• Communications of Mathematical Education
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• v.27 no.2
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• pp.121-134
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• 2013

Linear Algebra are arguably the most popular math subjects in colleges. We believe that students' learning and understanding of linear algebra can be improved substantially if we incorporate the latest advanced information technologies in our teaching. We found that the open source mathematics program 'Sage' (http://sagemath.org) can be a good candidate to achieve our goal of improving students' interest and learning of linear algebra. In particular, we developed a simple mobile content which is available for Sage commands on common cell phones in 2009. In this paper, we introduce the mobile Sage which contains many Sage functions on a smart-phone and the mobile linear algebra content model(lecture notes, and video lectures, problem solving, and CAS tools) and it will be useful to students for self-directed learning in college mathematics education.

• Proceedings of the Korea Society of Mathematical Education Conference
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• 2006.04a
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• pp.25-37
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• 2006

영재를 위한 수학교육은 우리의 당면과제 중 하나이다. 능력 있는 학생들의 학습이 속진에 한정되는 것 보다는 심화자료 및 수학적 소프트웨어와 함께 하는 것이 더 의미 있을 것으로 기대된다. 본 연구는 스프레트쉬트를 사용한 수학적 아이디어의 탐구에 관한 것이다. 다음에 대해 논의하기로 하겠다. i) 스프레드쉬트는 비전통적이면서도 이용이 용이하며, 수학적 통찰을 위한 매개물이다. ii) 풍부하고, 흥미릅고, 가치있는 수학적 주제에 대해 스프레드쉬트를 이용할 수 있다. iii) 스프레드쉬트를 사용하여 학생들이 수학적 아이디어에 대한 흥미를 고취시킬 수 있다. iv) 스프레드쉬트는 학생들에게 그들의 창의적인 시각화 기술을 공개할 기회를 줌으로써 수학에 대한 폭넓은 도식적 이해를 제공한다. v) animation을 포함한 스프레드쉬트 도식들의 적절한 사용은 유익하면서도 흥미롭다. vi) 학생들은 일상생활에 나타나는 수학의 흥미로움을 발견할 것이다. vii) 교사는 지금의 지도방식에 스프레드쉬트를 통합할 수 있다. 특히 스프레드쉬트는 다음과 같은 면모도 가지고 있다. i) 창의적인 수학적 스프레드쉬트 모델들의 실제 과정들이 그 자체로써 수학적 개념발달에 이용될수 있다. ii) 스프레드쉬트 모델은 심화된 주제의 탐색을 위한 의미 있는 탐구과제를 제공한다. iii) 스프레드쉬트는 현장에서 사용되는 실제적 수학 도구이다. - 과학자나 공학도들의 사용도 증가되고 있다. 이것의 사용은 학생들이 현장에서 사용할 기술을 취득하게 할 수 있고, 같은 컴퓨터의 소프트웨어를 사용하는 가족의 대화 수단이 되기도 한다. 본 연구에서 우리는 스프레드쉬트의 4가지 실증적 예를 들어 보겠다. 또한 다른 영역에서 발전된 스프레드쉬트 모델의 몇 가지 도식적 산출물도 포함 할 것이다. 우리는 가장 대중적인 스프레드 쉬트인 Microsoft Excel 프로그램을 사용하였다. Excel의 수행과 Excel 연산의 설명을 담은 CD와 함께 다양한 사례들에 대한 논의는 (8)을 참고하기 바란다. 본고에서는 graphic animation 기술, 스크롤바의 사용을 간단하게 개괄하겠다. '동적형상들(movies)'를 만들 수 있는 간단한 매크로의 사용 등의 내용들은 각 자료를 사용할 수 있는 Excel 파일의 예와 함께 [1]과 [8]에 설명하였었다. 많은 인쇄물과 on-line 참고문헌, 매체자료들도 함께 제공하였다.

• Journal of Industrial Convergence
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• v.19 no.6
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• pp.59-66
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• 2021

Globally, the prolonged pandemic of COVID-19 (COVID-19) has had a great impact on all industries. In particular, in the field of education, online classes (non-face-to-face) had some negative perceptions of online classes, such as lack of preparation for learning and student dissatisfaction with the class. According to the current situation survey in 2020, non-face-to-face classes accounted for about 56% of the class, and streaming real-time classes and video content-based classes accounted for most of the class. This study empirically analyzes the problems to be solved by online classes through the 2020-2021 survey (software application practical class university students), and explains the detailed program and development plan (implementation result). This study intends to contribute to the development of online learning development of each educational institution after the end of the corona crisis.

• Journal of Digital Contents Society
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• v.19 no.2
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• pp.415-423
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• 2018

In recent years, Computer-based learning, such as machine learning and deep learning in the computer field, is attracting attention. They start learning from the lowest level and propagate the result to the highest level to calculate the final result. Research literature has shown that systematic learning and growth can yield good results. However, systematic models based on systematic models are hard to find, compared to various and extensive research attempts. To this end, this paper proposes the first TNT(Transitive Nested Triangle)model, which is a growth and fusion model that can be used in various aspects. This model can be said to be a recursive model in which each function formed through geometric forms an organic hierarchical relationship, and the result is used again as they grow and converge to the top. That is, it is an analytical method called 'Horizontal Sibling Merges and Upward Convergence'. This model is applicable to various aspects. In this study, we focus on explaining the TNT model.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.13 no.2
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• pp.49-61
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• 2003

Electronic voting schemes must provide universal verifiability and receipt-freeness, as well as basic properties such as privacy, eligibility, to make the election fair and transparent. But it is difficult to provide both universal verifiability and receipt-freeness because they are mutually contradictory in their objective. To date, most electronic voting schemes provide only one of these properties and those few that provide both properties are not practical due to heavy computational load. In this paper, we present an efficient electronic voting scheme that provides both properties. The proposed scheme uses a trusted third party called HR(Honest Randomizer) and requires only one-way untappable channels from HRs to voters. Among the schemes that assume only one-way untappable channel this scheme requires the least amount of computation. Among the schemes that provide both properties, this scheme uses the weakest physical assumption. We also discuss the security of the system and compare our scheme with other related schemes.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.17 no.5
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• pp.27-38
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• 2007

One of the most important security issues of e-mail service is user privacy. Currently, various security protocols, like PGP(pretty Good Privacy), S/MIME(Secure/Multipurpose Internet Mail Extension), have been proposed. These protocols, however, do not provide forward secrecy. Recently, some security protocols that provide forward secrecy were proposed. But all of them require changes to the current e-mail infrastructure. Moreover, contrary to authors' intention, some of them do not actually provide perfect forward secrecy. In this paper, we propose a new practical e-mail security protocol. The proposed protocol provides perfect forward secrecy and uses a practical e-mail model that dose not require any changes to existing e-mail servers. It encrypts and authenticates messages efficiently using elliptic curve based signcryption scheme. In addition, we provide a way to send secure group e-mails.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.18 no.5
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• pp.103-113
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• 2008

Reducing handoff latency is essential in providing seamless multimedia service in Wireless LAN based on the IEEE 802.11 standard. Reducing authentication delay is critical in reducing handoff latency. To this end, several authentication protocols for fBst handoff have been proposed. Mishra et al. used proactive key distribution to improve the authentication delay incurred in the current standard and Park et al. proposed a new authentication protocol based on Blom's key pre-distribution scheme. In this paper, we propose an enhanced authentication protocol based on Bresson et al.'s group key protocol. If a mobile node has previously access the network, our proposed protocol only requires simple hash operations in providing mutual authentication between a mobile node and access points. Our protocol is more efficient than Park et al.'s and Mishra et al.'s technique can be used in our protocol to further enhance our protocol.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.20 no.2
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• pp.73-90
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• 2010

Recently, Tan et al. introduced a serverless search protocol in which a mobile reader maintains a tag authentication list and authenticates a tag using the list without connecting authentication server. A serverless RFID system is different from general RFID systems which use on-line server models. In the serverless RFID system, since the mobility of a personalized reader must be considered, we have to protect not only the privacy of a tag but also the privacy of a mobile reader. In this paper, we define new security requirements for serverless RFID search system and propose a secure serverless RFID search system. In our system, since tag authentication information maintained by a reader is updated in every session, we can provide the backward untraceability of a mobile reader. Also we use an encrypted timestamp to block a replay attack which is major weakness of search protocols. In addition, we define a new adversary model to analyze a serverless RFID search system and prove the security of our proposed system using the model.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.20 no.1
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• pp.17-31
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• 2010

In VANET (Vehicular Ad hoc NETwork), vehicles can efficiently verify a large number of signatures efficiently using batch verification techniques. However, batch verification performed independently in each vehicle raises many redundant verification cost. Although, an RSU (Road Side Unit) can perform the batch verification as a proxy to reduce this cost, it additionally requires an efficient method to identify invalid signatures when the batch verification fails. In this paper, we analyze several ways of constructing a distributed batch verification system, and propose an efficient distributed batch verification system in which participating vehicles perform batch verification in a distributive manner for a small size signature set. In our proposed system, each node can report the batch verification result or the identified invalid signatures list and the RSU who received these reports can identify the invalid signatures and efficiently exclude them.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.23 no.2
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• pp.67-71
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• 2023

Recently, there are increasing cases of managing software labs by assigning virtual PCs in the cloud instead of physical PCs to each student. In this paper, we design and implement a Linux-based software practice platform that allows students to efficiently build their environments in the cloud. In our platform, instructors can create and control virtual machine templates for all students at once, and students practice on their own machines as administrators. Instructors can also troubleshoot each machine and restore its state. Meanwhile, the biggest obstacle to implementing this approach is the difficulty of predicting the costs of cloud services instantly. To cope with this situation, we propose a model that can estimate the cost of cloud resources used. By using daemons in each user's virtual machine, we instantly estimate resource usage and costs. Although our model has very low overhead, the predicted results are very close to the actual resource usage measured by cloud service providers. To further validate our model, we used the proposed platform in a Linux practice lecture for a semester and confirmed that the proposed model is very accurate.