• 전력전자학회:학술대회논문집
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• 전력전자학회 2007년도 하계학술대회 논문집
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• pp.52-54
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• 2007

The LEO satellite generates the power during day and consumes the power during night, so the power changes repeatedly. The power fluctuation must be verified, because it affects the mission operation and lifetime of satellite. This study describes the test-set for verification of Electrical Power Subsystem and two verification items using it. The verification test of EPS will be useful to predict the mission lifetime and to decide the mission operation of satellite.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2003년도 The Fifth Asian Computational Fluid Dynamics Conference
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• pp.248-250
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• 2003

Thermal analysis is performed to protect the propulsion system of low-earth-orbit earth observation satellite from unwanted thermal disaster like propellant freezing. To implement thermal design adequately, heater powers for the propulsion system estimated through the thermal analysis are decided. Based on those values anticipated herein, the average power for propulsion system becomes 22.02 watts when the only one redundant catalyst bed heater is turned on. When for the preparation of thruster firing, 25.93 watts of the average power is required. All heaters selected for propulsion components operate to prevent propellant freezing meeting the thermal requirements for the propulsion system with the worst-case average voltage, i.e. 25 volts.

• 한국산업정보학회논문지
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• 제19권1호
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• pp.31-41
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• 2014

정지궤도위성은 다수의 탑재체를 하나의 위성체 플랫폼에 탑재하고 2010년 6월 26일에 발사되었다. 전력계는 태양 및 식 기간 상태에서 완전 조절 $50V_{DC}$ 전력 버스를 제공한다. 위성에서 요구되는 전력은 태양전지 배열기 윙에서 생성되며, 에너지는 192.5Ah 용량의 리튬-이온 배터리에 저장된다. 본 논문은 전력계의 성능 평가를 향후 정지궤도위성 설계에 활용하기 위해 전력계의 중요 설계 변수들을 선정하고, 지상에서 시험 결과와 궤도상에서 운영 결과를 비교 분석하였다. 설계로부터 궤도상에서 운영 결과까지의 성능 평가를 통해 전력계는 중요한 성능감소 없이 정상적으로 동작되고 있음을 입증하였다.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume I
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• pp.204-207
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• 2006

COMS will receive two different meteorological signals in S-Band from IDACS (Image Data Acquisition and Control System) in ground station before transmitting them in L-Band to user station. MODCS (Meteorological Ocean Data Communication Subsystem) in satellite released the value of required PFD (Power Flux Density) to receive two signals. Thus, DATS (Data Acquisition and Transmission Subsystem) needs to send two signals to satellite with a satisfied EIRP. The value of minimum HPA (High Power Amplifier) output power was estimated by subtracting antenna directional gain and path loss between antenna and HPA from the needed EIRP in this paper. Besides the minimum output power of HPA, the maximum output power was also calculated with considering IMD (Inter-Modulation Distortion) characteristics. IMD is always occurred in the output of HPA when LRIT and HRIT are amplified by using single HPA as COMS application. In this paper, the setting of maximum output power was determined when the IMD of modelled HPA was corresponded to the requirement of MODCS.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2004년도 Proceedings of ISRS 2004
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• pp.498-500
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• 2004

QPSK (Quaternary Phase Shift Keying) will be adopted as the modulation of HRIT (High Rate Information Transmission) which is transmitted to COMS (Communication, Ocean and Meteorological Satellite) through HPA (High Power Amplifier) in ground segment. Due to the nonlinearity of HPA, IMD (Inter-Modulation Distortion) of multi-carrier signals and PAPR (Peak-to-Average Power Ratio) of modulated HRIT must be considered to estimate the output power of HPA. In this paper, we measured the PAPR to various the roll-off factor of RRC (Root Raised Cosine filter) which is filtering the modulated HRIT signal for reducing ISI (Inter-Symbol Interference) and bandwidth. It was found that the minimum PAPR is 2.78dB at 0.5 of roll-off factor for scrambled data. It's 2.78dB of P APR will be in output power selecting in COMS earth station.

• 전자공학회논문지A
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• 제32A권9호
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• pp.1167-1176
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• 1995

This paper suggests a method for optimal power assignment of the satellite transponder input carriers in the Multi-level & Multi-bandwidth system. The interference and the noise effects analyzed for the optimal power assignment are intermodulation product caused by the nonlinear transponder characteristics, adjacent channel interference, co-channel interference, and thermal noise in the satellite link. The Fletcher- Powell algorithm is used to determine the optimal input carrier power. The performance criteria for optimal power assignment is classified into 4 categories according to the CNR of destination receiver earth station to meet the requirement for various satellite link environment. We have performed mathematical analysis of objective functions and their derivatives for use in the Fletcher-Powell algorithm, and presented various simulation results based on mathematical analysis. Since the satellite link, it is meaningful to model and analyze these effects in a unified manner and present the method for optimal power assignment of transponder input carriers.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2005년도 Proceedings of ISRS 2005
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• pp.98-100
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• 2005

This paper describes link analysis on the processed data, HRIT (High Rate Information Transmission) and LRIT (Low Rate Information Transmission), for the preliminary design of interface between COMS (Communication, Ocean and Meteorological Satellite) and ground station. At the MODAC (MeteorologicaVOcean Data Application Center), the processed data are transmitted to user station via COMS with normalization and calibration by pre-processing of MI (Meteorological Imager) data. Due to consider satellite as radio relay, overall analysis containing uplink and downlink is needed. Specific link parameters can be obtained with using the outcomes of SRR (System Requirement Review) which was held on 13-14 June 2005, in Toulouse. From the relation between overall link margin and output power of HPA (High Power Amplifier) of MODAC, it is shown that even though the minimum power related with COMS receiving power range is transmitted at MODAC, the obtained link margin of HRIT could be above 3 dB at user station which antenna elevation angle is 10 degree.

• Journal of information and communication convergence engineering
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• 제6권2호
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• pp.129-133
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• 2008

In this paper, modified power control algorithms are proposed for a satellite mobile communications system with ATC (ancillary terrestrial component). In order to increase system capacity and reduce the transmitting power of the user's equipment, we propose the modified power control scheme consisting of the modified closed-loop and open-loop power control. The modified CLPC (closed-loop power control) algorithm, combining the delay compensation algorithms and pilot diversity, is mainly applied to the ATC link in urban areas because it is more suitable to the short RTD (round-trip delay). In the case of rural areas where ATCs are not deployed or a signal is not received from ATCs, combining monitoring transmitting power equipment and OLPC (open-loop power control) algorithms using an efficient pilot diversity is mainly applied to the link between the user's equipment and the satellite. Two power control algorithms are applied equally to the boundary areas where two kinds of signals are received in order to ensure coverage continuity. The simulation results show that the modified power control scheme has good performance compared to conventional power control schemes in a GEO (geostationary earth orbit) satellite system with ATC.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 B
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• pp.1040-1042
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• 2002

In general, satellite electrical power system plays an important role in its mission performance. To perform the mission successfully, the satellite should be provided with the sufficient power until end of life. In this paper shows that electrical boxes' design characteristic, energy balance analysis and power performance in satellite real operation.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년 학술대회 논문집 정보 및 제어부문
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• pp.497-499
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• 2006

There are several types of communication method which is used for the supply of electric power stably. But the communication methods used in KEPCO have weak points in the viewpoint of economy, technology and management. The Satellite communication systems have competitive power in price and technology for national wide utility owing to its wide area coverage and stability. This paper presents various adapted examples of the Power industry using he satellite communication systems.