• Journal of Satellite, Information and Communications
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• v.12 no.2
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• pp.56-60
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• 2017

This paper describes the design and implementation of fall-down detection algorithm based on image processing. The fall-down detection algorithm separates objects by using background subtraction and binarization after grayscale conversion of the input image acquired by the camera, and recognizes the human body by using labeling operation. The recognized human body can be monitored on the display image, and an alarm is generated when fall-down is detected. By using computer simulation, the proposed algorithm has shown a detection rate of 90%. We verify the feasibility of the proposed system by verifying the function by using the prototype test implemented on the DSP image processing board.

• The KIPS Transactions:PartC
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• v.8C no.2
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• pp.198-206
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• 2001

· 21세기 도고 정보화 사회에서의 위성통신은 현존 위성 시스템에서 주로 제공하는 국가간 장 거리 전화, 방송 중계 서비스 등을 포함한 광범위한 대용량 디지털 멀티미디어 서비스 형태 의 트래픽을 처리하여 재분배하는 고성능, 다기능 정보통신으로 발전하고 있다. 이에 따라 전세계적으로 위성 수의 증가에 따른 위성궤도 부족과 주파수 자원의 고갈 등의 문제점을 야기시키게 되었다. 이를 해결하기 위해서는 기존의 단순 중계기의 역할뿐만 아니라, 위성탑 재 IF/RF 스위칭 기술, 기저대역 신호처리 기술, 다중 빔 안테나 기술 등을 포함한 OBP 탑 재 위성 시스템이 필요하게 된다. 따라서 본 논문에서는 기본적으로 멀티미디어 서비스를 제공하고 주파수 재사용 기법을 적용한 다중 스폿 빔을 송수신하는 차세대 OBP 탑재 위성 B-ISDN 중계망 접속 방식을 설계하고, 설계된 위성 B-ISDN 중계망 다중 접속 방식의 성 능을 평가하였다.

• Journal of Satellite, Information and Communications
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• v.11 no.2
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• pp.14-17
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• 2016

This paper describes the implementation of automatic number-braille converter based on image processing for the blind people. The algorithm is consists of four main steps. First step is binary image conversion of the input image obtained by the camera. the second step is segmentation operation by means of dilation and labelling of the character. Next step is calculation of cross-correlation between segmented text image and pre-defined text-pattern image. The final step is generation of brail output which is relevant to input image. The computer simulation result was showing 91.8% correct conversion rate for arabian numbers which is printed in A4-sheet and practical possibility was also confirmed by using implemented automatic number-braille converter based on DSP image processing board.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.10
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• pp.728-737
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• 2019

In this study, the minimized on-board computer (OBC) module for integrated navigation is developed, which provides satellites' relative position information in formation flying and cluster operation situations. The scalability is considered to apply the user-selected wireless communication module and Global Positioning System (GPS) receiver for navigation, while considering to meet the structural design standard of nano-satellites. As a result of the product development and production, the processing speed of integrated navigation and real-time data synchronization is satisfied for cluster operation nano-satellites by using micro controller unit (MCU). From a heat/vacuum, vibration and radiation test, the OBC was confirmed to be operated in space environments. From these results, a mass production system of OBC was made which is a key part of development on satellite formation flying and cluster/constellation missions that the community demands are increasing.

• Journal of Satellite, Information and Communications
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• v.4 no.1
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• pp.36-44
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• 2009

The key technologies of GNSS receiver for GNSS sensor station are under development as a part of a GNSS ground station in ETRI. This paper presents the GNSS receiver implementation and signal processing result which is implemented based on FPGA to process the Galileo E1 and E5 signal. To verify the working and performance for GNSS receiver which is implemented based on FPGA, live signal received from GIOVE-B which is second test satellite is used. We gather GIOVE-B signal by using prototyping antenna and RF/IF units including IF-component. To verify Galileo E1 and E5 signal processing function from GIOVE-B, FPGA based signal processing module is implemented as a prototyping hardware board.

• Journal of Communications and Networks
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• v.12 no.6
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• pp.529-532
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• 2010

Multi-carrier demultiplexer/demodulator (MCDD) in an on-board processing (OBP) satellite used for digital multimedia services has two typical architectures according to the channel demultiplexing procedure: Multistage multi-carrier demultiplexer (M-MCD) or poly-phase fast Fourier transform (PPF). During the channel demultiplexing, phase and quantization errors influence the performance of MCDD; those errors affect the bit error rate (BER) performance of M-MCD and PPF differently. In this paper, we derive the phase error variances that satisfy the condition that M-MCD and PPF have the same signal to noise ratio according to quantization bits, and then, with these results, analyze the BER performances of M-MCD and PPF. The results provided here may be a useful reference for the selection of M-MCD or PPF in designing the MCDD in an OBP satellite communications system.

• Korean Journal of Remote Sensing
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• v.23 no.2
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• pp.137-144
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• 2007

In KORDI (Korea Ocean Research and Development Institute), the KOSC (Korea Ocean Satellite Center) construction project is being prepared for acquisition, processing and distribution of sensor data via L-band from GOCI (Geostationary Ocean Color Imager) instrument which is loaded on COMS (Communication, Ocean and Meteorological Satellite); it will be launched in 2008. Ansan (the headquarter of KORDI) has been selected for the location of KOSC between 5 proposed sites, because it has the best condition to receive radio wave. The data acquisition system is classified into antenna and RF. Antenna is designed to be $\phi$ 9m cassegrain antenna which has 19.35 G/T$(dB/^{\circ}K)$ at 1.67GHz. RF module is divided into LNA (low noise amplifier) and down converter, those are designed to send only horizontal polarization to modem. The existing building is re-designed and arranged for the KOSC operation concept; computing room, board of electricity, data processing room, operation room. Hardware and network facilities have been designed to adapt for efficiency of each functions. The distribution system which is one of the most important systems will be constructed mainly on the internet. and it is also being considered constructing outer data distribution system as a web hosting service for offering received data to user less than an hour.

• Journal of Astronomy and Space Sciences
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• v.24 no.2
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• pp.155-166
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• 2007

We have designed a high resolution proton and electron telescope for the detection of high energy particles, which constitute a major part of the space environment. The flux of the particles, in the satellite orbits, can vary abruptly according to the position and solar activities. In this study, a conceptual design of the detector, for adapting these variations with a high energy resolution, was made and the performance was estimated. In addition, a parallel processing algorithm was devised and embodied using FPGA for the high speed data processing, capable of detecting high flux without losing energy resolution, on board a satellite.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.1236-1238
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• 2003

The Earth's total magnetic field was extracted from on board TAM (Three Axis Magnetometer) observations of KOMPSAT-1 satellite between June 19th and 21st, 2000. In the pre-processing, the TAM's telemetry data were transformed from ECI (Earth Centered Inertial frame) to ECEF (Earth Centered Earth Fixed frame) and then to spherical coordination, and self-induced magnetic field by satellite bus itself were removed by using an on-orbit magnetometer data correction method. The 2-D wavenumber correlation filtering and quadrant-swapping method were applied to the pre-processed data in order to eliminate dynamic components and track-line noise, respectively. Then, the spherical harmonic coefficients are calculated from KOMPSAT-1 data. To test the validity of the TAM's geomagnetic field, Danish/NASA/French ${\phi}$rsted satellite's magnetic model and IGRF2000 model were used for statistical comparison. The correlation coefficient between ${\phi}$rsted and TAM is 0.97 and IGRF and TAM is 0.96. It was found that the data from on board magnetometer observations for attitude control of Earth-observing satellites can be used to determinate the Earth's total magnetic field and that they can be efficiently used to upgrade the global geomagnetic field coefficients, such as IGRF by providing new information at various altitudes with better temporal and spatial coverage.

• Journal of Satellite, Information and Communications
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• v.6 no.1
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• pp.68-74
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• 2011

In this paper, we present the enhancement results such as availability and accuracy using the GPS L1 and Galileo E1 signal combination. To enhance the acquisition and tracking performance of signal processing in GNSS receiver. several tracking loops with integrator, discriminator, and loop filter module are applied. Also, this paper presents the performance comparison results between prototype receiver equipped with hardware board and software receiver. Also the tracking loop performance of real hardware receiver is verified by comparing with tracking accuracy, sensitivity occurred by the Spirent simulator. Especially, to process the Galileo E1 signal, it is used the a power early late type which is the typical type for DLL discriminator.