• Journal of KIISE:Databases
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• v.34 no.2
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• pp.109-118
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• 2007

Recently, flash memory is used to store data in mobile computing devices such as PDAs, SmartCards, mobile phones and MP3 players. These devices need index structures like the B-tree to efficiently support some operations like insertion, deletion and search. The BFTL(B-tree Flash Translation Layer) technique was first introduced which is for implementing the B-tree on flash memory. Flash memory has characteristics that a write operation is more costly than a read operation and an overwrite operation is impossible. Therefore, the BFTL method focuses on minimizing the number of write operations resulting from building the B-tree. However, we indicate in this paper that there are many rooms of improving the performance of the I/O cost in building the B-tree using this method and it is not practical since it increases highly the usage of the SRAM memory storage. In this paper, we propose a BOF(the B-tree On Flash memory) approach for implementing the B-tree on flash memory efficiently. The core of this approach is to store index units belonging to the same B-tree node to the same sector on flash memory in case of the replacement of the buffer used to build the B-tree. In this paper, we show that our BOF technique outperforms the BFTL or other techniques.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.9
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• pp.50-61
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• 2018

A precedent defense project study was carried out in the early stage of the project to support efficient determination of the acquisition method of the determined weapons system. A precedent study in the early stage of the project has been neglected, but lack of performance and increased costs are continuing problems. In a precedent study on a number of items within a limited time frame, expected risks during project implementation were not identified and reduced by failing to review the key review element in depth. Therefore, in this paper, we studied the application of the FTA/FMEA technique used in the system safety analysis process to identify key factors to be considered when carrying out the defense research project. The methodology for the development of the key review items was established through the improvement of the FTA/FMEA technique in order to meet specific conditions and given conditions. Based on the results of this study, we redefined core key factors in the precedent study stage, thereby eliminating unnecessary and anticipated risks that may arise in the future project management aspects of the defense project. It is anticipated that this will reduce costs and time in terms of the lifecycle of the weapon system and promote stable operation of the project through reduction of risk.

• Journal of The Korean Association of Information Education
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• v.8 no.3
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• pp.353-360
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• 2004

World Wide Web is not more meaningless sea of information but is becoming the Semantic Web that provides many users with meaningful information. The starting point is the XML and metadata, RDF is a stopover which gives technique to relate arbitrary web resources. And now, the semantic and logic of web resources can be settled in the Ontology. A lot of educational multimedia web resources in Korea have produced their metadata with KERIS's KEM(Korea Educational Metadata). Therefore our country have to start the study of the semantic and logic in web resources. But, many researchers in Korea are more eager to study Dublin Core's DC and SCORM's LOM metadata specification than KEM. Thus the study of method about sharing and integrating these three metadata specifications should be performed before the study of semantic and logic in web resources in Korea. We design the Ontology to integrate these three metadata specifications and implement the prototype system using this Ontology. These three metadata have some elements that have same labels and meanings, and other elements have different labels and same meanings. To match these different labels which have same meanings, we adapted the one-to-one mapping technique in designing our Ontology. This designed Ontology was imported as "integrated schema" in our prototype searching system to integrate three different metadata in databases. Moreover we know that the more specific property design of class in Ontology was needed in order to provide users with more informed searching results such as synonym, antonym, hierarchy and associations.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39A no.5
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• pp.271-279
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• 2014

In this paper, the two design techniques of the embedded system which provides a wireless image observation with temporary ad-hoc network are proposed and developed. The first method is based on the embedded system design technique for a nearly real-time wireless short observation application, having a specific remote monitoring node with a built-in image processing function, and having the maximum rate of 1 fps (frame per second) wireless image transmission capability of a $160{\times}128$size image. The second technique uses the embedded system for a general wireless long observation application, consisting of the main node, the remote monitoring node, and the system controller with built-in image processing function, and the capability of the wireless image transmission rate of 1/3 fps. The proposed system uses the wireless ad-hoc network which is widely accepted as a short range, low power, and bidirectional digital communication, the hardware are consisted of the general developed modules, a small digital camera, and a PC, and the embedded software based upon the Zigbee stack and the user interface software are developed and tested on the implemented module. The wireless environment analysis and the performance results are presented.

• Proceedings of the Korea Multimedia Society Conference
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• 2003.05b
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• pp.455-459
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• 2003

In the great motive power which promotes the Game of future to develop. three main factors focus on 3D Graphics, Network and Virtual Reality. the Network technique as necessary elemental technique in Next-generation on-line game is being researched largely. However, from viewing the features of on-line game, if many users meet in same server, it not only causes heavy load to the server and brings inconvenience to the users, but also increases expense to the service provider and creates a problem which is to put up server or not. A proposal is going to do hybrid distributed system a client hardly depends on server for this paper, and to be able to enjoy a network game through information alternating current between clients. depended on the existing server, and the most message processing did a design in order to achieve between clients. A design way to propose is as follows. Primarily it was done in order proposed a message grade anger process way, and to be able to manage server or a client according to importance of message, and, with the second, did a Client-Server method and a Pear-to-Pear method at the same time, and a chase did efficiency. Third is going to propose other problem solving way by message grade anger in multi-anger and a security section of a message cue.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.1
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• pp.188-196
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• 2021

Korea has invested heavily in projects related to national rivers, but there is no evaluation technique and system to manage river projects that can evaluate the effectiveness of the river projects after they are completed. Their absence leads to the inability of information on river construction sections, analysis of project effects, and benchmarking between projects. This may cause over-budget, overlapping investment problems due to the implementation of similar projects in the same section, and incorrect business elements may be repeatedly utilized. In order to solve this shortcoming, this study developed river project evaluation techniques and a river project (construction) management system. The development of evaluation techniques enables comparison and analysis between projects and can be utilized in establishing maintenance plans. The system can also provide inquiry of construction information, visualization of construction, and management of performance items. In this study, the evaluation techniques developed through prior research were modified and supplemented, and the effectiveness was verified by applying them to national river projects in A river and B river. It is expected that the evaluation techniques and system utilization measures presented will increase the work efficiency of river projects and enhance the efficiency of river projects.

• Composites Research
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• v.35 no.6
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• pp.371-377
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• 2022

Triboelectric nanogenerator (TENG) devices have generated a lot of interest in recent decades. TENG technology, which is one of the technologies for harvesting mechanical energy among the energy wasted in the environment, is obtained by the dual effect of electrostatic induction and triboelectric charging. Recently, a multilayer thin film stacking method (or layer-by-layer (LbL) self-assembly technique) is being considered as a method to improve the performance of TENG and apply it to new fields. This LbL assembly technology can not only improve the performance of TENG and successfully overcome the thickness problem in applications, but also present an inexpensive, environmentally friendly process and be used for large-scale and mass production. In this review, recent studies in the accomplishment of LbL-based materials for TENG devices are reviewed, and the potential for energy harvesting devices reviewed so far is checked. The advantages of the TENG device fabricated by applying the LbL technology are discussed, and finally, the direction and perspective of this fabrication technology for the implementation of various ultra-thin TENGs are briefly presented.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.5B
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• pp.859-870
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• 2000

In this paper, an efficient H/W implementation technique for guard interval in OFDM(Orthogonal Frequency Division Multiplexing) systems is proposed and applied to ASIC chip design of an OFDM-based 25 Mbps wireless ATM modem. In OFDM systems, a cyclic prefix, longer than the largest multipath delay spread, is usually inserted to maintain the orthogonality of subchannels, by making the linear convolution of the channel ok like circular convolution inherent to the discreate Fourier domain, as well as to prevent the ISI(Intersymbol Interference) within the OFDM block. However, the OFDM system using the cyclic prefix requires an additional H/W in transmitter in order to store the original samples and to append the cyclic prefix to the beginning of each block. In this paper, a new approach using a cyclic prefix, even with a significantly lower H/W complexity. Finally, the performance of the proposed approach is demonstrated by applying it to ASIC chip design of an OFDM-based 25 Mbps wireless ATM modem.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.5B
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• pp.974-984
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• 2000

A CMOS voltage driver circuit for voltage down converter is proposed. An adaptive biasing technique is used to enhance load regulation characteristics. The proposed driver circuit uses the NMOS transistor as a driving transistor, so it does not suffer from large Miller capacitances which is one of the problems with conventional PMOS driving transistor, and hence achieves good phase margin and stable frequency response. No additional complex circuit for frequency compensation such as compensation capacitor is required in this implementation. For the same current capability, the size of NMOS transistor in driver circuit is smaller than that of PMOS counterpart. So the smaller die area can be achieved. The circuits is implemented using a 0.8 ${\mu}{\textrm}{m}$ CMOS process and has a die area of 150 ${\mu}{\textrm}{m}$ x 360 ${\mu}{\textrm}{m}$. Proposed circuit has a quiescent power of 60 . In the current driving range from 100 $mutextrm{A}$ to 50 ㎃, load regulation of 5.6 ㎷ is measured.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.21 no.1
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• pp.81-87
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• 2003

It is very difficult assignment that grasp three-dimensional real life in Web base network environment. But, the recent simulation tools embody third dimension elements within 2 dimensions screen that is limited through third dimension implementation technology. Many GIS tools are offering excellent functions for third dimension data creation. But, research about design of third dimension GIS that use virtual reality technique in Web environment is status that is unprepared. So, in this research embodied third dimension topography map using virtual reality modelling language to produce active third dimension VR map that can supply visual information for direction, visual point that want in World Wide Web without support of expensive Map exclusive use program. And these 3D Web-Map is thought that possibility is enough as next generation map medium.