• KIISE Transactions on Computing Practices
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• v.21 no.1
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• pp.58-63
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• 2015

In this work, we present a novel fountain code-based hybrid P2P storage system that combines cloud storage with P2P storage. The proposed hybrid storage system minimizes data transmission time while guaranteeing high data retrieval and data privacy. In order to guarantee data privacy and storage efficiency, the user transmits encoded data after performing fountain code-based encoding. Also, the proposed algorithm guarantees the user's data retrieval by storing the data while considering each peer's survival probability. The simulation results show that the proposed algorithm enables fast completion of the upload transmission while satisfying the required data retrieval and supporting the privacy of user data under the system parameters.

• The Journal of the Korea institute of electronic communication sciences
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• v.11 no.6
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• pp.611-618
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• 2016

The suggested paper studies communications network and system technology, designing data to sync to both USB memories and cloud storages at the same time, which would allow users to safely keep and manage data even in case of network troubles, affecting cloud storages, and/or loss of physical USB memories, resulting in lost data in the physical memory. The need of secure data management policy for cloud storage users form the basis of this study, offering solutions to network failures and loss of physical storage by creating hybrid cloud system. To provide convenience to windows users, the UI design should integrate that of windows explorer to maximize security and convenience.

• Proceedings of the Korea Contents Association Conference
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• 2016.05a
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• pp.485-486
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• 2016

이 논문에서는 비휘발성 메모리 (NVRAM)과 DRAM을 결합하여 고속의 신뢰성 있는 하이브리드 블록 스토리지를 개발한다. 기존의 DRAM을 기반으로 하는 리눅스의 RAM 디스크는 고속의 입출력성능을 제공하지만, 시스템 고장이 발행할 경우 모든 데이터를 잃어버리게 된다. 일부에서 DRAM과 하드디스크를 결합하여 시스템 고장에도 안정적으로 데이터를 유지하기 위한 방법이 제안된바 있지만, 입출력 성능이 RAM 디스크에 비해 상당히 저하된다. 이 논문에서는 DRAM, NVRAM, 하드디스크를 결합하여 DRAM의 입출력 성능에 가까우면서 안정적으로 데이터를 저장할수 있는 블록 스토리지를 개발한다.

• Journal of Korea Multimedia Society
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• v.15 no.5
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• pp.651-663
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• 2012

Networked digital signage downloads necessary multimedia contents from a large-sized storage on WAN to its local disk of a limited size before starting their playback. If the required time to download the entire contents gets longer, a start time to play the contents at the digital signage could be delayed. In this paper, we propose a hybrid storage architecture that not only inserts an iSCSI storage layer between the existing local disk and the WAN storage, but offers a contents caching scheme in order to obtain all the necessary contents in digital signage rapidly. The proposed caching scheme determines how to place the downloaded contents both in the local disk and the iSCSI storage. Uniquely, the proposed caching scheme manages the iSCSI storage space by dividing it into two regions: (1) in one region, the digital signage can play the contents directly without downloading them into the local disk; (2) in the other region, the digital signage cannot. Performance evaluations on a simulator and an actual system with workloads of various contents show that a contents-downloading time of the hybrid storage architecture is at maximum three times shorter than that of the existing storage architecture.

• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.1
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• pp.109-116
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• 2021

Since RDF (Resource Description Framework) triples are modeled as graph, we cannot directly adopt existing solutions in relational databases and XML technology. In order to store, index, and query Linked Data more efficiently, we propose a convergence indexing method combined R*-tree and K-dimensional trees. This method uses a hybrid storage system based on HDD (Hard Disk Drive) and SSD (Solid State Drive) devices, and a separated filter and refinement index structure to filter unnecessary data and further refine the immediate result. We perform performance comparisons based on three standard join retrieval algorithms. The experimental results demonstrate that our method has achieved remarkable performance compared to other existing methods such as Quad and Darq.

• Journal of the Korea Society of Computer and Information
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• v.19 no.7
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• pp.113-130
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• 2014

In this paper, we propose BLOCS algorithm to find sequence of data that should be saved in cache device of hybrid storage system which uses SSD as a cache device. BLOCS algorithm which uses a sequence pattern mining scheme, creates a set of frequently requested sectors with respect to requested order of sectors. To compare the performance of the proposed scheme, we introduce Distance (DIST) based scheme, Request Frequency (FREQ) based scheme, and Frequency times Size (F-S) based scheme. We measure the hit ratio and I/O latency of different caching schemes using hybrid storage caching simulator. We acquired booting workload along with ten scenarios of launching applications and use the workloads as input to the cache simulator. After experiment with booting workload, we find that BLOCS scheme gives hit ratio of 61% which is about 15% higher than the least performing DIST scheme.

• Proceedings of the Korea Information Processing Society Conference
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• 2009.11a
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• pp.247-248
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• 2009

램 디스크는 주기억장치의 일부 영역을 스토리지로 이용하는 디스크 시스템이다. 램 디스크는 반도체 메모리에 데이터를 저장하고 접근하기 때문에 디스크 입출력 성능은 매우 높다. 그러나, 휘발성 메모리를 이용하는 램 디스크는 전원 공급이 중단되면 그 저장 내용이 소실되는 단점을 가지고 있다. 본 논문에서는 리눅스 장치 구동기 수준에서 램 디스크 서비스와 동시에 하드 디스크 등의 비휘발성 저장 장치에 데이터를 저장, 서비스하는 하이브리드 디스크 시스템을 제안한다.

• Proceedings of the KAIS Fall Conference
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• 2010.05a
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• pp.176-178
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• 2010

본 논문에서는 전통적인 RAID-1 미러링에 기반을 둔 헤테로-미러링이라는 하는 새로운 저장 장치 관리 기법을 제안한다. 헤테로-미러링 기반의 스토리지 관리는 SSD에서 발생 가능한 프리징 현상을 피하기 위한 쓰기-부하 밸런싱과 쓰기 지연 연산을 통하여 RAID-1 처리 성능을 개선한다.

• The KIPS Transactions:PartA
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• v.12A no.2 s.92
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• pp.171-180
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• 2005

In distributed systems data are replicated and stored at several nodes to increase the availability and overall performance. Here Quorum protocol doffing a certain set of replicas required for read/write operation exists for global concurrency control. One of the representative replication Protocols - the Tree Quorum protocol - has a drawback of rapidly growing number of replicas as the level increases, while the Grid protocol requires the same operation cost even without any failure. In this paper, thus, we propose a new replication protocol called hybrid protocol which capitalizes the merits of the existing protocols and solves the problems of them at the same time. The proposed hybrid protocol has very low operation cost in the absence of failure like the tree quorum protocol, and has relatively lower operation cost and higher availability than existing protocols when failure occurs by employing tree architecture as the overall organization while each level of the tree is organized as a row of a grid architecture. It is thus effective to be applied to survival storage system. We conduct cost and availability analysis of the proposed protocol through mathematical modeling, and response time and throughput are compared with those of the Tree Quorum protocol through computer simulation.

• Proceedings of the Korean Information Science Society Conference
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• 2011.06b
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• pp.321-322
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• 2011

차세대 저장매체로 각광받고 있는 BPRAM을 이용해, NAND Flash memory의 결점을 보완하고자 하는 많은 연구들이 진행되고 있다. 본 논문에서는 BPRAM과 NAND Flash를 이용하여, 계층적 스토리지에 사용하는 하이브리드 파일 시스템인 Compressing Metadata File System(CMFS)을 개발하였다. CMFS는 Mount time에 필요한 메타데이터를 BPRAM에 저장하여 마운트 시간을 줄이고, 메타데이터를 Update하기 위한 Overhead를 줄이기 위해 부분 갱신 기법을 개발하였다. 또한 메타데이터의 저장을 위해 필요한 BPRAM의 용량를 줄이기 위해 메타데이터를 경량화 및 압축하고, 압축률을 높이기 위해 Hybrid Coding 압축기법을 개발하여 적용한다. Marvel PXA320(806MHz) 보드를 이용하여 CMFS의 성능을 측정하였으며, 타 압축 기법보다 높은 메타데이터의 압축률을 보였다.