• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.1
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• pp.119-125
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• 2005

The current automotive is seeking the improvement of performance, the prevention of environmental pollution and the saving of energy resources according to miniaturization and lightweight of the components. And the variance analysis on the basis of structure analysis and DOE is applied to the lower control am. We have proposed a statistical design model to evaluate the effect of structural modification by performing the practical multi-objective optimization considering weight, stress and fatigue lift. The lower control arm is performed the fatigue analysis using the load history of real road test. The design model is determined using the optimization of acquired load history with the fatigue characteristic. The characteristic function is made use of the optimization according to fatigue characteristics to consider constrained function in the optimization of DOE. The structure optimization of a lower control arm according to fatigue characteristics is performed. And the optimized design variable is D=47 m, T=36mm, W=12 mm. In the real engineering problem of considering many objective functions, the multi-objective optimization process using the mathematical programming and the characteristic function is derived an useful design solution.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.1
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• pp.92-99
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• 2006

The swirl ratio of a charge in the cylinder was estimated by calculating the ratio of the rotary speed of charge which could be simulated from the rotary speed of paddle in the swirl measurement apparatus, to the engine speed which could be calculated by measuring intake air flow rate. The automation of the swirl ratio measurement for cylinder head was achieved by controling both valve lift in cylinder head and a suction pressure of surge tank using two step-motors. The number of measurement position for calculating mean swirl ratio was varied by adjusting the interval of valve lift. The mean swirl ratio with varying the number of measurement position showed nearly constant value. Two measurement methods for measuring the swirl ratio were compared, one was to control the suction pressure of the surge tank with PID (proportional, integral, differential) mode with by-pass valve controlled by the step motor and the other did not control the surge tank pressure by fixing the by-pass valve. The difference of the mean swirl ratio between the two measurement methods showed nearly constant value with varying the number of measurement position. This means that the w/o PID control method could be preferred to the PID control method which has been used, due to the simpleness of the swirl measurement.

• Journal of the Korean Institute of Gas
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• v.21 no.3
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• pp.33-38
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• 2017

The domestic vehicles remodeling the "CNG Bi-fuel Kit" are mostly in operation with installing the mechanical regulator applying the Diaphragm. However, due to the material characteristics of Diaphragm and characteristics of mechanical pressure control method, various problems are happening. This study tries to deduce the improvement plan through the checking of performance characteristics according to the pressure control method of CNG regulator and progress of comparative analysis. According to the test result, the decompression method applying the Diaphragm has advantage compared to the method applying the Piston. Furthermore, it was confirmed that through the electronic pressure control, it is possible to improve the general performance of the regulator.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.1853-1856
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• 2003

This paper considers the problem of longitudinal control of a platoon of automotive vehicles on a straight lane of a highway and proposes control laws in the event of loss of communication between the lead vehicle and the other vehicles in the platoon. Since safety plays a key role in the development of an Automated Highway System, fault-tolerant control is vital. In this paper, we develop a control algorithm in vehicle platooning and prove that this control algorithm is stable for certain class of faults such as parameter uncertainties. The performance of the controller is demonstrated through a series of simulations incorporating various vehicles and AHS faults. Results of simulation shows that the vehicles have good performance in spite of simple automotive and AHS failure, such as actuator failure,that is to say, engine input failure, communication failure between lead vehicle and the another vehicles.

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.9
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• pp.1-9
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• 1999

Liquid Petroleum Gas (LPG) has been widely used for commercial light-duty vehicles worldwide. Since LPG has a higher octane number and a lower maximum combustion temperature than gasoline , it becomes more popular fuel for reducing exhaust emissions. In tihs study, mathematical models of air intake and fuel delivery system are presented, and a PI-controller is designed for air-fuel ratio control. Hardware and software of an engine control module (ECM) are designed for an LPG engine. The ECM is built using a Motorola MC68HC05. In order to control the air-fuel ratio at stoichiometry, the PI-control algorithm is implemented in the ECM. The experiment results show the proto LPG ECM and its control scheme perform well to meet the stoichiometric air-duel ratio requirement.

• International Journal of Automotive Technology
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• v.8 no.4
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• pp.477-481
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• 2007

In this article we present a new, reference model based, unified strategy for engine control. Three main modes are considered: first is the driver control mode where the driver controls the engine via the pedal position; second is the dashpot mode, that is, when the driver takes his foot off the pedal; and, lastly is the idle speed control mode. These modes are unified so that seamless transitions between modes now becomes possible. The unification is achieved due to the introduction of a reference model for the engine speed whereby only the desired engine speed is different for different modes while the structure of the control system remains the same for all the modes. The scheme includes an observer that estimates unknown engine load torque. A proof of robustness with respect to unknown load disturbances both within the operating modes and during intermode transitions is given.

• International Journal of Automotive Technology
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• v.5 no.2
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• pp.69-76
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• 2004

This paper evaluates the effectiveness of four-wheel-steering system from the viewpoint of lane-keeping control theory. In this paper, the lane-keeping control system is designed on the basis of the four-wheel-steering automobiles whose desired steering response is realized with the application of model matching control. Two types of desired steering responses are presented in this paper. One is zero-sideslip response, the other one is steering response which realizes zero-phase-delay of lateral acceleration. Using simplified linear two degree-of-freedom bicycle model, simulation study and theoretical analysis are conducted to evaluate the lane-keeping control performance of active four-wheel-steering automobiles which have different desired steering responses. Finally, the evaluation is conducted on straight and curved roadway tracking maneuvers.

• International Journal of Automotive Technology
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• v.5 no.2
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• pp.89-94
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• 2004

In this paper, a safe control strategy is considered in the situation when a platoon of vehicles need to decelerate rapidly. When the vehicles ate spaced closely, it is known that the reference information should be transmitted to the whole platoon to minimize the undesirable effects of small leader disturbances. However, the vehicle control should also depend on the preceding vehicle position to maintain the desired distance. Tracking the preceding vehicle position can lead to amplification of the control input along the following vehicles, therefore the vehicles in the rearward generally exert larger maximum control input than the vehicles in the front. The theoretical bounds for the $i^{th}$ vehicle control input are calculated using a linear vehicle and controller model. In the simple illustrative example, the designed controller maintains string stability, and the control inputs of the following vehicles stay within bounds.

• International Journal of Automotive Technology
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• v.5 no.3
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• pp.201-208
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• 2004

Response characteristics of the CVT system for a parallel hybrid electric vehicle (HEV) are investigated. From the experiment, CVT ratio control algorithm for the optimal engine operation is obtained. To investigate the effect of the CVT system dynamic characteristics on the HEV performance, a hardware in the loop simulation (HILS) is performed. In the HILS, hardwares of the CVT belt-pulley and hydraulic control valves are used. It is found that the engine performance by the open loop CVT ratio control shows some deviation from the OOL in spite of the RCVs open loop control ability. To improve the engine performance, a closed loop control of the CVT ratio is proposed with variable control gains depending on the shift direction and the CVT speed ratio range by considering the nonlinear characteristics of the RCV and CVT belt-pulley dynamics. The HILS results show that the engine performance is improved by the closed loop control showing the operation trajectory close to the OOL.

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.4
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• pp.129-138
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• 2004

In this paper, we propose a method to apply a decentralized control algorithm for passive velocity field control using virtual flywheel system to cooperative 3-wheeled mobile robots, and these subsystem are under nonholonomic constraints. The considered robotic systems convey a common rigid object in a horizontal plain. Moreover we will proof the passivity and robustness for cooperative mobile robotic systems with decentralized passive velocity field control. Finally, The effectiveness of proposed control algorithm is examined by numerical simulation for cooperation tasks with 3-wheeled mobile robot systems.