• Proceedings of the KIEE Conference
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• 2001.11c
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• pp.130-133
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• 2001

VoIP(voice over internet protocol) technology is based on IP protocol. The IP protocol can be involved in two types of communication: unicasting and multicasting. Unicasting is the communication between one sender and one receiver. It is one-to-one communication. Multicasting is one-to-many communication. So that, many receivers can get same data from one sender simultaneously. and, the different protocol are proposed for VoIP; H.323, SIP and MGCP. MGCP is perfect server-client protocol, so MGCP is very attractive VoIP protocol to ISP. This paper uses MGCP and offers modified MGCP for conference call. So that, Modified MGCP is compatible to MGCP, and supports conference call using IP-multicast.

• Annual Conference of KIPS
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• 2007.05a
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• pp.1087-1090
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• 2007

The security issues related to IPv6 protocol have been focused on by many researchers and engineers. Especially, extension headers of IPv6 protocol provide various functionalities such as IP security, mobile IP, and in principle, it is said to give much more effective network services than the previous protocol, IPv4. In this paper, the cases are surveyed in which fragment header, that is one of many extension headers in IPv6 protocol, is abused and made to be the sources of threats. Prevention mechanisms are also surveyed to countermeasure the threats.

• Journal of KIISE:Information Networking
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• v.37 no.1
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• pp.72-83
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• 2010

Group communication in a wireless mesh network is complicated due to dynamic intermediate mesh points, access control for communications between different administrative domains, and the absence of a centralized network controller. Especially, many-to-many multicasting in a dynamic mesh network can be modeled by a decentralized framework where several subgroup managers control their members independently and coordinate the inter-subgroup communication. In this study, we propose a topology-matching decentralized group key management scheme that allows service providers to update and deliver their group keys to valid members even if the members are located in other network domains. The group keys of multicast services are delivered in a distributed manner using the identity-based encryption scheme. Identity-based encryption facilitates the dynamic changes of the intermediate relaying nodes as well as the group members efficiently. The analysis result indicates that the proposed scheme has the advantages of low rekeying cost and storage overhead for a member and a data relaying node in many-to-many multicast environment. The proposed scheme is best suited to the settings of a large-scale dynamic mesh network where there is no central network controller and lots of service providers control the access to their group communications independently.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.2 no.1
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• pp.14-19
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• 1977

Our social needs many kinds of different circulation method, so the function of communication has been changed the whole situation through the process of many transitions. The form of our civilization is changing into the social which is full of information owing to the development of mass communication. The value of using the information is murk heightening by it's own high dependence. The using of information is being rapidly enlarged, at the same time the development of technique on the information management is caused by the development of communication technique. Thus geometrical operation of both of the above has changed the function of communication. Maybe we will have to present all the primary factors on the communication transition from the social side in order to develop communication method.

• Journal of Information Science Theory and Practice
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• v.4 no.3
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• pp.28-42
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• 2016

Smartphones have become one of the most prevalent information devices in the current information environment. Although many people use smartphones for communication and information acquisition, these two functions are closely related and cannot be separated. However, many studies have focused on identifying each function of a smartphone independently. There are few studies that investigate the relationships between communication and information acquisition functions on smartphones. This research empirically analyzed and identified the relationships between these two functions of smartphones by conducting a survey. The results of the analysis showed that the activities for information acquisition make differences in communication on a smartphone. People who want to acquire more information tend to use a smartphone for communication purposes. Besides, communication activities on a smartphone also affect the acquisition of information. In addition, communication activities on a smartphone also affect the establishment of interpersonal relationships that lead to the acquisition of more information. From these results, it is identified that communication activities and information acquisition are interrelated when satisfying the information needs of smartphone users. Especially, communication activities on a smartphone positively affect people's information activities and enhance information acquisition.

• Archives of design research
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• v.12 no.2
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• pp.109-118
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• 1999

Korea adopted a university education ,which it would have been many changes and innovations until modem developed university has its distinct feature. Design education is started just before release of korea and it has inclueded various majors in many changes until now. On the basis of 'Design', multi-media design has been happened and it shows the em of computer. With this change, the School Curriculum was tried many revisions and major subjects has had many changes reflecting the trend of the times. The Visual Communication Design Education is no exception to this. Especially the Visual Communication Design Education has a special quality that accept ail kinds of medium which can deliver on visual angle. Also it takes the problem that how to receive and teach new medium-Computer. The University education that original subject and new computer subject are mixed appropriately must be established promptly. We reside at the very point where past and present merge toward the future of computer graphic design.

• Journal of Korean Elementary Science Education
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• v.37 no.1
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• pp.54-65
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• 2018

The purpose of this study was to investigate the characteristics of lesson planning of pre-service elementary teachers to develop scientific communication skills for elementary school students. For this purpose, lesson plans and lesson planning journals written by the 53 pre-service teachers were collected and analyzed. The results of the research were as follows. The pre-service elementary teachers used an implicit and contextual approach to develop scientific communication skills. Teaching and learning activities for enhancing scientific communication were mainly conducted in words or in writing. There were many activities expressing elementary school students' thoughts and presenting the results of experiments in the lesson plan. There were many cases in which the pre-service teachers' lesson plans did not include the evaluation of scientific communication skills. In their lesson plans, there are a lot of mutual activities between teachers and students, team and whole students, and inter-students within teams together, and students' individual activities from requests of teachers. We found that the pre-service teachers had various difficulties when they planned the science lesson to develop scientific communication skills. The pre-service teachers were less likely to refer to specialized materials related to science education when planning their classes.

• Journal of Astronomy and Space Sciences
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• v.37 no.1
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• pp.11-18
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• 2020

Satellite optical communication has gained significant attention owing to its many quality features (e.g., a larger bandwidth, license free spectrum, higher data rate, and better security) compared to satellite microwave communication. Various experiments have been performed during many space missions to demonstrate and characterize inter-satellite links, downlinks, and uplinks. Korea has also planned to establish an experimental communication system using a geostationary earth orbit (GEO) satellite and the Geochang station as an optical ground station for low Earth orbit (LEO)-to-ground optical relay links. In this study, the performance of inter-satellite communication links and downlinks was investigated for the new Korean experimental communication system in terms of link margin, bit error rate (BER), and channel capacity. In particular, the performance of the inter-satellite links was analyzed based on the receiving apertures and the transmitting power, while that of the downlink was analyzed in terms of atmospheric turbulence conditions and transmitting power. Finally, we discussed two system parameters of receiving aperture and transmitting power to meet the three criteria of link margin, BER, and channel capacity.

• International Journal of Advanced Culture Technology
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• v.5 no.4
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• pp.38-43
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• 2017

Many students prefer to study abroad to increase their chances of having a better future. While studying abroad they may encounter difficulties such as adapting to the culture of the country they are studying in. Chinese students coming to Korea are no exception to this, and when they are studying abroad, the new environment they are in may cause them hardships which may impact on their social life and even their academic performance. In order to develop their careers, they face many difficulties and challenges. Cultural differences they experience may change their attitudes, thoughts, and values. This research focuses on international students who are not yet certain about their future plans. In order to grasp levels of daily life satisfaction, ease of communication, and future planning orientation, this study conducted a survey of Chinese students who study in Korea. The empirical analysis showed that students with high level of life satisfaction have a tendency to enter graduate school. However, communication has no relation to future planning orientation.

• Communications of the Korean Institute of Information Scientists and Engineers
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• v.4 no.1
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• pp.16-25
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• 1986

Data communication is the transmission of coded information between terminals and computers or between multiple computers. A large, complex, and geographically dispersed present industrial society requires processing of real-time inputs that must be collected from many different locations and production of real-time outpts that must be distributed to many defferent locations. As one of many alternatives to meet the above requirement, a data communication system can be used.