• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.36 no.6
• /
• pp.616-620
• /
• 2008

High reliability is the important parameter on designing satellite system and it is also important to design hish speed data processing unit. To make high speed satellite processing unit, it is needed to utilize space processor, high speed data interface technology, mass memory control technology and data protection technology under space radiation environment.

• Proceedings of the Korean Information Science Society Conference
• /
• 2007.10b
• /
• pp.388-392
• /
• 2007

계속적으로 변화하는 방대한 양의 EMS 데이터를 실시간 취득하여, 사용자가 원하는 데이터만 추출해서 원하는 포맷으로 저장하여 추후 활용할 수 있는 HDMS 시스템에 대하여 소개한다. HDMS 시스템은 K-EMS 과제의 일부분으로 개발되었다. 공유메모리를 사용하여 데이터를 처리하는 실시간 DBMS로부터 추출된 대용량 데이터를 고속으로 디스크 DBMS로 입력하고, 데이터 손실에 대한 Risk를 감소시키기 위하여 동적인 파티션 추가삭제를 통하여 자동으로 분산저장하며, 자동 백업 기능을 제공하여 사용자의 편의성을 증진한다. 데이터를 장기간 보관하고, 보관된 데이터에 대한 데이터 검색 기능을 제공하기 위하여 백업과 관련된 메타데이터를 관리한다. 관리된 메타데이터를 이용하여 사용자의 요구에 의해 백업파일을 시스템에 자동으로 복구하여 온라인 보관주기가 경과한 데이터에 대해 조회가 가능하도록 한다. HDMS시스템은 CIM 기반으로 데이터베이스가 구축되어 향후 K-EMS 외의 타 시스템과의 데이터 통합 및 연계가 용이하고 여러 분야에서 데이터 재활용이 가능할 것으로 예상된다.

• The Journal of the Acoustical Society of Korea
• /
• v.20 no.6
• /
• pp.34-39
• /
• 2001

An adaptive multi-rate (AMR) speech coder was adopted as a standard of W-CDMA by 3GPP and ETSI. The AMR coder is based on the CELP algorithm operating at rates ranging from 12.2 kbps down to 4.75 kbps, and it is a source controlled codec according to the channel error conditions and the traffic loading. In this paper, we implement the DSP S/W of the AMR coder using OakDSPCore. The implementation is based on the CSD17C00A chip developed by C&S Technology, and it is tested using test vectors, for the AMR speech codec, provided by ETSI for the bit exact implementation. The DSP B/W requires 20.6 MIPS for the encoder and 2.7 MIPS for the decoder. Memories required by the Am coder were 21.97 kwords, 6.64 kwords and 15.1 kwords for code, data sections and data ROM, respectively. Also, actual sound input/output test using microphone and speaker demonstrates its proper real-time operation without distortions or delays.

• Journal of KIISE:Information Networking
• /
• v.32 no.3
• /
• pp.415-426
• /
• 2005

Wireless internet, which becomes a hot social issue, has limitations due to the following characteristics, as different from wired internet. It has low bandwidth, frequent disconnection, low computing power, and small screen in user terminal. Also, it has technical issues to Improve in terms of user mobility, network protocol, security, and etc. Wireless internet server should be scalable to handle a large scale traffic due to rapidly growing users. In this paper, wireless internet proxy server clusters are used for the wireless Internet because their caching, distillation, and clustering functions are helpful to overcome the above limitations and needs. TranSend was proposed as a clustering based wireless internet proxy server but it has disadvantages; 1) its scalability is difficult to achieve because there is no systematic way to do it and 2) its structure is complex because of the inefficient communication structure among modules. In our former research, we proposed the All-in-one structure which can be scalable in a systematic way but it also has disadvantages; 1) data sharing among cache servers is not allowed and 2) its communication structure among modules is complex. In this paper, we proposed its improved scheme which has an efficient communication structure among modules and allows data to be shared among cache servers. We performed experiments using 16 PCs and experimental results show 54.86$\%$ and 4.70$\%$ performance improvement of the proposed system compared to TranSend and All-in-one system respectively Due to data sharing amount cache servers, the proposed scheme has an advantage of keeping a fixed size of the total cache memory regardless of cache server numbers. On the contrary, in All-in-one, the total cache memory size increases proportional to the number of cache servers since each cache server should keep all cache data, respectively.

• Journal of Broadcast Engineering
• /
• v.19 no.2
• /
• pp.240-249
• /
• 2014

According to the compressive sensing theory, it is possible to perfectly reconstruct a signal only with a fewer number of measurements than the Nyquist sampling rate if the signal is a sparse signal which satisfies a few related conditions. From practical viewpoint for image applications, it is important to reduce its computational complexity and memory burden required in reconstruction. In this regard, a Block-based Compressive Sensing (BCS) scheme with Smooth Projected Landweber (BCS-SPL) has been already introduced. However, it still has the computational complexity problem in reconstruction. In this paper, we propose a method which modifies its stopping criterion, tolerance, and convergence control to make it converge faster. Experimental results show that the proposed method requires less iterations but achieves better quality of reconstructed image than the conventional BCS-SPL.

• Journal of the Korea Computer Graphics Society
• /
• v.24 no.3
• /
• pp.61-71
• /
• 2018

When triangular meshes are generated from the point clouds in global space reconstructed through camera pose estimation against captured RGB-D streams, the quality of the resulting meshes improves as more triangles are hired. However, for 3D reconstructed models beyond some size threshold, they become to suffer from the ugly-looking artefacts due to the insufficient precision of RGB-D sensors as well as significant burdens in memory requirement and rendering cost. In this paper, for the generation of 3D models appropriate for real-time applications, we propose an effective technique that extracts high-quality textures for moderate-sized meshes from the captured colors associated with the reconstructed point sets. In particular, we show that via a simple method based on the mapping between the 3D global space resulting from the camera pose estimation and the 2D texture space, textures can be generated effectively for the 3D models reconstructed from captured RGB-D image streams.

• Journal of KIISE:Computer Systems and Theory
• /
• v.33 no.6
• /
• pp.326-336
• /
• 2006

Due to the evolution of wired and wireless communication technologies and the Internet, multimedia services such as Internet broadcast and VOD have been prevalent recently. RTP is designed to be suitable for transmission of real-time multimedia data on the Internet by IETF While a variety of applications have utilized different RTPs implemented as a library, embeddedRTP is RTP-based kernel-level protocol that resolved performance issues of this kind of RTPs. This paper proposes the ExtendedERTP protocol based on existing embeddedRTP. This new protocol resolves a couple of issues such as packet processing overhead and buffer requirement and combines its APIs with BSD socket APIs which have been widely utilized in network applications. This paper demonstrates that this integration makes it possible to transmit real-time multimedia data through the accustomed interface of BSD socket APIs with nominal extra overhead. This paper also proposes a scheme for improving packet processing time by 15$\sim$20% and another scheme for reducing memory requirement for packet processing to about 3.5%, comparing with those of embeddedRTP.

• Journal of the Korea Computer Graphics Society
• /
• v.17 no.2
• /
• pp.17-26
• /
• 2011

This paper presents an interactive progressive image transmission method, which enables a remote user to interactively select and transmit preferred regions from an index image. Our enhanced quadtree decomposition using PSNR-based rules and new implicit quadtree coding provide better rate-distortion performance than previous quadtree coders as well as leading bit plane methods. An adaptive traversal of child nodes is introduced for better visual display of restored images. Depth-first traversal combined with breadth-first traversal of the quadtree to accomplish interactive transmission as presented, results in a method that provides competitive performance at a low level of computational complexity. Moreover, our decoding requires only simple arithmetic which is enabling our method to be used for real-time mobile applications.

• Journal of KIISE:Information Networking
• /
• v.36 no.1
• /
• pp.57-67
• /
• 2009

Packet forwarding in the Internet routers is to find out the longest prefix that matches the destination address of an input packet and to forward the input packet to the output port designated by the longest matched prefix. The IP address lookup is the key of the packet forwarding, and it is required to have efficient data structures and search algorithms to provide the high-speed lookup performance. In this paper, an efficient IP address lookup algorithm using binary search is investigated. Most of the existing binary search algorithms are not efficient in search performance since they do not provide a balanced search. The proposed binary search algorithm performs perfectly balanced binary search using switch pointers. The performance of the proposed algorithm is evaluated using actual backbone routing data and it is shown that the proposed algorithm provides very good search performance without increasing the memory amount storing the forwarding table. The proposed algorithm also provides very good scalability since it can be easily extended for multi-way search and for large forwarding tables

• Journal of KIISE:Information Networking
• /
• v.35 no.6
• /
• pp.482-496
• /
• 2008

Packet classification in the Internet routers requires multi-dimensional search for multiple header fields for every incoming packet in wire-speed, hence packet classification is one of the most important challenges in router design. Hierarchical packet classification is one of the most effective solutions since search space is remarkably reduced every time a field search is completed. However, hierarchical structures have two intrinsic issues; back-tracking and empty internal nodes. In this paper, we propose a new hierarchical packet classification algorithm which solves both problems. The back-tracking is avoided by using the set-pruning and the empty internal nodes are avoided by applying the binary search tree. Simulation result shows that the proposed algorithm provides significant improvement in search speed without increasing the amount of memory requirement. We also propose an optimization technique applying controlled rule copy in set-pruning.