a line network.

• Journal of the Institute of Convergence Signal Processing
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• v.14 no.1
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• pp.62-69
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• 2013

This paper proposes real-time video transmission system by the car-mounted cameras based on MOST Network. Existing vehicles transmit videos by connecting the car-mounted cameras in the form of analog. However, the increase in the number of car-mounted cameras leads to development of the network to connect the cameras. In this paper, DSP is applied to process MPEG 2 encoding/decoding for real-time video transmission in a short period of time. MediaLB is employed to transfer data stream between DSP and MOST network controller. During this procedure, DSP cannot transport data stream directly from MediaLB. Therefore, FPGA is used to deliver data stream transmitting MediaLB to DSP. MediaLB is designed to streamline hardware/software application development for MOST Network and to support all MOST Network data transportation methods. As seen in this paper, the test results verify that real-time video transmission using proposed system operates in a normal matter.

• Journal of the Korea Society of Computer and Information
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• v.10 no.1 s.33
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• pp.181-188
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• 2005

Chinese Postman Problem (CPP) is a problem that finds a shortest tour traversing all edges or arcs at least once in a given network. The Chinese Postman Problem on Mixed networks (MCPP) is a Practical generalization of the classical CPP and it has many real-world applications. The MCPP has been shown to be NP-complete. In this paper, we transform a mixed network into a symmetric network using virtual arcs that are shortest paths by Floyd's algorithm. With the transformed network, we propose a Genetic Algorithm (GA) that converges to a near optimal solution quickly by a multi-directional search technique. We study the chromosome structure used in the GA and it consists of a path string and an encoding string. An encoding method, a decoding method, and some genetic operators that are needed when the MCPP is solved using the Proposed GA are studied. . In addition, two scaling methods are used in proposed GA. We compare the performance of the GA with an existing Modified MDXED2 algorithm (Pearn et al. , 1995) In the simulation results, the proposed method is better than the existing methods in case the network has many edges, the Power Law scaling method is better than the Logarithmic scaling method.

• The Transactions of the Korea Information Processing Society
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• v.5 no.7
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• pp.1933-1942
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• 1998

분류 벡터 양자화(classified vector quantization: CVQ)〔2의 부코드북을 설계함에 있어서, 경쟁 학습 네트워크〔5〕-〔7〕 는 소속도의 이분법적 표현으로 상당한 소속도를 가지는 벡터들이 학습 과정에 무시되는 경향을 가진다. 이를 개선하기 위해 제안된 퍼지 경쟁 학습 네트워크〔8〕는 각 클러스터가 연속적인 소속도를 가진다는 개념을 도입하여 이와 같은 문제들을 해결했다. 그러나 퍼지 경쟁 학습 네트워크를 CVQ에 적용할 경우, 각 부코드북의 크기를 시행착오로 결정해야 하는 문제점을 여전히 가지고 있으며, 이러한 문제점들의 개선을 위하여 본 논문에서는 수정 퍼지 경쟁 학습 네트워크(modified fuzzy competitive learning network)를 제안한다. 수정 퍼지 경쟁 학습 네트워크는 퍼지 학습 네트워크가 가지는 이 분법적 소속도를 연속적인 소속도로 확장하여, 학습 과정중에 나타날 수 있는 지역 최소점 도달을 억제하였다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.4C
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• pp.391-399
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• 2006

We propose a novel low complexity video encoder, at the expense of a complex decoder, where video frames are intra-coded periodically and frames in between successive intra-coded frames are coded efficiently using a proposed irregular binning technique. We investigate a method of forming an irregular binning which is capable of quantizing any value effectively with only small number of bins, by exploiting the correlation between successive frames. This correlation is additionally exploited at the decoder, where the quality of reconstructed frames is enhanced gradually by applying POCS(projection on the convex sets). After an image frame is reconstructed with the irregular binning information at the proposed decoder, we can further improve the resulting quality by modifying the reconstructed image with motion-compensated image components from the neighboring frames which are considered to contain image details. In the proposed decoder, several iterations of these modification and re-projection steps can be invoked. Experimental results show that the performance of the proposed coding scheme is comparable to that of H.264/AVC coding in m mode. Since the proposed video coding does not require motion estimation at the encoder, it can be considered as an alternative for some versions of H.264/AVC in applications requiring a simple encoder.

• The KIPS Transactions:PartB
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• v.10B no.6
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• pp.695-704
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• 2003

This paper proposes a new scheduling technique to play multimedia data streams in mobile terminals. The paper explores the characteristics of multimedia data streams , firstly. On basis of these characteristics, selection of specific data stream can be possible as well as transcoding protest. Our approach aims at reducing the early-stage delay time more effectively since it makes possible to select and transcodes some specific streams by employing a selection policy rather than transcoding all streams in the playing process Thus, this paper suggests a stream selection policy for the transcoding based on EPOB (End Point of Over Bandwidth). It aims to lower the required bandwidth of multimedia streams than the network bandwidth level and also to minimize early-stage delay time for multimedia streams, which is to be played in mobile terminals.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.4
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• pp.800-807
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• 2007

Web services came true a services integration, but the XML document decreases the efficiency or the whole application program with connects frequently in relatively slow communication media like network environment embedded system or use the resource limited small-sized instrument like mobile. Thereupon, ITU-T and ISO/IEC suggested encoding standard of binary XML. In this paper, implementation, of Fast XML encoding system through introduction Fast Infoset algorithm and Fast Schema algorithm for web services increase performance. And, offered of test bed that build of Fast Web Services system through Fast XML Encoder.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2018.11a
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• pp.170-173
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• 2018

최근 360 비디오를 지원하는 가상현실 시스템에 대한 수요가 높아지면서, 사용자의 편의를 위해 다양한 방법이 제안되고 있다. Moving Picture Experts Group (MPEG) 에서는 제한적인 사용자 경험을 제공하는 3DoF 를 넘어 3DoF+, 6DoF 표준을 진행하고 있고, 이에 따른 많은 연구도 활발히 진행되고 있다. 사용자가 앉아있는 상태에서 머리의 움직임에 따라 제한적인 자유도를 제공하는 3DoF+ 시스템은 여러 고해상도의 360 비디오 전송을 요구하여 네트워크 대역폭에 상당한 부담을 준다. 본 논문은 3DoF+ 360 비디오 전송 시 대역폭의 효율적 사용을 위한 비트레이트 절감 방안을 제안한다. 이를 위해, 본 논문은 360 비디오의 프로젝션을 변경하여 해상도를 줄이면서도 정보 손실을 최소화할 수 있는 방법을 제시하고 결과를 설명한다. 프로젝션 변경을 위해 360 라이브러리를 사용하였고, 인코딩과 디코딩 시 효율 측정을 위해 HEVC Test Model (HM)을 사용하였다. 최종적으로 구현된 시스템은 360 비디오를 최적의 프로젝션으로 변환 후 인코딩, 디코딩을 거치고 다시 360 비디오로 변환하는 과정을 지원한다.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1968-1969
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• 2011

본 논문에서는 패턴 인식을 위한 다중 출력을 가지는 Interval Type-2 퍼지 집합을 이용한 퍼지 집합 기반 퍼지 뉴럴 네트워크를 소개한다. Interval Type-2 퍼지 집합 기반 퍼지 뉴럴 네트워크는 각 입력 변수에 따른 서로 분리된 입력 공간을 분할함으로서 네트워크 및 규칙을 구성한다. 규칙의 전반부는 퍼지 입력 공간을 개별적으로 분할하여 표현하고, 각 공간은 Interval Type-2 퍼지 집합으로 구성된다. 규칙의 후반부는 패턴 인식을 위한 다중 출력을 가지며 Interval 집합을 이용하여 다항식으로서 표현된다. 다항식의 계수인 연결가중치는 오류역 전파 알고리즘을 이용하여 학습한다. 또한 실수 코딩 유전자 알고리즘을 이용하여 제안된 네트워크를 최적화한다. 제안된 네트워크는 표준 모델로서 널리 사용되는 수치적인 예를 통하여 평가한다.