• 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 IKEEE
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• v.2 no.1 s.2
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• pp.1-14
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• 1998

In this paper, Antenna, LNA, Mixer, VCO, and Modulation/Demodulation in Baseband processor which are the RF main components in Wireless LAN system for ultra high-speed communications network are studied. Antenna bandwidth and selective fading due to multipath can be major obstacles in high speed digital communications. To solve this problem, wide band MSA which has loop-structure magnetic antenna characteristics is designed. Distributed mixer using dual-gate GaAs MESFET can achieve over 10dB LO/RF isolation without hybrid, and minimize circuit size. As linear mixing signal is produced, distortions can be decreased at baseband signals. Conversion gain is achieved by mixing and amplification simultaneously. Mixer is designed to have wide band characteristics using distributed amplifier. In VCO design, Oscillator design method by large signal analysis is used to produce stable signal. Modulation/Demodulation system in baseband processor, DS/SS technique which is robust against noise and interference is used to eliminate the effect of multipath propagation. DQPSK modulation technique with M-sequences for wideband PN spreading signals is adopted because of BER characteristic and high speed digital signal transmission.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.9A
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• pp.867-875
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• 2005

In this paper, we fabricated along distance wireless communication transmitter and receiver over the 100 which used NRD technology. To make the transmitter and receiver of 400Hz band using the non radiative dielectric wave guide, transmitter was composed of gm oscillator, m modulator and antenna, receiver was composed of local gum oscillator, balanced mixer, 3dB direction coupler and antenna. Also we executed a wireless communication image transmission examination to the transmitter and receiver. We receive the image information in real-time data transmission from receiver after we send the image signal in the wireless distance of the 10km. Therefore, the 400Hz band U transmitter and receiver to be developed will be used widely for the transmission system CATV or broadband transmission system. This will be utilized also to the link device of a long distance high speed wireless communication network.

• Proceedings of the Technology Innovation Conference
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• 2003.06a
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• pp.90-107
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• 2003

참여정부의 출범과 한께 과학기술계에서는 동북아 과학기술 허브 구축방안 논의가 활발히 진행되고 있으나, 현재까지 이러한 논의는 법제도의 정비 및 과학기술특구 건설 등의 이슈에 한정되고 있는 실정이며, 더욱이 이를 뒷받침할 실증적 연구는 미미하다. 허브란 개념이 네트워크에서의 중심성(centrality)을 의미 하며, 현재 및 미래의 과학학기술협력 네트워크 발전에 정보통신기술이 중요한 역할을 수행함을 고려할 때, 우리나라의 초고속통신망 인프라를 십분 활용한 차세대 과학기술 정보인프라의 구축을 통한 동북아 사이버 연구네트워크상의 허브화(궁극적으로는 e-Science의 허브화를 지향)는 지역 클러스터 건설을 통한 물리적 허브화 못지 않게 중요하다 하겠다. 본 연구는 먼저 네트워크 분석기법을 동아시아의 과학기술협력 네트워크에 적용하여 주요 네트워크 지수를 실증적으로 진단하고, 특히 이를 유럽연합의 과학기술협력 네트워크의 패턴과 비교 분석하였다. 유럽 연합은 1984년부터 과학기술 협력 프로그램인 Framework Program을 시작하여 일찍부터 역내 과학기술협력 프로그램을 운영해 온 경험을 가지고 있고, 2000년부터는 자발적 협력과 네트워킹을 통해 유럽의 연구 개발 활동을 통합·조정하기 위해 새롭게 제안된 유럽 연구개발권 (European Research Area) 형성이 구체화되고 있어, 동북아 과학기술협력 네트워크를 건설하는데 좋은 벤치마킹 대상이라 할 수 있다. 이 보고서에서는 유럽 연구개발귄이라는 우산 아래서 유럽의 과학기술 활동이 조정 및 통합되는 과정을 살펴보고, 이를 위한 과학기술 정보인프라의 주요 기능을 컨텐트 (연구정보서비스와 메타데이터 표준), 시스템 (슈퍼 컴퓨팅, 광대역 네트워크, GRID), e-Science 응용연구 별로 살펴보았다. 끝으로 유럽의 경험을: 교훈삼아 동북아 e-Science 네트워크의 건설을 위한 정책적 시사점과 동북아 연구개발정보 Portal 및 APEC APGrid 연구망 등의 구체적인 정보인프라 구축방안을 도출하였다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.10A
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• pp.1517-1531
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• 1999

The Internet is recently evolving into the directions which is capable of incorporating stream-type services such as voice and video services. However, the existing Internet can only support a best-effort delivery model and thus it is difficult to satisfy these requirements as well as to provide the QoS beyond a certain degree. Accordingly, it is imperative to develop QoS based routing algorithm in order to allow the routing by the user's QoS demand and to be applied into wide area networks. In this thesis, we presented new routing algorithms and made performance evaluations. The proposed algorithms allow the routing by the user’s QoS demand level in order to provide the diverse Internet application services based on ATM network environment that is expected to play a role as an infrastructure of high-speed communication network. They also have a feature of shortening the waiting time for address analysis and have a quality-proven characteristics with enhanced network scalability.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.4A
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• pp.385-392
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• 2006

It is widely accepted that high user densities in mobile multimedia environments can only be achieved with micro- and pico-cell. The smaller cell size causes frequent handovers between cells, and decreases permissible handover processing delay. This may result in the handover failure, in addition to the loss of some packets during the handover. In these cases, re-transmission is needed in order to compensate errors, which in turn triggers a rapid degradation of throughput. In this paper, we propose a new handover scheme for the next generation mobile communication systems, in which the handover setup process is done in advance before a handover request by predicting the handover cell based on mobile terminal's current position and moving direction. Simulation is performed in order to analyze the handover failure rate and packet loss rate. Simulation results show that our proposed method provides a better performance than the conventional method.

• Journal of the Economic Geographical Society of Korea
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• v.11 no.2
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• pp.175-191
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• 2008

In the early stage of industrial development, most of software companies were agglomerated at the CBD(Central Business Districts) in Seoul. However, the spatial distribution pattern of Korean Software industry has been changed according to the propagation of broadband, the change in rents, the governmental policy for industrial districts. In this research, using the software year book at 1997 and 2007, the emerging new pattern was analyzed using spatial clustering analysis. As a results of research, the spatial distribution was expanded in morphological changes. However, it was found that there was not a significant difference in a degree of accumulation. In the aspect of behavioral movement of companies, they tend to be relocated from the CBD to urban fringes and their movement is related to the product life cycle in selecting the clustered place.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.5
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• pp.1104-1113
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• 2007

As there have recently been a rapid development in a supercomputer network infrastructure and an increase in the use of wireless terminals such as a PDA and cellular phone, people realize that it is highly required that they develope a various types of application services to integrate wireless network and engage them. On top of that, because current appliances are being converted into digital domestic appliances, and network and such appliances react upon each other, domestic appliances are now evolving to Internet appliances. Thus, people eager to establish a home network, which can offer a various sorts of services to customers because such appliances can share and send the data when such appliances are connected to power lines, telephone wires, and IEEE1394. Along with this, people are also enthusiastically conducting a study on Internet Application, which monitor and control the internet appliances triggered by connecting home network and supercomputer network. This study focuses on designing and developing an integrated wireless home server by effectively integrating wire and wireless network: It can approach and control each internet appliance connected with the home network inside and outside the house. In this study we also test it with an internet appliance simulator.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.639-639
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• 2015

최근 지식정보 사회는 IT가 핵심 구성요소인 스마트 사회로 변모하고 있으며, 인간과 사물 간 의사소통에서 사물과 사물 간 의사소통까지 확장하고, IT간 융합에서 나아가 타 산업과 융합하는 지능형 사회로 나아가고 있다. '공간'에 대한 정보는 '시간'과 함께 인간이 생활하는데 있어 반드시 알아야 하는 가장 근본적인 정보로써, 공간에서 발생하는 정보를 기반으로 다른 사람들과 소통을 하고 목적을 충족함으로써 삶의 질을 향상시킨다. 현대 사회에서 공간정보는 중요한 인프라 가치를 증대시키므로 새로운 사회 패러다임 전환을 위한 필수적인 요소라 할 수 있다. 따라서 본 연구에서는 수재해 정보 플랫폼 구현에 앞서 사용자의 니즈를 만족시키고 효용가치 증대가 가능하도록 공간정보서비스 활용 방안 연구를 하고자 한다. 공간정보는 시대의 흐름에 따라 형태 및 생산?활용방법이 달라졌으나 항상 중요한 정보로 인식되어 왔으며, 미래 공간정보는 단순 콘텐츠 영역을 뛰어넘어 상황(Context)정보까지 범위를 확장하였다. (1)미국의 공간정보는 시설, 기록관리 및 지도와 같은 공공분야에서 현재는 업무통합관리, 의사결정지원 등에서 데이터 웨어하우스(Data Warehouse)로서의 역할 담당한다. (2)일본은 아시아 최고의 원천기술력을 보유하고 있으며, 높은 수준의 GIS, RS(위성항측), ITS(지능형 교통 시스템) 기술을 기반으로 하고 있다. (3)영국은 지리정보시스템과 공공서비스를 접목하여 시민의 요구에 부응하는 고객맞춤형서비스 제공을 국가정보화의 우선과제로 선정하고 있다. (4)우리나라는 초고속통신망과 모바일 기술 등 세계 최고 수준의 인프라를 확보하고 있어, 이러한 인프라 기반융 복합 공간정보서비스를 이용하는데 안정적인 기반을 확보하고 있다. 본 연구는 국내외 공간정보서비스의 패러다임 변화 및 추진 동향 등을 제시하였으며, 수재해정보 플랫폼 활용에 능동적 적극적으로 접근할 수 있는 기반을 마련하였다. 공간정보서비스를 활용하여 커뮤니케이션 강화, 수재해 정보 서비스의 효율성 증진, 재해부문 선진화 측면에서 발전적 영향을 미칠 수 있으며, 특히 각종 현안에 대한 미래 예측 및 대응에 기여할 것으로 판단된다.

• The Transactions of the Korea Information Processing Society
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• v.5 no.11
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• pp.2943-2953
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• 1998

As communication networks become very fast, the scope of applications is varied and applications using multi-party communications in which more than one communication station participate, have been increased. In this paper, multicast servers are designed and implemented by two different schemes (centralized multicast server scheme and distributed multicast server scheme). Both scheme contain three operation for joining/leaving of a node, operation for transmitting the name of the group and messages to the server, and operation for a node to read messages and clear shared memory. Based on their implementations, two multicast server schemes are compared in terms of complexity, extendibility, efficiency and real-time aspects. As a result, the average transfer time of the distributed multicast server scheme is shorter than that of the centralized multicast server scheme. Finally, we designed the multi-party real-time communication method to guarantee QoS in multicast.