• The Journal of Korean Institute of Next Generation Computing
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• v.14 no.5
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• pp.60-70
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• 2018

A software defined storage (SDS) is being deployed in cloud environment to allow multiple users to virtualize physical servers, but a solution for optimizing space efficiency with limited physical resources is needed. In the conventional data deduplication system, it is difficult to deduplicate redundant data uploaded to distributed storages. In this paper, we propose a distributed deduplication method using similarity-based clustering and multi-layer bloom filter. Rabin hash is applied to determine the degree of similarity between virtual machine servers and cluster similar virtual machines. Therefore, it improves the performance compared to deduplication efficiency for individual storage nodes. In addition, a multi-layer bloom filter incorporated into the deduplication process to shorten processing time by reducing the number of the false positives. Experimental results show that the proposed method improves the deduplication ratio by 9% compared to deduplication method using IP address based clusters without any difference in processing time.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2018.05a
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• pp.169-171
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• 2018

본 연구의 목적은 재결요약서의 구성과 사고 기술 방법 등을 고찰하여 분석을 통해 재결요약서의 오류들을 보완하고자 한다. 해양안전심판원에서 간행하고 있는 재결요약서는 사건명, 해양사고관련자, 판시사항, 원인판단 주제어, 사건개요, 주문, 참고사항, 교훈 등으로 구성되어있다. 약 4,200건의 재결요약서를 수집하여 분석하였다. 분석 결과 단순한 오타를 포함하여 내용중복의 오류, 용어의 혼용 등의 문제들이 있었다. 이러한 오류 수정을 통해 사용자의 요구에 부합하는 재결요약서 작성에 필요한 내용들을 연구하고자 한다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2022.11a
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• pp.51-53
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• 2022

MIV(MPEG Immersive Video)의 시험모델 TMIV 는 다시점의 비디오와 깊이(depth) 비디오를 입력 받아 시점 사이의 중복성을 제거한 후 남은 텍스처(texture)와 깊이로 텍스처 아틀라스(atlas)와 깊이 아틀라스를 각각 생성하고 이를 압축한다. 각 화소별 점유(occupancy) 정보는 깊이 아틀라스에 포함되어 압축되는데 압축 손실로 인한 점유맵 오류를 방지하기 위하여 임계값 T = 64 로 설정한 보호대역을 사용한다. 기존에 설정된 임계값을 낮추어 깊이 동적범위를 확대하면 보다 정확한 깊이값 표현으로 부호화 효율을 개선할 수 있지만 보호대역 축소로 점유맵 오류가 증가한다. 본 논문에서는 TMIV 의 부호화기와 보호화기에 비대칭 임계값을 사용하여 보호대역 축소로 인한 점유맵 오류를 보정하면서 보다 정확한 깊이 값 표현을 통하여 부호화 효율을 개선하는 기법을 제안한다. 제안기법은 깊이 동적범위 확대와 비대칭 임계값 기반의 점유맵 오류 보정을 통하여 CG 시퀀스에서 2.2% BD-rate 이득과 주관적 화질 개선을 보인다.

• Journal of IKEEE
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• v.26 no.3
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• pp.437-444
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• 2022

This paper proposes a CRC error verification method for SPI and I2C buses of automotive semiconductors. In automotive semiconductors, when an error occurs in communication and an incorrect value is transmitted, fatal results may occur. Unlike LIN communication and CAN communication, in communication such as SPI and I2C, there is no frame for detecting an error, so some definitions of new standards are required. Therefore, in this paper, the CRC error detection mode is newly defined in the SPI and I2C communication protocols, and the verification is presented by designing it in hardware.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.7A
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• pp.1063-1075
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• 2000

This paper proposes an adaptive error concealment technique for compressed video. Since redundancy is extracted out during compression process, compressed video is vulnerable to errors which occur during transmission of video over error prone networks such as wireless channels and Internet. Error concealment is a process of reconstructing video out of damaged video bit stream. We proved that scalable encoding is very useful for error concealment. Analysis of experiments shows that some part of image is better concealed by using base layer information and other part of image is better concealed by using previous frame information. We developed a technique which enables to decide which methodology is more effective, adaptively, based on motion vectors and regional spatial activity. We used H.263v2 for scalable encoding, but, our approach could be applied to all DCT based video codec.

• Proceedings of the Korea Contents Association Conference
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• 2007.11a
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• pp.445-448
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• 2007

A Serials Union Catalog is an essential Bibliographic Control tool for integrated and shared the serials information which is scattered to the domestic libraries. It provides reliable informations about serials to user through creating optimized catalogs and holding informations. It is important of the consistency of the bibliographic record and the record's duplication ratio is an important criterion about Database Quality Assessment. This paper checks bibliographic data elements and proposes the duplicate detection process to improve union catalog quality for minimizing duplicate detection.

• Journal of the Korean Society for Library and Information Science
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• v.37 no.4
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• pp.69-88
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• 2003

This study intends to develop a new duplicate detection algorithm to improve database quality. The new algorithm is developed to analyze by variables of language and bibliographic type, and it checks elements in bibliographic data not just MARC fields. The algorithm computes the degree of similarity and the weight values to avoid possible elimination of records by simple input error. The study was peformed on the 7,649 newly uploaded records during the last one year against the 210,000 sample master database. The findings show that the new algorithm has improved the duplicates recall rate by 36.2%.

• Journal of Advanced Navigation Technology
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• v.18 no.1
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• pp.67-73
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• 2014

Due to the development of the communication technology and the high-performance mobile device, the number of video streaming service user has been increasing. Video streaming services in the restricted network environments need error control to support users for the Ultra High Definition(UHD) video delivery. Packet-level FEC method was used to control the error for delay-sensitive video service, but it has a defect in huge occupation of network resources by redundant packets. In this paper, we proposed a packet-level FEC algorithm which maintains the video quality by previous FEC methods and also reduces the occupation of network resource in the restricted network environments. The proposed algorithm controls the redundant rate with using the delivery characteristic of the video coding technology, and improves the efficiency of network resources by reducing the traffic by around 33% in comparison with the previous FEC methods.

• Journal of KIISE:Information Networking
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• v.29 no.3
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• pp.277-285
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• 2002

This paper proposes and analyzes an error control scheme for the transmission control based real-time communication, such as FDDI, TDMA, and wireless LAN, which delivers the message according to the round robin fashion after the off-line bandwidth allocation. Taking into account the time constraint of each message, the proposed error control scheme makes the receiver transmit the error report via asynchronous traffic while the sender resend the requested message via overallocated access time which is inevitably introduced by the bandwidth allocation procedure for hard real -time guarantee. The error control procedure does not interfere other real -time message transmissions. In addition, as each frame contains the size of the message it belongs, the receiver can recognize the end of completion of message transmission. This enables earlier error report to the receiver so that the sender can cope with more network errors. The analysis results along with simulation performed via SMPL show that the proposed scheme is able to enhance the deadline meet ratio of messages by overcoming the network errors. Using the proposed error control scheme, the hard real -time network can be built at cost lower than, but performance comparable to the expensive dual link network.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.11a
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• pp.605-609
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• 2002

Reliable multicast data transmission in a 1:N environment needs more sophisticated error control mechanism than that of in 1:1 environment due to ACK implosion and duplicated retransmission. Although there have been many related research on error control in reliable multicast, real implemented protocols are rare. As one of the reliable multicast transport protocols, ECTP is selected as an international standard reliable multicast protocol by ITU-T and ISO and implemented on RedHat 7.2 machine by us. In this paper, we evaluate the performance of the error control mechanism in the respect of throughput and generated control packet numbers with a real implementation code. From the results, it is concluded that the suitable values of error control parameters can be obtained from the local group size and network environments.