• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.16 no.7
• /
• pp.1344-1349
• /
• 2012

The Korean DGPS station transmits the 200 bps GPS enhancement signal using the MSK modulation in frequency range of 283.5 kHz to 325 kHz. The land-based stations of 6 sites provide the service area of 80 km with the output power of 500 W. The ocean-based stations of 11 sites provide the output power of 300 W, which provide the DGPS service to 185 kM. Some places are serviced from two or three DGPS stations. The interferences among the DGPS stations using the high power can be occurred. Also, the performances of the user terminasl in dual service area can be degraded. In this paper, the protection ratios for the DGPS service are defined. Using the MF wave propagation model, the interferences among the DGPS stations and the adjacent wireless ground stations are analyzed. Also, the performances of DGPS user terminals are analyzed in the viewpoint of interference.

• The KIPS Transactions:PartC
• /
• v.9C no.4
• /
• pp.581-588
• /
• 2002

In this paper, we newly propose the optical CDMA routing scheme for the radio access network. At the radio base station (RBS), the received radio signals are multiplied by the PN codes and converted to the CDMA radio signals. In the next optical CDMAS are performed and multiplxed by using the PN codes which are the addresses of the routing mobile switching center (MSC). At the MSC, the CDMA radio signals are routined to another MSC by the CDM receiver at the routing node. In the case MSC is equal to the desired MSC, the radio signal is correlated by the two-layerd spectrum despreading at a time. Finally we theoretically analyze the signal-to-interference and noise power ratio of regenerated signal and the routing error probability and show the availability of proposed scheme.

• Journal of Korean Society for Geospatial Information Science
• /
• v.10 no.3 s.21
• /
• pp.107-114
• /
• 2002

The cadastral surveying is essential for the effective management of a country, the D/B building of NGIS. Many of GPS applications require a positioning accuracy of several centimeters for rover in real-times. But, to achieve higher positioning accuracies in real-time, the double differencing technique should be implemented using carrier phase data. Corrected observations at the reference station can be transmitted and used to form double difference observations at the rover using a data link. In this study, the area accuracy of cadastral survey using the RTK GPS will be assessed, and will produce area of parcel of land. As the result of comparison among area by TS, planer surveying and RTK GPS. parcels-register for site is analyzed by this data. The results show that mean error of area calculated min. $2.42m^{2}{\sim}\;max.\;13.69m^{2}$ and RMSE calculated min. $0.00329\;{\sim}\;max.\;0.01846$.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.26 no.6
• /
• pp.617-624
• /
• 2008

In general, RTK-GPS(Real Time Kinematic GPS) based on the single reference station is able to determinate the high accurate position of rover on the spot using error correction information of transmitted carrier phase from the base station via wireless modem. However, single reference station method has some weak points to decrease positioning accuracy because it must be obtained carrier phase from the each satellite continuously, allowed to transmit without obstacle and limited to short base line distance between base and rover station. This paper aims to attempt network based GPS carrier phase differential positioning using three multi reference stations to overcome the method of single reference station and RTK network is realized by real time monitoring program with Visual C++. The optimum error correction value of three multi reference stations by RTK networking is selected automatically to correct the position of rover station. In this paper, this algorithm is applied to determine sea water level using GPS buoy, and the accuracy results of water level change were analyzed and compared with each other using single and multi reference stations.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.32 no.1A
• /
• pp.125-133
• /
• 2007

In this paper, the frequency sharing issue between cellular time division duplex-orthogonal frequency division multiple access (TDD-OFDMA) Systems and terrestrial Fixed Systems has been studied. The conventional advanced minimum coupling loss (A-MCL) includes only the formulation to calculate the interference from one interfering system. Therefore, A-MCL must be modified to assess the aggregated interference from base stations(BS) and mobile stations(MS). By applying the modified model, the coexistence analysis are done according to the average number of MS per sector, BS-to-BS distance, and the main beam direction of the terrestrial fixed system. In the case of 20 MS per sector, the BS-to-BS distance and the minimum distance between a terrestrial fixed system and BS are 5.8 km and 2.5 km, respectively. It is about 25dB that the difference between maximum and minimum interference signal power which varies with the main beam direction of the terrestrial fixed system. Moreover, for 40% of the main beam direction of the terrestrial fixed system, interference signal power is less than the maximum permissible interference.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.18 no.2
• /
• pp.282-288
• /
• 2014

The DGPS reference station is a national infrastructure generating GPS correctional information and transmitting the signal for Differential GPS. Currently, Korea has applied and operated the software-based DGPS reference station as a standard of the next generation proposed by the USCG in order to improve the hardware-based DGPS reference system. However, software-based DGPS reference station proposed by USCG was changed in software method, only for form. There is no advantage to changing software-based because the most critical part of architecture has not been improved. In this paper, we have designed a new software-based marine DGPS station architecture that a reference station software and a monitor station were integrated. The new marine DGPS station architecture based on software is a more simplified structure than it used to be and can be utilized in the DGPS reference station.

• Korea Trade Review
• /
• v.42 no.6
• /
• pp.51-67
• /
• 2017

This study analyzes the relationship between globalization and income inequality. The empirical model is developed based on Kuznets' hypothesis of the inverse U curve. The effects of factor abundancy and globalization which is characterized by trade and FDI on income inequality are analyzed. 127 member countries of WTO are classified into 4 groups according to GNI. The period of analysis is 21 years from 1995 to 2015. Results show that 3 groups of countries excluding one group that is high income countries supports Kuznets' hypothesis which is the inverse U curve. Secondly, expansion of trade decreases income inequality of middle income countries but increases high and low income countries. Thirdly, FDI increases income inequality of middle and low income countries. Finally, the increase in capital abundancy lowers income inequality because the capital accumulation increases the productivity of labor.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2022.11a
• /
• pp.209-211
• /
• 2022

우리나라 R-Mode(Ranging Mode) 항법시스템은 국제해사기구(IMO, International Maritime Organization)에서 요구하는 항구 입출항용 항법 요구성능(정밀도 10m)을 만족하도록 개발을 진행하고 있다. R-Mode 항법시스템은 위성국 송출을 기반으로 하는 GPS와 달리 지상국 송출을 기반으로 한다. 또한 신호가 세기가 높아서 의도적 전파간섭이 어려우므로 국제해사기구가 요구하는 강인한 PNT(Resilient PNT) 시스템에 적합한 것으로 평가받고 있다. 이러한 요구조건과 기회신호(SoOp, Signal of Opportunity)의 국내 환경에 맞추어 중파(MF, Middle Frequency) 및 초단파(VHF, Very High Frequency)를 이용하는 항법시스템을 개발하고 있다. 해양수산부의 지원으로 2020년에 착수하여 4국의 중파 R-Mode 송신국과 3국의 초단파 VDES R-Mode 송신국 구축을 진행하고 있다. 항법 성능을 확보하기 위하여 R-Mode 보정시스템과 R-Mode 감시시스템을 구축하였다. 해양에서 R-Mode 항법시스템의 성능을 검증하기 위하여 중파 R-Mode 수신기, VDES R-Mode 수신기 및 이를 포함하는 통합항법수신기를 함께 개발하고 있다. 항법 송신기 및 수신기의 성능 검증을 위한 테스트베드는 기존의 지상파 항법(eLoran) 서비스 영역, 중파 R-Mode 서비스 영역 및 주요 항만 등을 고려하여 충청남도 서산시 대산항 지역으로 선정하였다. 보정국 및 감시국을 포함하는 테스트베드 기지국은 대산항에 설치하여 운영을 시작하였다. 테스트베드 실해역 시험을 통한 성능 검증은 2023년 상반기에 진행될 계획이다.

• 한국ITS학회:학술대회논문집
• /
• 2003.11a
• /
• pp.241-246
• /
• 2003

• 정보화사회
• /
• s.107
• /
• pp.75-77
• /
• 1996

위성통신에서는 위성에 실린 고가의 중계기를 가능하면 많은 지구국이 공용하는 편이 효율적이 된다. 그 때문에 중계기에 할당된 주파수 대역을 나누어 각 지구국에 할당해야 한다. 또 자동차와 휴대전화 등의 이동통신에서도 기지국과 이동기를 연결하는 무선회선에서는 다수의 가입자가 제한된 무선을 이용할 수 있는 것과 같은 방법을 사용할 필요가 있다.