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정홍규(Hongkyu Jung),송충섭(Chungseob Song),임동민(Dongmin Lim),김두현(Doohyun Kim) 한국자동차공학회 2010 한국자동차공학회 학술대회 및 전시회 Vol.2010 No.11
Correlation between vehicle dynamics analysis and test results is very important to develop chassis subsystem using objective performance target of the vehicle. This paper presents correlation between test and simulation results such as kinematic and compliance analysis for the half vehicle and handling analysis for the full vehicle. Specially, chassis components are considered flexibility effects and analyzed contribution for the K&C and R&H performance. Guide lines of the full vehicle modeling for the handling analysis are suggested using handling analysis correlation results.
정홍규(Hongkyu Jung),송충섭(Chungseob Song),김완구(Wangoo Kim),이창욱(Changwook Lee),배대성(Daesung Bae) 한국자동차공학회 2012 한국자동차공학회 학술대회 및 전시회 Vol.2012 No.11
Recently importance of Virtual Development Process (VDP) has been increased more and more to reduce the time and cost in developing many industrial products. To achieve the successful VDP, a design process including analysis types, design specifications, and items for each component must be standardized. Hyundai Motors Company(HMC) and VirtualMotion have incorporated to develop the several standard design processes for some vehicle dynamics components in DAFUL/CAR on top of for DAFUL that is an integrated solver for multi-body dynamics and FEA dynamics. Hyundai Motors Company has developed various toolkits, based on analysis and design technology of HMC.
현가장치 함수모델을 이용한 자축식 현가장치 해석 및 시험검증
정홍규(Hongkyu Jung),김상섭(Sangsup Kim),박준홍(Joonhong Park),이준모(Joonmo Lee) 한국자동차공학회 2004 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
This paper presents an enhanced parametric vehicle dynamic modeling that includes kinematic and compliance characteristics of suspension more accurately. The relative displacement and orientation of a wheel(toe, camber, side view spin angle, wheelbase, tread) with respect to car body are represented as a function of the vertical displacement of the wheel input. This can be obtained from kinematic and compliance tests(K&C tests) of vehicle suspensions. A functional suspension model is proposed as kinematic describing functions of the suspension, that represents the relative wheel displacement in polynomial form in terms of the vertical displacement of the wheel center. The relative velocity and acceleration of the wheel are represented in terms of the first and second derivatives of the kinematic describing function. The equations of motion for the full vehicle dynamic model are systematically derived using velocity transformation method of multi-body dynamics. The comparison of the test and simulation results demonstrated the validity of the proposed functional suspension modeling method for axle type suspension.
정홍규(Hongkyu Jung),김광열(Kwangyul Kim),신요안(Yoan Shin) 대한전자공학회 2012 電子工學會論文誌-TC (Telecommunications) Vol.49 No.6
차세대 무선통신 시스템에서 다중 경로 페이딩의 영향을 효율적으로 감소시키기 위한 방법으로 최근 협력통신 시스템이 각광을 받고 있다. 협력통신 시스템은 정보를 전송하기 위해서 다양한 페이딩 계수를 가지고 있는 협력 릴레이를 사용하기 때문에, 모든 릴레이를 협력통신에 참여 시키는 것은 자원의 낭비를 초래한다. 그러므로 무선자원을 효율적으로 사용하기 위해서는 최적의 릴레이를 선택적으로 사용할 필요가 있다. 본 논문에서는 무선 협력통신 네트워크에서 발생하는 이러한 문제를 해결하기 위하여 Q-Learning 알고리즘을 이용한 협력 릴레이 선택 기법을 제안한다. Q-Learning에서는 자가 학습을 위해서 상태, 행동, 그리고 보상에 대한 파라미터를 정의한다. 이러한 파라미터가 잘 정의 될 때 Q-Learning을 이용하여 우수한 통신 성능을 얻을 수 있다. Q-Learning 알고리즘의 우수성을 보이기 위해서, 수학적인 분석을 통해서 최적의 협력 릴레이를 얻는 기법과 통신 성능을 비교하였다. 모의실험 결과, 제안된 기법에서 Q-Learning 알고리즘 내의 보상을 주는 방식에 따라, 비교 기법과 유사한 심벌오율 성능을 얻으면서 보다 더 적은 협력 릴레이를 선택하는 것을 보였다. 따라서 본 논문에서 제안된 기법은 다수의 릴레이를 사용하는 차세대 무선통신 시스템의 성능 향상을 위한 좋은 접근 방식의 하나로 판단된다. As a scheme to efficiently reduce the effects of multipath fading in next generation wireless communication systems, cooperative communication systems have recently come into the spotlight. Since these cooperative communication systems use cooperative relays with diverse fading coefficients to transmit information, having all relays participate in cooperative communication may result in unnecessary waste of resources, and thus relay selection schemes are required to efficiently use wireless resources. In this paper, we propose an efficient relay selection scheme through self-learning in cooperative wireless networks using Q-learning algorithm. In this scheme, we define states, actions and two rewards to achieve good SER (Symbol Error Rate) performance, while selecting a small number of cooperative relays. When these parameters are well-defined, we can obtain good performance. For demonstrating the superiority of the proposed Q-learning, We compared the proposed scheme with Q-learning and a relay selection scheme with a mathematical analysis. The simulation results show that, compared to a scheme that obtains optimum relays through a mathematical analysis, the proposed scheme uses resources efficiently by using smaller numbers of relays with comparable SER performance. According to these simulation results, the proposed scheme can be considered as a good attempt for future wireless communication.
경쟁차 R&H 성능 달성을 위한 감쇠력 설계 기준에 대한 연구
문하경(Hakyung Moon),정홍규(Hongkyu Jung) 한국자동차공학회 2017 한국자동차공학회 학술대회 및 전시회 Vol.2017 No.11
We have used the initial S/ABS damping force referring to previous models or the competitive cars. Vehicle test teams have depended on trial & error to fix damping force, which results too much time to fix damper and that delays the vehicle development. To predict damping force is not only to improve vehicle R&H performance efficiently but also to reduce the tuning time. Through this study, suspension designers can design damping forces and add them on drawings before producing prototype vehicles.