• 한국자동차공학회논문집
• /
• 제19권6호
• /
• pp.23-29
• /
• 2011

In this study, a camber angle generating mechanism for front and rear suspension is suggested. An experimental device is implemented and tested. A full vehicle model with camber angle generating device by using ADAMS/Car is modeled. Step steer simulations are carried out for investigating the effects of vehicle handling performance due to camber angle change of front and rear wheel. According to results, the camber angle of rear suspension affects the vehicle handling performance during both simulations. Therefore, when the vehicle makes the right turn or left turn, left and right wheel of front and rear suspension should have the proper orientation for improving the handling performance, respectively.

• 한국철도학회논문집
• /
• 제19권6호
• /
• pp.833-843
• /
• 2016

최근 철도 화물 수송은 컨테이너 전세 열차뿐만 아니라 시멘트, 철강 등 일반 화물의 전용열차 수가 증가하고 있고, 이에 따라 영차 수송 계획은 점차 단순해지고 있다. 반면에 공화차 수송의 경우, 수송 계획 최적화 시스템의 부재로, 사령의 경험에 의해 공화차 배분이 이루어지고 있으며, 이의 효율성 여부는 검증된 바 없고, 공화차 배분을 위한 별도의 의사결정지원시스템의 필요성은 여전히 존재한다. 본 연구에서는 연구 문헌상의 공화차 배분 최적화 모형뿐만 아니라 2010년 전후로 개발 되었다가 최근 사용이 중단된 화물수송최적화 시스템(KTOCS)상의 공화차 배분 최적화 모형을 비판적으로 살펴본 후, 수송 문제를 활용한 새로운 공화차 배분 최적화 모형 및 해법을 제시한다. 이 최적화 모형은 기존 모형과 달리, 추가 제약이 있는 수송문제에 포함되는 아크를 동적으로 생성해내는 열생성 기법에 기초하고 있다. 이를 이용한 우리나라 전체 철도 네트워크에 대한 시뮬레이션 결과, 실적 상에 나타난 공화차 km를 상당히 낮출 수 있는 것을 확인할 수 있었다.

• 대한기계학회논문집A
• /
• 제28권8호
• /
• pp.1125-1134
• /
• 2004

This paper presents a mathematical model which is about the dynamics of not only a two wheel steering vehicle but a four wheel steering vehicle. A sliding mode ABS control strategy and PID rear wheel control logic are developed to improve the brake and cornering performances, and enhance the stability during emergency maneuvers. The performances of the controllers are evaluated under the various driving road conditions and driving situations. The numerical study shows that the proposed full car model is sufficient to accurately predict the vehicle response. The proposed ABS controller reduces the stopping distance and increases the vehicle stability. The results also prove that the ABS controller can be employed to a four wheel steering vehicle and improves its performance. The four wheel steering vehicle with PID rear wheel controller shows increase of stability when a vehicle speed is high and sharp cornering maneuver when a vehicle speed is low compared to that of a two wheel steer vehicle.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2005년도 춘계학술대회 논문집
• /
• pp.1095-1098
• /
• 2005

Most electronic chassis control systems until today have been designed with optimization on its own performance. However, According to the increase of the interest regarding a vehicle safety and development of information technique, the integration technique of current chassis systems is being emphasized. Each enterprise proposed it with name of GCC(Global Chassis Control) or UCC(Unified Chassis Control). This study realizes control algorithm of suspension and brake by using the vehicle model of low degree of freedom as the primary stage of realization of integrated chassis control system. The proposed algorithm build the simulation environment connected to the CarSim having full vehicle model of 27 degree of freedom for raising the thrust of results

• 한국전산유체공학회지
• /
• 제19권1호
• /
• pp.41-46
• /
• 2014

The aerodynamic drag of high-speed train has been calculated and the effect of bogie side fairing on the aerodynamic drag has been investigated. Computational Fluid Dynamics (CFD) simulation based on steady-state 3 dimensional Navier-Stokes equation has been conducted employing FLUENT 12 and the aerodynamic model of HEMU-430x, the Korean next generation high-speed train under development has been built using GAMBIT 2.4.6. Three types of bogie side fairing configuration, the proto-type without fairing, half-covered fairing to avoid the interference with the bogie frame and full-covered fairing have been adopted to the train model to compare the drag reduction effects of the bogie side fairing configurations and the numerical results yields that the bogie side fairing can reduce the aerodynamic drag of the 6-car trainset up to 7.8%. The aerodynamic drag coefficient of each vehicle as well as the flow structures around the bogie system have also been examined to analyze the reason and mechanism of the drag reduction by bogie side fairing.

• International Journal of Automotive Technology
• /
• 제6권2호
• /
• pp.149-159
• /
• 2005

A full nonlinear finite element P185/70Rl4 passenger car radial-ply tire model was developed and run on a 1.7-meter-diameter spinning test drum/cleat model at a constant speed of 50 km/h in order to investigate the tire transient response characteristics, i.e. the tire in-plane free vibration modes transmissibility. The virtual tire/drum finite element model was constructed and tested using the nonlinear finite element analysis software, PAM-SHOCK, a nonlinear finite element analysis code. The tire model was constructed in extreme detail with three-dimensional solid, layered membrane, and beam finite elements, incorporating over 18,000 nodes and 24 different types of materials. The reaction forces of the tire axle in vertical (Z axis) and longitudinal (X axis) directions were recorded when the tire rolled over a cleat on the drum, and then the FFT algorithm was applied to examine the transient response information in the frequency domain. The result showed that this PI 85/70Rl4 tire has clear peaks of 84 and 45 Hz transmissibility in the vertical and longitudinal directions. This result was validated against more than 10 previous studies by either theoretical or experimental approaches and showed excellent agreement. The tire's post-impact response was also investigated to verify the numerical convergence and computational stability of this FEA tire model and simulation strategy, the extraordinarily stable scenario was confirmed. The tire in-plane free vibration modes transmissibility was successfully detected. This approach was never before attempted in investigations of tire in-plane free vibration modes transmission phenomena; this work is believed to be the first of its kind.

• International Journal of Automotive Technology
• /
• 제6권2호
• /
• pp.141-148
• /
• 2005

In order to reduce the time and costs of improving the performance of vehicle suspensions, the techniques for optimizing damping and air spring characteristic were proposed. A full vehicle model for a bus is constructed with a car body, front and rear suspension linkages, air springs, dampers, tires, and a steering system. An air spring and a damper are modeled with nonlinear characteristics using experimental data and a curve fitting technique. The objective function for ride quality is WRMS (Weighted RMS) of the power spectral density of the vertical acceleration at the driver's seat, middle seat and rear seat. The objective function for handling performance is the RMS (Root Mean Squares) of the roll angle, roll rate, yaw rate, and lateral acceleration at the center of gravity of a body during a lane change. The design variables are determined by damping coefficients, damping exponents and curve fitting parameters of air spring characteristic curves. The Taguchi method is used in order to investigate sensitivity of design variables. Since ride and handling performances are mutually conflicting characteristics, the validity of the developed optimum design procedure is demonstrated by comparing the trends of ride and handling performance indices with respect to the ratio of weighting factors. The global criterion method is proposed to obtain the solution of multi-objective optimization problem.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2000년도 하계학술대회 논문집 D
• /
• pp.2949-2952
• /
• 2000

A new neural networks and learning algorithm are proposed in order to measure nonlinear heights of complexed road environments in realtime without pre-information. This new neural networks is Error Self Recurrent Neural Networks(ESRN), The structure of it is similar to recurrent neural networks: a delayed output as the input and a delayed error between the output of plant and neural networks as a bias input. In addition, we compute the desired value of hidden layer by an optimal method instead of transfering desired values by back-propagation and each weights are updated by RLS(Recursive Least Square). Consequently. this neural networks are not sensitive to initial weights and a learning rate, and have a faster convergence rate than conventional neural networks. We can estimate nonlinear models in realtime by ESRN and learning algorithm and control nonlinear models. To show the performance of this one. we control 7 degree of freedom full car model with several control method. From this simulation. this estimation and controller were proved to be effective to the measurements of nonlinear road environment systems.

• 대한기계학회논문집A
• /
• 제30권10호
• /
• pp.1284-1292
• /
• 2006

Heat treatment is a controlled heating and cooling process to improve the physical and/or mechanical properties of metal products without changing their shapes. Today finite element method is widely used to simulate lots of manufacturing processes including heat treatment and surface hardening processes, which aims to reduce the number of time- and cost-consuming experimental tryouts. In this study we tried, using this method, to simulate the full carburizing process that consists of carburizing, diffusing and quenching, and to predict the distribution of carbon contents, phase fraction and hardness, thermal deformation and other mechanical characteristics as the results. In the finite element analysis deformation, heat transfer, phase transformation and diffusion effects are taken into consideration. The carburizing process of a lock gear, a part of the car seat recliner, that is manufactured by the fine blanking process is adopted as the analysis model. The numerical results are discussed and partly compared with experimental data. And a combination of process parameters that is expected to give the highest surface hardness is proposed on the basis of this discussion.

• 대한기계학회논문집
• /
• 제16권9호
• /
• pp.1643-1653
• /
• 1992

본 연구에서는 해석적 모우드해석 결과인 모우드 형상벡터를 이용하여 효과적 인 가진점과 응답측정점을 선정하는 기존의 두 방법에 대해 간략히 기술하고 비교검토 하고자 하였다. 첫번째 방법은 주파수응답함수에서 관심있는 모우드의 공진피크치와 관련있는 모우드상수를 이용하는 것이고, 두번째 방법은 계의 관심있는 모우드에 대한 동적 특성을 가장 잘 나타낼 수 있도록 특이치분해(singular value decomposition) 기 법을 적용함으로써 계의 대표자유도(master degree of freedom) 지점들을 선저하는 것 이다.우선 단순한 계인 외팔보아 알루미늄평판에 대해 두 방법을 적용함으로써 비 교검토하였고, 이 결과로부터 두번째 방법의 우수성을 확인할 수 있었다. 이에 따라 보다 복잡한 형상을 갖는 승용차의 부분구조물인 조향휠고정대 (deck cross member : DCM)에 대해서 두번째 방법을 이용하여 모우드 시험을 수행하고 그 결과에 대하여 논 하였다.