• Journal of Auto-vehicle Safety Association
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• v.15 no.2
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• pp.13-20
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• 2023

This paper presents a fault tolerant control strategy for Steer-by-Wire (SbW) systems. Among many problems to be solved before commercialization of SbW systems, maintaining reliability and fault tolerance in such systems are the most pressing issues. In most previous studies, dual steering motors are used to achieve actuation redundancy. However, relatively few studies have been conducted to introduce fault tolerant control strategies using rear wheel steering system. In this work, an actuator fault in front wheel steering is compensated by active rear wheel steering. The proposed fault tolerant control algorithm consists of disturbance observer and sliding mode control. The fault tolerant control performance of the proposed approach is validated via computer simulation studies with Carsim vehicle dynamics software and MATLAB/Simulink.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.1
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• pp.174-182
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• 2014

Recently, not only common types of hybrid electric vehicle (HEV) such as series or parallel but many other types of HEVs including 4WD hybrid electric vehicle have been developed and released. In this study, analysis of fuel economy and driving performance for 2WD and 4WD HEV are conducted using backward simulation based on dynamic programming. To analyze the characteristics of 4WD HEV, tire slip model based on vehicle dynamics was applied to the backward simulation program. As a result, 2WD HEV shows better fuel economy than 4WD HEV because of relatively simple configuration. However, in a severe road condition, 4WD HEV shows better driving performance that 2WD HEV had about 6% of impossible time to follow the driving cycle though the 4WD HEV had no impossible time.

• Transactions of the Korean Society of Automotive Engineers
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• v.2 no.5
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• pp.101-109
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• 1994

Recently, four-wheel steering systems have been developed and studied as one of the latest automotive technologies for improving the handling characteristics of a vehicle. In much of the proposed four-wheel steering systems, the side slip angle at the vehicle's center of gravity is maintained at zero. This approach allows the greater maneuverability at low speed by means of counter-phase rear steering and the improved stability at high speed through same-phase rear steering. In this paper, the effects of several four-wheel steering systems are studied and discussed on the responsiveness and stability of the vehicle by using the linear analysis. Especially, the effects of the cornering stiffnesses of both front and rear wheels are investigated on the yaw velocity gain and critical speed of the vehicle.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2642-2647
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• 2007

This study represents numerical study on the thermal and fluid flow characteristics of exhaust gas in a motorcycle muffler. The reference engine was used 124.cc small displacement. Numerical analysis with computational fluid dynamics(CFD) was carried out to investigate the exhaust gas that flow into a motorcycle muffler. The STAR-CD S/W used to three dimensional steady state CFD analysis in a muffler. And than We got the information of static pressure it is used to structural analysis ant the first baffle plate using the commercial CAE code ANSYS workbench. Exhaust gas flow third chamber from frist chamber and running second chamber. A simulation result shows that each chamber of muffler temperature is about 460 K, 445 and 463K and pressure is about 22,000 Pa, 16,000 Pa and 10,000 Pa.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.6
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• pp.137-142
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• 2006

This research represents the catalytic converter for application in the motorcycle. Present research model type is monolithic catalytic converter and this type have been widely used for satisfaction on and the regulations of pollutant emissions in automobiles. The flow characteristics in a single monolith automotive catalytic converter were investigated by using a computational simulation method without chemical reaction. So we limit the discussion to the effect of flow uniformity in the catalytic converter. Simulation result shows that the flow uniformity of megaphone type catalytic converter is higher than that of a base type. Therefore, the megaphone type is more suitable to motorcycle.

• Journal of Drive and Control
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• v.11 no.2
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• pp.16-21
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• 2014

The purpose of this paper is to construct a control algorithm for improving the driving efficiency of 4-wheel-drive in-wheel electric vehicles. The main parts of the vehicle were modeled and the input-output relations of signals were summarized using MATLAB/Simulink. A performance simulator for 4-wheel-drive in-wheel electric vehicles was developed based on the co-simulation environment with a commercial dynamic behavior analysis program called Carsim. Moreover, for improving the driving efficiency of vehicles, a torque distribution algorithm, which distributes the torque to the front and rear wheels, was included in the performance simulator. The effectiveness of the torque distribution algorithm was validated by the SOC simulation using the FTP-75 driving cycle.

• Journal of the korean Society of Automotive Engineers
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• v.12 no.3
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• pp.21-29
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• 1990

Equipments of passenger cars with modern technologies are gaining their importance. Related with such developments, the four-wheel steering system (4WS) was introduced recently to a few passenger cars in the market. The most important research goal on this new steering system is improvement of active safety, in other words, improvement of handling characteristics of vehicle stability and maneuverability. This paper presents a computer-based study about the effects of 4WS system on the vehicle handling characteristics. A simple bicycle model of 2 d.o.f. is used for the development of four wheel control algorithms of 4WS system, and the rear wheel control strategies are applied to a complex vehicle model of 16 d.o.f. for simulation of selected ISO-driving tests. The 4WS systems, which reduce the sideslip angle at the mass center of vehicle to almost zero, show much improved handling characteristics compared to that of the conventional 2WS system. These 4WS systems, however, result in vehicles with eigen-steer characteristics of extreme understeer behaviour.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.5
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• pp.138-144
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• 2006

This research represents the catalytic converter for application in the motorcycle. Present research model type is a monolithic catalytic converter and this type has been widely used for satisfaction on and the regulations of pollutant emissions in automobiles. The experiment range is found for light-off temperature time of the catalyst converter. And we has to experiment for effective area of catalytic monolith. The experimental result indicated an increase effective area in the catalytic monolith. Specialty, it was found from the result that the more positive effect from result of thermal image camera in the megaphone model. The rate of effective area for base model was about 8.97% and megaphone model was 41.52%, 34.60%, 33.43%, 25.43% and 17.82% on the diffuser angle $4^{\circ}$ to $8^{\circ}$. Comparing with base type, megaphone type has more suitable for application to motorcycle.

• Broadcasting and Media Magazine
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• v.24 no.1
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• pp.63-72
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• 2019

고령인구의 증대 및 출생 인구의 감소로 과소지와 대중교통 취약지역이 확산되고 있다. 이러한 인구구조의 변화는 교통약자의 독립적 이동이 더욱 불편해지고, 물류의 수송이 어려워 진다. 한편, 도심은 차량의 포화상태로 대기환경의 질이 나빠지고 도심도로는 주차장으로 변질될 뿐만 아니라, 운전자와 보행자 모두에게 안전의 위협이 되고 있다. 이러한 환경과 이동의 효율성을 극대화 하는 방안으로 친환경자동차와 자율주행기술의 접목이 연구개발 중이다. 자율주행기술은 자율주행차와 도로 인프라에 ICT가 융 복합되어 이동과 수송분야의 새로운 산업과 서비스 창출이 가능하다. 본 고에서는 교통약자의 이동과 물류의 수송을 지원하는 자율주행기술의 개발 동향을 살펴본다. 특히 광화문, K-City 등의 도심 자율주행서비스 테스트 경험을 통해 해결해야 하는 복잡한 도심 주행 환경의 인지와 교차로 및 합류로, 비정형 도로환경에서의 주행협상기술의 필요성을 소개한다. 도심의 주행 환경은 고속도로와 같은 자동차 전용도로와 달리, 신호등과 교차로, 2륜 이동체 및 버스 등이 다양하게 혼재된 것으로 인지 및 판단 기능의 고도화가 적극적으로 요구된다. 그리고, 다양한 자율주행서비스 시장을 확산하기 위해 요구되는 이동하는 공간과 시간을 메꿔 줄 미디어 콘텐츠의 역할에 대해 설명하고자 한다.

• Journal of the KSME
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• v.25 no.3
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• pp.198-203
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• 1985

제동시 균형 문제나 약간 무거운 조향력등의 전륜구동장치을 설계하기 위한 단점들은 Negative 또는 Zero scrub Radius 의 현가장치를 가능케 하는 이론적 기술적 보완 및 해결이 되고 또한 X형 브레이크 파이프 개발로 한 회로 파열에서도 더욱 안정된 제동을 할 수 있게 된다. 따라서 (1) 중. 소형 승용차에서 절대적 비중을 차지하고 있는 실내 유효공간을 훨씬 크게할 수 있는 점 (2) 후륜구동에 비해 손쉽고 갑싸게 4륜 독립 현가장치가 가능하기 때문에 승차감에서 탁월한 개선이 이루어 진다는 점 (3) 우수한 직진(방향) 안정성과 선회성능을 얻을 수 있는 점 (4) 경량화 및 전동(轉動) 손실 감소에 따른 연비 향상 등의 커다란 장점으로 전륜구동차는 기술적인 면에서 후륜구동차에 비하여 그 격을 달리하고 있으며 몇 년 전부터 모든 자동차 회사가 신규 설계 개발중인 차는 전륜구동차로 밝혀지고 있으며 사용자의 전륜구동차에 대한 선호도는 계속 크게 증가할 것으로 보인다.