• Journal of Korean Institute of Industrial Engineers
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• v.24 no.2
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• pp.241-249
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• 1998

In this paper, we seek to find an optimal allocation of link capacity in a data communication network. The architecture of the data communication network considered in the study is an online-service network based on public switched telephone network(PSTN) and packet switched data network(PSDN). In designing the architecture of the network, we need to deal with various measures of quality of service(QoS). Two important service measures are the call blocking probability in PSTN and the data transfer delay time in PSDN. Considering the tradeoff between the call blocking probability and the data transfer delay time in the network, we have developed the optimal link capacity allocation model that minimizes the total link cost, while guarantees the call blocking probability and the data transfer delay time within an acceptable level of QoS. This problem can be formulated as a non-linear integer programming model. We have solved the problem with tabu search and simulated annealing methods. In addition, we have analyzed the sensitivity of the model and provided the insight of the model along with computational results.

• Journal of Computing Science and Engineering
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• v.7 no.3
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• pp.187-197
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• 2013

Security has long been a challenging problem in wireless networks, mainly due to its broadcast nature of communication. This opens up simple yet effective measures to thwart useful communications between legitimate radios. Spread spectrum technologies, such as direct sequence spread spectrum (DSSS), have been developed as effective countermeasures against, for example, jamming attacks. This paper surveys previous research on securing a DSSS channel even further, using physical layer attributes-keyless DSSS mechanisms, and watermarked DSSS (WDSSS) schemes. The former has been motivated by the fact that it is still an open question to establish and share the secret spread sequence between the transmitter and the receiver without being noticed by adversaries. The basic idea of the latter is to exploit the redundancy inherent in DSSS's spreading process to embed watermark information. It can be considered a counter measure (authentication) for an intelligent attacker who obtains the spread sequence to generate fake messages. This paper also presents and evaluates an adaptive DSSS scheme that takes both jam resistance and communication efficiency into account.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.6
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• pp.2754-2759
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• 2011

With information communications and RFID/USN environments merged wire/wireless networks are generalized. In this viewpoint, WAP is used by communication protocol for the data communication in the field of wireless environment. WTLS developed for the secure communications optimize TLS adapted wireless environment in the TCP/IP internet protocol. But WTLS denote WAP security problem, end-to-end problem, and power consumption, etc. Therefore in this paper we proposed WTLS cryptographic algorithm eliminated WTLS disadvantages. Proposed algorithm solved power consumption, calculated complexity, and security problems because it is not unique but hybrid form.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.7
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• pp.1419-1424
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• 2005

This paper suggests a new cipher mode of operation which can recover cryptographic synchronization. First, we study the typical cipher modes of operation, especially focused on cryptographic synchronization problems. Then, we suggest a statistical cipher-feedback mode of operation. We define the error sources mathmatically and simulate propagation errors caused by a bit insertion or bit deletion. In the simulation, we compare the effects of changing the synchronization pattern length and feedback key length. After that, we analyze the simulation results with the calculated propagation errors. finally. we evaluate the performance of the statistical cipher-feedback mode of operation and recommand the implementation considerations.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.9
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• pp.2031-2039
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• 2010

This article first defines the concept of ubiquitous learning, and then examine ways to design the educational environment for e-Learning and u-Learning. Next, identifies some disadvantages before seeking possible solutions. Finally, the article explores visions of how ubiquitous learning might look in the future. With the advent of information, communication and computer technologies, the needs and demands for ubiquitous learning are largely emerging, enabling students to easily access everything they want anytime, anywhere. In particular, the advance of high-speed broadband networks such as DMB, WiBro and WCDMA and the proliferation of portable digital devices including DMB, PDA and high-performance mobile phones will encourage the widespread adoption of u-Learning.

• Journal of information and communication convergence engineering
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• v.12 no.1
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• pp.19-25
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• 2014

The wireless sensor networking standard DASH7 operates in low-power communication with a better transmission quality in active RFID networks. The DASH7 security standard supports public key cryptography. At present, the DASH7 standard uses the message authentication code in the network layer for authentication and integrity. However, its security standard is still in an incubation stage with respect to the implementation of a crypto exchange over a DASH7 network. Effective key management is an important factor for privacy and security. If organizations are not careful about where and how keys are stored, they leave the encrypted data vulnerable to theft. In this regard, we present a key management system designed for efficient key management through public key infrastructure authentication as well as a non-repudiation feature for the DASH7 standard. We analyze the performance of the proposed system on a basis of various performance criteria such as latency and throughput.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.3B
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• pp.130-137
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• 2005

Wireless communication environment is changing rapidly as we use new wireless communication technology such as WiBro to access high speed Internet. As a result, reliable data transmission using TCP is also expected to increase. Since TCP assumes that it is used in wired network, TCP suffers significant performance degradation over wireless network where packet losses are related to non-congestion loss. Especially RTO imposes a great performance degradation of TCP. In this paper, we analyze the loss recovery probabilities based on previous researches, and use simulation results of our algorithm to show that it prevents performance degradation by quickly detecting and recovery losses without RTO during fast recovery.

• Proceedings of the KIEE Conference
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• 2000.11d
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• pp.663-665
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• 2000

For the control system of thermal turbine in fuel and nuclear power plant, as high reliability and availability are required, redundant control system is generally applied. This paper presents the configuration and design of such a redundant control system that can be suitable for control and monitoring of the turbine. System components such as I/O system, communication networks, voting system are designed, and especially the new intelligent voter using serial communication are proposed. The characteristics of the implemented control system is independence of the control, protection and monitoring functions, and discrimination of the redundancies, and high availability. The control functions such as speed control, load control, valve control and protective functions such as overspeed and PLU are designed in detail.

• Journal of Contemporary Eastern Asia
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• v.11 no.1
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• pp.1-20
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• 2012

This study analyzes messages from Korean TV debates on the conflict over U.S. beef imports and the process of negotiations over the imports in 2008. The authors have conducted a content analysis and a semantic network analysis by using KrKwic and CONCOR. The data was drawn from nine TV debates aired by three major TV networks in Korea (MBC, KBS, and SBS) from 27 April 27 2008 to 6 July 2008. The results indicate substantial differences in the semantic structure between arguments by the government and those by civic groups. We also investigated the relationship between the terms frequently used by both sides (i.e., the government and civic groups), and the terms used exclusively by one side. There was a gradual increase in the number of terms frequently used by both sides over time, from the formation of the conflict to its escalation to its resolution. The results indicate the possibility of general agreement in conflict situations.

• Journal of Digital Convergence
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• v.12 no.7
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• pp.267-272
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• 2014

Many people have used a internet at various purposes. Internet have been used the optimal space to share informations by information producer or consumer. But, recently, through the development of networks and devices, The Internet is expanding beyond PCs and mobile devices into enterprise assets such as field equipment, and consumer items such as cars and televisions. The Internet of Things will enable forms of collaboration and communication between people and things, and between things themselves, hitherto unknown and unimagined. This paper presents various meanings of IoT, and describe the electronic and car domain of internet of things.