• Journal of Software Assessment and Valuation
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• v.15 no.2
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• pp.95-100
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• 2019

In this paper, we propose a simple hardware reporting method for errors in soft-RAID systems of Linux OS. Compared with other reporting methods, the proposed method displays error status intuitively without any additional access process such as log-in process or home-page access. In particular, the server actively displays the error status, so the administrator can take immediate action. In order to confirm the effectiveness of the proposed method, the experimental circuit was constructed and the experimental results showed that the error was actively displayed when an error occurred in the storage device. As such, a soft-RAID system can perform almost the same function as a hardware RAID system, thereby ensuring server data reliability at low cost.

• Journal of KIISE:Computing Practices and Letters
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• v.13 no.4
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• pp.213-225
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• 2007

Flash memory is widely used as a storage device for potable equipments such as digital cameras, MP3 players and cellular phones because of its characteristics such as its large volume and nonvolatile feature, low power consumption, and good performance. However, a block in flash memories should be erased to write because of its hardware characteristic which is called as erase-before-write architecture. The erase operation is much slower than read or write operations. FTL is used to overcome this problem. We compared the performance of the existing FTL algorithms on Windows-based OS. We have developed a tool called FTL APAT in order to gather I/O patterns of the disk and analyze the performance of the FTL algorithms. It is the log buffer scheme with full associative sector translation(FAST) that the performance is best.

• The KIPS Transactions:PartD
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• v.15D no.6
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• pp.755-766
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• 2008

Recently, NAND flash memory is becoming into the spotlight as a next-generation storage device because of its small size, fast speed, low power consumption, and etc. compared to the hard disk. However, due to the distinct characteristics such as erase-before-write architecture, asymmetric operation speed and unit, disk-based systems and applications may result in severe performance degradation when directly implementing them on NAND flash memory. Especially when a B-tree is implemented on NAND flash memory, intensive overwrite operations may be caused by record inserting, deleting, and reorganizing. These may result in severe performance degradation. Although ${\mu}$-tree has been proposed in order to overcome this problem, it suffers from frequent node split and rapid increment of its height. In this paper, we propose Log-Structured B-Tree(LSB-Tree) where the corresponding log node to a leaf node is allocated for update operation and then the modified data in the log node is stored at only one write operation. LSB-tree reduces additional write operations by deferring the change of parent nodes. Also, it reduces the write operation by switching a log node to a new leaf node when inserting the data sequentially by the key order. Finally, we show that LSB-tree yields a better performance on NAND flash memory by comparing it to ${\mu}$-tree through various experiments.

• The Journal of Engineering Geology
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• v.7 no.1
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• pp.11-26
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• 1997

Through the Korea-Germany joint project, a novel method, that is, an optical Corescanner (Stereophotogramrnetry) of acquisition, evaluation and display of struct-ural elements of drill cores has heen realized. AH scannable cores can he digitally stored on a storage device(dat tape, optical disc etc.) and available for further an-alysis using diverse software facilities. The use of this scanning technique was d-emonstrated on the cores derived from the metamorphosed sedimentary rocks in our country. Recent studies showed a great potential of using the Corescanner with high resolution not only for avoiding ambiguities of drill log interpretation due to the capability of accurate quantative analysis of structural elements, but also for replacing the cores themselves as a data-base one via completely copying of the core outlook.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07a
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• pp.13-16
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• 2004

The reliability of 1.550m-wavelength InGaAs mesa waveguide photodiodes(WGPDs), which developed for 40-Gbps optical receiver applications, fabricated by metal organic chemical vapor deposition is investigated. Reliability is examined by both high-temperature storage tests and the accelerated life tests by monitoring dark current and breakdown voltage. The median device lifetime and the activation energy of the degradation mechanism are computed for WGPD test structures. From the accelerated life test results, the activation energy of the degradation mechanism and median lifetime of these devices in room temperature are extracted from the log-normal failure model by using average lifetime and the standard deviation of that lifetime in each test temperature. It is found that the WGPD structure yields devices with the median lifetime of much longer than $10^6$ h at practical use conditions. Consequently, this WGPD structure has sufficient characteristics for practical 40-Gbps optical receiver modules.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.1
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• pp.229-235
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• 2015

ICT healing platform is based on bio-signal and life habit information target to alarm early sickness concept prevention chronic pain. ICT(Information & Communication Technology) healing platform target on personal lead health management care of several health agencies and open of the (hospital, fitness center, health examination center, personal health device) personal health information together to personal device. Support Analysis Platform and Open API to vitalization optional services. In this paper proposal to access personality healing data Open Gateway Framework of Healing Platform Adaptor (HPAdaptor) ICT healing platform means Data relaying link to EMR(Electronic health record), korean medicine, life log, wellness, chronic pain, and fineness several personal health data provider and service provider personal healing data with software engine. After Design HPAdaptor can use for data and service provider record storage, mobile platform and analytics platform need data service or platform relying reference model.

• Journal of Digital Convergence
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• v.16 no.10
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• pp.235-241
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• 2018

The printout management system should analyze the pattern of existence of personal information (resident number, card number) in the output log and users should be provided with functions such as warning message pop-up, forced printing termination, mailing to administrator, independently logs management. Authentication management can also be performed only by registered users by installing an agent on a user PC, and it should have a restriction function to permit or deny work according to user information. In addition, when printing/copying/scanning using this equipment, it is possible to use document printing and multifunction copier after ID card authentication and ID/PW should be input to device when ID card is not used. In this study, we developed these interfaces with WOWSOFT co., Ltd, a security company that has better technology than the existing printout security methods, to construct the printout management system. Also we designed the interface of basic functions necessary for printout management and contributed to the establishment of printout management system.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2023.05a
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• pp.98-99
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• 2023

In the maritime digital forensic part, it is very important and difficult process that analysis of data and information with vessel navigation system's binary log data for situation awareness of maritime accident. In recent years, analysis of vessel's navigation system's trajectory information is an essential element of maritime accident investigation. So, we made an experiment about corruption with various memory device in navigation system. The analysis of corruption test in seawater give us important information about the valid pulling time of sunken ship for acquirement useful trajectory information.

• Journal of KIISE:Computer Systems and Theory
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• v.35 no.1
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• pp.18-29
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• 2008

NAND Flash memory has been growing popular storage device for the last years because of its low power consumption, fast access speed, shock resistance and light weight properties. However, it has the distinct characteristics such as erase-before-write architecture, asymmetric read/write/erase speed, and the limitation on the number of erasure per block. Due to these limitations, various Flash Translation Layers (FTLs) have been proposed to effectively use NAND flash memory. The systems that adopted the conventional FTL may result in severe performance degradation by the hot data which are frequently requested data for overwrite in the same logical address. In this paper, we propose a novel FTL algorithm called Adaptive Flash Translation Layer (AFTL) which uses sector mapping method for hot data and log-based block mapping method for cold data. Our system removes the redundant write operations and the erase operations by the separating hot data from cold data. Moreover, the read performance is enhanced according to sector translation that tends to use a few read operations. A series of experiments was organized to inspect the performance of the proposed method, and they show very impressive results.