• Journal of KIISE
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• v.45 no.3
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• pp.303-310
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• 2018

LoRaWAN(Long Range Wide Area Network) is a standard for low-power, long-range, low-speed communication as announced in the LoRa Alliance. LoRaWAN addresses the physical layer and medium access control layer and the technology used in the physical layer is referred to as LoRa. LoRa can be used for remote monitoring and remote control in maritime conditions. However, unlike land, marine environment is not only difficult to construct an infrastructure for service provision, but also difficult to analyze LoRa performance in maritime. In this study, we construct an infrastructure using cloud platform and analyze LoRa link performance in maritime conditions.

• Proceedings of the Korea Contents Association Conference
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• 2007.11a
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• pp.172-177
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• 2007

Reference linking based on a identification system is being widely used both domestically and overseas. National R&D information contains all information related to the R&D programs such as the output and equipment information resulting from the participant and project information. The reference linking service enables the user to freely look up output of a certain program, participant of a project, equipment information from the project or participant and all other information that originates from a R&D project without having to search for it. The reference linking service in the area of national R&D will enable the linking of heterogeneous information produced at different sources.

• Proceedings of the Korea Information Processing Society Conference
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• 2008.11a
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• pp.1222-1223
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• 2008

본 논문에서는 1분에 최대 200 개의 위치보고를 처리하여야 하는 제주 택시 텔레매틱스 시스템에서 보다 효율적인 트래킹과 택시 배차를 위해 맵 매칭에 의해 차량이 위치한 도로를 검색하는 모듈을 설계하고 구현한다. 구현된 모듈은 위치기반 서비스에 있어서 저비용 효율적으로 맵 매칭을 구현하기 위해 쉐이프 파일을 직접 순차적으로 처리하고 보고지점과 세그먼트들로 이루어진 삼각형의 면적을 기반으로 매칭 링크를 검색한다. 이 기능은 차량의 진행방향을 판단하거나 도로 내에서의 위치 비율을 계산하는데 용이하며 다양한 부가 정보를 생성할 수 있다. 구현된 시스템에서 실제 히스토리 데이터에 대해 맵 매칭을 수행한 결과 95% 이상 해당 링크를 검색하였다.

• Journal of the Korean Society for information Management
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• v.37 no.2
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• pp.145-169
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• 2020

The purpose of this study is to find the cause and solution of the situation where library LOD does not spread after the introduction of library LOD. Research methods include literature research, case studies, and expert interviews. The improvement plan presented in this study is that first, the library needs to avoid the redundancy of the LOD construction target and build the only and specialized data. Second, libraries need to develop LOD services that reflect user needs and implement convenient LOD interfaces. Third, libraries need to establish identification system of data and build a authority file. Fourth, libraries need to recognize the necessity of data opening and linking to librarians and users, and provide opportunities for education and publicity. Fifth, it is necessary to use LOD for integrated search and to establish an integrated platform for search of library LOD. Sixth, libraries need to strengthen cooperation for LOD issuance and utilization, and form a working-level consultative body. Seventh, the government should pursue strong policies with a continuous commitment to LOD promotion and need to continue to provide budget support.

• Proceedings of the Korea Society for Simulation Conference
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• 2000.11a
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• pp.91-96
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• 2000

차세대 무선 통신 서비스의 응용은 다양한 형태로 발전하고 있다. 그 중에서 응급상황이나 학내망 같이 특수한 경우에 제공될 수 있는 시나리오로 다중 홉(Multi-hop) 다중 링크(Multi-link) ad-hoc 망을 들 수 있다. Ad-hoc망은 한정된 자원 문제와 변화가 심한 링크 용량문제가 있으며, 다중 홉상의 노드가 이동함으로 토폴로지의 동적 변화문제도 발생한다. 이러한 망의 노드는 송·수신단 역할을 할 뿐만 아니라 패킷을 전달하는 중간 노드의 역할도 하기 때문에 파워의 절약 매카니즘이 절실히 필요하게 된다. 본 논문은 PAMAS에 기반하여, 별도의 제어 채널에 버퍼를 두어 송·수신자 주소와 전송할 데이터의 크기의 정보를 버퍼에 기록하여 예약하고 제어 채널에서 데이터 채널의 파워를 제어할 수도 있으므로 데이터 전송에서 충돌을 예방하고 효율적으로 파워를 절약할 수 있다. 데이터 전송 발생율을 바꿔가며 시뮬레이션 결과 일반적인 방법을 사용한 노드들보다 훨씬 좋은 파워 절약을 이루고 있음을 알 수 있었다.

• Convergence Security Journal
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• v.7 no.4
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• pp.73-81
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• 2007

Users of World Wide Web (Web) experience difficulties in the retrieval of pertinent information due to the increased information provided by Web sites and the complex structure of Web documents that are continuously created, deleted, restructured, and updated. Web providers' efforts to maintain their sites are tend to be less than that of site creation due to the expenses required for maintenance. If information of relationship among Web documents and their validity is provided to Web managers as well as Web developers, they can better serve users. In order to grasp the whole structure of a Web site and to verify the validity of hyperlinks, traversal and analysis of hyperlinks in a Web document are required to provide information for effective and efficient creation and maintenance of the Web. In this paper, we introduce a Web Editor specialized for Web maintenance. We emphasized on two aspects: first, the analysis of HTML Tags to extract hyperlink information and second, establishment of the relationship among hyperlinked documents, and verification of the validity of them.

• Journal of KIISE:Information Networking
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• v.32 no.5
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• pp.551-560
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• 2005

To reduce the amount of the signaling messages occurred in movement, HMIPv6 has been introduced as the hierarchical mobility management architecture tor MIPv6 by regarding the locality of movements. When approaching the visited link, the authentication procedure should be done successfully prior to any motility support message exchanges. The AAA(Authentication, Authorization and Account) authentication service is applied gradually to the wireless LAN and Cellular networks. However, It may bring about the service latency for the sessions of requiring the real-time processing due to not providing the optimized signaling in local and frequent movements. In this paper, we propose the authentication architecture with 'delegation' scheme to reduce the amount of signaling message and latency to resume for local movements by integrating it with HMIPv6 architecture. We provide the integrated authentication model and analyze the performance and effectivity of our proposal and finally offer the analysis materials comparing to the exiting authentication scheme. It cuts down the cost to $33.6\%$ at average measurement.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.19 no.5
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• pp.70-81
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• 2020

Point-by-point data, which is abundantly collected by vehicles with embedded GPS (Global Positioning System), generate useful information. These data facilitate decisions by transportation jurisdictions, and private vendors can monitor and investigate micro-scale driver behavior, traffic flow, and roadway movements. The information is applied to develop app-based route guidance and business models. Of these, speed data play a vital role in developing key parameters and applying agent-based information and services. Nevertheless, link speed values require different levels of physical storage and fidelity, depending on both collecting and reporting intervals. Given these circumstances, this study aimed to establish an appropriate collection interval to efficiently utilize Space Mean Speed information by vehicles with embedded GPS. We conducted a comparison of Probe-vehicle data and Image-based vehicle data to understand PE(Percentage Error). According to the study results, the PE of the Probe-vehicle data showed a 95% confidence level within an 8-second interval, which was chosen as the appropriate collection interval for Probe-vehicle data. It is our hope that the developed guidelines facilitate C-ITS, and autonomous driving service providers will use more reliable Space Mean Speed data to develop better related C-ITS and autonomous driving services.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.2
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• pp.360-368
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• 2008

In this paper, in order that the various QoS(Qualify of Service)s that are required by different traffic class are guaranteed in the random access channels in multi-service multi-user OFDMA systems, the backoff-based random access algorithm is proposed and corresponding performance is analyzed in terms of the access success probability, the throughput, the average delay and the blocking probability. Through the numerical analysis, it is shown that the proposed backoff-based random access algorithm can provide the differentiated QoSs to random access attempts according to their service class.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.11A
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• pp.1630-1641
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• 2000

본 논문은 셀룰러 시스템 상향 링크에서 음성데이터 및 실시간 영상데이터로 구성된 화상전화서비스, 고속 및 저속 데이터베이스의 다중 전송률 멀티미디어 서비스를 통합 지원할수 있는 CDMA R-ALOHA 프로토콜을 제안하였다. 제안된 프로토콜은 액세스슬롯과 전송슬롯으로 구분된 프레임의 구조를 이용한 코드할당 방식으로 전송슬롯에서의 간섭을 줄였다. 그리고, 각 서비스의 트래픽 특성에 따른 전송코드 예약과 화상전화서비스 사용자의 핸드오프호를 고려하여 분석된 각 서비스 부시스템의 Markov-chain 모델을 이용한 각 서비스의 채널 경쟁 사용자수 추정을 기반으로 서비스별 액세스 허용확률을 제안하여, 액세스슬롯에서의 패킷 충돌을 감소시키고 핸드오프호의 우선권을 보장할 수있다. 또한 화상전화서비스의 영상데이터 전송정보를 이용한 코드 예약방식을 제안하여, 음성 트래픽을 패킷의 손실이 없이 지원하였고 고속 및 저속 데이터베이스를 통해 채널 이용효율을 극대화하였다.