• Transactions of the Society of Information Storage Systems
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• v.3 no.2
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• pp.86-93
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• 2007

In this paper we explain why future probe storage systems will use patterned media. As a model system, magnetic patterned media will be discussed, even though their data density is limited to about $7Tbit/in^2$. The first results on magnetic probe storage on patterned media are presented, and the problem of switching field distribution is discussed in detail. Finally we will present the first steps into two-dimensional coding for patterned media.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.5 no.5
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• pp.909-937
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• 2011

Energy efficiency is one of the most critical issues in the design of wireless sensor networks. In object-tracking sensor networks, the data storage and query processing should be energy-conserving by decreasing the message complexity. In this paper, a Prediction-based Energy-conserving Approximate StoragE schema (P-EASE) is proposed, which can reduce the query error of EASE by changing its approximate area and adopting predicting model without increasing the cost. In addition, focusing on reducing the unnecessary querying messages, P-EASE enables an optimal query algorithm to taking into consideration to query the proper storage node, i.e., the nearer storage node of the centric storage node and local storage node. The theoretical analysis illuminates the correctness and efficiency of the P-EASE. Simulation experiments are conducted under semi-random walk and random waypoint mobility. Compared to EASE, P-EASE performs better at the query error, message complexity, total energy consumption and hotspot energy consumption. Results have shown that P-EASE is more energy-conserving and has higher location precision than EASE.

• Journal of the Korea Society of Computer and Information
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• v.24 no.9
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• pp.1-8
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• 2019

In this paper, we propose a performance isolation of shared space for virtualized SSD based storage systems, to solve the weakness in a VSSD framework. The proposed scheme adopts a CFQ scheduler and a shared space-based FTL for the fairness and the performance isolation for multiple users on virtualized SSD based storage systems. Using the CFQ scheduler, we ensure SLOs for the storage systems such as a service time, a allocated space, and a IO latency for users on the virtualized storage systems. In addition, to improve a throughput and reduce a computational latency for garbage collection, a shared space-based FTL is adopted to maintain the information of SLOs for users and it manages shared spaces among the users. In our experiments, the proposal improved the throughput of garbage collection by 7.11%, on average, and reduced the computational latency for garbage collection by 9.63% on average, compared to the previous work.

• Transactions of the Society of Information Storage Systems
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• v.1 no.1
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• pp.1-22
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• 2005

There are two important trends in the modern information society, including digital networking and ubiquitous environment. Thus it is strongly required to develop new information storage devices such as high density storages to match the increased data capacity and small size storage devices to be applied to the mobile multimedia electronics. So far, many approaches have been studied for the high density memory, including the holographic memory, super-RENS and near-field recording using solid immersion lens (SIL) or nano-probe for the ODD (Optical Disk Drive) system, and the perpendicular magnetic recording and heat-assisted magnetic recording for the HDD (Hard Disk Drive) system. In addition, new mobile storage devices have been prepared using 0.85" HDD and 30mm ODD systems from a lot of foreign and domestic companies and institutes. In this paper, the recent technology trend for the next generation information storage system is summarized to offer a research motivation and encouragement to new researchers in this field with an emphasis on the technical issues of the increase of data capacity and decrease of device size.

• Journal of Korean Library and Information Science Society
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• v.34 no.2
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• pp.187-207
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• 2003

With the rapidly evolving information technologies and the Internet, a network-based storage management system is required that can efficiently save, search, modify, and manage digital contents which are increasing by geometric progression. Recently, the SAN became highlighted as a solution to such issues as the integrated data management for heterogeneous systems, the effective utilization of storage systems, and the limitation of data transfer. SAN allows for effective management and sharing of bulk data by directly connecting the storage systems, which used to be independently connected to servers, to the high-speed networks such as optical channels. In this study, I researched on the technologies, standardization and market trends of storage management systems, and performed comparative analyses of the structures, components, and performances for achieving the integration of diverse system storage systems as well as the virtualization of storage systems.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.17 no.4
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• pp.1182-1199
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• 2023

Fractional repetition (FR) codes can achieve exact uncoded repair for multiple failed nodes, with lower computational complexity and bandwidth overhead, and effectively improve repair performance in distributed storage systems (DSS). The actual distributed storage system is dynamic, that is, the parameters such as node storage overhead and number of storage nodes will change randomly and dynamically. Considering that traditional FR codes cannot be flexibly applied to dynamic distributed storage systems, a new construction scheme of adaptive-and-resolvable FR codes based on hypergraph coloring is proposed in this paper. Specifically, the linear uniform regular hypergraph can be constructed based on the heuristic algorithm of hypergraph coloring proposed in this paper. Then edges and vertices in hypergraph correspond to nodes and coded packets of FR codes respectively, further, FR codes is constructed. According to hypergraph coloring, the FR codes can achieve rapid repair for multiple failed nodes. Further, FR codes based on hypergraph coloring can be generalized to heterogeneous distributed storage systems. Compared with Reed-Solomon (RS) codes, simple regenerating codes (SRC) and locally repairable codes (LRC), adaptive-and-resolvable FR codes have significant advantages over repair locality, repair bandwidth overhead, computational complexity and time overhead during repairing failed nodes.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.11
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• pp.1558-1561
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• 2020

In this paper, we propose a blockchain scheme to enhance fault tolerance in distributed storage blockchain systems. Traditional blockchain systems suffer from ever-increasing storage cost. To overcome this problem, distributed storage blockchain techniques have been proposed. Distributed storage blockchain schemes effectively reduce the storage cost, but there are still limitations in reducing recovery cost and fault tolerance. The proposed approach recovers multiple errors within a group by utilizing locally repairable codes with availability. This improves the fault tolerance of the blockchain systems. Simulation results show that the proposed scheme enhances the fault tolerance while minimizing storage cost and recovery cost compared to other state-of-art schemes.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.25 no.1
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• pp.155-164
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• 2015

Information dispersal algorithm guarantees high availability and confidentiality for data and is one of the useful solutions for faulty and untrusted dispersed storage systems such as cloud storages. As the amount of data stored in storage systems increases, data deduplication which allows to save IT resources is now being considered as the most promising technology. Hence, it is necessary to study on an information dispersal algorithm that supports data deduplication. In this paper, we propose an information dispersal algorithm and proof of ownership for client-side data deduplication in the dispersed storage systems. The proposed solutions allow to save the network bandwidth as well as the storage space while giving robust security guarantee against untrusted storage servers and malicious clients.

• Transactions of the Society of Information Storage Systems
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• v.3 no.1
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• pp.40-42
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• 2007

• Transactions of the Society of Information Storage Systems
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• v.1 no.2
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• pp.137-142
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• 2005

In this paper, we propose a new servo system design strategy to reduce the position error signal(PES) and track mis-registration(TMR) in magnetic disk drive systems. The proposed method provides a systematic design procedure based on the plant model and an optimal solution via an optimization with a 'Robust Random Neighborhood Search(RRNS)' algorithm. In addition, it guarantees the minimum PES level as well as stability to parametric uncertainties. Furthermore, the proposed method can be used to estimate the performance at the design stage and thus can reduce the cost and time for the design of the next generation product. The reduction of PES as well as robust stability is demonstrated by simulation and experiments.