• Journal of Digital Contents Society
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• v.19 no.3
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• pp.497-503
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• 2018

RHEL 7, the leader in the enterprise Linux market, has dramatically increased the maximum support specification, such as file system size, file size, etc., by changing the default file system from EXT to XFS. It's not just an increase in support specifications, it's working on daemons, and it's showing excellent performance on high-performance disks such as high-capacity disks and solid state drives. Changes in the file system mean changes in direct operating techniques, such as changing related commands, changing backup tools, and changing disk quota settings. The changes to the XFS file system are making a lot of changes to the operation of the Linux system, but we believe that the position of the Linux operating system in the server field will become stronger.

• The KIPS Transactions:PartD
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• v.17D no.6
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• pp.383-394
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• 2010

Flash memory based SSDs are currently being considered as a promising candidate for replacing hard disks due to several superior features such as shorter access time, lower power consumption and better shock resistance. However, SSDs have different characteristics from hard disk such as difference of unit and time for read, write and erase operation and impossibility for over-writing. Because of these reasons, SSDs have disadvantages on hard disk based systems, so FTL(Flash Translation Layer) is designed to increase SSDs' efficiency. In this paper, we propose an advanced logical address mapping method for increasing SSDs' performance, which is named HAMM(Hybrid Address Mapping Method). HAMM addresses drawbacks of previous block-mapping method and super-block-mapping method and takes advantages of them. We experimented our method on our own SSDs simulator. In the experiments, we confirmed that HAMM uses storage area more efficiently than super-block-mapping method, given the same buffer size. In addition, HAMM used smaller memory than block-mapping method to construct mapping table, demonstrating almost same performance.

• The KIPS Transactions:PartD
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• v.17D no.6
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• pp.395-404
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• 2010

Solid-State Disks (SSDs) have been currently considered as a promising candidate to replace hard disks, due to their significantly short access time, low power consumption, and shock resistance. SSDs, however, have drawbacks such that their write throughput and life span are decreased by random-writes, nearly regardless of SSDs controller designs. Previous studies have mostly focused on better designs of SSDs controller and reducing the number of write operations to SSDs. We suggest another method that reallocates data pages that tend to be simultaneously written to contiguous blocks. Our method gathers write operations during a period of time and generates write traces. After transforming each trace to a set of transactions, our method mines frequent itemsets from the transactions and reallocates the pages of the frequent itemsets. In addition, we introduce an algorithm that reallocates the pages of the frequent itemsets with moderate time complexity. Experiments using TPC-C workload demonstrated that our method successfully reduce 6% of total logical block access.

• Journal of information and communication convergence engineering
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• v.21 no.1
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• pp.24-31
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• 2023

The solid-state drive (SSD) possesses higher input and output speeds, more resistance to physical shock, and lower latency compared with regular hard disks; hence, it is an increasingly popular storage device. However, tiny components on an internal printed circuit board (PCB) hinder the manual detection of malfunctioning components. With the rapid development of artificial intelligence technologies, automatic detection of components through convolutional neural networks (CNN) can provide a sound solution for this area. This study proposes applying the YOLOv5 model to SSD PCB component detection, which is the first step in detecting defective components. It achieves pioneering state-of-the-art results on the SSD PCB dataset. Contrast experiments are conducted with YOLOX, a neck-and-neck model with YOLOv5; evidently, YOLOv5 obtains an mAP@0.5 of 99.0%, essentially outperforming YOLOX. These experiments prove that the YOLOv5 model is effective for tiny object detection and can be used to study the second step of detecting defective components in the future.

• The KIPS Transactions:PartA
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• v.18A no.4
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• pp.135-142
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• 2011

This research is to design an effective buffer structure and its management for flash memory based high performance SSDs (Solid State Disks). Specifically conventional SSDs tend to show asymmetrical performance in read and /write operations, in addition to a limited number of erase operations. To minimize the number of erase operations and write latency, the degree of interleaving levels over multiple flash memory chips should be maximized. Thus, to increase the interleaving effect, an effective buffer structure is proposed for the SSD with a hybrid address mapping scheme and super-block management. The proposed buffer operation is designed to provide performance improvement and enhanced flash memory life cycle. Also its management is based on a new selection scheme to determine random and sequential accesses, depending on execution characteristics, and a method to enhance the size of sequential access unit by aggressive merging. Experiments show that a newly developed mapping table under the MBA is more efficient than the basic simple management in terms of maintenance and performance. The overall performance is increased by around 35% in comparison with the basic simple management.

• Proceedings of the KAIS Fall Conference
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• 2008.05a
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• pp.218-219
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• 2008

Solid State Disks(SSD) are one of the best candidates to support next storage technology in desktop and server computing environment. The features of non-volatility, low power consumption, and fast access time for read operations are sufficient grounds to support SSD as major components of future storages. This paper describes a technical trend of HDD based RAID technology and proposes a new RAID system for SSD.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2536-2539
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• 2008

A study has been made on how to occur inertial oscillations in a rotating flow. The flow is considered to be induced by differentially-rotating top and bottom disks with infinite radius. The top and bottom disks are assumed to be set in motion over a finite initial start-up time duration from initial solid body rotation ($\Omega$) to each finial state, i.e., the top disk is rotating at the angular velocity (${\Omega}+{\Delta}{\Omega}$) and the bottom disk (${\Omega}-{\Delta}{\Omega}$). The system Reynolds number, which is a reciprocal of conventional Ekman number in rotating flows, is very high so that a boundary layer flow near disks is pronounced. From a strict theoretical analysis, it is clearly found the fact that inertial oscillation in a rotating flow is caused by excessive input of torque during start-up phase. Above finding comes from the following physics of theoretical result: in the case of abrupt start-up within very shorter time-duration than spin-up time scale, the inertial oscillation is magnified but it could be completely depressed in the case of mildly accelerated start-up, i.e., start-up process being established over diffusion time scale.

• Vacuum Magazine
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• v.4 no.2
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• pp.4-9
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• 2017

Dusty plasmas consisting of electrons, ions, neutral gas molecules, and small solid-state 'dust' particles are ubiquitous. Examples include plasma processing, fusion plasmas, polar mesospheric clouds, Saturn's rings, comet tails, and protoplanetary disks. Since Voyager I and II discovered dusty plasmas in our solar system, dusty plasmas have been extensively studied from space & basic sciences to semiconductor & display industries. Here, a brief review on dusty plasma research is given and some remarkable results are introduced.

• Journal of Advanced Navigation Technology
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• v.13 no.4
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• pp.509-514
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• 2009

In this paper, we designed and analyzed 256GB DRAM-based SSD storage using DDR1 memory and PCI-e interface. SSD is a storage system that uses DRAM or NAND Flash as primary storage media. Since the SSD read and write data directly to memory chips, which results in storage speeds far greater than conventional magnetic storage devices, HDD. Architecture of the proposed SSD system has performance of high speed data processing duo to use multiple RAM disks as primary storage and PCI-e interface bus as communication path of RAM disks. We constructed experimental system with UNIX, Windows/Linux server, SAN Switch, and Ethernet Switch and measured IOPS and bandwidth of proposed SSD using IOmeter. In experimental results, it has been shown that IOPS, 470,000 and bandwidth,800MB/sec of the DDR-1 SSD is better than those of the HDD and Flash-based SSD.

• Journal of Internet of Things and Convergence
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• v.10 no.2
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• pp.109-114
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• 2024

Enterprise storage systems that require high data reliability are applying RAID (Redundant Array of Independent Disks) systems to recover from data loss and failure. In particular, RAID 5 ensures space efficiency and reliability by distributing parity across multiple storage devices. However, when storage devices have different capacities, RAID is built based on the smallest capacity storage device, resulting in wasted storage space. Therefore, research is needed to solve this resource management problem. In this paper, we propose a method for RAID grouping of each independent NAND flash memory block in a RAID consisting of SSD (Solid State Disk) with external SSDs as well as internal SSDs. This method is divided into a policy for delivering block information inside SSDs to the RAID system and a policy for RAID grouping of physical addresses delivered from the RAID system. This method allows us to maintain a RAID that does not waste resources when SSDs of different capacities are grouped into RAID5. Finally, we demonstrate the effectiveness of the proposed method through experiments.