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고속 도플러 편이 환경에서 최적 시간지연을 갖는 다중모드 모노펄스 신호처리에 관한 연구
이재문,임재성,안희수,Lee, Jaemoon,Lim, Jaesung,Ahn, Huisoo 한국군사과학기술학회 2016 한국군사과학기술학회지 Vol.19 No.5
Multi-mode monopulse system is widely used for satellite terminal like UAV because of high tracking accuracy and low size/weight profile. In order to calculate tracking error, Multi-mode monopulse system utilizes high-order mode signal, and it should have enough C/N(carrier to noise) level therefore tracking system needs narrow band filtering of received satellite beacon signal as much as possible. However, UAV suffers for beacon frequency drift derived from Doppler effect due to satellite figure 8 movement and UAV maneuvering. Therefore wideband signal processing needs to be considered in advance for exact doppler compensation and consequent time delay. In this paper, we propose the multi-stage Digital Signal processing system for beacon signal, which could minimize the signal delay under high Doppler and low C/N condition.
Ku 대역 다중모드 모노펄스 위성추적시스템을 위한 커플러 구현 및 안테나 추적정확도 분석
이재문,임재성,박도현,Lee, Jaemoon,Lim, Jaesung,Park, Dohyun 한국군사과학기술학회 2016 한국군사과학기술학회지 Vol.19 No.3
This paper proposes a Ku-band multi-mode coupler and its monopulse tracking system, which can be applied to a unmaned aircraft vehicle(UAV) platform. In general, the carrier-to-noise(C/N) level of the beacon signal from a Ku-band commercial satellite is relatively weak compared to that of a military satellite because the Ku-band satellite has been designed for commercial services. Therefore, this paper proposes a coupler and its multi-mode monopulse tracking system satisfying the tracking accuracy under a low C/N environment and analyzes the tracking accuracy. After that, we perform a real satellite tracking test and compare the accuracy of the test with the analysis result before validating the performance of the architecture of the proposed satellite tracking system.
3-level인버터를 이용한 과변조영역에서의 간접벡터 유도전동기 구동
이재문(Jaemoon Lee),정헌선(Junghun Sun),노세진(Sejin Nho),이은규(Eunkyu Lee),염상구(Sangkyu Yeum),최재호(Jaeho Choi) 전력전자학회 2007 전력전자학술대회 논문집 Vol.- No.-
This paper presents the over-modulation strategy and indirect vector control drive of NPC type PWM inverter. NPC inverter has three level phase voltage output.It can perform in high voltage through assembling switching components. It has less harmonics and surge voltage stress at motor terminals than the 2 level inverter in same switching frequency through 3 level voltage. The conventional railway vehicle has used the vector control to MI=0.907 and the slip-frequency control from MI=0.907 to six-step mode. The slip-frequency control has bad motive power and slow torque control response. But vector control has good motive power and can instant torque control. In this paper, output voltage is controlled linearly from linear region to six-step mode by using over-modulation strategy. And NPC inverter is used.
이재문(Jaemoon Lee),최재호(Jaeho Choi),이은규(Eunkyu Lee),염상구(Sanggu Yeom) 대한전기학회 2007 대한전기학회 학술대회 논문집 Vol.2007 No.4
This paper proposes a linearization technique for the 3 level NPC type inverter, which increases the linear control range of inverter up to the G-step inverter. The overmodulation range is divided into two modes depending on the modulation index(MI), In mode I, the reference angles are derived from the Fourier series expansion of the reference voltage corresponds to the MI. In mode Ⅱ, the holding angles are also derived in the same way. Therefore, it is possible to obtain the linear control and the maximized utilization of PWM inverter output voltage.
베인형 바이너리 브레이크 진공 펌프에 관한 해석적 연구
이준용(Junyong Lee),이헌균(Heonkyun Lee),허형석(Hyungseok Heo),황병성(Byeongseong Hwang),이재문(Jaemoon Lee),김홍기(Hongki Kim) 한국자동차공학회 2015 한국자동차공학회 부문종합 학술대회 Vol.2015 No.5
Vane type binary vacuum pump is the equipment that make vacuum in the brake booster using the negative pressure caused by the rotation of the rotor for decelerating or stopping the vehicle. Mechanical vacuum pump in diesel engine, the negative pressure of engine intake manifold in the gasoline engine is used as the primary vacuum source. Recently, according to the introducing engine downsizing and turbo charger technology for improving fuel efficiency, electric vacuum pump is used as additional vacuum source. In this study, the effect on flow rate and outlet pressure with respect to the design parameter such as clearance, vane angle and outlet position has been examined using CFD analysis.
EHPS 시스템 특성 분석을 위한 객관적 평가에 관한 연구
이경훈(Kyunghun Lee),최형진(Hyungjeen choi),김도현(Dohyun Kim),김상천(Sangcheon Kim),이재문(Jaemoon Lee),김인상(Insang Kim),이현권(Hyunkwon Lee) 한국자동차공학회 2011 한국자동차공학회 부문종합 학술대회 Vol.2011 No.5
본 연구에서는 EHPS 시스템을 개발하기 위해서 선진 EHPS 시스템이 장착된 차량 조향 특성을 분석하였다. 이를 위해 선진 EHPS 시스템이 장착된 차량에 대한 실차 주행시험을 통해 차량의 동적 거동에 대한 차량 특성 및 조향 시스템에 적용되는 부하조건 등을 계측하고, 이를 기반으로 대상차량 및 조향시스템에 대한 성능과 제어인자에 대한 연구를 수행하였다. 시간영역에서 조향 각, 조향 토크, 측면 가속도 영역에 대한 다양한 신호들의 분석을 위해서 조향각, 조향 토크 축을 정의역으로 한 이력(Hysterisis) 루프를 도시하여 세로 좌표 데드밴드, 가로 좌표 데드밴드, 기울기 인자들을 구하고, 그 인자들을 이용해 조향 특성을 분석하였다.
이헌균(Heonkyun Lee),이준용(Junyong Lee),허형석(Hyungseok Heo),황병성(Byeongseong Hwang),이재문(Jaemoon Lee),김홍기(Hongki Kim) 한국자동차공학회 2014 한국자동차공학회 부문종합 학술대회 Vol.2014 No.5
Recently, the electric driven auxiliary vacuum pump is becoming widely used to assist braking performance of vehicle. In this paper, the performance of the vane type vacuum pump is analyzed by computational fluid dynamic method. The characteristic of the flow rate and pulsation of discharge pressure is predicted on the vacuum pump including an vane, rotor and cam ring. Also, the influence on the performance of the various design factors of discharge port has been investigated such as position size and number of hall.