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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.
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.
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.
정정래(Jeongrae Jeong),김길영(Kil-yeong Kim),박상준(Sangjun Park) 대한기계학회 2016 대한기계학회 춘추학술대회 Vol.2016 No.12
In this paper, the structural fatigue evaluation of the main rotor actuator(MRA) for rotorcraft is performed. All fatigue load cases of the MRA are estimated based on performance. The stress values for impulse and low/high cycle fatigue loads are calculated on typical components of the MRA using commercial Finite Element Analysis S/W. The calculated stress results are converted to alternating stresses using modified Goodman equation and then the fatigue margins of each case are evaluated by comparing alternating stresses with each material fatigue strength.
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.
김정래(Jeongrae Kim),김태준(Teajun Kim),배수용(Suyong Bae),황승민(Seongmin Hwang),이도희(Dohee Lee) 한국자동차공학회 2020 한국자동차공학회 학술대회 및 전시회 Vol.2020 No.11
Automatic transmission is convenient for drivers to drive. Because of fuel economy regulations and , recognition about pollution, Many kinds of Multi-Step Automatic Transmissions are developed. This study has developed an optimal shift control parameter calculation model for automatic transmission. It was carried out for the purpose of quickly developing the TCU shift control base hydraulic data(TCU ROM). As part of the first study, we investigated the torque on the output side and the optimum shifting time of the 8-speed automatic front wheel. Analysis on this survey data can predict responsiveness and shifting. The second study constructed the optimal(ideal) hydraulic model of the control parameters at the shifting time using the automatic transmission hardware specification. Finally, the model were simulated in Matlab Simulink to prove the validity of the development results, and the reliability of the model was finally verified by applying it to a test vehicle. As a result, the precision and robustness of the TCU shift hydraulic pressure value was verified using the shift control parameter calculation model. In addition, it is possible to shorten the overall development schedule through the rapidity of the TCU base ROM production.
GPS 전리층 모델의 장기간 가용성 및 정확도 변화 분석
김정래 ( Jeongrae Kim ),김용래 ( Yongrae Kim ) 한국항행학회 2023 韓國航行學會論文誌 Vol.27 No.6
The Klobuchar ionospheric model included in GPS navigation messages provides ionospheric correction information to single-frequency users. This ionospheric model accuracy has a significant impact on the accuracy of navigation solutions. We examine the GPS navigation messages from 1993 to 2022 and analyze their accuracy, presence of coefficients and accuracy of the Klobuchar model. Early GPS navigation messages often did not include ionospheric data, and even when they did include ionospheric models, the accuracy was often quite low. From 2002, when the accuracy of the ionospheric model was stabilized, until 2022, the accuracy of the ionospheric model is analyzed by comparing it with the ionospheric model of the International GNSS Service (IGS). Changes in accuracy per day and per year and accuracy differences along geomagnetic latitude are analyzed.