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위성간 상대거리 관측을 이용한 한국형 위성항법시스템의 실시간 궤도결정
신기해,오형직,박상영,박찬덕 한국항공우주학회 2015 한국항공우주학회 학술발표회 논문집 Vol.2015 No.4
본 논문에서는 한국형 위성항법시스템(Korea Regional Navigation Satellite System, KRNSS)의 지상국이 궤도력을 위성으로 송신할 수 없는 경우에 대비한 독립적/실시간 궤도 결정을 다룬다. 한국형 위성항법 시스템의 후보 위성군으로 지구정지궤도(Geostationary Orbit, GEO) 위성 3기와 타원경사지구동기궤도(Elliptical Inclined Geosynchronous Orbit, EIGSO) 위성 4기를 고려한다. 위성간 상대거리 관측(Inter-satellite Link, ISL)과 확장 칼만 필터(Extended Kalman Filter, EKF)를 사용하여 실시간 궤도결정을 수행한다. 확장 칼만 필터의 성능에 영향을 주는 주요 행렬들에 대한 체계적인 분석을 수행한 뒤, 위성간 상대거리 관측의 오차 수준이 0.3~0.7m일 경우 m급 궤도결정 정밀도를 달성할 수 있음을 확인하였다. This paper presents stand-alone/real-time orbit determination of Korea Regional Navigation Satellite System(KRNSS) when ground station fails to transmit ephemeris to satellites. Three geostationary orbit(GEO) satellites and four elliptical inclined geosynchronous orbit(EIGSO) satellites are considered to form a candidate KRNSS. Inter-satellite links are used as observation data, and extended Kalman filter(EKF) is applied as real time estimation method. Parametric analysis of EKF-related matrices is presented, and simulation results show that 0.3~0.7m observation accuracy can achieve meter-level orbit determination.
신기해,이영준,김영현,김단비,이종석,임정호,이옥환 한국식품저장유통학회 2014 한국식품저장유통학회지 Vol.21 No.4
Brassica spp. vegetables have been known to have biological activities such as anti-cancer and anti-inflammatory activities. In this study, we investigated the in vitro physicochemical characteristics and antioxidant activities of commonly used Brassica spp. sprout vegetables such as kohlabi (Brassica oleracea var. gongyloides), red radish (Raphanussativus L. var. sativus), broccoli (B. oleracea var. italica), cabbage (B. rapavar. glabra Regel), rape (B. napus), radish (R. sativus), and tatsoi (B. campestris var. narinosa) sprouts. Our results showed that the vegetables with the highest total phenolics contents were the radish sprout (24.40±1.24 mg TAE/g) and kohlabi sprout extracts (23.97±0.46 mg TAE/g). Furthermore, the vegetable with the highest total flavonoid content was the radish sprout extract (15.30±1.35 mg CE/g). However, the kohlabi sprout extract showed the highest DPPH radical scavenging value (IC50 = 1.95 mg/mL) and ORAC value (79.03 mM TE/g). In addition,the six kinds of Brassica spp. sprout vegetable extracts, except tatsoi, significantly inhibited the reactive oxygen species (ROS) production and showed thatintracellular oxidative stress is closely related tothe accumulation of differentiated adipocytes and fat during the adipogenesis of 3T3-L1 preadipocytes. These results suggest that Brassica spp. sprout vegetables, especially kohlabi and radish sprout extracts, can be used to develop natural antioxidants.
Real-Time Orbit Determination for Future Korean Regional Navigation Satellite System
신기해,오형직,박상영,박찬덕 한국우주과학회 2016 Journal of Astronomy and Space Sciences Vol.33 No.1
This paper presents an algorithm for Real-Time Orbit Determination (RTOD) of navigation satellites for the Korean Regional Navigation Satellite System (KRNSS), when the navigation satellites generate ephemeris by themselves in abnormal situations. The KRNSS is an independent Regional Navigation Satellite System (RNSS) that is currently within the basic/ preliminary research phase, which is intended to provide a satellite navigation service for South Korea and neighboring countries. Its candidate constellation comprises three geostationary and four elliptical inclined geosynchronous orbit satellites. Relative distance ranging between the KRNSS satellites based on Inter-Satellite Ranging (ISR) is adopted as the observation model. The extended Kalman filter is used for real-time estimation, which includes fine-tuning the covariance, measurement noise, and process noise matrices. Simulation results show that ISR precision of 0.3–0.7 m, ranging capability of 65,000 km, and observation intervals of less than 20 min are required to accomplish RTOD accuracy to within 1 m. Furthermore, close correlation is confirmed between the dilution of precision and RTOD accuracy.