• 한국자동차공학회논문집
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• 제23권1호
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• pp.11-17
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• 2015

Recently, the in-wheel motor vehicle is rapidly developed to solve energy exhaustion and environmental problems. Especially, it has the advantage of independently driving the torque control of each wheel in the vehicle. However, due to the weight increase of wheel, the comfort of vehicle riding and performance of road holding become worse. In this paper, to compensate the poor performance, a simultaneous control of the driving torque and semi-active suspension system is investigated. A vehicle model is generated using CarSim Software and validated by field tests. Co-simulation of CarSim and MATLAB/Simulink with control logics is carried out, and it is found that simultaneous control of the driving torque and semi-active suspension system can improve driving stability and durability of the in-wheel motor system.

• 대한조선학회논문집
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• 제58권4호
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• pp.253-261
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• 2021

This paper describes the process of evaluating maneuverability in still water of an unmanned surface vehicle based on data measured by performing sea trials. First, we set up a test scenario that is easy to analyze the maneuverability of the unmanned surface vehicle and to identify and verify the dynamics model. Since the attitude of hull varies according to the speed of the unmanned surface vehicle which has a planing hull shape, the relationship between waterjet RPM, speed and attitude is analyzed by performing straight forward tests at various speeds. The turning tests of the unmanned surface vehicle in which the waterjet angle rotates while turning are performed by changing the waterjet rotation angle under the condition of two representative speeds to analyze turning ability. The turning ability of the unmanned surface vehicle includes speed reduction, yaw rate, heel, and turing diameter at steady turning phase according to the speed and RPM.

• 한국자동차공학회논문집
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• 제24권3호
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• pp.310-318
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• 2016

The demands for vehicle safety systems such as ABS and ESC have been increased. Accurate vehicle state estimation is required to realized the abovementioned systems and tire-friction coefficient is crucial information. Estimation of lateral tire-road friction coefficient using pneumatic trail information is mainly dealt in this paper. Pneumatic trail shows unique characteristics according to the wheel side slip angle and these property is highly sensitive to vehicle lateral motion. The proposed algorithm minimizes the use of conventional tire models such as magic formula, brushed tire model and Dugoff tire model. The pure side slip maneuver, which means no longitudinal dynamics, is assumed to achieve the ultimate goal of this paper. A simulation verification using Carsim and Simulink is performed and the results show the feasibility of the proposed algorithms.

• International Journal of Automotive Technology
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• 제8권3호
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• pp.309-317
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• 2007

In this study, we conducted a vibration fatigue analysis of the lower control arm in a vehicle suspension system. The vehicle was driven during the tests so that the dynamic effects could be taken into account. The dynamic load of the frequency domain was superimposed on the frequency response analysis. We performed a virtual proving ground test using multi-body dynamics, along with a finite element analysis and fatigue life predictions. Shape optimization was also considered using the design of the experimental approach, and a response surface analysis was performed to improve the durability performance of the lower control arm. We identified the elements that had the most influence on the optimal shape of the finite element model and analyzed the sensitivity of those elements. Then the optimal points that minimized the amount of damage to the areas of interest were determined through a response surface analysis. The results suggested that the fatigue life of the model increased as its mass was not increased excessively, and demonstrated that these design procedures yielded an appropriate optimized lower control arm model.

• 한국시스템다이내믹스연구
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• 제14권4호
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• pp.37-62
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• 2013

The purpose of this paper is to find out some clues about effectiveness and implementing timing of the control measures against Foot-and-Mouth Disease (FMD) in Korea. To do that, the case of FMD, which broke out during November 2010 in Korea, is examined and constructed as a system dynamics simulation model. The implications of simulation result are as follows. First of all, it is most effective measure to prevent the movement of vehicle from infected farmhouse to other noninfected farmhouses, which are located far away, in the early stage of FMD diffusion. Secondly, earlier vaccination can be adopted as a reliable means to control the epidemic when FMD spreads widely. Finally, reducing the time to vaccinate the whole noninfected livestock is a little help to restrain the additional infections of FMD.

• 한국해양공학회지
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• 제8권2호
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• pp.131-140
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• 1994

Dynamics of AUV has heavy nonlinearities and many unknown parameters due to its bluff shape and low cruising speed. Intelligent algorithms, therefore, are required to overcome these nonlinearities and unknown system dynamics. Several identification techniques have been suggested for the application of control of underwater vehicles during last decade. This paper applies the neural network to identification and motion control problem of AUVs. Nonlinear dynamic systems of an AUV are identified using feedforward neural network. Simulation results show that the learned neural network can generate the motion of AUV. This paper, also, suggest an adaptive control scheme up-dates the controller weights with reference model and feedforward neural network using error back propagation.

• 한국융합학회논문지
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• 제3권4호
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• pp.35-44
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• 2012

본 연구에서 모사 프로그램이 6WD/6WS를 가진 특수 목적 차량의 비정상상태 코너링 성능을 조사하기 위해 개발되었다. 6WD 차량은 비포장 도로에서 작전을 수행하기 좋은 성능을 가지고 있고 안전한 성능을 가진 것으로 신뢰받고 있다. 그러나, 6WS 차량들의 코너링 성능은 관련 문헌을 통해서는 언뜻 이해가 어렵다. 본 논문에서는 6WD/6WS 차량들은 비선형 차량 동력학, 타이어 모델, 운동학적 효과 등을 포함한 18 자유도 시스템으로 모델링 되었다. 그리고 그 차량 모델은 입/출력과 차량변수가 수식화된 접근 방법으로 쉽게 변환될 수 있도록 MATLAB/SIMULINK를 사용한 모사 프로그램으로 구성되었다. 6WS 차량의 코너링 성능은 브레이크 휠과 피봇팅 각각으로 해석되었다. 모사 결과들을 보면, 코너링 성능은 전후 휠 조향 뿐만이 아니라 중간 휠 조향에 따라 좌우됨을 보여준다. 덧붙여, 새로운 6WS 제어법칙은 측면 미끄러짐 각을 최소화하기 위해 제안되었다. 차량변경 모사 결과들은 제안된 제어법칙의 6WS 차량의 장점을 보여준다.

• 한국자동차공학회논문집
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• 제13권4호
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• pp.121-128
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• 2005

In most researches on the ride comfort analysis of passenger vehicles, the flexibility of the vehicle body has been not considered as an important factor, because the resonance frequencies of the vehicle body related to pitching, yawing and rolling motions are below 10Hz while the resonance frequencies of the vehicle body related to the flexibility are above 20Hz approximately. Nevertheless, the paper shows that the consideration of the local flexibility (or local stiffness) of the 4 corners on which shock absorbers are mounted influences the ride comfort. A simple beam model is devised to qualitatively examine the effect of the change of the local stiffness of the vehicle body on the ride comfort. Based on the results obtained from the analysis of the one-dimensional model, multi-body dynamic analysis considering the flexibility of the vehicle body is performed using ADAMS and MSC/NASTRAN. Natural frequencies and mode shapes computed by MSC/NASTRAN are used as input data for multi-body dynamic analysis in ADAMS. Through simulations using ADAMS, it has been found that the ride comfort can be improved by changing the local stiffness of the vehicle body and that the simulation results agree with experiment results.

• 한국소음진동공학회논문집
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• 제12권6호
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• pp.461-468
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• 2002

Computer simulation is essential to design the suspension elements of railway vehicle. By computer simulation, engineers can assess the feasibility of the given design factors and change them to get a better design. But if one wishes to perform complex analysis on the simulation, such as railway vehicle dynamic, the computational time can become overwhelming. Therefore, many researchers have used a surrogate model that has a regression model performed on a data sampling of the simulation. In general, metamodels(surrogate model) take the form y($\chi$)＝f($\chi$)＋$\varepsilon$, where y($\chi$) is the true output, f($\chi$) is the metamodel output, and is the error. In this paper, a second order polynomial equation is used as the RSM(response surface model) for high speed train that have twenty-nine design variables and forty-six responses. After the RSM is constructed, multi-objective optimal solutions are achieved by using a nonlinear programming method called VMM(variable matric method) This paper shows that the RSM is a very efficient model to solve the complex optimization problem.

• 한국정밀공학회지
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• 제17권2호
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• pp.80-88
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• 2000

This paper presents a method to optimize the bump steer characteristics (the change of toe angle with vertical wheel travel) with respect to hard points in the double wishbone front suspension of the four-wheel-drive vehicle using the design of experiment, multibody dynamics simulation, and optimum design program. Front and rear suspensions are modeled as the interconnection of rigid bodies by kinematic joints and force elements using DADS. The design variables with respect to the kinematic characteristics are obtained through the experimental design sensitivity analysis. An object function is defined as the area of absolute differences between the desired and experimental toe angle. By the design of experiment and regression analysis, the regression model function of bump steer characteristics is extracted. The design variables that make the toe angle optimized are selected using the optimum design program DOT. The lane change simulations and tests of the full vehicle models are implemented to evaluate the improvement of vehicle handling performances by the optimization of front bump steer characteristics. The results of the lane change simulations show that the vehicle with optimized bump steer has the weaker understeer tendency than the vehicle with initial bump steer.