• The Journal of Information Systems
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• v.6 no.1
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• pp.159-180
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• 1997

Database sharing system(DBSS) refers to a system for high performance transaction processing. In DBSS, the processing nodes are locally coupled via a high speed network and share a common database at the disk level. Each node has a local memory, a separate copy of operating system, and a DBMS. To reduce the number of disk accesses, the node caches database pages in its local memory buffer. However, since multiple nodes may be simultaneously cached a page, cache consistency must be ensured so that every node can always access the latest version of pages. In this paper, we propose efficient buffer invalidation schemes in DBSS, where the database is logically partitioned using primary copy authority to reduce locking overhead. The proposed schemes can improve performance by reducing the disk access overhead and the message overhead due to maintaining cache consistency. Furthermore, they can show good performance when database workloads are varied dynamically.

• Proceedings of the KIEE Conference
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• 2005.10b
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• pp.198-200
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• 2005

Recently, intellectual property problem caused by illegal copy or circulation of digital contents with computer and advance of network. it will lose producer's desire and cause economic losses. so we need to demand ownership protection technology for prevent illegal copy without an owner consent and protect ownership with effect. in this paper, we change digital image at frequency domain and choose a factor choosing frequency area with human perceptibility. we inserted repetitive and adaptive watermark on the whole image by Labview Machine Vision. watermark inserted into the high frequency concentrated textual area with Wavelet Transform and then reduced damage of image by human visual feature after inserted watermark

• Proceedings of the KIEE Conference
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• 2005.10b
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• pp.258-260
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• 2005

With the start of terrestrial digital broadcast, we can view HD digital contents in TV. Also we can record, play, redistribute digital contents over the various way. Therefore the protection of Digital Contents Right became the important issue. In this paper, we implement a manager that prevents indiscriminate digital contents redistribution of the terrestrial digital broadcast contents. For protection of Digital contents Right, we use BF(Broadcast Flag) that we can control viewing or copy digital contents with.

• Journal of Communications and Networks
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• v.5 no.3
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• pp.222-229
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• 2003

In this paper, we propose a delayed multiple copy retransmission (DMCR) scheme for data communication in wireless networks, by which multiple copies of a lost link layer frame are retransmitted one-by-one with a retransmission delay in between. The number of the copies gradually increases with the number of retransmissions. Furthermore, for implementation of the DMCR scheme in practical mobile communication system, we also propose a dynamic retransmission scheme by interleaving and a new round-robin scheduling algorithm. We compare our scheme with the previous non-delayed retransmission schemes on the performance of frame loss probability, channel capacity and total transmission time. Numerical results show that the DMCR scheme can achieve higher performance. The effect of the delay time on endto-end TCP throughput is investigated as well.

• Journal of Korea Society of Digital Industry and Information Management
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• v.5 no.4
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• pp.99-108
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• 2009

In the security environments of heterogeneous multidatabase systems, not only the existing local autonomy but also the security autonomy as a new constraint are required. From global aspects, transactions maintain consistent data value when they assure serializability. Also, secure properties must protect these transactions and data values to prevent direct or indirect information effluence. This paper proposes scheduling algorithm for global transactions to ensure multilevel secure one-copy quasi-serializability (MLS/1QSR) in security environments of multidatabase systems with replicated data and proves its correctness. The proposed algorithm does not violate security autonomy and globally guarantees MLS/1QSR without indirect information effluence in multidatabase systems.

• Proceedings of the Korean Information Science Society Conference
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• 1998.10b
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• pp.3-5
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• 1998

WWW(World Wide Web)의 발전은 인터넷의 대중화에 크게 기여를 했다. WWW은 쉬운 사용자 인터페이스와 다양한 멀티미디어 정보의 제공, 통일된 그래픽 사용자 인터페이스, 그리고 전세계 어디에서라도 손쉽게 접근할 수 있는 장점을 가지고 있다. WWW이 점차 발전하면서 인터넷을 통한 대용량의 멀티미디어 데이터의 처리가 필요하게 되었다. 이러한 변화에 따라 대용량의 데이터를 저장, 관리, 검색할 수 있는 데이터베이스 시스템과 WWW을 연결한 것이 WWW 데이터베이스이다. 본 논문에서는 기존에 서면으로 제출되어 심사되고 HARD COPY 형태로 보관되어 오던 논문심사 관리 과정을 개선하기 위해 WWW 데이터베이스를 사용한 논문심사 관리 시스템을 개발한다. WWW 데이터베이스를 사용함으로써 기존의 방법에서 발생되던 논문의 우편 전송 시간의 지연문제, 논문심사 시간의 지연문제, HARD COPY 논문 관리의 한계 등을 해결하였다. 본 논문에서 제시한 논문 심사 관리 시스템을 사용함으로써 학회 회원은 WWW을 이용해서 논문을 논문심사 관리 시스템 서버로 제출할 수 있다. 논문심사 과정의 내역이 데이터베이스에 저장되기 때문에 논문 제출자는 WWW을 이용해서 논문심사 결과를 조회할 수 있다.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.35S no.4
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• pp.85-95
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• 1998

In this paper, a new watermarking method for a copy protectionof images is proposed. The proposed method adaptively embeds a watermark in the frequency domain of images using human visual system model. For this purpose, the Just Noticeable Differences(JNDs) of each frequency coeffeicient value of a luminance plane is first found using Watson and Solomon's visual system model. An invisible maximum watermark value with is different in every position according to the characteristics of images is determined usig JND and Minkowski metric. A low frequency domain is divided into two sets based on a PN-sequence to protect thewatermark from the attack. The watermarks are added to one set of coefficients and detecting a watermark, the difference between the mean values of absolute coefficient values of both sets is calculated. The embedded watermark is tested using statistical hypothesis based on test static dertermined by the ean difference. To demonstrate the perfromance of the proposed method, the new watermarking method is applied to a high frequency image and low frequency images. Experimenatal results show the watermark is invisible and robust to JPEGlossy compression and noise.

• The KIPS Transactions:PartC
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• v.13C no.7 s.110
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• pp.837-842
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• 2006

According to the development of the internet technology, many people can access many kind of digital contents. This approach can infringe the copyright and right owner-ship. Currently many people research the DRM(Digital Rights Management) for protect digital content after digital content downloaded. This paper propose the system that client player witch encrypted using PKI have symmetric key and CCI (copy control information), decrypt digital content witch encrypted when digital content created.

• Journal of the Korean Graphic Arts Communication Society
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• v.18 no.2
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• pp.69-82
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• 2000

Recently, as the prepress mainstream is changed to the digital workflow, various digital proofing systems such as high price dye sublimation printers and low price ink jet printers are widely used in printing industry. CRT monitors are also often used as a soft proofing device. However, it is very difficult to match the color image displayed on CRT monitors to the actual images printed on papers, because the color space of CRT monitors is RGB color system, and it is different with the CMY color system of the printing devices. Therefore, proper color compensations are needed to match the colors between hard-copy proofs on the printing device and soft copy proofs on CRT monitors. This paper shows the LUT and gamut mapping method considering the printing characteristics of output device is useful for the compensation.

• Proceedings of the Korea Information Processing Society Conference
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• 2008.11a
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• pp.1012-1015
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• 2008

The packet capturing becomes a bottleneck in the network intrusion detection and monitoring system as the network performance developing. Many approaches, zero copy, interrupt coalescing and NAPI which attempt to improve packet capturing performance of Linux, are inefficient. PF_RING is a new type of network socket that dramatically improves the packet capture speed, but not perfect. This paper proposes some solutions which can improve the memory utilization and save some data copy time based on the commodity network adapters rather than on the commercial network adapters.