• Journal of the Korea Institute of Information Security & Cryptology
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• v.23 no.1
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• pp.45-56
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• 2013

When a signer signs a message, strong designated verifier signature allows the signer to designate a verifier. Only the designated verifier can make sure that the signature is generated by the signer. In addition, no one except the designated verifier can know the signature generated by some signer. In this paper, we propose an identity-based strong designated verifier signature scheme where users' public keys are identities. Our proposed scheme is the first identity-based strong designated verifier scheme from lattices. Naturally, our proposed scheme is secure against quantum computing attacks and has low computational complexity.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.6 no.8
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• pp.1336-1345
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• 2002

Materialized views in data warehouse play important roles in rapidly answering to users's requests for information Processing. More views in data warehouse, can respond to the users more rapidly because the user's requests may be processed by using only the materialized views with higher probabilities rather than accessing base relations. The limited duration, during which the materialized views are updated due to base relations's changes, limits the number of materialized views in data warehouse. In this paper, we propose efficient policy for updating the materialized views, which can save the update duration of views although MIN/MAX values frequently change in base relation. The policy updates the materialized views by distinguishing whether MIN/MAX values's changes in the base relation are insert value or delete value. Then, the number of accesses to the base relation is descreased when updating the MIN/MAX values in the materialized views.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.10
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• pp.2217-2223
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• 2012

As smartphone users are over 20 million, companies, which offer cloud computing services, try to support various mobile devices. If so, users can use the same cloud computing service using mobile devices, as sharing document. When user share the work, there are problem in configuration management, data confidentiality and integrity. In this paper, we propose a method that cloud computing users share document efficiently, edit encrypted docuements, and manage configuration based on homomorphic encryption, which integrity is verifiable.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.05a
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• pp.401-403
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• 2015

This paper describes an efficient hardware design of 128-bit block cipher algorithm LEA(lightweight encryption algorithm). In order to achieve area-efficient and low-power implementation, round block and key scheduler block are optimized to share hardware resources for encryption and decryption. The key scheduler register is modified to reduce clock cycles required for key scheduling, which results in improved encryption/decryption performance. FPGA synthesis results of the LEA processor show that it has 2,364 slices, and the estimated performance for the master key of 128/192/256-bit at 113 MHz clock frequency is about 181/162/109 Mbps, respectively.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.3
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• pp.462-478
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• 1994

Conventional hypermedia systems provide a simple data model based on nodes and link, and give us the limited capability in information retrieval such as browsing and navigating following the links. In this paper, we design and implement a hypermedia system (AHEAD) with enhanced data modeling and querying capability, which are strongly supported in object-oriented database technology. The AHEAD makes it possible to model the accurate data semantics and relationships in application domain, to represent useful information related to nodes and links, and to define the structure and manipulation operations of multimedia data. It also support the various querying capabilities by using modeling information.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.11C
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• pp.1092-1099
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• 2006

Future wireless communication systems will employ spatial multiplexing with multiple antennas at both transmitter and receiver to take advantage of larger capacity gains as compared to the systems that use a single antenna. However, in order to reduce higher hardware costs and computational burden, it will require an efficient transmit-receive antenna selection algorithm, which we propose in this paper. Through simulation and comparative analysis of various existing methods and the one we propose in this paper, the algorithm we propose was validated as nearer to the optimal selection technique than existing nearly optimal antenna selection schemes.

• Journal of the Korea Computer Graphics Society
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• v.12 no.3
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• pp.13-20
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• 2006

모바일 환경에서 고급 그래픽스 기술을 적용하고자 하는 시도로 최근 3D 그래픽 엔진을 탑재한 단말기가 출시되고 있다. 이 단말기는 OpenGL ES 1.x을 기준으로 고정된 파이프라인을 통해 그래픽 연산을 처리하고 있으므로 사용자가 다양한 그래픽 표현을 수행하는데 제약이 따른다. 최근 PC 환경의 그래픽 엔진에서는 고정 기능의 파이프라인이 아닌 프로그래밍 가능한 파이프라인을 제공하여 기존 고정 파이프라인에서 불가능했던 유연한 그래픽스 기술을 제공하고 있다. PC환경의 프로그래밍 가능한 파이프라인은 DirectX와 OpenGL 그래픽 라이브러리에 의해 제공되고 있지만, 모바일 환경에서는 이를 지원하기 위한 관련 제품이 아직 출시되지 않고 있는 상태이다. 본 논문에서는 2005년 9원에 발표된 프로그레밍 가능한 그래픽스 파이프라인에 대한 표준인 OpenGL ES 2.0에 기반한 효율적인 셰이더 구조와 이 의 구동방식을 제시한다. 본 연구는 PC상에서 소프트웨어로 개발되었고, 연구 결과는 그래픽스 하드웨어 설계를 위한 검증용으로 사용될 수 있을 뿐 아니라 응용 프로그래머의 모바일 콘텐츠 제작을 위하여 활용될 수 있다.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.46 no.1
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• pp.1-10
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• 2009

Recently, Shin and Park proposed an authentication protocol using the hash function and the XOR operation in RFID/USN environment. However, Shin and Park's proposed authentication protocol is vulnerable to spoofing attack and location tracking attack and tag key exposure attack, and it does not provide tag anonymity. In this paper, we propose an improved authentication protocol for the RFID/USN environment that can withstand those attacks. The proposed authentication protocol provides more improved secrecy and communication efficiency because it decreases the communication rounds compared with the Shin and Park's protocol.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.6
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• pp.37-42
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• 2008

In H.264/AVC decoder, intra predictor, motion compensator, and deblocking filter need to read reference images in external frame memory in decoding process. They read external frame memory very frequently, which lowers system operation speed and increases power consumption. This paper proposes a intra predictor integrated with motion compensator without external frame memory. It achieves power reduction and memory bandwidth minimization by exploiting data reuse of common and repetitive pixels. The proposed infra predictor achieves more than $45%\;{\sim}\;75%$ cycle time reduction compared with conventional intra predictors.

• Journal of Korea Spatial Information System Society
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• v.9 no.2
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• pp.81-91
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• 2007

In this paper, we have proposed the non-duplication loading method for supporting spatio-temporal analysis in spatial data warehouse. SDW(Spatial Data Warehouse) extracts spatial data from SDBMS that support various service of different machine. In proposed methods, it extracts updated parts of SDBMS that is participated to source in SDW. And it removes the duplicated data by spatial operation, then loads it by integrated forms. By this manner, it can support fast analysis operation for spatial data and reduce a waste of storage space. Proposed method loads spatial data by efficient form at application of analysis and prospect by time like spatial mining.