• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1750-1751
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• 2011

본 연구에서는 K-water에서 무궁화 5호 위성을 이용하여 홍수예경보망의 원격 데이터 취득하는데 있어서, 위성통신단말장치의 효율적인 운영을 위하여 위성통신단말장치에 대한 모니터링 및 유지관리를 할 수 있는 상태진단 프로그램을 개발 적용하여 홍수예경보시스템의 운영 효율화를 도모하고자 한다.

• Defense and Technology
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• no.10 s.284
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• pp.62-73
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• 2002

현재 군에서 사용 중인 통신위성의 활용현황은 무궁화 위성 2호 트랜스폰더(Transponder) 1조를 임대하여 상용휴대용, 차량용, 해상용, 공중용 단말기를 이용하여 운용중에 있으며, 해사통신위성(INMARSAT)을 활용하여 원거리 통신망으로 운용중에 있다. 그러나 이와 같은 위성통신 체계만으로는 한반도 지역의 미래전장을 주도적으로 이끌어 갈 수 있는 지휘통제통신체계를 구현할 수 없기에 앞으로 개발 될 위성통신체계에 대한 사용자, 즉 군의 운용관점에서 요구사항을 식별하여 제시하고자 한다.

• Defense and Technology
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• no.11 s.285
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• pp.62-73
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• 2002

현재 군에서 사용 중인 통신위성의 활용현황은 무궁화 위성 2호 트랜스폰더(Transponder) 1조를 임대하여 상용휴대용, 차량용, 해상용, 공중용 단말기를 이용하여 운용중에 있으며, 해사통신위성(INMARSAT)을 활용하여 원거리 통신망으로 운용중에 있다. 그러나 이와 같은 위성통신 체계만으로는 한반도 지역의 미래전장을 주도적으로 이끌어 갈 수 있는 지휘통제통신체계를 구현할 수 없기에 앞으로 개발 될 위성통신체계에 대한 사용자, 즉 군의 운용관점에서 요구사항을 식별하여 제시하고자 한다.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.4 no.3
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• pp.37-44
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• 1993

The earth station antenna operating on a GEO communication satellite is influenced by sun interference in the period of the spring or the autumn eqinox. Such phenomena are also undertaken by ray-bending phenomena in atmosphere. Therefore the prediction time of sun interference does not theoretically match actual interference time. In this paper, the actual sun interference time has been analyzed in consideration of ray-bending phenomenon, the size of main reflector of earth station antenna and elevation angle between an earth station antenna and a satellite. Ray-bending phenomenon in atmosphere is proved to be disregarded if the Mugungwha satellite is luanched in 1995. The analysis results are compared with actual measurement values of sun interference time at local earth stations and the two data are in accord well.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.9
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• pp.75-81
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• 2003

The longitude and latitude of a geosynchronous satellite are not defined as a point in space because of various external perturbations. To perform the missions of a satellite for a communication and broadcasting, the satellite must be positioned within a predefined station keeping box in given limited space longitude. In this study, we propose east-west station keeping box larger than that of north-south station. By using the derived error equation, we verified the Koreasat station keeping box allocation by assuming one week and two weeks of station keeping cycle.

• Journal of the Korean Society for Railway
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• v.14 no.3
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• pp.211-215
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• 2011

Generally, sound power is one of the most significant factors to predict and assess noise from sound sources. However, many researchers developed indirect methods to calculate the sound power with noise level because it is impossible to measure sound power directly while a train is running. In this paper, we propose a method to estimate sound power generated due to wheel/rail interaction and propulsive equipment from the measurement of noise emitted from rolling stocks and verify the estimation method by comparing with the other sound power estimation formula. We also analyze the sound power of rolling stocks which are operating in domestic lines such as EMU, Mukoonghwa, KTX using the method proposed in this paper.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.488-497
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• 2010

8100 series Electric locomotive was imported from SIEMENS of Germany on 2001. 8100 series model is modified from BR152 model to be complied with national environment. After 8100 series Electric locomotive carried out main line test for long time, 8200 series Electric locomotive produced in 10 locomotives with improvement and supplement on some parts. the one of supplement is to install the HEP equipment. In paper, about total harmonic distortion of HEP equipment power, it compares the result of combination with the result of actual measurement. It checks whether the measurement meets the specification of design or not. And it describes international standard about total harmonic distortion of supply system.

• Journal of Astronomy and Space Sciences
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• v.21 no.3
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• pp.221-232
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• 2004

Gauss method for the initial orbit determination was tested using angle-only data obtained by orbit propagation using TLB and SGP4/SDP4 orbit propagation model.. As the analysis of this simulation, a feasible time span between observation time of satellite resulting the minimum error to the true orbit was found. Initial orbit determination is performed using observational data of GPS 26 and Koreasat 2 from 0.6m telescope of KAO(Korea Astronomy Observatory) and precise orbit determination is also performed using simulated data. The result of precise orbit determination shows that the accuracy of resulting orbit is related to the accuracy of the observations and the number of data.

• Journal of Satellite, Information and Communications
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• v.11 no.3
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• pp.104-109
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• 2016

A technology of GEO satellite communications starts from Koreasat program in Korea. Payload equipment of EQM Ku and Ka band transponders had been developed and space-qualified Ka band payload in COMS was successfully launched in June, 2010. For the purpose of military communications, Dehop-Rehop transponder was developed in Koreasat5 as ANASIS system and DAT(Digital Active Transponder) and DCAMP(Digital Channel AMPlifier) transponders are now under development. In this paper, from the study of military satellite communications trend, a direction of military communication satellite is suggested based on the current GEO SATCOM technologies in Korea. Considering the limit of frequency resources, a technology of battlefield adaptive transponder with medium capacity against high moveable jamming tactics would be efficient for the future military SATCOM system. Mid-sized military satellites with frequency hopping and mid-capacity transponders can be a solution of vitalizing the GEO satellite programs.

• Journal of Advanced Navigation Technology
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• v.7 no.2
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• pp.101-107
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• 2003

In this study, we provide a single element log-periodic antenna that the feeding networks and array structures are aperture coupled and series dipole array type. We made the antenna for direct receiving the Moogoongwha satellite broadcasting signal. The transmission power was able to feed the patch dipole in series due to lay perpendicularly 8 series patch dipole on tapered slot. The patch dipole radiation pattern which fed in series power, make the main beam direction up $37^{\circ}{\sim}42^{\circ}$ within the BS/CS bandwidth. The main beam gain was measured 9.31~11.03 dBi. Using 32 elements to array the elements properly, we acquire $4{\times}8$ array structure on limited PCB board. As a result, it has been found that the new planar DBS antenna structure have high gain over 10dBi and acceptable elevation angle over 42 degree, and we can apply this result to commercial DBS reception antenna manufacturing.