• Journal of the Korea Society of Computer and Information
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• v.10 no.4 s.36
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• pp.259-274
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• 2005

In this paper, we propose a methodology to estimate the number of users in e-Commerce systems. There have been a lot of previous work under the closed-LAN system environment. But the study on the number of acceptable users in real network environment is hard to find in the literature. Our research applies a Hybrid Simulation by using QoS results for end-to-end high-speed Internet service, and experiments are performed with regard to LAN and WAN, network equipments, and various network bandwidth. As result of the experiments we observed that the response time of high-speed Internet service media(Wireless LAN, ADSL, Cable, VDSL) depends heavily on the sequence and depth of transactions and on the ratio of transactional and non-transactional interactions. That is, as the network and application get more loads, the number of acceptable users decreases. By adding a cache server and an L4 switch to the simulation model, we analysed the changes in the number of users and client response time.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.1
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• pp.25-32
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• 2008

This paper presents the reflection and transmission measurements conducted at the 60GHz suitable to provide a high speed wide band service. Mean received power and standard deviation are calculated and used to compare the characteristics of radio wave propagation to the various obstacles between transmitting and receiving antennas at the frequency. The results show that the transmitted signal strength by the steel door and copper plate are about 40dB lower than in free space, those by the rubber plate, glass and styroform are about 3dB lower than in free space. Also, the re(looted signal strengths at the 60 degree grazing angle show that in case by the partition is about 23dB lower, by the surface of a wall is about 6dB lower than by the copper plate. The presented results can be used for the design of 60 GHz picocell communication network that the reflected and transmitted waves affect to the service area.

• Journal of Satellite, Information and Communications
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• v.4 no.1
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• pp.1-7
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• 2009

As the information age comes out, the aspect of future war brings about the many changes in terms of war-fighting environment. Accordingly, information superiority and intelligence-centric warfare have been important and new war-fighting concept such as NCW(network centric warfare) have been turned up. This paper proposed all-weather core-strategy communications systems guaranteeing not only the real-time transmission of the information collected in a battlefield and expansion, automation, and rapidity of a battlefield but also broadband, mobility, survivability, and flexibility. The proposed military satellite communications system is classified into wideband mass capacity link, survivability, and the system supporting OTM(on the move) communication for the real-time transmission of battlefield information. This paper analyzed the essential operation concepts and core schemes of the U.S. Army's next generation system, TSAT(Transformational Satellite Communication System). Base on the analysis results, this paper proposed that the architecture of next generation military satellite communications systems for NCW have to provide the data rate, anti-jamming capability, network control and management capability which are optimally adaptable for the wireless channel environments such as jamming and interference and to support the variety of platforms like high-speed mobile vehicles, micromini devices, super-high speed unmanned aerial vehicles. Finally, this paper also proposed that next generation military satellite communications systems need the technologies such as the adaptable multi-antenna, laser link, and next-generation anti-jamming waveform.

• Journal of Satellite, Information and Communications
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• v.6 no.2
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• pp.15-19
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• 2011

The T-DMB(Terrestrial Digital Multimedia Broadcasting) which was developed by the convergence of digital broadcasting technology and communication technology provides us with very good quality of music like CD, and provides TV services in a super express train like the KTX whose velocity is over 300 Km per hour. The T-DMB is diffusing toward the world as a technology which is be able to provide the various convergent services of broadcasting and communication through mobile phone, PDA, dedicated terminal, and so on. A business model needed for the diffusion of the T-DMB toward the world was established and utilized to expand the T-DMB into Vietnam in the paper. In addition, this paper describes not only some predicting methods for the technological valuation of the T-DMB Total Solution, but also a case study on the marketing related to establishing the T-DMB system in order to provide the paid services in Vietnam. Finally, A couple of business models needed to globally expand the T-DMB have been provided.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.7
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• pp.902-909
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• 2023

This study evaluated the performance test of a small-sized LTE-Maritime(LTE-M) transceiver that was developed and promoted to expand the use of intelligent maritime traf ic information services led by the Ministry of Oceans and Fisheries with the aim of supporting the prevention of maritime accidents. Accoriding to statistics, approximately 30% of all marine accidents in Korean water occur with ships weighing less than 3 tons. Therefore, the blind spots of maritime safety must be supplemented through the development of small-sized transceivers. The small transceiver may be used in fishing boats that are active near coastal waters and in water leisure equipment near the coastline. Therefore, verifying whether sufficient performance and stable communication quality are provided is necessary, considering the environment of their real usage. In this study, we reviewed the communication quality goals of the LTE-M network and the performance requirements of small-sized transceivers suggested by the Ministry of Oceans and Fisheries, and proposed a test plan to appropriately evaluate the performance of small-sized transceivers. The validity of the proposed test method was verified for six real-sea areas with a high frequency of marine accidents. Consequently, the downlink and uplink transmission speeds of the small-sized LTE-M transceiver showed performances of 9 Mbps or more and 3 Mbps or more, respectively. In addition, using the coverage analysis system, coverage of more than 95% and 100% were confirmed in the intensive management zone (0-30 km) and interesting zone (30-50 km), respectively. The performance evaluation method and test results proposed in this paper are expected to be used as reference materials for verifying the performance of transceivers, contributing to the spread of government-promoted e-navigation services and small-sized transceivers.

• Journal of Industrial Convergence
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• v.22 no.2
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• pp.55-62
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• 2024

Visible light communication, which transmits information using visible light, has advantages such as ultra-high speed, ultra-delay, and ultra-connectivity, so research is being conducted as a way to complement 6G communication. In this paper, a study was conducted to overcome the performance degradation caused by the RGB mixing ratio in visible light communication. In a visible light communication system using LED lighting, the role of lighting is an important function, and when used for communication, the performance difference according to the RGB mixing ratio inevitably occurs. In particular, if the intensity of light is below a certain standard, the problem of deteriorating the performance of the entire system occurs. In this study, when a certain performance or less occurs in the communication system caused by the difference in the mixing ratio among the three RGB channels, the remaining two signals except the LED with the best performance are transmitted to STBC (Space-Time Block Coding) to ensure the quality of communication. A computer simulation was performed to verify the performance of the proposed system, and it can be seen that the performance of the proposed system is improved compared to the existing system.

• Journal of The Korean Association of Information Education
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• v.3 no.1
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• pp.65-74
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• 1999

People in the world can send and get useful information from anywhere via internet. Using the internet for educational purposes has been studied for several years. In this paper, we have been designed and implemented video database systems for English education. In the system we have studied ways to build and retrieve useful information from video database systems. By using our system we can easily find required video segment and can play it in real-time way by using streaming techniques.

• The Transactions of the Korea Information Processing Society
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• v.5 no.12
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• pp.3275-3284
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• 1998

In this paper, we deseribe a Medical Image Information System. Our system stores and manages 5 dimensional medical image data and provides the 3 dimensional medical data via the Internet. The Internet standard VR format. VRML(Virtual Reality Modeling Language) is used to represent the 3I) medical image data. The 3D images are reconstructed from medical image data which are enerated by medical imaging systems such ans CT(Computerized Tomography). MRI(Magnetic Resonance Imaging). PET(Positron Emission Tomograph), SPECT(Single Photon Emission Compated Tomography). We implemented the medical image information system shich rses a surface-based rendering method for the econstruction of 3D images from 2D medical image data. In order to reduce the size of image files to be transfered via the Internet. The system can reduce more than 50% for the triangles which represent the surfaces of the generated 3D medical images. When we compress the 3D image file, the size of the file can be redued more than 80%. The users can promptly retrieve 3D medical image data through the Internet and view the 3D medical images without a graphical acceleration card, because the images are represented in VRML. The image data are generated by various types of medical imaging systems such as CT, MRI, PET, and SPECT. Our system can display those different types of medical images in the 2D and the 3D formats. The patient information and the diagnostic information are also provided by the system. The system can be used to implement the "Tele medicaine" systems.

• Proceedings of the Korean Information Science Society Conference
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• 2001.10b
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• pp.601-603
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• 2001

초고속 인터넷 망의 구축에 따라 정보통신 교육이 활성화에 힘입어 직.간접적으로 응용하기 위한 노력이 지속적으로 진행되어 왔다. 웹 기반 원격강의는 원거리 학습자들의 학습욕구를 자기 주도적인 학습이 되도록 전체적인 수업을 진행하므로 학습과정에서의 질의 응답을 교수자에게 면대면으로 제공하지 못하였다. 따라서 학습자가 요구한 질의 내용을 잘못 이해함에 따라 교수자가 학습과정에서의 피드백 제공을 하지 못함으로써 개인학습의 동기부여가 감소됨에 따라 흥미를 입게 되었다. 따라서, 본 논문에서는 웹 기반 서비스에 대한 체계적인 분석 및 설계를 위해 네비게이션 모델을 통해 질의 응답을 지원하는 QALT(Question Answer Learning Tool)를 설계 및 구현한다. 원격강의는 웹 상에서 기본적인 컨텐츠를 제시하고 그를 통해 수업이 진행되는 과정에서의 질의 응답의 문제점을 개선하기 위해 일다대(One-To-Many)의 서비스를 제공한다. 또한. 학습자는 교수자가 지정한 교육용 서버를 통해 텍스트 형식이 아닌 강의자료로 쓰인 문서파일에 직접 작성하여 질의 응답을 가능하게 된다. 그로 인해 교수자와 학생간의 질의 응답을 통해 상호작용을 원활하게 할 수 있는 보조학습도구로써의 사용이 증가될 것이다. 또한 서버에서의 폴더 서비스와 메일링 서비스를 통해 실시간 질의 응답이 가능함으로써 학습자는 강의파일에서 그림에 관한 질문에 효과를 볼 수 있고 교수자는 질문 받은 내용의 위치를 시각적으로 쉽게 볼 수 있으므로 빠른 응답이 가능하게 될 것이다.

• The Transactions of the Korea Information Processing Society
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• v.5 no.12
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• pp.3230-3243
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• 1998

액세스망 기술 분야는 초고속 정보통신 서비스를 제공하기 위하여 유·무선 전달 매체 처리기술, 액세스망 구성 방식 기술, 기존 인프라를 이용하는 고도의 DSL기술 등이 복합되어 사업자의 망 구축 여건에 따라 다양한 형태로 실현되고 있다. MAIN1)은 기존 동선상에서 전화 및 데이터 서비스는 물론 광대역서비스 제공을 위해 VDSL기술을 채용하며, 망 구성방식으로는 ATM/SDH 또는 ATM/PON 기반으로 FTTx 방식의 통합 액세스망 플랫폼이다. 그러나 액세스망은 다수 망사업자와 서비스사업자 환경과 공중망과 사설망이 혼재하며, 새로운 요소기술이 복합되는 망 영역이므로 소요장치의 OAM 뿐만 아니라 망관리에 대한 체계적인 OA&M이 요구되고 있다. 액세스망의 OA&M은 비용 효과적인 액세스망 실현과 실제 망 운용비용과는 상호 상반된 관점을 가진다. 본 논문은 다양한 형태의 액세스망에 대해 통합 관점의 망 관리와 시스템 관리를 위한 체계적인 OA&M 정립을 목적으로 한다. 이를 위하여 통합 엑세스망 플랫폼에 대한 망관리 설계 접근 방법 및 고려사항에 대해 논하고, MAIN의 관리 구조 모델을 제시한다. 또한 MAIN 하드웨어 구조에서 NEL 시스템의 운용관리 및 소요기술에대한 OAM 기능과 망관리 기능 구현을 통하여 MAIN 엑세스망의 OA&M 실현 구조를 조명 함으로서 관련 액세스망 OA&M 구현 시 기본 참조 모델로 제안한다.