• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.8 no.6
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• pp.520-527
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• 2015

The key exchange protocols are very crucial tools to provide the secure communication in the broadband satellite access network. They should be required to satisfy various requirements such as security, key confirmation, and key freshness. In this paper, we present the security functions in ETSI(European Telecommunications Standards Institute), and analyze the specification of the security primitives and the key exchange protocols for the authenticated key agreement between RCST(Return Channel Satellite Terminal) and NCC(Network Control Centre). ETSI key exchange protocols consists of Main Key Exchange, Quick Key Exchange, and Explicit Key Exchange. We analyse the pros and cons of key exchange protocols based on performance analysis and performance evaluation.

• International Journal of Internet, Broadcasting and Communication
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• v.16 no.1
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• pp.55-62
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• 2024

International exchange implementing the Internet began inevitably due to the pandemic, but it provided Digital Nomads with new experiences in their lives using the Internet. This study the possibility and challenge of international exchange implementing the Internet identified. To this end, we explored its strengths and weaknesses through interviews and descriptions of students who participated in international exchange. As a result, we identified that students were positive in the diverse aspects of communication tools and ways, whereas they were negative because they felt difficulties in the physical environment, inaccessible physical conditions especially. They were also negative in the emotional exchange, an ice-breaking which needed much more time than offline exchange. Therefore, we identified in the case of designing or conducting student activities implementing the Internet, including international exchange, the possibility of activities implementing the Internet could be much more extended if their developer various programs considered in the introduction step.

• International Journal of Internet, Broadcasting and Communication
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• v.12 no.3
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• pp.125-130
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• 2020

At the end of 1997, the volatility of the exchange rate intensified as the nation's exchange rate system was converted into a free-floating exchange rate system. As a result, managing the exchange rate is becoming a very important task, and the need for forecasting the exchange rate is growing. The exchange rate prediction model using the existing exchange rate prediction method, statistical technique, cannot find a nonlinear pattern of the time series variable, and it is difficult to analyze the time series with the variability cluster phenomenon. And as the number of variables to be analyzed increases, the number of parameters to be estimated increases, and it is not easy to interpret the meaning of the estimated coefficients. Accordingly, the exchange rate prediction model using artificial neural network, rather than statistical technique, is presented. Using DNN, which is the basis of deep learning among artificial neural networks, and LSTM, a recurrent neural network model, the number of hidden layers, neurons, and activation function changes of each model found the optimal exchange rate prediction model. The study found that although there were model differences, LSTM models performed better than DNN models and performed best when the activation function was Tanh.

• Journal of the Korean Professional Engineers Association
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• v.23 no.1
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• pp.49-63
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• 1990

A signalling system generally designates electrical conditions and transmissionㆍreceiving programs of exchange control use signals concerning the establishmentㆍreleaseㆍtariff etc of calls between telephone subscribers and an exchange office or inter-exchange offices. In signalling system, different systems are being used according as communication service for control. With the development of exchange and transmission technique and higher functional advance, there exist many kinds of signalling systems. As for the signalling system used in international communication, an international standardization is specially important for the exchange of each country to operate properly and execute a smooth exchange connection. A term "signalling system" is chiefly used in telephone exchange system, while in telex exchange system "signalling condition, " and in data exchange system "protocol" is used. "protocol" is used.; is used.

• Journal of Communications and Networks
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• v.12 no.6
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• pp.592-599
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• 2010

In recent years, significant improvements have been made to the techniques used for analyzing satellite communication and attacking satellite systems. In 2003, a research team at Los Alamos National Laboratory, USA, demonstrated the ease with which civilian global positioning system (GPS) spoofing attacks can be implemented. They fed fake signals to the GPS receiver so that it operates as though it were located at a position different from its actual location. Moreover, Galileo in-orbit validation element A and Compass-M1 civilian codes in all available frequency bands were decoded in 2007 and 2009. These events indicate that cryptography should be used in addition to the coding technique for secure and authenticated satellite communication. In this study, we address this issue by using an authenticated key-exchange protocol to build a secure and authenticated communication channel for satellite communication. Our protocol uses identity-based cryptography. We also prove the security of our protocol in the extended Canetti-Krawczyk model, which is the strongest security model for authenticated key-exchange protocols, under the random oracle assumption and computational Diffie-Hellman assumption. In addition, our protocol helps achieve high efficiency in both communication and computation and thus improve security in satellite communication.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.9 no.2
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• pp.162-170
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• 2016

The key exchange protocols are very important to provide the secure communication in broadband satellite access network. However key exchange protocol of ETSI(European Telecommunications Standards Institute) is vulnerable to man-in-the-middle-attack by using Diffie-Hellman algorithm. And the key exchange protocol using certification is not useful in satellite environment. We propose the key exchange protocol using Timestamp which have the resistant to man-in-the-middle-attack. Proposed protocol is able to prevent the man-in-the-middle-attack by calculated time value. Also showing experiment results, we prove that proposed protocol improve memory usage, communication amount and calculation amount than other protocols.

• Journal of the Korean Society of Safety
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• v.17 no.2
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• pp.100-105
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• 2002

This study proposed and examined a model in which perceived organizational support and leader-member exchange are linked to safety communication safety commitment, and accidents. In addition, a moderating effect of role overload in the relationship between safety communication and safety commitment and that of performance monitoring in the relationship between safety commitment to accidents. Data were collected from 193 workers in a railroad company. The results indicated that the goodness of fitness of the proposed model was acceptable. More specifically, both perceived organizational support and leader-member exchange were significantly related to safety communication and safety communication was, in turn, significantly related to safety commitment which was ultimately related to accidents. Also, the moderating effects of both role overload and performance monitoring were found. Implications of these findings for safety and the possible roles of variables in the organizational level are discussed.

• Journal of Elementary Mathematics Education in Korea
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• v.12 no.2
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• pp.165-183
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• 2008

This study is to help to understand the influence of exchange writing activity in the elementary mathematics on students' mathematical communication skill. Various technical activities had been implemented during the classes and the ideas from those activities had been interpreted into writings in the final stage of the classes. Those writings, then, were distributed to other students or teachers in order to devise a teaching model for exchange writing, which is to be applied to the 3rd grade classes and to identify the influence on the in mathematical communication skill. From this study, we could get such conclusions as follows: First, there was considerable difference between experimental group practicing exchange writing and control group engaging in normal learning activities in the progress of their mathematical communication skill (group discussion), writing skill and expressivity when examining their average communication skill using t-method. Similar trend had been witnessed when self-evaluating their mathematical communication skill. Second, when it comes to the mathematical tendency, experimental group showed a higher tendency in positiveness compared to the control group. Therefore, we might conclude that the exchange writing has a positive influence on the students' mathematical tendency, especially on their curiosity or interest in teaming, willingness to study and their comprehension of its importance.

• Journal of information and communication convergence engineering
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• v.3 no.3
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• pp.163-166
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• 2005

The Key exchange protocols are very crucial tools to provide the secure communication in the broadband satellite access network. They should be required to satisfy various requirements such as security, Key confirmation, and Key freshness. In this paper, Two authenticated key exchange protocols TPEKE-E(Two Pass Encrypted Key Exchange-Exchange-Efficient) and TPEKE-S(Two Pass Encrypted Key xchange-Secure) are introduced. A basic idea of the protocols is that a password can be represented by modular addition N, and the number of possible modular addition N representing the password is $2^N$. The TPEKE-E is secure against the attacks including main-in-the-middle attack and off-line dictionary attack, and the performance is excellent so as beyond to comparison with other authenticated key exchange protocols. The TPEKE-S is a slight modification of the TPEKE-E. The TPEKE-S provides computational in feasibility for learning the password without having performed off line dictionary attack while preserving the performance of the TPEKE-E.

• Journal of Communications and Networks
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• v.8 no.4
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• pp.461-474
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• 2006

A group key exchange protocol is a cryptographic primitive that describes how a group of parties communicating over a public network can come up with a common secret key. Due to its significance both in network security and cryptography, the design of secure and efficient group key exchange protocols has attracted many researchers' attention over the years. However, despite all the efforts undertaken, there seems to have been no previous systematic look at the growing problem of key exchange over combined wired and wireless networks which consist of both stationary computers with sufficient computational capabilities and mobile devices with relatively restricted computing resources. In this paper, we present the first group key exchange protocol that is specifically designed to be well suited for this rapidly expanding network environment. Our construction meets simplicity, efficiency, and strong notions of security.