• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.469-475
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• 1991

In this paper, we suggest the exact perturbation analysis(Exact_PA) technique with respect to the buffer storage in tandem queueing networks, through which the optimal buffer storage design problem is considered. The discrete event dynamic equations for the departure time of a customer are presented together with the basic properties of Full Out(FO) and No Input(NI) with respect to the buffer storage. The new perturbation rules with respect to the buffer storage are suggested, from which the exact perturbed path can be obtained. The optimal buffer storage problem is presented by introducing a performance measure consisting of the throughput and the buffer storage cost. An optimization algorithm maximizing this performance measure is derived by using the Exact_PA technique. The proposed perturbation analysis technique and the optimization algorithm are validated by numerical examples.

• Journal of KIISE:Computing Practices and Letters
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• v.8 no.4
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• pp.389-398
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• 2002

As XML has been proposed a standard format for organizing and exchanging data in the internet, many applications on managing XML data have been developed. Especially, there are many studies for storing XML documents. It is important to evaluate the performance for efficient storage techniques. In this work, we suggest an efficient technique for storing XML documents using an object-relational database model. We verify the efficiency of a new storage technique through the performance evaluation on XML storage techniques. The contributions of this paper is that we suggest an efficient storage technique using an existing data management model and evaluate the performance for storage techniques for XML documents including an new storage technique.

• Water for future
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• v.18 no.3
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• pp.253-264
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• 1985

Basically, there are two ways viewing the reservoir storage-yield relationship., The most common viewpoint is the determination of the storage required at a given reservoir to supply a required yield. This type of problem is usually encountered in the planning and early design phases of a reservoir. The second viewpoint is the determination of yield from a given amount of storage. This often occurs in the final design phases or in re-evaluation of an existing reservoir for a more comprehensive analysis. The purpose of this study is to improve the present methodology estimating the storage-yield relationship for a reservoir design or a reservoir operation. The Residual Mass curve Technique, the slightly modified version of Low Flow Techniques and the Transition Probability Matrix Technique are reviewed and examined for the best fit technique to find the reservoir storage-yield realtionship. The historical data during 1917~1940 at the proposed Hongchun damsite and the synthetic data simulated by Thomas-Fiering model are utilized to examine the reservoir storge-yield relationship with three techniques in detail. After the three techniques which estimate the reservoir storage-yield relationship were reviewed extensively, it was concluded that the Residual Mass Curve Technique and the slightly modified version of Low Flow Techniques were suitable for a preliminary design, but the Transition Probability Matrix Technique Provided satisfactory results as a final design technique because it reflected the variation of a monthly yield as well as seasonlly.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.7
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• pp.3794-3820
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• 2019

In recent years, a cloud environment with the ability to detect illegal behaviours along with a secured data storage capability is much needed. This study presents a cloud storage framework, wherein a 128-bit encryption key has been generated by combining deoxyribonucleic acid (DNA) cryptography and the Hill Cipher algorithm to make the framework unbreakable and ensure a better and secured distributed cloud storage environment. Moreover, the study proposes a DNA-based encryption technique, followed by a 256-bit secure socket layer (SSL) to secure data storage. The 256-bit SSL provides secured connections during data transmission. The data herein are classified based on different qualitative security parameters obtained using a specialized fuzzy-based classification technique. The model also has an additional advantage of being able to decide on selecting suitable storage servers from an existing pool of storage servers. A fuzzy-based technique for order of preference by similarity to ideal solution (TOPSIS) multi-criteria decision-making (MCDM) model has been employed for this, which can decide on the set of suitable storage servers on which the data must be stored and results in a reduction in execution time by keeping up the level of security to an improved grade.

• Smart Media Journal
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• v.5 no.1
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• pp.69-77
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• 2016

This paper proposes a software defined storaging method to converge the network virtualization technique and the RAID of distributed storage environment. The proposed method designs software based storage which it apply a flexible control and maintenance of storages. In addition, the method overcomes the restricted of physical storage capacity and cut costs of data recovery. The proposed failover recovery technique based on Software-Defined RAID has been tested the substantial verification and the performance using public AWS and Google Storage.

• Journal of the Korea Society of Computer and Information
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• v.14 no.4
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• pp.9-17
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• 2009

In this paper, we propose a dynamic load distribution technique at the operating system level in mobile storage systems with a heterogeneous storage pair of a small form-factor and disk and a flash memory, which aims at saving energy consumption as well as enhancing I/O performance. Our proposed technique takes a combinatory approach of file placement and buffer cache management techniques to find how the load can be distributed in an energy and performance-aware way for a heterogeneous mobile storage air of a hard disk and a flash memory. We demonstrate that the proposed technique provides better experimental results with heterogeneous mobile storage devices compared with the existing techniques through extensive simulations.

• JSTS:Journal of Semiconductor Technology and Science
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• v.15 no.5
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• pp.570-576
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• 2015

Existing flash storage devices such as universal flash storage and solid state disk support command queuing to improve storage I/O bandwidth. Command queuing allows multiple read/write requests to be pending in a device queue. Because multi-channel and multi-way architecture of flash storage devices can handle multiple requests simultaneously, command queuing is an indispensable technique for utilizing parallel architecture. However, command queuing can be harmful to the latency of fsync system call, which is critical to application responsiveness. We propose a dynamic queue depth adaptation technique, which reduces the queue depth if user application is expected to send fsync calls. Experiments show that the proposed technique reduces the fsync latency by 79% on average compared to the original scheme.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.4 no.5
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• pp.877-895
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• 2010

The state-of-the-art techniques of storing XML data, modeled as an XML tree, are node-based in the sense that they are centered around XML node labeling and the storage unit is an XML node. In this paper, we propose a generalization of such techniques so that the storage unit is an XML subtree that consists of one or more nodes. Despite several advantages with such generalization, a major problem would be inefficiency in XPath processing where the stored subtrees are to be parsed on the fly in order for the nodes inside them to be accessed. We solve this problem, proposing a technique whereby no parsing of the subtrees involved in XPath processing is needed at all unless they contain the nodes of the final query result. We prove that the correctness of XPath processing is guaranteed with our technique. Through implementation and experiments, we also show that the overhead of our technique is acceptable.

• 정보저장시스템학회:학술대회논문집
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• 2005.10a
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• pp.246-247
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• 2005

This study suggested fanless thermal design using CAE technique for the information storage system under the serious thermal problem. At first, main heat flow was controlled by CAE based fanless heat sink design not to influence sensitive optical pick-up sensor. Then, vent parametric studies found a thermal solution about highly concentrated case top heat due to fanless. These CAE results were verified by experimental methods. As a consequence of newly designed thermal path, thermal specification of optical pick-up sensor was satisfied and fanless thermal design for the information storage system was achieved.

• IEMEK Journal of Embedded Systems and Applications
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• v.14 no.2
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• pp.63-69
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• 2019

Recently, ultra-low latency flash storage devices such as Z-SSD and Optane SSD were introduced with the significant technological improvement in the storage devices which provide much faster response time than today's other NVMe SSDs. With such ultra-low latency, $10{\mu}s$, storage devices the cost of context switch could be an overhead during interrupt-driven I/O completion process. As an interrupt-driven I/O completion process could bring an interrupt handling overhead, polling or hybrid-polling for the I/O completion is known to perform better. In this paper, we analyze tail latency problem in a polling process caused by process scheduling in data center environment where multiple applications run simultaneously under one system and we introduce our adaptive polling selection technique which dynamically selects efficient processing method between two techniques according to the system's conditions.