• Journal of information and communication convergence engineering
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• v.8 no.3
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• pp.277-280
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• 2010

We report that broadcast messages in Mobile WiMAX networks should be synchronized throughout all the base stations to gain the benefit of beamforming technique. A simple synchronization implementation of broadcast messages in Mobile WiMAX networks is presented. Using this technique, the interference between broadcast messages and beamformed messages can be reduced.

• Educational Technology International
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• v.13 no.1
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• pp.49-77
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• 2012

The development of mobile devices and network technology is changing the ways in which people communicate with one another. Mobile text message has emerged as one of the most frequently used form of communication, which also gave rise to various non-verbal texts such as emoticons. Nonetheless, the use of text messages has largely been denied in education because text messages often involve colloquial and non-verbal texts considered inappropriate or grammatically incorrect by the teacher. In efforts to provide a theoretical framework to better understand mobile e-text communication, this research compared the practical usages of non-verbal texts in the mobile e-learning environment. The study developed three types of text messages according to the degree of using non-verbal texts and their phraseology as instructors' messages, which were then distributed to 259 students via mobile text messaging. The perceptions of students were analyzed using a semantic differential scale and a questionnaire. The results showed clear differences in students' perceptions of non-verbal text and traditional text, and that optimally designed non-verbal texts turned out to encourage the students' interaction the most out of the three types of text messages. Following the discussion of the results, an expanded theoretical framework beyond Ong's concepts of orality and literacy is also suggested to understand the evolution of mobile e-text communication in education.

• Journal of KIISE:Information Networking
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• v.27 no.1
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• pp.39-47
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• 2000

This paper is to propose an efficient and reliable control procedure of Base Station Controller of mobile communication system for bulk input messages which was delivered instantaneously. We divided the input messages that are processed by the base station controller of the mobile communication system into two things ; they are messages related to call connection and o&m(operation and maintenance). In addition, we analyzed the properties of the input messages and then performed computer simulation on each input message by using M/M/1/K queueing model in term of the following viewpoints : the loss probability of input messages, the average queue length, the utilization of process controller(server),the average waiting time in queue. And we compared the performance of the two input messages in the overload controlling which was caused by the congested input messages.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.05a
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• pp.241-244
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• 2003

Recently, IETF Mobile IP WG focus on security problem issues in Mobile IPv6 and provide appropriate protocol to solve them. These include the protections of Binding Updates both to home agents and correspondent nodes, prefix discovery messages and transporting data packets. In Mobile IPv6, control traffics between home agents and mobile nodes uses IPsec to avoid that mobile nodes and correspondent nodes may be vulnerable to attacks. It is used, however, Return Routability procedure for correspondent node to assure that the right mobile node is sending the messages. In this paper, we propose method of IPser processing to protect messages between home agents and mobile nodes.

• Journal of KIISE:Information Networking
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• v.35 no.4
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• pp.345-354
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• 2008

Recently, small-scale mobile network which is composed of many mobile devices in a man becomes popular. Also, Examples of large-scale mobile network can be thought access networks deployed on public transportation such as ships, trains and buses. To provide seamless mobility for mobile nodes in this mobile network, binding update messages must be exchanged frequently. However, it incurs network overhead increasingly and decreases energy efficiency of mobile router. If we try to reduce the number of the messages to cope with the problem, it may happen the security -related problems conversely Thus, mobile router needs a effective algorithm to update location information with low cost and to cover security problems. In this paper, mobility management scheme based on mobile router's mobility pattern is proposed. Whenever each mobile router leaves a visiting network, it records related information as moving log. And then it periodically computes mean resident time for all visited network, and saves them in the profile. If each mobile router moves into the visited network hereafter, the number of binding update messages can be reduced since current resident time may be expected based on the profile. At this time, of course, security problems can happen. The problems, however, are solved using key credit, which just sends some keys once. Through extensive experiments, bandwidth usages are measured to compare binding update messages in proposed scheme with that in existing scheme. From the results, we can reduce about 65% of mobility-management-related messages especially when mobile router stays more than 50 minutes in a network. Namely, the proposed scheme improves network usage and energy usage of mobile router by decreasing the number of messages and authorization procedure.

• Journal of KIISE:Information Networking
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• v.31 no.1
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• pp.27-36
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• 2004

Frequent occurrence of binding update messages may incur high overhead in Mobile IP supporting users mobility. Thus, it needs to develop algorithms to deal with the situation. In this paper, we propose new lifetime assignment schemes for dynamic binding update considering the locality property related with mobile node's movement. Each mobile node maintains a profile which is based on log containing useful information about its visiting subnets. That is, it determines dynamic binding update lifetime for currently visiting subnet by computing past mean resident time recorded in the profile. In addition, we note that the resident time depends on the time when each node enters a subnet and thus, we devise another lifetime assignment algorithm. Extensive experiments are made to compare our schemes with existing Mobile IPv6 where major facts for performance comparison are both the number of binding update messages and the number of binding request messages. From the results, we come to know that our schemes obtain highly considerable performance improvements in terms of communication cost by decreasing the number of those messages.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.11
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• pp.2409-2424
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• 1997

Multicasting to mobile hosts(MHs) based on broadeasting results in overloaded unnecessary messages in case of th number of recipient MHs is relatively small compared with that of nodes in a network. In this paper we propose an improved multicast protocol in which messages are selectively flooded only to the (radio) cells within some distance from the cells where destination MHs reside most recently, so that the number of unnecessary messages carried in broadcasting is reduced. Detailed procedures for the protocol are provided and protocol properties are proven.

• Journal of Information Technology Applications and Management
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• v.18 no.4
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• pp.21-40
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• 2011

Emoticons perform an important role as an enhancement to written communication, in areas such as Windows Live Messenger instant messaging, e-mails, mobile Short Message Services (SMS), and others. Emoticons are graphic images used in communications to indicate the feelings of people exchanging messages via mobile technology. In this research, the perceived usefulness of the emoticon in mobile phone text messages is verified with consumers using the five construct model of Huang. A K-means clustering technique for separating three groups based on levels of perceived usefulness of mobile emoticons is used with a structural equation model test using Smart PLS 2.0, and the bootstrap re-sampling procedure. We analyzed relationships among use of emoticons, enjoyment, interaction, information richness, and perceived usefulness. The results show there are relationships among use of emoticons, enjoyment, interaction, perceived usefulness, and information richness, however enjoyment of emoticons did not significantly affect the perceived usefulness of messages with emoticons alone. The results suggest emoticons have different affects on emotion in both mobile, and Messenger contexts. Our study did not consider more detailed media properties, and thus more studies are needed. Our research results contribute to mobile communication activation, provides companies with an understanding of key characteristics of consumers who use emoticons, and provides useful implications for improving management and marketing strategies.

• Journal of the Korea Society of Computer and Information
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• v.12 no.4
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• pp.159-167
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• 2007

This study executed questionnaire surveys on 482 undergraduates of D-college to review the extents of spam letter messages received through the mobile phones of college students and the extents of their addiction to mobile phones. It was revealed that each college student received one or two spam letter messages on average a day. Among the received spam messages were the messages containing the contents of commodity advertisements most frequent and the surveys indicated that spam messages are hardly read. As for the addiction to mobile phones, the average score of addiction of the respondents was indicated to be 38.73 based on the full score of 100 and the number of the ones with the scores of 60 or more was 47 which is 9.75% and the ones with the scores of 70 or more was 13 which is 2.70%. Also the younger the students were, the higher were the numbers of the students included in the addictive group and the number of students from other areas included in the addictive group was high and the number of the students in 2years system included in the addictive group was higher than the number of the students in 3years system included in the addictive group.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.7
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• pp.2595-2602
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• 2010

This paper introduces a mobile spam filtering system that considers the style of short text messages sent to mobile phones for detecting spam. The proposed system not only relies on the occurrence of content words as previously suggested but additionally leverages the style information to reduce critical cases in which legitimate messages containing spam words are mis-classified as spam. Moreover, the accuracy of spam classification is improved by normalizing the messages through the correction of word spacing and spelling errors. Experiment results using real world Korean text messages show that the proposed system is effective for Korean mobile spam filtering.