• Journal of Internet Computing and Services
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• v.16 no.5
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• pp.99-105
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• 2015

Currently robots are widely used in schools for educational purpose. With wide spread of robot-based education, it is known that major advantage of robot-based education is to enhance creativity and logical thinking of students. Although robots can be very useful tools for assisting students' study activities, there have not been lots of teaching-learning models for robot-based education.In this paper, a teaching-learning model is presented for robot-based education. The proposed model is designed based on constructivism. The proposed model consists of 6 stages: preparation, design, assembling, demonstration run, evaluation, and application & extension. The proposed model has the following characteristics. First, the proposed model is designed to enhance creativity and logical thinking ability of learners. Learners are supposed to be involved in self-directed activities and required to provide results based on their own ideas. Teachers are supposed to mediate students only if necessary. Second, learners are encouraged to participate in activity via diverse interaction. The interaction in this model includes learner-to-learner interaction, learner-to-teacher interaction, and learner-to-expert interaction. The proposed model encourages learners to solve the problem with cooperating each other. Also, teachers are supposed to guide students if necessary and observe and monitor behavior of students all the time. Third, motivation is provided in the beginning stage of the instruction. Fourth, in the proposed model, both study results and study process are equally important. In the model, study process is reviewed at the final stage.

• Proceedings of the Korean Information Science Society Conference
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• 2007.10d
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• pp.505-509
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• 2007

Proxy Mobile IPv6 (PMIPv6)는 Mobile Node (MN)가 스스로 이동성을 지원하지 않더라도 Mobile Access Gate가 MN대신 이동성을 처리하여 IPv6 이동성을 지원하는 기술이다. 좀 더 향상된 핸드오버 성능을 얻기 위해 Proxy Mobile IPv6에서도 버퍼링을 통한 패킷 손실을 줄이는 기법을 사용할 수 있다. 하지만, IEEE 802.11 네트워크에서는 Handover 발생 직전에 MN이 어떠한 통보도 AP로 하지 않기 때문에 Handover시에 패킷 손실을 줄이기 위한 패킷 버퍼링 방법을 사용하기가 어렵다. 본 논문에서 PMIPv6에서 MAG와 AP가 MN의 이동성을 감지하여 버퍼링을 시작하고 Handover가 발생하였을 경우에 대비해 버퍼링을 하는 Cross-layer 버퍼링 방법을 제안한다. 이를 통해 PMIPv6에서도 MN의 변경 없이 Handover시에 발생하는 패킷 손실을 최소화 할 수 있다. 또한 간단한 성능 비교를 통하여 제안 방법이 기존 PMIPv6보다 우수함을 알 수 있다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.8
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• pp.4285-4299
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• 2019

Adversarial attack is a technique that causes a malfunction of classification models by adding noise that cannot be distinguished by humans, which poses a threat to a deep learning model. In this paper, we propose an efficient method to detect adversarial images using Gaussian process regression. Existing deep learning-based adversarial detection methods require numerous adversarial images for their training. The proposed method overcomes this problem by performing classification based on the statistical features of adversarial images and clean images that are extracted by Gaussian process regression with a small number of images. This technique can determine whether the input image is an adversarial image by applying Gaussian process regression based on the intermediate output value of the classification model. Experimental results show that the proposed method achieves higher detection performance than the other deep learning-based adversarial detection methods for powerful attacks. In particular, the Gaussian process regression-based detector shows better detection performance than the baseline models for most attacks in the case with fewer adversarial examples.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.4 no.3
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• pp.400-410
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• 2010

In an identity-based threshold broadcast encryption (IDTHBE) scheme, a broadcaster chooses a set of n recipients and a threshold value t, and the plaintext can be recovered only if at least t receivers cooperate. IDTHBE scheme is different from the standard threshold public key encryption schemes, where the set of receivers and the threshold value are decided from the beginning. This kind of scheme has wide applications in ad hoc networks. Previously proposed IDTHBE schemes have ciphertexts which contain at least n elements. In addition, the security of theses schemes relies on the random oracles. In this paper, we introduce two new constructions of IDTHBE for ad hoc networks. Our first scheme achieves S-size private keys while the modified scheme achieves constant size private keys. Both schemes achieve approximately (n-t)-size ciphertexts. Furthermore, we also show that they are provablesecurity under the decision bilinear Diffie-Hellman Exponent (BDHE) assumption in the standard model.

• Journal of the Korea Society of Computer and Information
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• v.27 no.9
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• pp.149-155
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• 2022

The popularity of e-commerce systems on the Internet is increasing day by day, and the recommendation system, as a core function of these systems, greatly reduces the effort to search for desired products by recommending products that customers may prefer. The collaborative filtering technique is a recommendation algorithm that has been successfully implemented in many commercial systems, but despite its popularity and usefulness in academia, the memory-based implementation has inaccuracies in its reference neighbor. To solve this problem, this study proposes a new time-aware collaborative filtering technique that integrates and utilizes the neighbors of each item and each user, weighting the recent similarity more than the past similarity with them, and reflecting it in the recommendation list decision. Through the experimental evaluation, it was confirmed that the proposed method showed superior performance in terms of prediction accuracy than other existing methods.

• Journal of Internet Computing and Services
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• v.20 no.1
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• pp.11-16
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• 2019

Wireless sensor network is important for precision farming to monitor the growth environment of crops in open field, but radio signals are susceptible to different types of interference such as weather and physical objects. This paper designs and implements an environmental monitoring and weather forecast acquisition systems for smart field irrigation based on LoRa(Long Range) and then applies it to a test bed. And we evaluate the network reliability in terms of packet transmission success rate by comparing its condition on two criteria; the existence of obstacle or rain. The results show that much rain falls can affect on packet loss in LoRa field networks with obstacles.

• Journal of the Korea Computer Industry Society
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• v.5 no.9
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• pp.859-872
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• 2004

With the rapid advance of computer and communication techonology, the recent trend of education environment is edveloping in the ubiquitous learning (u-learning) direction that learners select and organize the contents, time and order of learning by themselves. Since the amount of education information through the internet is increasing rapidly and it is managed in document in an effective way is necessary. The document clustering is integrated documents to subject by classifying a set of documents through their similarity among them. Accordingly, the document clustering can be used in exploring and searching a document and it can increased accuracy of search. This paper proposes an efficient incremental clustering method for a set of documents increase gradually. The incremental document clustering algorithm assigns a set of new documents to the legacy clusters which have been identified in advance. In addition, to improve the correctness of the clustering, removing the stop words can be proposed.

• The Journal of Korean Association of Computer Education
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• v.14 no.2
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• pp.23-32
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• 2011

The Internet is appearing a new paradigm called Web 2.0 which 'Participation', 'Sharing', 'Openness', 'Cooperation'. Web 2.0 is expanded by experts and general users and many people's ideas can solve more problems than an expert's idea. The collective intelligence is techniques that express the valuable of Web 2.0. For this reason, the collective intelligence has attracted attention because of its potential as an educational tool. The purpose of this study is to develop a PBL-based programming instruction model using collective intelligence to improve students' problem solving abilities and programming attitudes and verified its effectiveness. As a result, the developed instruction model showed significant differences in the students' problem solving abilities and programming attitudes. According to these results, these have been proved that a PBL-based programming instruction model using collective intelligence has an influence to the students' problem solving abilities and programming attitudes.

• The Journal of Korean Association of Computer Education
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• v.4 no.2
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• pp.125-133
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• 2001

With development of computer engineering and the examination theories, new techniques to use computers in making or administrating examinations had been studied and developed. Recently, studies on web-based testing are in progress with development of Internet and information and communication technology. However, as compared with development of these technical aspects, studies on the user legibility to provide learners with comfortable environment for the evaluation have been insufficient in fact. In the web-based testing, user legibility decreases the anxiety of examinees in the examination and plays an important role in measuring their competence exactly. In this study, we tried to provide the optimum web-based evaluation interface by obtaining information through a questionnaire for primary-school students. We think that principles suggested in this study can give a great help in making the web-based evaluation screen in future. Besides, studies on more various fields including making individual questions, instructing sentences and layout of multimedia factors as well as the principles mentioned in this study should be performed.

• Journal of Advanced Navigation Technology
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• v.12 no.1
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• pp.28-33
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• 2008

VoIP provided voice service using Internet is receiving footlights when it escapes an initial curiosity. VoIP interest became larger, because it can transfer existing phone service and deliver voice data through internet technology. Is inheriting as it is threats of IP base because a VoIP technology provides audiocommunication service taking advantage of an existing IP technology, and have new threats that happen from new know-hows for VoIP service offer. In this paper, presented about problem and consideration and countermeasure of examines about security threat of VoIP service, and applies security.