• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.22 no.6
• /
• pp.1231-1242
• /
• 2012

Traitor tracing schemes deter traitors from sharing their private keys by tracing at least one of the subscribers who were implicated in the construction of a pirate decoder. In general, it is assumed that the system manager in the scheme generates and distributes the subscribers' private key. But if the system manager knows the subscribers' private keys, he cannot convince a third party of a certain subscriber's piracy. To solve this problem, the system manager should not know the whole parts of subscribers' private keys and this leads to researches of asymmetric schemes. Moreover for the purpose of enhancing subscribers' privacy, there were two proposals of introducing anonymity onto asymmetric traitor tracing schemes, but one of them turned out to be a failure. In this paper, we point out that the other proposal also has flaws. We consider how to introduce anonymity to traitor tracing schemes, as a result, we suggest a new framework which is practical. We also construct a scheme by using an anonymous credential system and an asymmetric traitor tracing scheme. We prove the security of our scheme and consider the typical applications.

• The KIPS Transactions:PartD
• /
• v.11D no.1
• /
• pp.105-114
• /
• 2004

In this paper, we propose a collaboration method of diverse agents each others in multi-agent model and describe a node migration algorithm of Mobile-Agent (MA) using by the metadata of Naming-Agent (NA). Collaboration work of multi-agent assures stability of agent system and provides reliability of information retrieval on the distributed environment. NA, an important part of multi-agent, identifies each agents and series the unique name of each agents, and each agent references the specified object using by its name. Also, NA integrates and manages naming service by agents classification such as Client-Push-Agent (CPA), Server-Push-Agent (SPA), and System-Monitoring-Agent (SMA) based on its characteristic. And, NA provides the location list of mobile nodes to specified MA. Therefore, when MA does move through the nodes, it is needed to improve the efficiency of node migration by specified priority according to hit_count, hit_ratio, node processing and network traffic time. Therefore, in this paper, for the integrated naming service, we design Naming Agent and show the structure of metadata which constructed with fields such as hit_count, hit_ratio, total_count of documents, and so on. And, this paper presents the flow of creation and updating of metadata and the method of node migration with hit_count through the collaboration of multi-agent.

• Journal of the Korea Society of Computer and Information
• /
• v.17 no.5
• /
• pp.1-7
• /
• 2012

In this paper, we design and implement the simulator for WAN storage replication model performance evaluation in cloud computing environment. Each cloud of simulator is composed of virtual machine emulator and storage emulator. The virtual machine emulator is composed of read/write ratio module, the read/write sequence combination module, and the read/write request module. The storage emulator is composed of storage management module, data transfer module, read/write operations module, and overhead processing module. Using the simulator, we evaluate performance of migration scheme, pre-copy and the post-copy, considering about read/write ratio, network delay, and network bandwidth. Through simulation, we have confirmed that the average migration time of pre-copy was decreased proportional to the read operation. However, average migration time of post-copy was on the increase. Also, the average migration time of post-copy was increased proportional to the network delay. However, average migration time of pre-copy was shown uniformly. Therefore, we show that pre-copy model more effective to reduce the average migration time than the post-copy model. The average migration time of pre-copy and post-copy were not affected by the change of network bandwidth. Therefore, these results show that selects the storage replication model to be, the network bandwidth know not being the important element.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.32 no.7C
• /
• pp.616-626
• /
• 2007

In spatially multiplexed MIMO systems that enable high data rate transmission over wireless communication channels, the spatial demultiplexing at the receiver is a challenging task, and various demultiplexing methods have been developed recently by many researchers. Among the previous methods, maximum likelihood detection with QR decomposition and M-algorithm (QRM-MM)), and sphere decoding (SD) schemes have been reported to achieve a (near) maximum likelihood (ML) performance. In this paper, we propose a novel signal detection method that achieves a near ML performance in a computationally efficient manner. The proposed method is demonstrated via a set of computer simulations that the proposed method achieves a near ML performance while requiring a complexity that is comparable to that of the conventional MMSE-OSIC. We also show that the log likelihood ratio (LLR) values for all bits are obtained without additional calculation but as byproduct in the proposed detection method, while in the previous QRM-MLD, SD, additional computation is necessary after the hard decision for LLR calculation.

• Proceedings of the Korea Institutes of Information Security and Cryptology Conference
• /
• 2002.11a
• /
• pp.524-527
• /
• 2002

본 연구에서는 Support Vector Machine(SVM)을 이용한 호스트 기반 침임 탐지 방법을 제안한다. 침입 탐지는 침입과 정상을 판단하는 이진분류 문제이므로 이진분류에 뛰어난 성능을 발휘하는 SVM을 이용하여 침입 탐지 시스템을 구현하였다. 먼저 감사자료를 system call level에서 분석한 후, sliding window기법에 의해 패턴 feature를 추출하고 training set을 구성하였다. 여기에 SVM을 적용하여 decision model을 생성하였고, 이에 대한 판정 테스트 결과 90% 이상의 높은 침입탐지 적중률을 보였다.

• Proceedings of the IEEK Conference
• /
• 2001.06d
• /
• pp.215-218
• /
• 2001

본 연구에서는 저해상도 다분광 영상으로부터 고해상도 다분광 영상을 효과적인 추출하기 위해 인공지능의 한 기법인 신경회로망을 이용하여 중합을 위한 구조를 제안하였고, IKONOS 위성 영상에 적용하여 실험 및 결과를 제시하였다. 실험 결과에서 얻어진 화상은 비교적 좋은 분광특성을 나타내었으며, 향후, 본 연구의 중합방법은 토지 이용분류, 환경감시, 자원조사 등의 많은 분야와 지형공간정보 시스템의 데이터 활용 등 여러분야 응용될 경우 우수한 성능을 제공할 것으로 사료된다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
• /
• 1996.06a
• /
• pp.233-236
• /
• 1996

A new method of blocking effects reduction is proposed in this paper for use in low bitrate image coding. We use 28 DCT kernel functions of which boundary values are linearly independent, and Gram-Schmidt process is applied to the boundary values in order to obtain 28 boundary-orthonormal basis images. Then we use these basis images to obtain the correction terms for blocking artifacts reduction. A threshold of block discontinuity is introduced for improvement of visual quality by reducing image blurring. We also investigate the number of basis images needed for efficient blocking artifacts reduction when the compression ratio changes.

• Proceedings of the KIEE Conference
• /
• 2006.04b
• /
• pp.176-178
• /
• 2006

This paper is intended to research the speed response of switched reluctance motor (SRM) using sliding mode control method when load is changing. The simulation compare only control by PI controller with control by PI controller and sliding mode controller. It compare with speed response using MATLAB/SIMULINK.

• Proceedings of the KIEE Conference
• /
• 2011.07a
• /
• pp.1197-1198
• /
• 2011

발전기 여자시스템(Excitation System)은 동기발전기의 계자권선에 직류전류를 공급하고 계자전압을 조정하여 발전기의 전압 및 계통의 무효전력을 제어하는 기능을 수행한다. 본 논문에서는 발전기 여자시스템의 모델링 기법과 현장 운전데이터를 이용한 여자시스템의 모델링 결과들을 기술하였다.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.61 no.4
• /
• pp.629-631
• /
• 2012

In Cognitive Radio network, spectrum selection scheme is one of a important part to manage idle spectrums efficiently. However, in CR networks, they have to adopt time-varying channel availability to minimize the interference to primary users (PU), and be able to manage spectrum resources efficiently. In this paper, we proposed a modified PF scheduler which can be appropriate to schedule downlink CR users and channels, by considering the fairness and the throughput as well as the primary user characteristics of each channel.