• Smart Media Journal
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• v.4 no.2
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• pp.62-67
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• 2015

During several decades, hard disk drive(HDD) has been used in most computer systems as secondary storage and, however, the performance enhancement of HDD is limited by its mechanical properties. On the other hand, although the flash memory based solid state drive (SSD) has more advantages over HDD such as high performance and low noise, SSD is still too expensive for common usage and expected to take several years to replace HDD completely. Therefore, SSD caching mechanism using the SSD as a cache of high capacity HDD has been highlighted lately. The representatives of SSD caching mechanisms are typically bcache, dm-cache, Flashcache, and EnhanceIO. Each of them has its own internal mechanism and implementation, and this makes them to show their own pros. and cons. In this paper, we analyze the characteristics of each SSD caching mechanisms and compare the performance of them under various workloads. We expect that our contribution will be useful to enhance the performance of SSD caching mechanisms.

• Journal of KIISE:Information Networking
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• v.32 no.6
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• pp.705-715
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• 2005

A peer-to-peer web caching has been studied recently as it can reduce the traffic converged on the server side and can support the traditional web caching model. Although the peer-to-peer web caching has the merit of having additional cache space from the local caches of peers without additional infrastructure, several constraints such as dynamic participation and local caching strategy caused by the autonomy of peers in peer-to-peer networks nay limit the performance of the peer-to-peer web caching. To overcome these limitations, we propose an efficient directory-based peer-to-peer web caching system under dynamic participation of peers. In the proposed caching system, we present new peer selection and replica management schemes by introducing the concept of the object lifetime in P2P networks. We evaluate the effectiveness of the proposed system through trace-driven simulations with a web log dataset. Simulation results show that the proposed system has higher accuracy and fewer redirection failures than the conventional directory-based P2P web caching system in feasible peer-to-peer networks.

• Journal of Digital Convergence
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• v.17 no.9
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• pp.153-161
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• 2019

Discrimination of media object segments in wireless home proxies has a significant impact on caching delay, and caching delay degrades the performance of the proxy. In this paper, we propose a Single Fetching Smart Caching (SFSC) strategy and a Multi-Fetching Smart Caching (MFSC) strategy to improve the proxy performance of the home network and improve the caching performance for media object segments. The SFSC strategy is a technique that performs caching by sequential fetching of object segments requested by the home node one at a time, which guarantees a faster cache hit rate, and the MFSC strategy is a technique that caches the media object segments by blocking object segments requested by the home node one at a time, which improves the throughput of cache. Simulation results show that the cache hit rate and the caching delay are more efficient than the MFSC technique, and the throughput of the object segment is more efficient than that of the SFSC technique.

• Journal of information and communication convergence engineering
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• v.13 no.1
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• pp.27-35
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• 2015

Multiprecision multiplication is the most expensive operation in public key-based cryptography. Therefore, many multiplication methods have been studied intensively for several decades. In Workshop on Cryptographic Hardware and Embedded Systems 2011 (CHES2011), a novel multiplication method called 'operand caching' was proposed. This method reduces the number of required load instructions by caching the operands. However, it does not provide full operand caching when changing the row of partial products. To overcome this problem, a novel method, that is, 'consecutive operand caching' was proposed in Workshop on Information Security Applications 2012 (WISA2012). It divides a multiplication structure into partial products and reconstructs them to share common operands between previous and next partial products. However, there is still room for improvement; therefore, we propose a finely designed operand-caching mode to minimize useless memory accesses when the first row is changed. Finally, we reduce the number of memory access instructions and boost the speed of the overall multiprecision multiplication for public key cryptography.

• Journal of Industrial Technology
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• v.27 no.B
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• pp.185-192
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• 2007

Transcoding video proxy is necessary to support various bandwidth requirements for mobile multimedia and to provide adapting video streams to mobile clients. Caching algorithms for proxy are to reduce the network traffic between the content servers and the proxy. This paper proposes a Meta-tailed caching for transcoding proxy that is efficient to lower network load and CPU load. Caching of two different data types - transcoded video, and metadata - provides a foundation to achieve superior balance between network resource and computation resource at transcoding proxies. Experimental results show that the Meta-tailed caching lowers at least 10% of CPU-load and at least 9% of network-load at a transcoding proxy.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.5
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• pp.2319-2337
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• 2019

In this paper, we study the distributed cooperative caching for Internet content providers in a small cell of heterogeneous network (HetNet). A general framework based on bankruptcy game model is put forth for finding the optimal caching policy. In this framework, the small cell and different content providers are modeled as bankrupt company and players, respectively. By introducing strategic decisions into the bankruptcy game, we propose a caching value assessment algorithm based on analytic hierarchy process in the framework of bankruptcy game theory to optimize the caching strategy and increase cache hit ratio. Our analysis shows that resource utilization can be improved through cooperative sharing while considering content providers' satisfaction. When the cache value is measured by multiple factors, not just popularity, the cache hit rate for user access is also increased. Simulation results show that our approach can improve the cache hit rate while ensuring the fairness of the distribution.

• Journal of Information Processing Systems
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• v.18 no.6
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• pp.803-812
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• 2022

With the increasing number of mobile device users worldwide, utilizing mobile edge computing (MEC) devices close to users for content caching can reduce transmission latency than receiving content from a server or cloud. However, because MEC has limited storage capacity, it is necessary to determine the content types and sizes to be cached. In this study, we investigate a caching strategy that increases the hit ratio from small base stations (SBSs) for mobile users in a heterogeneous network consisting of one macro base station (MBS) and multiple SBSs. If there are several SBSs that users can access, the hit ratio can be improved by reducing duplicate content and increasing the diversity of content in SBSs. We propose a Deep Q-Network (DQN)-based caching strategy that considers time-varying content popularity and content redundancy in multiple SBSs. Content is stored in the SBS in a divided form using maximum distance separable (MDS) codes to enhance the diversity of the content. Experiments in various environments show that the proposed caching strategy outperforms the other methods in terms of hit ratio.

• Journal of Korea Multimedia Society
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• v.8 no.7
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• pp.943-952
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• 2005

This paper proposes a user's mobility based cooperative proxy caching policy for effective resource management of continuous media objects in mobile environments. This policy is different from the existing proxy caching policies in terms of how to exploit users' mobility. In other words, existing caching policies work based on the information about objects by referring to users' requests within a specified domain whereas the proposed caching policy runs by utilizing a number of users' requests across several domains. So, the proposed policy is applicable to random requests in mobile environments. Moreover, we also propose a replacement policy based on weights and playback time. To check the efficiency of the proposed caching policy, the proposed replacement policy is run with different size of caching unit: object or segment. The result of performance evaluation tells that segment sizes, ratio of users' mobility and weights are major factors for the efficient operation of the cooperative caching.

• The KIPS Transactions:PartB
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• v.11B no.6
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• pp.691-700
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• 2004

This paper proposes a user's mobility based cooperative proxy caching policy for effective resource management of continuous media objects in mobile environments. This policy is different from the existing proxy caching policies in terms of how to exploit users' mobility. In other words, existing caching policies work based on the information about objects by referring to user's requests within a specified domain whereas the proposed caching policy runs by utilizing a number of user's requests across several domains. So, the proposed policy is applicable to random requests in mobile environments Moreover, we also propose a replacement policy based on weights and playback time. To check the efficiency of the proposed caching policy, the proposed replacement policy is run with different size of caching unit object or segment. The result of performance analyze tells what a ratio of user's mobility is are major factors for the efficient operation of the cooperative caching.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.11
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• pp.1511-1517
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• 2018

Mobile Device-to-Device (D2D) caching networks can transmit multimedia data to users directly without passing through any network infrastructure by storing popular multimedia contents in advance that are popular among many mobile users at caching server devices (CSDs) in distributed manners. Thus, mobile D2D caching networks can significantly reduce backhaul traffic in wired networks and service latency time of mobile users. In this paper, we propose an efficient transmission scheme that can enhance the transmission efficiency of mobile D2D caching networks by using multiple CSDs that are caching the contents that are popular among mobile users. By sorting the multiple CSDs that are caching a content that mobile users want to receive according to their channel gains, the proposed scheme can reduce the complexity of algorithm significantly, compared to an optimal scheme based on Brute-force searching, and can also obtain much higher network transmission efficiency than the existing Blanket and Opportunistic transmission schemes.