• Journal of Communications and Networks
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• v.18 no.3
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• pp.493-501
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• 2016

In-network storage is an effective technique for avoiding network congestion and reducing power consumption in continuous data collection in wireless sensor networks. In recent years, network coding based storage design has been proposed as a means to achieving ubiquitous access that permits any query to be satisfied by a few random (nearby) storage nodes. To maintain data consistency in continuous data collection applications, the readings of a sensor over time must be sent to the same set of storage nodes. In this paper, we present an efficient approach to updating data at storage nodes to maintain data consistency at the storage nodes without decoding out the old data and re-encoding with new data. We studied a transmission strategy that identifies a set of storage nodes for each source sensor that minimizes the transmission cost and achieves ubiquitous access by transmitting sparsely using the sparse matrix theory. We demonstrate that the problem of minimizing the cost of transmission with coding is NP-hard. We present an approximation algorithm based on regarding every storage node with memory size B as B tiny nodes that can store only one packet. We analyzed the approximation ratio of the proposed approximation solution, and compared the performance of the proposed coding approach with other coding schemes presented in the literature. The simulation results confirm that significant performance improvement can be achieved with the proposed transmission strategy.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.5
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• pp.2449-2456
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• 2013

The column-oriented database storage is a very advanced model for large-volume data analysis systems because of its superior I/O performance. Traditional data storages exploit row-oriented storage where the attributes of a record are placed contiguously in hard disk for fast write operations. However, for search-mostly datawarehouse systems, column-oriented storage has become a more proper model because of its superior read performance. Recently, solid state drive using MLC flash memory is largely recognized as the preferred storage media for high-speed data analysis systems. In this paper, we introduce fast column-oriented data storage model and then propose a new storage management scheme using a cross compressed replication for the high-speed column-oriented datawarehouse system. Our storage management scheme which is based on two MLC SSD achieves superior performance and reliability by the cross replication of the uncompressed segment and the compressed segment under high workloads of CPU and I/O. Based on the results of the performance evaluation, we conclude that our storage management scheme outperforms the traditional scheme in the respect of update throughput and response time of the column segments.

• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.6
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• pp.1145-1152
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• 2021

In order to optimize the performance of 1.4P large storage, the characteristics of each chunk mode were investigated, and the chunk 512K mode was selected in terms of I/O speed. NVME storage system was configured and used to measure data server performance of large storage. By measuring the change in throughput according to the number of threads of the 1.4P large storage, the characteristics of the large storage system were identified, and it was confirmed that the performance was up to 133Gbps with a block size of 32KB. As a result of data transmission/reception experiment using globus-url-copy of GridFTP, it was found that this large storage has a throughput of 33Gbps.

• Journal of KIISE:Computing Practices and Letters
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• v.10 no.6
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• pp.448-459
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• 2004

Interoperability is an important requirement of portable storage devices that are used to exchange and share data among diverse hosts. However, the required interoperability cannot be provided if different host systems use different file systems. To address this problem, we propose a new type of storage device called FSOC(File System On a Chip) that contains the file system within the storage device. In this paper, we give an example of the design and implementation of a flash memory-based FSOC and propose the performance models of the conventional storage device and the FSOC. We also analyze the performance characteristics of the conventional storage device and the FSOC based on the proposed performance models, and provide several experimental results using real applications that validate the performance models.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.22 no.6
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• pp.369-374
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• 2010

A refrigerant-subcooling refrigeration system consisted of a typical single vapor-compression refrigeration cycle, a subcooler, and an ice storage tank. The degree of subcooling at the exit of the condenser can be increased by the heat exchange between the subcooler and the ice storage tank. The cold heat in the ice storage tank was stored by using the refrigeration cycle during night time and then used to absorb the heat from the subcooler during daytime. The performance of the refrigerant-subcooling refrigeration system was measured by varying the degree of subcooling. In addition, the performance characteristics of the present system were compared with those of a conventional refrigeration system. The mass flow rate of the present system was higher than that of the conventional system due to the increase in the degree of subcooling. Generally, the refrigerant-subcooling system showed superior performance to the conventional refrigeration system.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.6 no.4
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• pp.354-364
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• 1994

Experiments have carried out to investigate the effects of parameters, such as mass ratio of R141b-to-water, stirrer speed, brine inlet temperature, brine flowrate, and additives, on the performance of the cool storage system using R141b clathrate. The cool storage system in this experiment was composed of storage tank, refrigerator, and heater. The results show that the mass ratio of R141b-to-water, 1 : 3~1 : 3.5 gives the best performance and the stirring speed has optimum point as 600rpm. At this speed impeller Reynolds number is $1.01{\times}10^5$. The lower the inlet brine temperature and the highter the brine flowrate, the better performance. The addition of metal powder turned out to reduce the degree of supercooling. The supercooling reduction was proportional to the amount of the metal power. However when metal powder was added more than 0.1 wt%, there was no additional supercooling reduction. The surfactants shortened the time consumed for cool storage to the half of no surfactant added case.

• Proceedings of the SAREK Conference
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• 2007.11a
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• pp.119-123
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• 2007

Ventilation performance in the storage hall of Janggyeongpan Jeon has maintained for more than 600 years. Janggyeongpan Jeon in Haein temple has window structure of bi-level ventilating opening which consists of upper and lower window. Also, different size and shape of windows are adopted for various locations of the hall. In the present study, to analyze effect of shape of windows on ventilation performance in the storage hall, various design alternatives were considered. Numerical analysis of ventilation in the storage hall was investigated under the same simulation condition except for the shape of windows. Through the comparison of numerical results for various window designs, it was evaluated that the current windows shape gives best ventilation performance.

• KIPS Transactions on Computer and Communication Systems
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• v.3 no.12
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• pp.433-442
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• 2014

In this paper, we introduce the client side cache of distributed file system for enhancing read performance by eliminating the network latency and decreasing the back-end storage burden. This performance enhancement can expand the fields of distributed file system to not only cloud storage service but also high performance storage service. This paper shows that the distributed file system with client side SSD cache can satisfy the requirements of VDI(Virtual Desktop Infrastructure) storage. The experimental results show that full-clone is more than 2 times faster and boot time is more than 3 times faster than NFS.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.20 no.10
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• pp.645-653
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• 2008

Spiral-jacketed thermal storage tanks can greatly simplify solar heating systems while maintaining the thermal performance at a similar level as conventional systems with an external heat exchanger. Proper design of the spiral-jacket flow path is essential to make the most of solar energy, and thus to maximize the thermal performance. In the present work, computational fluid dynamics (CFD) analysis was carried out for a spiral-jacketed storage tank installed in a solar heating demonstration system. The results of the CFD analysis showed a good agreement with experimentally determined thermal performance indices such as the acquired heat, collector efficiency, and mixed temperature in the storage tank. This verified CFD modelling approach can be a useful design tool in optimizing the shape of spiral-jacket flow path and the flow rate of circulating fluid for better performance.

• Journal of KIISE
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• v.42 no.8
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• pp.954-960
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• 2015

It is important to improve the performance of storage in the home cloud environment within the virtualized IoT gateway since the performance of applications deeply depends on storage. Though SSD caching is applied in order to improve the storage, it is only used for read-cache due to the limitations of SSD such as poor write performance and small write endurance. However, it is important to improve performance of the write operation in the home cloud server, in order to improve the end-user experience. This paper propose a novel SSD caching which considers write-data as well as read-data. We validate the enhancement in the performance of random-write by transforming it to the sequential patterns.