• Proceedings of the KIPE Conference
• /
• 2015.11a
• /
• pp.223-224
• /
• 2015

도시철도에서 사용하는 전력공급 장치는 대부분 다이오드를 이용하여 전차선(DC)에 공급하고 있으며, 다이오드 특성상 단방향 전력공급이 가능하기 때문에 전동차의 회생제동으로 발생하는 회생 전력을 재사용 할 수 없는 단점을 가지고 있다. 따라서 본 논문에서는 전동차에서 발생하는 회생전력을 교류 모선으로 환원시켜주기 위하여 사이리스터를 이용한 양방향 더블컨버터를 제안한다. 더블컨버터의 제어 목적은 전차선의 부하에 따라 전압을 일정하게 유지시키면서 부하 조건에 따라 안정적인 모드 전환을 하는 것이다. 이를 위하여 더블컨버터의 병렬로 운전을 통하여 순차적인 모드 전환을 위한 알고리즘을 더블컨버터 시뮬레이션을 적용하여 검증하였다.

• Journal of Auto-vehicle Safety Association
• /
• v.11 no.3
• /
• pp.19-29
• /
• 2019

Recently, autonomous vehicles have been studied actively. Autonomous vehicles can detect objects around them using their on board sensors, estimate collision probability and maneuver to avoid colliding with objects. Many algorithms are suggested to prevent collision avoidance. However there are limitations of complex and diverse environments because algorithm uses only the information of attached environmental sensors and mainly depends on TTC (time-to-Collision) parameter. In this paper, autonomous driving algorithm using I2V communication-based cooperative sensing information is developed to cope with complex and diverse environments through sensor fusion of objects information from infrastructure camera and object information from equipped sensors. The cooperative sensing based autonomous driving algorithm is implemented in autonomous shuttle bus and the proposed algorithm proved to be able to improve the autonomous navigation technology effectively.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.20 no.1
• /
• pp.1-7
• /
• 2012

The brake-by-wire technology is a new automotive chassis system that allows standard braking operations by electronic components with lighter weights and faster response. The brake-by-wire units such as EMB (Electro-Mechanical Brake) are controlled by electronic sensors and actuators and, thus, the fault diagnosis is essential for implementation. In this study, a model-based fault diagnosis system is developed for the sensors based on the analytical redundancy method. The fault detection algorithm is verified in simulations for various faulty cases. A test bench is built including the EMB unit and the performance of the proposed fault diagnosis system is evaluated through the experiment.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2002.05a
• /
• pp.233-237
• /
• 2002

Vehicle Dynamics Control(VDC) has been a breakthrough and become a new terminology for the safety of a driver and improvement of vehicle handling. This paper examines the usefulness of a brake steer system (BSS), which uses differential brake forces for steering intervention in the context of VDC. In order to help the car to turn, a yaw moment can be achieved by altering the left/light and front/rear brake distribution. The steering function achieved through BSS can then be used to control lateral position in an unintended road departure system. A 8-DOF non-linear vehicle model including STI tire model will be validated using the equations of motion of the vehicle, and the non-linear vehicle dynamics. Since Fuzzy logic can consider the nonlinear effect of vehicle modeling, Fuzzy controller is designed to explore BSS feasibility, by modifying the brake distribution through the control of the yaw rate of the vehicle. The control strategies developed will be tested by simulation of a variety of situation; the possibility of VDC using BSS is verified in this paper.

• Proceedings of the KIEE Conference
• /
• 2009.07a
• /
• pp.2221_2222
• /
• 2009

본 논문에서는 BLDC 운전 중 각 상의 결상 사고에 따른 토크 및 속도의 최적화에 대해 연구하였다. BLDC 모터의 구동을 위하여 ATmega16이 사용되었으며 제어기법으로는 PWM(Pulse Width Modulation) 기법이 사용된다. 속도 제어는 Hall Sensor의 검출 속도에 따라 Duty비를 제어하여 이루어지며 회전자 위치는 Hall Sensor 검출 방식을 통하여 이루어진다. 이러한 BLDC 모터를 이용하여 예기치 못한 결상 상황의 발생 시 토크의 감소로 인한 급제동에 대비하여 부하에 상응하는 토크를 최대한 낼 수 있도록 알고리즘을 구현하였다.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.17 no.1
• /
• pp.20-28
• /
• 1992

Co-articulation is one of major factors that make connected word recognition difficult. This Study Considers the fact that the head Part Of the following word is changed by the Preceding word in a connection point, by applying the co-articulation model, and adj usting the following word .We choose a critical damping second order linear system for the co-articulation model, combining a one-stage DP matching recognition algorithm with this model, and Investigating the effects. The recognition experiment is carried out for 35 Korean 4 connected digits spoken by 5 male speakers, and recognition rate Is upgraded by 4.7 percent.

• Journal of Auto-vehicle Safety Association
• /
• v.5 no.2
• /
• pp.17-23
• /
• 2013

This paper describes an algorithm for Advanced Emergency Braking(AEB) with tire-road friction coefficient estimation. The AEB is a system to avoid a collision or mitigate a collision impact by decelerating the car automatically when forward collision is imminent. Typical AEB system is operated by Time-to-collision(TTC), which considers only relative velocity and clearance from control vehicle to preceding vehicle. AEB operation by TTC has a limit that tire-road friction coefficient is not considered. In this paper, Tire-road friction coefficient is also considered to achieve more safe operation of AEB. Interacting Multiple Model method(IMM) is used for Tire-road friction coefficient estimation. The AEB algorithm consists of friction coefficient estimator and upper level controller and lower level controller. The numerical simulation has been conducted to demonstrate the control performance of the proposed AEB algorithm. The simulation study has been conducted with a closed-loop driver-controller-vehicle system using using MATLAB-Simulink software and CarSim Vehicle model.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.16 no.10
• /
• pp.6949-6958
• /
• 2015

Radio based train control system performs train safe interval control by receiving in realtime the position information of trains driving in the control area of the wayside system and providing onboard system in each train with updated movement authority. The performance of the train control system is evaluated to calculate the minimum operation headway, which reflects the operation characteristics and the characteristics of the train as well as the interval control performance of the train control system. In this paper, we propose the operation headway calculation for radio based train control system and a new train interval control algorithm to improve the operation headway. The proposed headway calculation defines line headway and station headway by the estimation the safety margin distance reflecting the performance of the train control system. Furthermore the proposed Enhanced Train Interval Control(ETIC) algorithm defines a new movement authority including both distance and speed, and improves the train operation headway by using braking distance occurring inevitably in the preceding train. The proposed operation headway calculation is simulated with Korean Radio-based Train Control System(KRTCS) and the simulated result is compared to improved train interval control algorithm. According to the simulated results, the proposed operation headway calculation can be used as performance indicator for radio based train control system, and the improved train control algorithm can improve the line and station headway of the conventional radio based train control system.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.10 no.2
• /
• pp.392-397
• /
• 2006

This paper proposed yaw moment control scheme using braking and active rear wheel steering for improving driving stability especially in high speed driving. Its characteristics the unified chassis control system of two equipment that 4WS(4 Wheel Steering) and ESP(Electronic Stability Program). in this study the performance of the vehicle was compared each equipment. And conventional ABS and TCS can only possible to control the longitudinal movement of braking equipment and drive which can only available to control of longitudinal direction. There after new braking system ESP was developed, which controls both of longitudinal and lateral, with adding of the function of controlling Active Yaw Moment. On this paper, we show about not only designing of improved braking and steering system through establishing of the integrated control system design of 4WS and ESP but also designing of the system contribute to precautious for advanced vehicle stability problem.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.21 no.1
• /
• pp.240-257
• /
• 2022

Autonomous vehicles use various local sensors such as camera, radar, and lidar to perceive the surrounding environment. However, it is difficult to predict the movement of vulnerable road users using only local sensors that are subject to limits in cognitive range. This is true especially when these users are blocked from view by obstacles. Hence, this paper developed an algorithm for collision avoidance with VRU using V2X information. The main purpose of this collision avoidance system is to overcome the limitations of the local sensors. The algorithm first evaluates the risk of collision, based on the current driving condition and the V2X information of the VRU. Subsequently, the algorithm takes one of four evasive actions; steering, braking, steering after braking, and braking after steering. A simulation was performed under various conditions. The results of the simulation confirmed that the algorithm could significantly improve the performance of the collision avoidance system while securing vehicle stability during evasive maneuvers.