• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2006.05a
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• pp.81-90
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• 2006

The GNUnet proposed a file encoding method by 1KB block size to support anonimity of files, decentralizes encoded block to peers through unstructed mode and original data decoding method a block searching or encoded blocks. but, the encoding and block decentralizing method with $600\sim700MB$ large multimedia file appered two problems. First problem, it need addition R block and I block, which make about 4% of storage resource. Second problem, unstructured model added network load by broadcasting decentralizing method. Third problem, The critical point of keyword search function. This paper suggest variable encoding block size and structured model by block decentralizing solution. Suggested encoding method reduced block request supplementary block generation from 4% to 1%, network load by proposal structured model sending answer through dedicated peer to decentralize block and we defined content-based keyword and identifier of sharing file.

• Journal of Multimedia Information System
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• v.6 no.3
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• pp.139-146
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• 2019

This paper, wireless internet such as Wi-Fi has a vulnerability to security. Blockchain also means a 'Ledger' in which transaction information that occurs on a public or private network is encrypted and shared among the network participants. Blockchain maintains information integrity by making it impossible for a particular node to tamper with information arbitrarily, a feature that would result in changes in the overall blockchain hash value if any one transaction information that constitutes a block was changed. The complete sharing of information through a peer-to-peer network will also cripple hacking attempts from outside, targeting specialized nodes, and prepare for the "single point of failure" risk of the entire system being shut down. Due to the value of these Blockchain, various types of Blockchain are emerging, and related technology development efforts are also actively underway. Various business models such as public block chains such as Bitcoin, as well as private block chains that allow only certain authorized nodes to participate, or consortium block chains operated by a select few licensed groups, are being utilized. In terms of technological evolution, Blockchain also shows the potential to grow beyond cryptocurrency into an online platform that allows all kinds of transactions with the advent of 'Smart Contract'. By using Blockchain technology, the company makes suggestions to overcome the vulnerability of wireless Internet.

• Proceedings of the IEEK Conference
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• 2000.11c
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• pp.51-54
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• 2000

Due to the emerging of high-speed network, lots of interests of access to remote data have increased. Those interests motivate using of Cooperative Caching that uses remote cache like local cache by sharing other clients' cache. The conventional algorithm like GMS(Global Memory Service) has some disadvantages that occurred bottleneck and decreasing performance because of exchanges of many messages to server or manager. On the other hand, Hint-based algorithm resolves a GMS's server bottleneck as each client has hint information of all blocks. But Hint-based algorithm also causes some problems such as inaccurate information in it, if it has too old hint information. In this paper, we offer the policy that supplement bottleneck and inaccuracy； by using file identifier that can search for the lookup table and by exchanging oldest block information between each client periodically.

• Journal of IKEEE
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• v.24 no.3
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• pp.797-802
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• 2020

In this paper, we presents the design and implementation results of the FFT processor, which supports 4096 points of operation with less memory by sharing several memory used in the base-4 systolic array FFT processor into one memory. Sharing memory provides the advantage of reducing the area, and also simplifies the flow of data as I/O of the data progresses in one memory. The presented FFT processor was implemented and verified on the FPGA device. The implementation resulted in 51,855 CLB LUTs, 29,712 CLB registers, 8 block RAM tiles and 450 DSPs, and confirmed that the memory area could be reduced by 65% compared to the existing base-4 systolic array structure.

• Journal of KIISE
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• v.44 no.10
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• pp.1005-1018
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• 2017

Recently, virtualization has become an essential component of cloud computing due to its various strengths, including maximizing server resource utilization, easy-to-maintain software, and enhanced data protection. However, since virtualization allows sharing physical resources among the VMs, the system performance can be deteriorated due to device contentions. In this paper, we first investigate the I/O overhead based on the number of VMs on the same server platform and analyze the block I/O process of the KVM hypervisor. We also propose an in-memory block cache mechanism, called QBic, to overcome I/O virtualization latency. QBic is capable of monitoring the block I/O process of the hypervisor and stores the data with a high access frequency in the cache. As a result, QBic provides a fast response for VMs and reduces the I/O contention to physical devices. Finally, we present a performance measurement of QBic to verify its effectiveness.

• Smart Media Journal
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• v.10 no.1
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• pp.88-98
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• 2021

As blockchain technology has emerged as a security issue for IoT, technology which integrates block chain into IoT is being studied. In this paper is a research concerning token-based IoT service access control technology for data sharing, which propose a possessor focused data sharing technic by using the permissioned blockchain. To share IoT health data, a Hyperledger Fabric Network consisting of three organizations was designed to provide a way to share data by applying different access control policies centered on device owners for different services. In the proposed system, the device owner issues access control tokens with different security levels applied to the participants in the organization, and the token issue information is shared through the distributed ledger of the HFN. In IoT, it is possible to lightweight the access control processing of IoT devices by granting tokens to service requesters who request access to data. Furthmore, by sharing token issuance information among network participants using HFN, the integrity of the token is guaranteed and all network participants can trust the token. The device owners can trust that their data is being used within their authorized rights, and control the collection and use of data.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.49 no.8
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• pp.63-72
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• 2012

In this paper, we proposed a parallel architecture of line & block edge filter for high-performance H.264/AVC deblocking filter for Quad Full High Definition(Quad FHD) video real time processing. To improve throughput, we designed 4-parallel block edge filter with 16 line edge filter. To reduce internal buffer size and processing cycle, we scheduled 4-parallel zig-zag scan order as deblocking filtering order. To avoid data conflicts we placed 1 delay cycle between block edge filtering. We implemented interleaving buffer, as internal buffer of block edge filter, to sharing buffer for reducing buffer size. The proposed architecture was simulated in 0.18um standard cell library. The maximum operation frequency is 108MHz. The gate count is 140.16Kgates. The proposed H.264/AVC deblocking filter can support Quad FHD at 113.17 frames per second by running at 90MHz.

• Proceedings of the Korea Information Processing Society Conference
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• 2007.05a
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• pp.1167-1170
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• 2007

This paper introduces a data storage transport protocol internet Advanced Technology Attachment (iATA) for ATA storage devices that can be accessed over (TCP/IP) networks. As the access speed of Advanced Technology Attachment (ATA) type storage is increasing, the importance of sharing the ATA type storages over internet is also increasing. We are proposing a protocol in which we have implemented the basic ATA command set to access the ATA type remote storage devices over the TCP/IP networks.In this paper, we give basic details of the protocol and discuss the existing storage protocols which are mainly used for accessing block storage like internet Small Computer System Interface (iSCSI) Hyper Small Computer System Interface (HyperSCSI) and ATA over Ethernet (AoE).

• Journal of Information Technology Services
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• v.19 no.4
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• pp.125-138
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• 2020

This paper proposes a more advanced livestock insurance product by comparing the status of livestock management in Korea with Netherlands case. The project focused on blockchain technology, IoT based management manual and planned livestock insurance related to Insurtech. The livestock insurance policy automatically stores information on each block through sensors attached to livestock, so that the livestock manager carries out follow-up manual for each livestock. Blockchain technology contains numerous advantages such as distributed ledger and irreversibility. However, the sharing of transparent information can be a burden to the policyholder. To compensate it, new business model needs to be proposed to provide incentives to the policyholder. We focused on the data of Gyeonggi Province, which suffered the most from African swine fever (ASF) in Korea. The corresponding Insurtech based livestock insurance can enable policyholders and insurers to build trust by sharing objective and transparent information, and maximize their respective profits by enabling mutual control.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.14 no.10
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• pp.4136-4156
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• 2020

Recently, data can be safely shared or stored using the infrastructure of cloud computing in various fields. However, issues such as data security and privacy affect cloud environments. Thus, a variety of security technologies are required, one of them is security technology using CP-ABE. Research into the CP-ABE scheme is currently ongoing, but the existing CP-ABE schemes can pose security threats and are inefficient. In terms of security, the CP-ABE approach should be secure against user collusion attacks and masquerade attacks. In addition, in a dynamic cloud environment where users are frequently added or removed, they must eliminate user access when they leave, and so users will not be able to access the cloud after removal. A user who has left should not be able to access the cloud with the existing attributes, secret key that had been granted. In addition, the existing CP-ABE scheme increases the size of the ciphertext according to the number of attributes specified by the data owner. This leads to inefficient use of cloud storage space and increases the amount of operations carried out by the user, which becomes excessive when the number of attributes is large. In this paper, CP-ABE access control is proposed to block access of withdrawn users in dynamic cloud environments. This proposed scheme focuses on the revocation of the attributes of the withdrawn users and the output of a ciphertext of a constant-size, and improves the efficiency of the user decryption operation through outsourcing.