• The KIPS Transactions:PartD
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• v.11D no.1
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• pp.143-152
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• 2004

Recently, software programming method based on EJB for object oriented software design and implement has been used frequently. Usually, case that use permanent data that use Database in EJB base application is most. Part connected with Database-Access that take charge in Entity Bean class of server side creation program. In this paper using J2EE relationship DAO pattern class each separate. This is no much difference with existent pattern method, but in same pattern common classes are designed so that composition may be possible. And as well as use Entity Bean class that created each DBMS classes are different, is doing Rata Source so that connection work is available without alteration or creation of additional program in several DBMS environments.

• The KIPS Transactions:PartD
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• v.8D no.4
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• pp.439-450
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• 2001

Mobile agent is one of the promising ways of overcoming network load and latency. It is also a new software paradigm including those concepts of client/server, applet/servelet, and code-on-demand. In this paper, a new mobile agent concept with flexible replay scheme is proposed, which can deal with embarrassing situation when replying results should be accomplished in various distributed applications. For example, they are 1) a burden of bulky result, 2) a need of different replay scheme dependent on work type, 3) connection failure to the target node, and 4) a need of fast migration to next node to keep the itinerary. Regarding the source node, there may be another situation that it wants to be aware of whether its wi가 is completed or not. Three kinds of reply schemes are proposed for dealing flexibly with such situations. They are based on priority reply list where nodes to be replied are stored according to their priorities. An experimental supply chain management model using the proposed reply schemes is designed and implemented. It is one of good distributed applications appropriate for our reply schemes, because it requires different reply schemes according to work types and it is important to gather required information in time.

• Journal of Advanced Marine Engineering and Technology
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• v.35 no.4
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• pp.512-518
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• 2011

The marine equipment industry in Korea has been growing along with shipbuilding industry since early 1980s. Major shipbuilding might be predicted to shift to China in the near future. Moreover, new paradigm of e-navigation is about to get geared in the real world, which was specifically noted by IMO (International Maritime Organization). In order to catch up with rapid changes in the environments, the industry sector should move fast, the public sector should setup proper measures, and the academic sector should spur the research and development of new technologies. In this paper, international marin equipment markets and standardization trends are presented along with several representative R&D activities.

• Journal of Electrical Engineering and Technology
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• v.9 no.6
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• pp.2025-2035
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• 2014

The read range of UHF mobile readers can be extended by a booster for mobile RFID readers (BoMR). But in an environment where multiple BoMRs are installed, the read success rate may be decreased due to signal interference. This paper proposes three arbitration methods based on interference estimation with the purpose of enhancing the read success rate. A central arbitration server manages global information in centralized arbitration method (CAM) without broadcast/multicast communication facility. In fully distributed arbitration method (FDAM), all the arbitration messages are broadcasted from a BoMR to every BoMR, and each BoMR decides with broadcasted global information. Events in FDAM are serialized naturally with broadcasted messages. Cluster Distributed Arbitration Method (CDAM) forms clusters with multicasted BoMRs and a selected BoMR acts as an arbiter in the cluster. Such effects as lengthened read range, improved the read success rates of readers can be obtained by the proposed methods without any hardware modification. In order to evaluate the arbitration methods, the RFID system is modeled by using the DEVS formalism and simulated by using the DEVSim++.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.8
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• pp.1257-1264
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• 2017

In video content watching service, when a user requests video content, the content server has to transmit the entire video to the client for watching. This transmission delay increases as the size of video content increases. In order to solve the transmission delay problem, a prefetching technique can be used in which a video content to be watched by a user is predicted and transmitted to a client before the user requests it. In this paper, we propose a prefetching system considering multiple indices for video content. In the proposed method, video content to be prefetched is selected by comprehensively analyzing the order relation index indicating the order of viewing the videos of the users, the similarity index between the video contents, and the popularity index reflecting the viewing frequency of the video content. Experimental results show that the maximum accuracy is achieved when prefetching uses only the order relation index for movie contents.

• Journal of the Korean Society of Safety
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• v.29 no.5
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• pp.54-59
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• 2014

The record type receivers that are operated in large industrial sites have strength in preventing fire. However, because of its long circuit lines and multiple detectors, the receivers are vulnerable to lightning, noise, and breakdown of equipments, resulting in malfunction. In case of malfunctioning of detection circuits of main protection areas, such as electrical room and server room, potential release of gaseous extinguisher agents may lead to property and life damage. In this paper, we present the results on the characteristics of the transponder that initiates the solenoid valves, with respect to various electromagnetic and lightning inflow conditions. Based on the measured data, we analyzed the systematic problems of the transponder. In order to prevent receiver malfunctions, a sequential circuit was configured with two additional transponders and a timer. The circuit was tested with a simulator with preference and delay circuit algorithms.

• Korean Journal of Computational Design and Engineering
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• v.4 no.2
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• pp.87-99
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• 1999

We developed a Part Information Brokering System, namely PIBS, that can inter-link part suppliers and buyers using WWW(World Wide Web). The major contribution of this paper is that the system provides a 3D collaboration environment that enables multiple users to share the same workspace where they cooperatively manipulate part features in real time. PIBS carries out two major functions: one to maintain part data in a part library, and the other to provide the means for the clients to cooperate. An object-oriented database is used for the part library which stores apart information registered by part suppliers. VRML(Virtual Reality Modeling Language) the ISO standard for 3D visualization on WWW, is used to represent 3D part models. Several Java programs have been implemented to support synchronous and a synchronous communication of the 3D models. Once the users are interconnected through the system, a user's manipulation of part objects is transparently and instantaneously transmitted to the others. This means that all the participants can are the same view and movement of the 3D part models. Since the system is developed using a Java applet-server architecture, it requires no additional software other than standard web browser. The prototype system has been successfully implemented, and demonstrated its applicability to virtual 3D part information sharing.

• IEMEK Journal of Embedded Systems and Applications
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• v.1 no.2
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• pp.90-103
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• 2006

There are many file systems in various operating systems. Those are usually designed for server environments, where the common cases are usually 'multiple active users', 'great many small files' And they assume a big main memory to be used as buffer cache. So the existing file systems are not suitable for resource hungry embedded systems that process multimedia data streams. In this study, we designed and implemented a new file system which efficiently stores and retrieves multimedia data steams. The proposed file system has a very simple disk layout, which guarantees a quick disk initialization and file system recovery. And we introduced a new indexing-scheme, called the time-based indexing scheme, with the file system. With the indexing scheme, the file system maintains the relation between time and the location for all the multimedia streams. The scheme is useful in searching and playing the compressed multimedia streams by locating exact frame position with given time, resulting in reduction of CPU processing and power consumption. The proposed file system and its APIs utilizing the time-based indexing schemes were implemented firstly on a Linux environment, though it is operating system independent. In the performance evaluation on a real DVR system, which measured the execution time of multi-threaded reading and writing, we found the proposed file system is maximum 38.7% faster than EXT2 file system.

• Journal of Korea Multimedia Society
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• v.8 no.2
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• pp.279-286
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• 2005

As the mobile environment has been generalized, data synchronization with mobile devices or mobile device and PC/server is required. To deal with the problem, the consortium was established by the companies, such as Motorola, Ericsson, and Nokia, and released SyncML(Synchronization Markup Language) as a standard of industrial area for interoperating with data synchronization and various transmission protocol. But, in synchronization process, when more than two clients requested data synchronization, data conflict can be happened. This paper studies the various conflict reasons that can happen in data synchronization processes and groups them systematically Through the analyzed information, we compose the Change Log Information(CLI) that can keep track of the chased information about synchronization. And we suggest an operation policy using CLI. Finally, we design an algorithm and adapt the policy as a method for the safety and consistency of data.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.05a
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• pp.690-692
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• 2013

Cloud computing is an Internet-based technology, one of the Big Data era aspiring technology. Bring on the internet whenever you need to use multiple physical servers into one virtual server, cloud Cloud technology and large companies, such as leading U.S. IT company, Amazon, IBM, Google, Microsoft and the domestic firm Samsung, SK, KT, NHN the cloud market at home and abroad, and commercialization by investing in the future to continue to grow. The main reason for the introduction of the cloud and reduced operating costs, and to see the most problems is the leakage of personal information. In this paper, we propose a method to improve the security and vulnerability analysis of security technologies and cloud.