• Journal of Applied Reliability
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• v.12 no.3
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• pp.153-163
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• 2012

Recently, as a electronic components are becoming more high-density, so that electronic circuits have smaller pitches between the leads and are more vulnerable to insulation failure. And the reliability of electric insulation has become an ever important issue as device contact pitches and print patterns shrink. Ion migration occurs in highly humid environment as voltage is applied to an installed print circuit. Under highly humid and voltage applied circumstances, electronic components respond to applied voltages by electrochemical ionization of metals, and a conducting filament forms between the anode and cathode across a nonmetallic medium. This leads to short-circuit failure of the electronic component. In thesis, we study acceleration test of ion migration in FR-4 PCB plated with Sn. Voltage applied test of FR-4 PCB circuits plated with Sn was tested in the temperature and humidity environments. As a result of this test, equation of acceleration model was derived.

• Information Systems Review
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• v.10 no.2
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• pp.309-327
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• 2008

This research is a byproduct of a project initiated by a major airport in Korea. The airport aimed to enhance airside safety and weighed a few IT options that may strengthen its current safety practices. In order to satisfy requirements unique to the airport and to inherit existing legacy systems, a PCS-based mobile database system was proposed. We first discuss technical aspects of the system as well as design issues in mobile systems before we compare two specific alternatives for transactional service handoff. A simulation study comparing two types of coordination follows before we present a scheme that manages transaction processing and locating service in mobile environments. Finally, we discuss the limitations of the scheme from the perspectives of the airport in question along with other research issues.

• Journal of Korea Multimedia Society
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• v.12 no.10
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• pp.1397-1406
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• 2009

This paper propose the "Digital Format Registry(DFR)" to solve the problem related digital objects preservation system in the Korean Industry. Digital format registry is a kind of database that saves syntax and meaning informations of a digital file format and for giving help to make preserve in long-term even technical environment of a specific application has been changing. The role of the Technical Information Registry has been developed in this research and development is maintaining a technical information that is the foundation to maintain the long-term preservation and access to a digital objects. The function that can extract text information from a digital document object is implemented in DFR as a basic function at the first time in the world. This function make information consumers search a information that is needed easily and conveniently and can be used for development more effective records management system with retrieving the Key(index).

• Journal of Korean Society of Archives and Records Management
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• v.16 no.4
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• pp.79-120
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• 2016

Along with the changing computing environment, the production of public documents is moving to G-Cloud and On-nara System, which are re-engineered on G-Cloud. In this process, it is predicted that the Open Document Format (ODF) will replace the proprietary document format, HWP, and will become widely used in the near future. To preserve digital records produced in ODF, this study reviewed the current long-term preservation strategies and identified considerations for new formats. For ODF source files, it is suggested to eliminate the conversion to PDF/A-1 and preserve the documents in the extended ODF with added metadata of records management. Moreover, ODF is presented as an alternative format for preserving proprietary formats. Finally, this study reviewed the current long-term preservation format, i.e., NEO, and suggests a zipped BagIt package, which has an ISO 21320 specification.

• Proceedings of the KWS Conference
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• 2006.10a
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• pp.136-138
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• 2006

Recently a lots of problems have observed in high densified and high integrated electronic components. One of them is ion migration phenomena, which induce the electrical short of electrical circuit. Ion migration phenomena has been observed in the field of exposing the specific environment and using for a long time. Also as the RoHS restriction was started in July 1st, 2006, Pb-free solder was utilized in electronics assemblies. In this case, it is very important to compatible between components and printed circuit board(PCB), thus surface treatment materials of PCB was changed to Sn, Sn-3.0Ag-0.5Cu, Cu. Therefore these new application become to need to reevaluate the sensitivity about electrochemical ion migration. This study was evaluated the occurrence time of electrochemical ion migration using by water drop test. We utilized PCB(printed circuit board) having a comb pattern as follows 0.1, 0.318, 0.5, 1.0 mm pattern distance. Sn-3.0Ag-0.5Cu and Sn-37Pb were electroplated on the comb pattern. 6.5V and 15.0V were applied in the comb pattern and then we measured the electrical short time causing by occurring the ion migration. In these results, we evaluate the sensitivity and derived the prediction models of ion migration occurrence time depending on the pattern materials, applied voltage and pattern spacing of PCB conductor.

• Journal of Applied Reliability
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• v.16 no.3
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• pp.202-207
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• 2016

Purpose: The purpose of this study is main factors (environmental conditions, pattern spacing, pattern material) that effect the ion-migration of PCB. Methods: Recently, the electronic components are becoming more high density of electronic device, so that electronic circuits have smaller pitches between the patten and more vulnerable to insulation failure. so the reliability of electric insulation of device has become an ever important issue as device contact pitches of pattern. Usually, ion-migration occurs in high temperature and high humidity environment as voltage is applied to the circuit. Under high temperature and high humidity, voltage applied electronic components respond to applied voltages by metals's electrochemical ionization and a conducting filament forms between the anode and cathode across a nonmetallic medium. This leads to short-circuit failure of the electronic component. Results: we studied ion-migration that occurs in accordance with the main factors (environmental conditions, pitches, pattern material). The PCB pattern material was made by two different types of material (free solder, OSP) for this research and pitches of pattern is 0.15mm, 0.3mm, 0.5mm. PCB was experimented in the environmental conditions (high temperature $120^{\circ}C$, high temperature and high humidity $85^{\circ}C$, 85%RH) and was analyzed for ion-migration through the experiment results. Conclusion: We confirmed that environmental condition, pitches of pattern, pattern material had effect on ion-migration of PCB.

• Journal of the Microelectronics and Packaging Society
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• v.22 no.1
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• pp.43-49
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• 2015

By the trends of electronic package to be smaller, thinner and more integrative, organic printed circuit board is required to be finer Cu trace pitch. This paper reports on a study of failure mechanism for PCB with fine Cu trace pitch using biased HAST. In weibull analysis of the biased HAST lifetime, it is found that the acceleration factor (AF) of between $135^{\circ}C/90%RH/3.3V$ and $130^{\circ}C/85%RH/3.3V$ is 2.079. A focused ion beam (FIB) was used to polish the cross sections to reveal details of the microstructure of the failure mode. It is found that $Cu_xO/Cu(OH)_2$ colloids and Cu dendrites were formed at anode (+) and at cathode (-), respectively. Thus, this gives the evidence that Cu dendrites formed at cathode by $Cu^{2+}$ ion migration lead to a short failure between a pair of Cu nets.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.11
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• pp.101-106
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• 2005

A ground penetrating image radar (GPR) using an ultra wideband (UWB)impulse waveform is developed for non destructive detection of metallic pipelines buried under the ground. Dielectric constant of test field is measured and then a GPR system is designed for better detection up to 1 meter deep. By considering total path loss, volume of complete system, and resolution, upper and lower frequencies are chosen. First, a UWB impulse for the frequency bandwidth of the impulse is chosen with rising time less than 1 ns, and then compact planar UWB dipole antenna suitable for frequency bandwidth of a UWB impulse is designed. Also, to receive reflected signals, a digital storage oscilloscope is used. For measurement, a monostatic technique and a migration technique are used. For visualizing underground targets, simple image processing techniques of A-scan removal and B-scan average removal are applied. The prototype of the system is tested on a test field in wet clay soil and it is shown that the developed system has a good ability in detecting underground metal objects, even small targets of several centimeters.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.10a
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• pp.324-327
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• 2013

Recently, due to evolving cloud computing technology, we can easily and transparently utilize both local computing resource and remote computing resource in real life. Especially, enhancing smart device technologies and network infrastructures promote an increase of needs to share files between local smart devices and cloud storages. However, since smart devices have a limited storage space, storing files on cloud storage causes a starvation problem of local storage. It means that users can face a storage-lack problem even a cloud storage service provide a huge file storing space. In this research, we propose a method to manage files between smart devices and cloud storages. Our approach calculate file usage pattern based on recently used date, and then this approach determines local files being migrated. As a result, our approach is sufficient for handling data synchronization between big data storage farm and local thin client which contains limited storage space.

• Journal of the Korea Society of Computer and Information
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• v.16 no.7
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• pp.35-47
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• 2011

This paper proposes a set of rules to automatically generate OWL ontologies from relational databases. The purpose of the rules is to allow semantic access to existing RDB data without any database schema transformation and data migration process. In other words, the rules help a RDBMS play as a web ontology repository as well. However, the use of the mapping rules between RDB and OWL proposed by other studies for the objective causes troubles as follows. First, databases including the tables with a specific structure can't be translated into OWL. Second, the process for extracting an OWL individual unnecessarily lead to database join operations, or several SQL queries. On the other hand, our rules is designed to prevent these problems, can generate OWL classes and properties from database schemas and can generate OWL individuals from the database instances. In addition, an ontology generated by our rules is an OWL 2 DL ontology.