• 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.

• International Journal of Industrial Entomology and Biomaterials
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• v.48 no.1
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• pp.33-41
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• 2024

To investigate the effect of sawdust fermentation period and storage period after fermentation on development as food for P. brevitarsis larvae, individual and group breeding were conducted on berry sawdust and oak sawdust. In individual breeding, the growth period of P. brevitarsis larvae was reduced by 12 days from the 60-day fermentation of berry sawdust to the 40-day fermentation of berry sawdust, 30 days from the 90-day fermentation of oak sawdust, and the weight of the larvae was the heaviest. In group breeding, the time it takes for P. brevitarsis larvae to change from 1^st to 3^rd instar is about 30 days after hatching from 60-day fermentation of berry sawdust, while 90-day fermentation of oak sawdust took more than 60 days, so the growth speed was fast and the survival rate was good. The results of the farmhouse demonstration test were the same trend, and it was judged that it would be possible to produce P. brevitarsis larvae with berries fermented sawdust, and it would be advantageous in terms of economy. In addition, for both individual and group breeding, the growth period of P. brevitarsis larvae was longer as the storage period was longer, the weight of the larvae decreased, and the survival rate was no different. The development period of P. brevitarsis larvae was the longest in the storage period of 18 months for berries fermented sawdust, and the storage period of oak fermented sawdust was longer in the storage period of 12 months and 18 months. Therefore, considering the results of individual breeding and group breeding, the fermentation period was appropriate for 60 days for berries sawdust, and the storage period for berries sawdust was stable from 0 to 12 months, and 0 to 6 months for oak sawdust.

• Journal of Electrical Engineering and Technology
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• v.12 no.2
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• pp.726-737
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• 2017

The use of energy storage systems (ESSs) has become a feasible solution to solve the wind power intermittency issue. However, the use of ESSs increases the system cost significantly. In this paper, an optimal power flow control scheme to minimize the ESS capacity is proposed by using the zero-phase delay low-pass filter which can eliminate the phase delay between the dispatch power and the wind power. In addition, the filter time constant is optimized at the beginning of each dispatching interval to ensure the fluctuation mitigation requirement imposed by the grid code with a minimal ESS capacity. And also, a short-term power dispatch control algorithm is developed suitable for the proposed power dispatch based on the zero-phase delay low-pass filter with the predetermined ESS capacity. In order to verify the effectiveness of the proposed power management approach, case studies are carried out by using a 3-MW wind turbine with real wind speed data measured on Jeju Island.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.7
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• pp.1045-1052
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• 2013

In this study we deal with design procedures for the flywheel energy storage system that has the capacity to store the regenerative energy produced from the railway vehicles. The flywheel energy storage system (FESS) stores the regenerative electrical energy into the high speed rotational flywheel, by conversion the electrical energy into the mechanical rotational energy. Thus the FESS is composed of the energy conversion components, such as the motor and generator, mechanical support components, such as the rotational rotor, the magnetic bearings to support the rotor, and the digital controller to control the air gap between the rotor and the magnetic bearings. In this paper the design procedures for the rotor operating at the rigid mode and the magnetic bearings to support the rotational rotor without contact are presented.

• The KIPS Transactions:PartC
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• v.18C no.5
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• pp.293-302
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• 2011

The various information services can be delivered by smartphone through advanced high-speed mobile communication. A smartphone is a mobile device that offers more powerful computing capacity than feature phone. Therefore this device can provide such as web surfing, editing documents, playing video, and playing games. A lot of personal information stored on smartphone. Because it has High usability. Personal information Leaks if the smart phone is lost or stolen may become a big problem. In this paper we have analyzed existing method for providing secure storage and user authentication on mobile platform and derived security requirement. Therefore we propose the following scheme that satisfy security requirement. Proposed scheme providing secure storage with preventing authentication bypass, and availability from damaged data to access secure area.

• The Journal of Society for e-Business Studies
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• v.12 no.3
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• pp.251-268
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• 2007

We design and implement an efficient storage technique to improve query processing for a large RDF data set. The proposed techniques can minimize data redundancy compared to the existing techniques by splitting relation information and data information from triple formatted RDF data. Also, we can enhance query processing speed separating and connecting the entire query steps by relation and data based on the proposed storage technique. The proposed technique can be applied to the areas, such as e-Commerce, semantic web, and KMS to store and retrieve a large RDF data set.

• Journal of Broadcast Engineering
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• v.24 no.6
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• pp.956-964
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• 2019

In the age of personal media such as YouTube and Twitch, individual media content creation and consumption have become simpler. A huge amount of media content is created and consumed through platform services. In this regard, interest in copyright of media contents is increasing. In particular, the sound source is an indispensable element in almost all media contents production. In this paper, we propose a method to store the sound source and its signature using blockchain and distributed storage system to verify the copyright of music contents. We Identify the possibility of including the audio signature extraction result of the sound source as blockchain transaction data. Through experiments, we compare the input and output speed when the sound source and its signature are stored in the distributed storage system.

• Journal of the Korea Society of Computer and Information
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• v.22 no.2
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• pp.1-7
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• 2017

Recently, NAND flash memory, which is used as a storage medium, is replacing HDD (Hard Disk Drive) at a high speed due to various advantages such as fast access speed, low power, and easy portability. In order to apply NAND flash memory to a computer system, a Flash Translation Layer (FTL) is indispensably required. FTL provides a number of features such as address mapping, garbage collection, wear leveling, and hot data identification. In particular, hot data identification is an algorithm that identifies specific pages where data updates frequently occur. Hot data identification helps to improve overall performance by identifying and managing hot data separately. MHF (Multi hash framework) technique, known as hot data identification technique, records the number of write operations in memory. The recorded value is evaluated and judged as hot data. However, the method of counting the number of times in a write request is not enough to judge a page as a hot data page. In this paper, we propose hot data identification which considers not only the number of write requests but also the persistence of write requests.

• Composites Research
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• v.18 no.4
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• pp.8-13
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• 2005

Rotating circular disks are widely used in data storage devices as well as in traditional industrial machines. Faster rotating speed is required in data storage devices for higher data transfer rate. In this Paper an application of composite materials to CD is proposed to increase critical speeds and the strength analysis was performed. A differential equation of displacement is derived for the analytic stress distribution of rotating polar orthotropic disk. The stress distributions for typical GFRP and CFRP disks and the maximum allowable speeds subjected to a constraint of tensile strength are presented in addition to polycarbonate disk. The results show that the application of CFRP to rotating disk can increase the maximum allowable rotating speed but this may not be applicable to GFRP disk.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.6
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• pp.1138-1145
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• 2009

This paper presents an active and reactive power compensator for the wind power system with squirrel-cage induction generator. The output power of a wind power system changes irregularly according to the variation of wind speed. The developed system is able to continuously compensate the active and reactive power. The 3-phase inverter operates for the compensation of reactive power, while the DC/DC converter with super-capacitors operates for the compensation of active power. The operational feasibility of the proposed model was verified by simulations with PSCAD/EMTDC and the feasibility of hardware implementation was confirmed by experimental works with a scaled hardware model. The proposed compensator can be expected that developed system may be used to compensated the abrupt power variation due to sudden change of wind speed or sudden power-drop by tower effect. It can be also applied for the distributed generation and the Micro-Grid.