• 정보저장시스템학회논문집
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• 제3권2호
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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.

• 대한전기학회논문지:전력기술부문A
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• 제49권4호
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• pp.152-160
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• 2000

This paper presents an efficient evaluation method on the role of new energy storage systems, especially the secondary Battery Energy Storage (BES) systems, in the case where they are interconnected with the power distribution systems. It is important to perform the economic evaluation for the new energy storage systems in a synthetical and quantitative manner, because they are very costly in the early stage of their development and commercialization. In this paper, the multiple functions of BES systems, which are operated at distribution systems, such as load levelling, effective utilization of power distribution systems and uninterruptible power supply at the emergency conditions are classified and analyzed. And then the quantitative evaluation methods of the multiple functions for BES systems are proposed using the mathematical modelling.

• 한국도서관정보학회지
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• 제34권2호
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• pp.187-207
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• 2003

정보기술과 인터넷의 진화에 따라 기하급수적으로 증가하는 디지털콘텐츠를 효율적으로 저장, 검색, 변경, 관리할 수 있는 네트워크 기반 저장관리시스템이 요구되고 있다. 분산 네트워크 환경하에 이 기종 시스템의 데이터 통합관리, 저장 장치의 효과적인 활용, 데이터 전송 한계 등의 문제에 대한 해결방안으로 SAN이 대두되었다. SAN은 개별적으로 서버에 연결되던 저장장치들을 광 채널과 같은 고속네트워크에 직접 연결시켜 대용량 데이터를 효과적으로 관리하고 공유할 수 있도록 해주는 시스템이다. 본 연구는 저장관리시스템의 기술과 표준화 및 시장동향 조사와 다중 시스템 저장장치의 통합과 저장장치의 가상화를 이루기 위한 구조와 구성장치 및 성능을 비교 분석하였다.

• 대한산업공학회지
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• 제20권2호
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• pp.39-50
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• 1994

Most research results on the throughput of unit-load automated storage retrieval (AS/R) systems assume the randomized storage; that is, all slots In the entire rack are equally likely to be selected for the storage location. However, for the most existing AS/R systems which use Closest Open location storage policy, Park[6] mathematically showed that this assumption results in a significant difference from the actual performance of AS/R systems. In this study, we present more details about the performance of the unit-load AS/R systems by considering the rack utilization and rack density; and examine their impact on the throughput of AS/R systems by using computer simulation. A new storage policy named Shortest Cycle Location(SCL) is proposed. Simulation results indicate that the performance of SCL policy consistently outperforms the Closest Open location storage policy. We also define the "Extra-Cost Zone" compared to the "No-Cost Zone"[3] and explore its geometric and practical meaning.

• 한국컴퓨터정보학회논문지
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• 제24권9호
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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.

• 한국정보통신학회논문지
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• 제24권11호
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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.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2007년도 The 1st International Symposium on Advanced Magnetic Materials
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• pp.42.1-42.1
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• 2007

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제17권4호
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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.

• Industrial Engineering and Management Systems
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• 제4권2호
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• pp.136-144
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• 2005

This research deals with an order picking problem in automated storage and retrieval systems (AS/RS). When retrieval requests consist of multiple items and the items are in multiple stock locations, the storage/retrieval (S/R) machine must travel to numerous storage locations to complete each order. The aim of this research is to propose algorithms for the resolution of order picking problems with multiple stock locations to minimize the total time traveled by the S/R machine. We present and compare three alternatives for solving the problem based on enumeration, ordinary heuristic and genetic algorithms. We used a set of 180 different problems that are solved by these three algorithms. The results show that our proposed genetic algorithm is more efficient than the other two.

• 한국시뮬레이션학회논문지
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• 제10권3호
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• pp.71-82
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• 2001

Considering material handling delay which occurs between storage and processing stations, we propose an algorithm to estimate the required storage capacity, i.e., number of aisles and number of openings in vertical and horizontal directions in each aisle, of an automated storage/retrieval(AS/R) system. Due to the random nature of storage and retrieval requests, proportion of single and dual commands is not known in advance. Two design criteria, maximum permissible overflow probability and maximum allowable storage/retrieval(S/R) machine utilization, are used to compute the storage capacity. Most of studies assume that storage capacity of AS/R systems is given, although it is a very important decision variable in the design phase. Therefore, the proposed model can be effectively used in the design phase of new AS/R systems.