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이동형 다목적실용위성 소형 관제국의 Playback 하향 링크 및 원격 명령 상향 링크 채널 설계
안상일(Sang-Il Ahn),박동철(Dong-Chul Park) 한국전자파학회 2009 한국전자파학회논문지 Vol.20 No.4
본 논문은 이동 가능한 다목적실용위성의 소형 관제국 개발을 위한 playback 신호의 하향 링크 및 원격 명령신호의 상향 링크에 대해 수행한 채널 설계를 기술한다. 하향 링크 채널 설계로서 playback 신호의 수신 임계신호 대 잡음비로부터 요구 수신 성능을 도출하여 1.5 m 안테나 기반의 하향 링크 수신 성능인 6.5 ㏈/K의 G/T이내에서 만족함을 확인하였다. 상향 링크 채널 설계를 통하여 원격 명령 신호에 대한 위성에서의 수신 신호대 잡음비로부터 40 ㏈W의 송신 EIRP를 유도하였다. 구축된 소형 관제국을 이용하여 다목적실용위성 및 다목적실용위성 2호에 대해 양 방향 통신시험 및 운영 결과, 고각 10° 이상에서 상향 링크 및 playback 신호의 하향링크 채널의 요구 성능이 일관성 있게 만족함을 확인하였고, 장기간에 걸친 시험 결과로부터 시스템의 성능 열화가 거의 없음을 확인함으로써 설계상으로 추가적인 3 ㏈ 링크 마진을 고려하지 않은 소형 관제국의 채널 설계가 다목적실용위성에 대해 적절하였음을 검증하였다. This paper describes playback downlink and telecommand uplink channel design performed for a transportable small -sized KOMPSAT(Korea Multi-Purpose Satellite) ground station. As a result of downlink channel design, required receiving performance was calculated from the threshold signal-to-noise ratio of playback signal and it was revealed that this performance can be guaranteed in 1.5 m ground station with 6.5 ㏈/K of G/T. For the uplink channel design, 40 ㏈W of EIRP was derived from the threshold signal-to-noise ratio of telecommand signal received at on-board receiver. The implemented small-sized ground station based on design was evaluated to be fully acceptable for KOMPSAT TT&C(Telemetry, Tracking and Command) system and playback downlink design without taking account of additional 3 ㏈ system link margin was shown to be effective because it had provided constantly initial channel performance without any remarkable degradation over several years of tests with KOMPSAT and KOMPSAT-2, for both uplink and playback downlink in the elevation angle above 10°.
부 반송파를 사용하는 이동형 다목적실용위성 관제국에 대한 하향 링크 채널 설계
안상일(Sang-Il Ahn),박동철(Dong-Chul Park) 한국전자파학회 2009 한국전자파학회논문지 Vol.20 No.3
본 논문은 부 반송파를 사용하는 이동 가능한 다목적실용위성 소형 관제국의 하향 링크 채널 설계 내용을 기술한다. 먼저 전송 신호 방식을 해석한 후 이 해석 결과를 단계별로 적용하는 방법으로 하향 링크 채널을 설계하였다. 하향 링크 전송 신호인 실시간(real-time) 2 kbps 위성 상태 측정 데이터의 수신 임계 신호 대 잡음비와 위성 거리 측정 요구 성능을 만족하는 신호 대 잡음비 해석 결과를 적용하여 6.5 ㏈/K의 G/T를 갖는 소형 관제국의 하향 링크 채널을 설계하였다. 설계에 따라 구현된 소형 관제국의 G/T는 태양을 이용한 측정 결과, 6.62 ㏈/K가 됨을 확인하였다. 또한, 위성과의 연동 시험을 통해, 부 반송파를 사용하는 위성 상태 데이터 요구 수신성능을 만족하여 다목적실용위성 관제국의 하향 링크 채널로 적합하게 평가되었다. This paper describes the downlink design of a transportable small-sized KOMPSAT ground station using sub-carrier signal. Based on the analysis of the transmission modes of satellite real-time telemetry and range measurement signals, the downlink channel design of KOMPSAT ground station using sub-carrier signal was processed. By considering the threshold signal-to-noise ratio of real-time 2 kbps telemetry signal and the required signal-to-noise ratio for satellite range measurement, the small-sized KOMPSAT downlink channel with G/T value of 6.5 ㏈/K was designed. The real G/T of implemented ground station was proven to be 6.62 ㏈/K when measured using the Sun. Moreover, through interface test with KOMPSAT, the ground station has shown the required link performance for real-time telemetry acquisition using sub-carrier and was consequently evaluated to be adequate for a transportable small-sized KOMPSAT ground station.
안상일,장지호,Sang Il Ahn,Jee Ho Chang 대한안과학회 2013 대한안과학회지 Vol.54 No.3
Purpose: To objectively define the degree of cupping, the authors extracted 3-dimensional slope surface maps from Cirrus HDTM-OCT data and assessed their differentiating characteristics between normal subjects and glaucomatous patients. Methods: One eye from each of 40 normal subjects and 1 eye from each of 39 patients with glaucoma were examined using automated visual field perimetry and Cirrus HDTM-OCT. The Optic Disc Cube 200 × 200 protocol was performed. The individual OCT data were reconstructed as the 3-dimensional surface maps of the optic disc cup and the slope of each contour was calculated using custom-developed software. Several disc cup slope parameters were derived. The parameters measuring the internal features of the optic disc cup were calculated and compared between groups. Results: Sum of cup slope, sum of thresholded cup slope, and sum of thresholded cup slope / thresholded cup area parameters were differentiating factors between the normal and glaucoma groups (p < 0.05). The area under the receiver operating characteristic curve (AUROC) value of the slope parameters ranged from 0.718 to 0.753. The sum of thresholded cup slope / thresholded cup area parameter was well correlated with visual field mean deviation (r = -0.250, p = 0.028). Conclusions: The optic disc cup slope parameter obtained with OCT may be a useful parameter for representing glaucomatous cupping.
약물 유도 망막변성 생쥐 모델에서 안구내 면역세포에서의 F4/80와 nestin 발현 양상
안상일,온영훈,박태관,Sang Il Ahn,MD,Young Hoon Ohn,MD,PhD,Tae Kwann Park,MD,PhD 대한안과학회 2013 대한안과학회지 Vol.54 No.6
Purpose: To evaluate the expression patterns of F4/80 and nestin in the ciliary body and the optic nerve following N-methyl- N-nitrosourea (NMU)-induced retinal degeneration in adult mice. Methods: After intraperitoneal injection of MNU (60 mg/kg) in adult mice, the eyes were enucleated at 2, 4, 7 and 30 days. Hematoxylin and eosin (H&E) stain, terminal deoxyribonucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) stain and immunohistochemical stains of F/80 and nestin were performed. Results: After MNU treatment, the photoreceptors were destroyed by cell apoptosis. According to immunohistochemistry, F4/80 and nestin were not co-expressed in the control group, but F4/80 was expressed within the ciliary body and optic nerve in the MNU-treated group; the expression of nestin also increased. In the outer nuclear layer, F4/80 and nestin co-expressing cells were observed. Conclusions: In response to retinal damage, the F4/80 and nestin co-expressing cells migrated to the retina from the ciliary body and optic nerve and were activated.