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Ionospheric Storm and Spatial Gradient Analysis for GBAS
Jeongrae Kim,Tae Hyoung Yang,Young Jae Lee,Hyang Sig Jun,Gi Wook Nam 한국항해항만학회 2006 한국항해항만학회 학술대회논문집 Vol.1 No.-
High ionospheric spatial gradient during ionospheric storm is most concern for the landing approach with GNSS (Global Navigation Satellite System) augmentation systems. In case of the GBAS (Ground-Based Augmentation System), the ionospheric storm causes sudden increase of the ionospheric delay difference between a ground facility and a user (aircraft), and the aircraft position error increases significantly. Since the ionosphere behavior and the storm effect depend on geographic location, understanding the ionospheric storm behavior at specific regional area is crucial for the GNSS augmentation system development and implementation. Korea Aerospace Research Institute and collaborating universities have been developing an integrity monitoring test bed for GBAS research and for future regional augmentation system development. By using the dense GPS (Global Positioning System) networks in Korea, a regional ionosphere map is constructed for finding detailed aspect of the ionosphere variation. Preliminary analysis on the ionospheric gradient variation during a recent storm period is performed and the results are discussed.
Predicting IGS RTS Corrections Using ARMA Neural Networks
Kim, Mingyu,Kim, Jeongrae Hindawi Limited 2015 Mathematical problems in engineering Vol.2015 No.-
<P>An autoregressive moving average neural network (ARMANN) model is applied to predict IGS real time service corrections. ARMA coefficients are determined by applying a neural network to IGS02 orbit/clock corrections. Other than the ARMANN, the polynomial and ARMA models are tested for comparison. An optimal order of each model is determined by fitting the model to the correction data. The data fitting period for training the models is 60 min. and the prediction period is 30 min. The polynomial model is good for the fitting but bad for the prediction. The ARMA and ARMANN have a similar level of accuracies, but the RMS error of the ARMANN is smaller than that of the ARMA. The RMS error of the ARMANN is 0.046 m for the 3D orbit correction and 0.070 m for the clock correction. The difference between the ARMA and ARMANN models becomes significant as the prediction time is increased.</P>
Extending Ionospheric Correction Coverage Area By Using A Neural Network Method
Kim, Mingyu,Kim, Jeongrae The Korean Society for Aeronautical and Space Scie 2016 International Journal of Aeronautical and Space Sc Vol.17 No.1
The coverage area of a GNSS regional ionospheric delay model is mainly determined by the distribution of GNSS ground monitoring stations. Extrapolation of the ionospheric model data can extend the coverage area. An extrapolation algorithm, which combines observed ionospheric delay with the environmental parameters, is proposed. Neural network and least square regression algorithms are developed to utilize the combined input data. The bi-harmonic spline method is also tested for comparison. The IGS ionosphere map data is used to simulate the delays and to compute the extrapolation error statistics. The neural network method outperforms the other methods and demonstrates a high extrapolation accuracy. In order to determine the directional characteristics, the estimation error is classified into four direction components. The South extrapolation area yields the largest estimation error followed by North area, which yields the second-largest error.
GA-ARMA Model for Predicting IGS RTS Corrections
Kim, Mingyu,Kim, Jeongrae Hindawi Limited 2017 International journal of aerospace engineering Vol.2017 No.-
<P>The global navigation satellite system (GNSS) is widely used to estimate user positions. For precise positioning, users should correct for GNSS error components such as satellite orbit and clock errors as well as ionospheric delay. The international GNSS service (IGS) real-time service (RTS) can be used to correct orbit and clock errors in real-time. Since the IGS RTS provides real-time corrections via the Internet, intermittent data loss can occur due to software or hardware failures. We propose applying a genetic algorithm autoregressive moving average (GA-ARMA) model to predict the IGS RTS corrections during data loss periods. The RTS orbit and clock corrections are predicted up to 900 s via the GA-ARMA model, and the prediction accuracies are compared with the results from a generic ARMA model. The orbit prediction performance of the GA-ARMA is nearly equivalent to that of ARMA, but GA-ARMA’s clock prediction performance is clearly better than that of ARMA, achieving a 32% error reduction. Predicted RTS corrections are applied to the broadcast ephemeris, and precise point positioning accuracies are compared. GA-ARMA shows a significant accuracy improvement over ARMA, particularly in terms of vertical positioning.</P>
국내 과일·채소음료시장의 소비활성화를 위한 시장분석 및 마케팅 전략
김정래 ( Kim Jeongrae ),김범수 ( Beom-su Kim ),김성진 ( Seong-jin Kim ),박지훈 ( Ji-hoon Park ),김종화 ( Jonghwa Kim ) 한국식품유통학회 2022 한국식품유통학회 학술대회 Vol.- No.하계
최근 국내 과채류음료 시장의 성장이 크게 둔화되고 있다. 그동안 과채류음료는 국내 가공용 과일, 채소의 대량 수요처로서 그 중요성이 강조되어 왔으나, 탄산음료, 액상커피 등의 대체품이 등장하면서 과채음료 시장이 급속히 위축되고 있다. 이에 본 연구에서는 소비자의 과채류음료에 대한 선택속성(원료, 가격, 첨가물, 포장용기)을 살펴보고, 그에 따른 마케팅전략을 제시하였다. 이를 위하여 마케팅 분야에서 널리 사용되는 컨조인트 분석의 부분가치 함수모형을 이용하였으며, 시장세분화를 위한 군집분석을 실시하였다. 그 결과, 국내 과채류시장은 ‘맛선호그룹’, 원료선호그룹’,‘편의선호그룹’으로 세분될 수 있으며, 그에 따른 그룹별 마케팅전략을 제시하였다.
김정래(Jeongrae Kim),박규식(Kyushik Park),김광일(Kwangil Kim) 한국자동차공학회 2009 한국자동차공학회 학술대회 및 전시회 Vol.2009 No.11
An electro-mechanical actuator is increasingly applied for the active roll control system to improve fuel efficiency and to simplify system configurations. The electric active roll control system (eABC System) has an advantage of rapid response, but it needs gear box with high reduction ratio to generate high torque for vehicle roll attitude control. This reduction gear amplifies the effect of friction and rotating inertia when the actuator rotates, and it influences negative effect on riding performance. The paper introduces some arrangements of motor and gears of the actuator for eARC system, and proposes the optimized actuator structure to improve ride feeling by estimating dynamic characteristics of each arrangement through simulating the dynamic model of the system.
김정래 ( Jeongrae Kim ),김종우 ( Jong-woo Kim ),권순민 ( Soon-min Kwon ),박총명 ( Chong-myung Park ),정인범 ( In-bum Jung ) 한국정보처리학회 2008 한국정보처리학회 학술대회논문집 Vol.15 No.2
유비쿼터스 컴퓨팅 환경에서는 사용자의 의도를 정확히 파악하고 그에 따른 정확한 정보 또는 서비스를 제공하는 것이 중요하다. 현재 보편적으로 사용 중인 키보드와 마우스는 직관성이 결여되었거나 휴대성이 부족하므로 유비쿼터스 환경에 적합한 새로운 입력 시스템이 필요하다. 본 논문에서는 2축 가속도 센서와 2개의 압력센서를 사용하여 무선 센서네트워크 환경에서 사용자의 손동작을 감지하여 컴퓨터를 직관적으로 사용할 수 있는 유비쿼터스 환경에 적합한 입력 시스템(u-Glove)을 설계 및 구현한다.
편대비행 위성용 거리 및 가속도 관측기 시뮬레이션 모델링
김정래(Jeongrae Kim) 한국항공우주학회 2005 韓國航空宇宙學會誌 Vol.33 No.2
NASA와 독일 DLR의 Gravity Recovery and Climate Experiment (GRACE)는 편대비행을 하는 두 개의 저궤도 위성을 이용하여 지구중력장을 측정하는 연구이다. 주요 관측 장비는 위성 사이의 거리를 측정하기 위한 초단파 거리측정기와 비중력 가속도를 측정하기 위한 정전기 방식의 3축 가속도계이다. 기본설계 및 허용오차 분석 등에 활용하기 위하여 정밀한 관측기 시뮬레이션 모델을 개발하였는데, 본 논문에서는 이러한 모델링 기법과 이를 적용한 궤도 및 중력장 추정기법에 관해 살펴보았다. NASA/DLR Gravity Recovery and Climate Experiment (GRACE) mission, which consists of two co-orbiting low altitude satellites, is to measure the Earth gravity field with unprecedented accuracy. Its key instruments include inter-satellite ranging systems and three-axis accelerometers. For the preliminary design and requirements analysis, extensive instrument simulation models are developed. These modeling techniques and orbit-gravity field estimation techniques are described.