• Proceedings of the KSR Conference
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• 2008.06a
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• pp.721-732
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• 2008

This paper is concerned with the life-cycle cost(LCC) analysis of the urban transit vehicle. LCC is the core part of analyzing the total cost of acquisition and ownership of a system. LCC in railway industry has been focused on the prediction of investment for railway vehicles. Therefore, to investigate future cost for operation and maintenance in detail, it is necessary to evaluate the LCC of the vehicle systematically. This study is focused on making a fundamental model for estimating the LCC of the urban transit vehicle. To develop a appropriate LCC model, we broadly analyzed specs and standards and compared the LCC model developed in other country. Moreover, this paper proposes strategies to develop an unique LCC model for the urban transit vehicle.

• Journal of the Korea Society for Simulation
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• v.9 no.3
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• pp.91-102
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• 2000

The distribution routing problem is one of the important problems in distribution and supply center management. This research is concerned with an integrated distribution routing problem for multi-supply centers based on improved genetic algorithm and GUI-type programming. In this research, we used a three-step approach; in step 1 a sector clustering model is developed to transfer the multi-supply center problem to single supply center problems which are more easy to be solved, in step 2 we developed a vehicle routing model with time and vehicle capacity constraints and in step 3, we developed a GA-TSP model which can improve the vehicle routing schedules by simulation. For the computational purpose, we developed a GUI-type computer program according to the proposed methods and the sample outputs show that the proposed method is very effective on a set of standard test problems, and it could be potentially useful in solving the distribution routing problems in multi-supply center problem.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.11
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• pp.1955-1961
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• 2007

In this paper, we propose the mathematical model for the vehicle system including running characteristics. The well defined model for a system is necessary to study and to enhance system performance. To model the dynamic properties of vehicle system, we have considered two fundamental parts. The first part is the motion equations for vehicle based on Newton's second law. The second part is the torque dynamics of the traction motor. These parts are affected by outer conditions such as adhesive coefficient, running resistance and gradient resistance. The each parts are presented by the numerical formula. To test the driving characteristics of the developed model, we performed the simulations by dynamic system simulation software, "SIMULINK" and the results are given for several conditions.

• International Journal of Automotive Technology
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• v.8 no.1
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• pp.49-57
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• 2007

This paper proposes a traction control system (TCS) that uses a sliding mode wheel slip controller and a PID throttle valve controller. In addition, a yaw motion controller (YMC) is also developed to improve lateral stability using a PID rear wheel steering angle controller. The dynamics of a vehicle and characteristics of the controllers are validated using a proposed full-car model. A driver model is also designed to steer the vehicle during maneuvers on a split ${\mu}$ road and double lane change maneuver. The simulation results show that the proposed full-car model is sufficient to predict vehicle responses accurately. The developed TCS provides improved acceleration performances on uniform slippery roads and split ${\mu}$ roads. When the vehicle is cornering and accelerating with the brake or engine TCS, understeer occurs. An integrated TCS eliminates these problems. The YMC with the integrated TCS improved the lateral stability and controllability of the vehicle.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.152.1-152.1
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• 2011

This study analyzes transitions to a green path in transportation system in South Korea. We develop transportation system model with four new technology options, green cars; Hybrid electric vehicle, plug-in hybrid vehicle, electric vehicle and fuel cell vehicle. Among those technologies fuel cell vehicle is the best option assuming no GHG emissions when driving. We use MESSAGE model to get an optimal solution of pathway for high deployment of fuel cell vehicles under the Korea BAU transportation model. Among hydrogen production sources, off gas hydrogen is most economic since it is hardly used to other chemical sources or emits in South Korea. According to off gas hydrogen projection it can run 1.8 million fuel cell vehicles in 2040 which corresponds to 10% of all passenger cars expected in Korea in 2040. However, there are concerns associated with technology maturity, cost uncertainty which has contradictions. But clean pathway with off gas and renewable sources may provide a strong driving force for energy transition in transportation in South Korea.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.147-152
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• 2006

This paper presents the dynamic characteristics of MR impact damper for vehicle collision system. Various types of mechanism have been proposed for reduce transmitted force to vehicle chassis and finally protect occupants from injury. In the case of frontal collision, the bumper make main role of isolation material for collision attenuation. In this study, proposed bumper system composed of MR impact damper and structures. The MR impact damper is to adopted MR fluid which has reversible properties with applied magnetic field. MR fluid operates under flow mode with Bingham flow and bellows is used for generation of fluid flow. Mathematical model of MR impact damper incorporated with MR fluid is established. Field dependent damping force is investigated with time and frequency domain. The MR impact damper is then incorporated with vehicle crash system. The governing equation of motion of vehicle model is formulated considering occupant model. Dynamic characteristics of vehicle collision system investigated with computer simulation.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.48 no.6
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• pp.71-81
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• 2011

Unlike a typical internal combustion engine vehicle, the powertrain system of the pure electric vehicle, consisting of battery, inverter and motor, has direct effects on the vehicle performance and dynamics. Then, the specific modeling of such complex electro-mechanical components enables the insight into the longitudinal dynamic outputs of the vehicle and analysis of entire powertrain systems. This paper presents the dynamic model of electric vehicle powertrain systems based on theoretical approaches to predict and analyze the final output performance of electric vehicles. Additionally, the correlations between electric input signals and the final output of the mechanical system are mathematically derived. The proposed model for powertrain dynamics of electric vehicle systems are validated with a reference electric vehicle model using generic simulation platform based on Matlab/Simulink software. Consequently, the dynamic analysis results are compared with electric vehicle simulation model in some parameters such as vehicle speed/acceleration, and propulsion forces.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.10
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• pp.4698-4716
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• 2017

Wireless signal transmission is influenced by environmental effects. These effects have also been challenging for Vehicular Ad hoc Network (VANET) in real-time communication. More specifically, in an urban environment, with high mobility among vehicles, a vehicle's status from the transmitter can instantly trigger from line of sight to non-line of sight, which may cause loss of real-time communication. In order to overcome this, a deterministic signal propagation model is required, which has less complexity and more feasibility of implementation. Hence, we propose a realistic path loss model which adopts ray tracing technique for VANET in a grid urban environment with less computational complexity. To evaluate the model, it is applied to a vehicular simulation scenario. The results obtained are compared with different path loss models in the same scenario based on path loss value and application layer performance analysis. The proposed path loss model provides higher loss value in dB compared to other models. Nevertheless, the performance of vehicle-vehicle communication, which is evaluated by the packet delivery ratio with different vehicle transmitter density verifies improvement in real-time vehicle-vehicle communication. In conclusion, we present a realistic path loss model that improves vehicle-vehicle wireless real-time communication in the grid urban environment.

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.9
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• pp.105-111
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• 1999

The paper presents development of a Hardware-In-the-Loop simulation (HILS) system for the purpose of testing performance, stability, and reliability of an electronic power steering system(EPS). In order to realistically test an EPS by the proposed HILS apparatus, a simulated uniaxial dynamic rack force is applied physically to the EPS hardware by a pnumatic actuator. An EPS hardware is composed of steering wheel &column, a rack & pinion mechanism, andas motor-driven power steering system. A command signal for a pneumatic rack-force actuator is generated from the vehicle handling lumped parameter dynamic model 9software) that is simulated in real time by using a very fast digital signal processor. The inputs to the real-time vehicle dynamic simulation model are a constant vehicle forward speed and from wheel steering angles driven through a steering system by a driver. The output from a real-time simulation model is an electric signal that is proportional to the uniaxial rack force. The vehicle handling lumped parameter dynamic model is validated by a fully nonlinear constrained multibody vehicle dynamic model. The HILS system simulation results sow that the proposed HILS system may be used to realistically test the performance stability , and reliability of an electronic power steering system is a repeated way.

• Journal of Electrical Engineering and Technology
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• v.10 no.5
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• pp.2162-2169
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• 2015

Cruise control is a technology for automatically maintaining a steady speed of vehicle as set by the driver via controlling throttle valve and brake of vehicle. In this paper we investigate cruise controller design method with consideration for distance to vehicle ahead. We employ linear time varying (LTV) model to describe longitudinal vehicle dynamic motion. With this LTV system we approximately model the nonlinear dynamics of vehicle speed by frequent update of the system parameters. In addition we reformulate the LTV system by transforming distance to leading vehicle into variation of system parameters of the model. Note that in conventional control problem formulation this distance is considered as disturbance which should be rejected. Consequently a controller can be designed by pole placement at each instance of parameter update, based on the linear model with the present system parameters. The validity of this design method is examined by simulation study.