• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.5C
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• pp.523-531
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• 2003

Java applets are downloaded from web server through internet and executed in Java Virtual Machine of clients'browser. Before execution of java applets, JVM checks bytecode program with bytecode verifier and performs runtime tests with interpreter. However, these tests will not protect against undesirable runtime behavior of java applets, such as denial of service attack, email forging attack, URL spoofing attack, or annoying sound attack. In order to protect malicious applets, a technique used in this paper is java bytecode modification. This technique is used to restrict applet behavior or insert code appropriate to profiling or other monitoring efforts. Java byte modification is divided into two general forms, class-level modification involving subclassing non-final classes and method-level modification used when control over objects from final classes or interface. This paper showed that malicious applets are controlled by java bytecode modification using proxy server. This implementation does not require any changes in the web sever, JVM or web browser.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38C no.2
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• pp.155-164
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• 2013

Two design techniques for more accurate and more convenient hybrid positioning system with visible light communication (VLC) and ad-hoc wireless network infrastructure are proposed, in order to overcome the problems of high estimation error, high cost, and limited service range of the conventional positioning techniques. First method is based on a non-carrier VLC based hybrid positioning technique for applications involving of low data rate optical sensing and narrow-range visible light reception from transmitter, and long-range positioning. The second method uses a 4 MHz carrier VLC-based hybrid positioning technique for a high data rate optical sensing and wide-range visible light receiving from transmitter, and mid-range positioning applications. In indoor environments with obstacles where there are long-range 7731.4cm and mid-range 2368cm distances between an observer and a target respectively, the hybrid positioning developed with two design techniques are tested, and the proposed system is verified and analyzed in this paper.

• The Journal of the Korea institute of electronic communication sciences
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• v.7 no.6
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• pp.1337-1342
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• 2012

In recent years, many researches in Home Networking are being progressed actively. Most of techniques for Home Networking are based on wired but the technique for wireless connection is also needed. This paper focuses on wireless connection in Home Networking. Of many of wireless technologies, such as Wireless LAN, Bluetooth, or HomeRF, we especially propose to apply the new technique called Wireless Sensor Network. We present hardware and protocol stack design consideration for wireless sensor node and wireless sensor network, and then we present how to apply wireless sensor network to Home Networking and how to constitute Wireless Home-Networking with a variety of sensor nodes. Finally, we introduce the wireless sensor node system designed by us and conclude this paper.

• Journal of The Korean Association of Information Education
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• v.22 no.3
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• pp.385-396
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• 2018

This research supports the idea that manipulative devices can be an effective modality tool for learning abstract concepts involved with identifying geometric shapes and enhance learners' problem solving and motivation. Until recently specified manipulative device has been adapted only in traditional classroom environment and it has been very rare to find devices that is designed for online-basis. This study focused on designing and implementing an educational software which guide learners with geoboard in identification and characteristics of polygons. In addition to the function to draw and to delete various shapes, this software helps learners immediately assess the outcome. The results of the Delphi Technique show promising evidence for it being a very efficient means to learn geometric shapes and increase learners' motivation to learn the subject matter.

• Korean Journal of Childcare and Education
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• v.7 no.2
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• pp.115-135
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• 2011

The purpose of this study was to developing a cooperative learning model utilize storytelling technique to the Preliminary childhood teachers whose learning was in order to improve ability and collaboration of making relationships a teams members by the cooperative learning which was performed on the basis of the confidence after understanding themselves and others. To achieve the purpose, the study was performed by dividing into two stages. First, the draft of storytelling based cooperative learning model was proposed by performing a literature survey and a case study. Second, the draft model was applied to the actual work. And the draft was modified and developed to the final model on the basis of the draft model's strenth and implemented to 39 students who were the sophomore of child care education department and enrolled the profession class of at B college P city for 8 weeks. From the implementation result of the model, it was obtained that there was the positive reaction on applying storytelling technique to the beginning stage of cooperative learning. And adding of 'Re-constitution role sharing team' step in the original steps was suggested. In the end, this model was modified and issued based on the research result. The researchers proposed a cooperative learning model storytelling based for Preliminary childhood teachers which consists 6 phases : (1) understanding cooperative learning (2) Building the team and role sharing team (3) theme setting and theme structuralization (4) Re-constitution role sharing team (5) announcement of the results and evaluating (6) reflection of general.

• Journal of KIISE:Software and Applications
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• v.31 no.4
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• pp.498-504
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• 2004

This paper presents a new text classifier based on a feature projection technique. In feature projections, training documents are represented as the projections on each feature. A classification process is based on individual feature projections. The final classification is determined by the sum from the individual classification of each feature. In our experiments, the proposed classifier showed high performance. Especially, it have fast execution speed and robustness with noisy data in comparison with k-NN and SVM, which are among the state-of-art text classifiers. Since the algorithm of the proposed classifier is very simple, its implementation and training process can be done very simply. Therefore, it can be a useful classifier in text classification tasks which need fast execution speed, robustness, and high performance.

• The KIPS Transactions:PartD
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• v.14D no.7
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• pp.829-840
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• 2007

Dirty Data Cleansing technique so far have aimed to integrate large amount of data from various sources and manage data quality resided in DB so that it enables to extract meaningful information. Prompt response to varying environment is required in order to persistently survive in rapidly changing business environment and the age of limitless competition. As system requirement is recently getting complexed, Service Oriented Architecture is proliferated for the purpose of integration and implementation of massive distributed system. Therefore, SOA necessarily needs Data Exchange among services through Data Cleansing Technique. In this paper, we executed quality management of XML data which is transmitted through events between services while they are integrated as a sole system. As a result, we developed Dirty Data Cleansing Service based on SOA as focusing on data cleansing between interactive services rather than cleansing based on detection of data error in DB already integrated.

• The KIPS Transactions:PartA
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• v.17A no.2
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• pp.63-72
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• 2010

Recently, the need for multimedia devices, such as digital TV, and camcorder has increased. These devices provide many services on multimedia files such as playing, recording, and editing. Throughout these services, in case of storing edited large-scaled multimedia files, existing file system have several capability problems that are taking too much time and requiring disk I/O. In this paper, we propose the use of Linux Ext2 file system based 'Block-Link file (BL-file) system' in order to solve these problems. For the BL-file system, when editing and storing large-scaled files, there is no data input or output but only modification of the metadata. Additionally, by sharing data blocks between multimedia files, we can save disk spaces. Moreover, because the managing of data block sharing information is more convenient than the existing FWAE technique, we can lessen system overhead. The BL-file system is based on Ext2 file system and implemented in a Linux environment, and the usefulness of the proposed technique is validated by applying the Linux multimedia file-editing tool 'Avidemux'.

• The Transactions of the Korea Information Processing Society
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• v.6 no.9
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• pp.2384-2392
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• 1999

Software engineers are used to analyse the error behavior of computer programs using test cases which are collected for the testing phase when software errors are detected. In actual software testing and debugging, it is important to adopt dynamic slicing technique which is concerned on all the statements to be affected by the variables of current inputs and to use technique of its implementations. The traditional dynamic slicing has focused on the single slicing criterion algorithm. It has been thought that it is needed to develope and implement algorithm for used multiple criteria variables program slicing, which finds every slicing criterion variable where it is used multiple criteria variables. In this paper, we propose an efficient algorithm to make dynamic program slices when it has used multiple criteria variables. The results of the implementation are presented by the making table on execution history and the dynamic dependence graph. Also we can find that the proposed dynamic program slicing approach using multiple criteria variables is more efficient than the traditional single case algorithm on the practical testing environment.

• Journal of Electrical Engineering and Technology
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• v.13 no.3
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• pp.1043-1051
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• 2018

The coordination of directional overcurrent relay (DOCR) is employed in this work, considering gray wolf optimizer (GWO), a recently designed optimizer that employs the hunting and leadership attitude of gray wolves for searching a global optimum. In power system protection coordination problem, the objective function to be optimized is the sum of operating time of all the main relays. The coordination of directional overcurrent relays is formulated as a linear programming problem. The proposed optimization technique aims to minimize the time dial settings (TDS) of the relays. The calculation of the Time Dial Setting (TDS) setting of the relays is the core of the coordination study. In this article two case studies of IEEE 6-bus system and IEEE 30-bus system are utilized to see the efficiency of this algorithm and the results had been compared with the other algorithms available in the reference and it was observed that the proposed scheme is quite competent for dealing with such problems. From analyzing the obtained results, it has been found that the GWO approach provides the most globally optimum solution at a faster convergence speed. GWO has achieved a lot of relaxation due to its easy implementation, modesty and robustness. MATLAB computer programming has been applied to see the effectiveness of this algorithm.