• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 2003.04a
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• pp.409-418
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• 2003

컴퓨터 기술과 정보통신기술의 발달로 인터넷이 보편화되고, 인터넷을 이용한 정보공유가 활성화되고 있으며, 이와 함께 위성영상정보에 대한 통합시스템 구축사업도 활발히 진행되고 있다. 본 논문에서는 공개키 기반구조(PKI)의 공개키 인증서와 권한인증기반구조(PMI)의 속성 인증서를 이용하여, 인터넷 웹서버 접근통제방안을 제시한다. 또한 웹서버에서의 권한인증을 통하여 분산된 위성영상정보 통합체계의 아카이빙시스템에 대한 효과적인 접근통제방안을 제시한다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.1
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• pp.153-156
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• 2005

현재 육상과 해상간의 통신은 Inmarsat 단말기를 이용하여 전화, 텔렉스, 팩스, 전자메일(E-mail) 및 데이터 통신을 한다. 기존 전자메일 프로그램은 비싼 통신요금과 저속의 위성통신 환경에서 최대한 통신비용을 줄이기 위한 목적으로 개발되었다. 그리고 팩스를 이용하는 경우는 관련문서를 출력 후, 송신하기 때문에 시간과 비용이 낭비된다. 이에 현재 많은 나라에서 Inmarsat을 이용한 육상과 선박간의 서로 다른 네트워크 상의 정보를 공유할 수 있는 방법을 모색하고 있다. 따라서 본 논문에서는 기존의 육상과 해상간의 전자메일 시스템과 팩스 기능을 통합한 육상과 해상을 모두 지원하는 인터넷 기반의 팩스 서비스 시스템에 관한 연구이다. 이를 위하여 기존 전자메일 시스템과 공중전화망(PSTN : Public Switched Telephone Network)을 연결하는 하드웨어적인 모듈을 설계하였다.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.20 no.4
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• pp.59-64
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• 2020

Occasionally, MODEM test in satellite communication systems are needed. But Rx terminals in satellite communications are designed to obtain high SNR generally, therefore artificial bad conditions and environments are demanded for the test. One of the typical method is satellite output power reduction. Using noise generator can be another method. However, these costs a lot of money, time, and procedures in reality. In order to overcome these problems, this paper proposes an artificial noise generation method for MODEM test in satellite communication systems. First of all, SNR of a general heterodyne Rx terminal is calculated. Based on the calculation, a new model which is including variable attenuator is proposed to increase noise level. Simulation results illustrate the variable attenuator can control SNR, and these show that MODEM test in satellite communication systems be possible.

• Journal of Korean Society of Transportation
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• v.17 no.3
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• pp.7-20
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• 1999

This Paper Presents a Internet-based Real-Time Automated Vehicle Location System(AVLS), which is able to Provide users with real-time vehicle Positioning information. When Inverted Differential GPS is available, this system does more aggressive position correction than GPS, and more useful for public transportation and commercial application than DGPS in terms of cost.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.12 no.6
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• pp.189-197
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• 2012

In this paper, we propose an optimal path search algorithm that applies the received signal strength between a mobile device and a satellite. Because the common path search algorithm is only based on the shortest path search, it is difficult to provide stable multimedia services for the satellite mobile devices. The proposed algorithm provides the stable communication environment for the satellite mobile devices based on received signal strength. In Satellite communications, changes in the radio quality are severe depending on the receiving environment. Therefore, an accurate analysis of the receiving environment characteristics is very important for providing stable multimedia services of satellite communications. The causes of radio attenuation are atmosphere attenuation, vegetation attenuation and buildings attenuation. These factors were applied to analyze the received signal strength. The proposed algorithm can search the optimal path in urban for stable satellite multimedia services.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.1
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• pp.45-52
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• 2015

Since the broadcast message in satellite signals the security of the data is extremely poor compared to other communication technologies such as the broadcast signal. Thus, encryption of the communication satellite has become a very important issue, an analysis of the communication performance of a general service is always required. In this paper, In order to analyze the encrypted communication the turbo code in an IP-based satellite communication applies the code rate compatible punctured and The wireless channel in consideration of the actual satellite communication was constructed by placing a weight on the Rayleigh fading and the Rician fading two channels. Retransmission-based error control scheme were constructed in the best performance of H-ARQ Type-II, III scheme of a number of ways that are recently considered. we analyzed the effects of normal service against a satellite communication network The security services were configured with encryption algorithms AES, ARIA (CTR, CBC mode).

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.10
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• pp.1190-1196
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• 2016

In this paper, a cross-layer interworking scheme for different protocols is proposed to provide an efficient internet services in very small aperture terminal (VSAT) based satellite communication systems. In addition, we implement the proposed interworking model and prove the feasibility of the proposed system. VSAT based satellite communication systems commonly use digital video broadcasting (DVB)-S2 standard. Unfortunately, DVB-S2 has inefficient parts to support IP based internet services because it has originally been designed to support broadcasting services. Generic stream encapsulation (GSE) protocol, which is a layer 2 protocol, has been proposed to mitigate this inefficiency. We propose a cross-layer interworking scheme to cooperate efficiently between IP and GSE protocols and between GSE protocol and DVB-S2, respectively. In addtion, we implement the proposed interworking schemes via computer softwares and prove the feasibility using NI-USRP and commercial DVB receiver.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.16 no.1
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• pp.121-127
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• 2016

Satellite communication is a communication method using a satellite as a repeater communication on the air and have a communication range is wide and is possible to transmit high-speed data, so Satellite communication has been highlighted as the next generation communication. However, because the distance between the ground and the satellite is far away, there is a disadvantage that propagation delay time is very long and packet is damaged. Therefore, this study was applied to Link Relay H-ARQ system in order to complement the damage to the packet. Furthermore, we propose the Modified Link Relay H-ARQ scheme is a new scheme to supplementation the delay time. By applying the Markov channel for implementing a channel of satellite communications, the results of analyzing the performance, when applying the Link Relay HARQ scheme, BER and PER performance was improved, when applying the Modified Link Relay H-ARQ scheme, Throughput performance was confirmed improvement.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2000.10a
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• pp.216-219
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• 2000

Recently, with the advent of satellite communication technologies, network access services through satellites have emerged as an alternaive to existing access network services. Of satellite access services including multimedia services, the high speed internet access service will be one of the important services. Particularly, the efficient transportation of real time internet traffic seems very essential. The aim of this research is to examine the applicability of the IETF RTP protocol in the satellite access network. The RTP has been developed for the QoS-met tranportation protocol of real time traffic over the existing best-effort internet. This paper summmarizes the RW protocol, and desciribes the architecture and the data structure of the implementation of the RTP.

• 정보화사회
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• s.128
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• pp.32-40
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• 1999

정보통신윤리위원회의 인터넷 내용등급제에 관한 연구결과를 토대로 '90년초에 공청회를 통해 의견을 수렴한 후 '99년 중반부터 시행하고, 내용등급제의 지속적인 관리와 개선을 위해 정보통신윤리위원회를 주축으로 하여 "인터넷 내용등급제 위원회(가칭)"를 구성하여 운영할 예정이다.