• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2006년도 International Symposium on GPS/GNSS Vol.2
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• pp.125-129
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• 2006

Japan has been investigating a new satellite based positioning system called Quasi-Zenith Satellite System (QZSS). Since the improvement of positioning availability in urban area is one of the most important advantages of the QZSS, multipath mitigation is a key factor for the QZSS positioning system. Therefore, Japan Aerospace Exploration Agency (JAXA) and GNSS Inc. have commenced the R&D of a pseudolite, which transmits the next-generation signal such as BOC(1,1), in order to evaluate the effect of multipath on the new signal. A prototype BOC pseudolite was developed in 2005, and ground tests showed a capability of generating proper pseudorange. Also, preliminary flight experiments using a pseudo quasi-zenith satellite, a helicopter on which the pseudolite is installed, were conducted in early 2006, and the BOC-type correlation function was monitored in real time.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 G
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• pp.3249-3252
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• 1999

In this paper, we present the Tele-PACS of radiology, which uses the communication network as asymetric satellite data communication system. The asymetric satellite data communication system uses receive-only satellite links for data delivery and PSTN(Public Switched Telephone Network) modem or N-ISDN(Integrate Services Digital Network) for communication. The satellite communication linking shows the very high-speed performance than terrestial linking such as 28.8 kbps modem linking and 56Kbps linking. The satellite linking is 5 - 10 times faster than the 56Kbps linking. We conclude that 1) Satellite networking is currently the cheapest and fastest solution for internet access. 2) Web-based Image-Viewer enables small size hospitals in rural area to connect to central PACS easily and to retrieve the image data reliably. 3) The suggested teleradiology system using satellite networking could be adequate to fast telemedicine and telecare for rural hospitals especially located in geographically isolated areas such as islands.

• 한국정보처리학회논문지
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• 제3권4호
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• pp.961-968
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• 1996

무궁화 위성 과제 중에서는 지구국 시스템에서 위성 링크를 통한 LAN 상호간의 접속을 제공하기 위한 시범위성 네트워크 모듈의 구현을 수행하였다. 이 시범 네트워 크는 위성을 통하여 다양한 응용들에 대한 수행을 검증하기 위한 시험을 지원할 수있 다.본 논문에서는 위성 전송시의 장단점을 고려하여 충분히 응용할 수 있는 위성-LAN 접속 구조를 제안하였다. 본 네트워크 구조는 두개의 노드에서 복수의 논리 접속을 수행하는 연결 중심형인 위성 프로토콜을 사용함으로서 높은 데이타 전송과 위성 접속 에러율에 대한 높은 성능을 제공한다. 또한, 프로토콜 변환 방법에 따라 라우터 접속을 수행할수 있다. 위성과 네트워크 접속의 구조는 4W 고출력 증폭기가 장착된 1.8m의 안테나, 위성통신용 모뎀, 위성 네트워크 접속 장치가 설계되었다. 이 시스 템은 최대 1.544 Mbps의 전송 속도를 자원할수 있으며 네트워크 관리면에서도 우수 하게 동작하였다.

• 한국항공우주학회지
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• 제34권10호
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• pp.80-91
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• 2006

위성공학을 전공하는 학생들에게 실질적이고 경험적인 교육을 제공하기 위해 HAUSAT-1과 HAUSAT-2 두 초소형 위성 개발 프로젝트 기반의 다학제간 우주비행체 설계 교육방법을 적용하였다. HAUSAT-1은 국내최초로 개발된 1 kg급의 초소형 피코 위성이다. HAUSAT-2는 25 kg급의 나노 위성으로 현재 준비행 모델(Proto-Flight Model)을 개발 중에 있다. 이들 설계 프로젝트는 연구와 설계 교육의 통합적 기능을 제공함으로써 대학의 고유기능인 과학 및 기술 연구와 설계 교육을 통한 전문 인력양성의 목표를 동시에 이루는 것이 가능하다. 이러한 복합시스템인 우주비행체 설계 교육을 통하여 참여 학생 전원이 우주비행체의 전 시스템 개발 과정을 직간접적으로 경험할 수 있게 하고, 최근 들어 각광을 받고 있는 다학제간 시스템 교육의 활성화를 이룰 수 있다.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2002년도 Proceedings of International Symposium on Remote Sensing
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• pp.751-756
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• 2002

Since the operation of the first satellite-based navigation services, satellite positioning has played an increasing role in both surveying and navigation, and has become an indispensable tool for precise relative positioning. However, in some situations, e.g. at a low angle of elevation, the use of satellites for navigation is seriously restricted because obstacles like buildings and mountains can block signals. As a mean to resolve this problem, the quasi-zenith satellite system has been proposed as a next-generation satellite navigation system. Quasi-zenith satellite is a system which simultaneously deploys several satellites in a quasi-zenith geostationary orbit so that one of the satellites always stay close to the zenith if viewed from a specific point on the ground of East Asia. Thus, if a position measurement function compatible with GPS is installed in the quasi-zenith and stationary satellites, and these satellites are utilized together with the GPS, four satellites can be accessed simultaneously nearly all day long and a substantial improvement in position measurement, especially in metropolitan areas, can be achieved. The purpose of this paper is to evaluate the effectiveness of quasi-zenith satellite system on positioning accuracy improvement through simulation by using precise orbital information of the satellites and a three-Dimensional digital map. Through this simulation system, it is possible to calculate the number of simultaneously visible satellites and available area of the positioning without the need of actual observation.

• 한국군사과학기술학회지
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• 제18권6호
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• pp.755-761
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• 2015

Satellite Air-defence Warning System receives the aircraft/ballistic track information and air defense control command obtained from Master Control & Reporting Center (MCRC) and Air Missile Defence Cell (AMD Cell) Systems. It consists of terminal and control system to propagate track information and air defense control command control via the military satellite communications. In this paper, there were described track information, air defense control command, the frame structure of modem to transmit a voice information and modulation/demodulator design, network synchronization methods via the satellite network.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2008년도 International Symposium on Remote Sensing
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• pp.232-235
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• 2008

The mission of the EO(electro-optical) based low earth orbit satellite is provision of the high-resolution images required for GIS(Geographical Information Systems) establishment and the applications for environmental, agriculture and ocean monitoring. AEISS(Advanced Earth Imaging Sensor System) which is the main payload on the satellite consists of EOS(electro-optical subsystem) and PDTS(Payload Data Transmission Sub-system). IDHU(Image Data Handling Unit) which is one of the major unit in PDTS is capable of compression, storage, encryption and encoding. In this paper, the payload system of the EO based satellite is briefly introduced and the influence of the compression on AEISS is analyzed.

• 항공우주기술
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• 제11권1호
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• pp.1-6
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• 2012

인공위성의 전력 시스템을 보호하기 위해서 퓨즈나 LCL (Latching Current Limiter) 등을 부하와 전원 공급 장치 사이에 연결한다. 본 논문에서는 인공위성에서 장착되는 퓨즈의 용량 선정 기법에 대해 논하였다. 퓨즈 용량 선정 방법에 대해 기술하였고, 병렬 (Parallel) 퓨즈 연결 방식을 수학식으로도 단일 (Single) 퓨즈 연결 방식으로 나타낼 수 있음을 보였다. 또한, 퓨즈에 연결되는 부하의 정확한 전류 특성이 알려지지 않은 상태에서 적절한 퓨즈 선정 기법을 새롭게 제시하였다.

• 한국위성정보통신학회논문지
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• 제12권2호
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• pp.65-70
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• 2017

The structure of MMSE receiver front-ended by CMA(Constant Modulus Array) array working in CDMA forward link which is applicable to LEO spread spectrum satellite communication system is proposed. By using the despreaded pilot signal of forward link as a reference signal, the CMA array can capture multi-path signals securely even in severely faded LEO satellite channel. The remaining MAI (Multiple Access Interference) is cancelled by the cascaded MMSE receiver. Besides theoretical development, through relevant computer simulation, it is proved that the proposed system shows much better BER performance than any other possible candidate systems. As a spatio-temporal receiver mounted on a mobile vehicle, the proposed system also reduces implemental cost and complexity by adopting the simplest algorithm for its spatial and temporal domain processing.

• Journal of Positioning, Navigation, and Timing
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• 제12권4호
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• pp.369-377
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• 2023

This paper presents the analysis results of navigation performance of Korea Augmentation Satellite System (KASS) test signals. Performance analysis was performed with Global Positioning System (GPS) and Satellite Based Augmentation System (SBAS) signals received from 7 KASS reference stations. And the performances were analyzed in terms of the signal strength, statistics for each SBAS message, coverage of ionospheric correction, accuracy, integrity, continuity, and availability. In addition, the navigation solutions provided by commercial receiver was analyzed and the performance experienced by general users was presented. Lastly, directions for further improvement of the KASS system were addressed. These performance analysis results can be used to confirm the feasibility of utilizing KASS in user applications.