• 한국자동차공학회논문집
• /
• 제6권2호
• /
• pp.1-11
• /
• 1998

The 4WS system is usually developed to improve the maneuverability at low speed and the straight line stability at high speed, but it is found to have the severe understeer characteristics at high speed. Therefore a 4WS vehicle requires to turn the steering wheel much more than a 2WS vehicle at high speeds even a driver goes through the same curved road. In this study, to enhance the cornering performance of the 4WS vehicle at high speed, a DYC 4WS system is proposed based on the nonlinear 4WS system and direct yaw moment control system. Especially the proposed DYC 4WS system is able to realize a zero side slip angle for vehicles and a cornering performance similar to the 2WS vehicle at high speed.

• 한국전산유체공학회:학술대회논문집
• /
• 한국전산유체공학회 2004년도 춘계 학술대회논문집
• /
• pp.17-22
• /
• 2004

A space launch vehicle departs the ground in a low speed, soon reaches a transonic and a supersonic speed, and then flies in a hypersonic speed into the space. Therefore, the design of a launch vehicle should include the prediction of aerodynamic characteristics for all speed regimes, ranging from subsonic to hypersonic speed. Generally, Empirical and analytical methods and wind tunnel tests are used for the prediction of aerodynamic characteristics. This research presents considerable factors for aerodynamic analysis of a launch vehicle using CFD. This investigation was conducted to determine effects of wake over the base section on the aerodynamic characteristics of a launch vehicle and also performed to determine effects of the sting which exist to support wind tunnel test model.

• 대한의용생체공학회:의공학회지
• /
• 제38권1호
• /
• pp.32-42
• /
• 2017

The aim of this study was to evaluate driving performance of Healthy and disabled groups (with or without driver's license) to control steering wheel by using steering assistive devices in the driving simulator. The persons with partial loss of use of all four limbs have problems in operation of the motor vehicle because of functional loss to operate steering wheel. Therefore, if steering assistive devices for grasping the steering wheel are used to control the vehicle on the road in persons with disabilities, the disabled persons can improve mobility in their community life by driving a motor vehicle safely. Ten healthy subjects (with or w/o driver's license) and ten subjects with physical disabilities (with or w/o driver's license) were involved in this study to evaluate driving performance to operate steering wheel by using four types of steering assistive devices (Single-pin, V-grip, Palm-grip, Tri-pin) in driving simulator. STISim Drive 3 software was used to test the steering performance in four scenarios: straight road at low and high speed of vehicle (40 km/h and 80 km/h), curved road at low and high speed of vehicle (40 km/h and 80 km/h). This study used two-way ANOVA in order to compare the effects of two factors (type of steering assistive device and subject group) in the three dependent variables of driving performance (the lateral position of vehicle, standard deviation of lateral position representing the variation of the left and right movement of the vehicle and the number of line crossing). The mean values of the three dependent variables (lateral position, standard deviation of lateral position, the number of line crossing) of steering performance were statistically significantly smaller for the healthy or disabled groups with driver's license than the other groups without driver's license on the curved road at high speed of vehicle compared to low speed of vehicle.

• 전기학회논문지
• /
• 제61권4호
• /
• pp.549-554
• /
• 2012

Noncontactable joystick for a low speed electric vehicle(LSEV) is developed. The joystick is proposed to replaced the steering wheel in a conventional LSEV. The main advantages of the proposed joystick are a durable and a stable in structure, simple and easy to control through discriminating the driving and braking area. To reduce error and stability in the joystick control, input and output signal of the joystick are manipulated by data averaging and differntiation. With this algorithm, the driving resolution and capability are improved. To verify the proposed algorithm, a simple prototype model which has two electric motors for propulsion and steering are used. Test results show that the prototype joystick control system is applicable to an LSEV dirve.

• 자동차안전학회지
• /
• 제14권4호
• /
• pp.6-15
• /
• 2022

In this study, a traffic light recognition algorithm was implemented and validated for low-speed special purpose vehicles in an urban environment. Real-time image data using a camera and YOLO algorithm were applied. Two methods were presented to increase the accuracy of the traffic light recognition algorithm, and it was confirmed that the second method had the higher accuracy according to the traffic light type. In addition, it was confirmed that the optimal YOLO algorithm was YOLO v5m, which has over 98% mAP values and higher efficiency. In the future, it is thought that the traffic light recognition algorithm can be used as a dual system to secure the platform safety in the traffic information error of C-ITS.

• 한국자동차공학회논문집
• /
• 제14권5호
• /
• pp.17-24
• /
• 2006

Anti-lock brake system(ABS) are designed to prevent wheel lock on all wheels of the vehicle by sensing wheel angular speed, processing the speed sensor signals in suitable digital electronic control circuits and comanding electrohydraulic actuators to control brake pressure. This study considers a control of ABS using wheel circumferential acceleration thresholds which avoids dangerous wheel locking due to excessive brake pressure during the vehicle braking and discusses the 3-channels, 3-sensors ABS system that employs "independent control" technique for the front wheels and "select low" technique for the rear wheels. The validities of the ABS such as vehicle stability, steerability and stopping distance during braking are assured through the vehicle tests on uniform asphalt straight roads.

• 한국도로학회논문집
• /
• 제11권1호
• /
• pp.59-67
• /
• 2009

센싱 기술의 발달로 다양한 종류의 매체를 이용한 우수한 차량 검지장비들이 개발되고 있는 요즘, 간단한 구조의 저가형 검지장비 또한 적은 예산으로 여러 곳에 설치할 수 있다는 장점 때문에 지속적인 연구가 이루어지고 있다. 본 연구에서는 저가형 차량 검지장비로서 센서를 사선으로 설치하여 좌우 및 전후 바퀴의 통과시간 간격과 차량의 윤거값을 적용하여 차량속도를 추정하는 방법을 제안하였다. 출고된 차량의 제원조사에서 얻어진 대표 윤거값을 축거와 뒤윤거의 비율에 따라 소형과 대형 차량으로 구분하여 적용하므로 기존의 연구보다 정확한 속도추정이 가능하도록 개선하였다. 특히, 소형과 대형차량을 구분하는 파라미터를 통하여 조사지점의 차종구성 비율을 고려한 정확도 보정이 가능하다. 간단하고 저가로 개발된 본 연구의 사선형 센서를 이용한 검지장비는 적은 비용으로 교통상황을 설명하는데 효율적으로 활용될 것으로 기대된다.

• 디지털융복합연구
• /
• 제16권9호
• /
• pp.173-178
• /
• 2018

에어백이 작동되는 중고속 추돌 사고의 경우 에어백 작동 전후의 차량 데이터가 차량의 EDM(Event Driven Memory)에 저장되어 그 추돌 속도를 쉽게 알 수 있다. 하지만 에어백이 작동하지 않는 저속영역에서 추돌하는 경우 그 속도를 산정하기가 어렵다. 또한 저속이라 하더라도 추돌속도에 따라 운전자의 부상 정도가 크게 영향을 받기 때문에 그 속도의 산정이 중요하다. 본 연구에서는 블랙박스에 저장된 영상 이미지를 분석하여 저속영역의 추돌속도를 연산하는 알고리즘을 제안하였다. 전기모터로 와이어로프를 이용하여 차량을 견인하는 방식으로 저속의 후방추돌 상황을 정확하게 재현하면서 다양한 차종과 속도에 대해 실험을 수행하였다. 이 때 블랙박스의 영상 이미지에서 두 차량의 거리가 좁아지는 비율과 전방 차량의 번호판 길이가 증가하는 비율이 동일함을 이용하여 추돌속도를 정밀하게 계산할 수 있다. 즉, 미리 측정된 초기거리와 블랙박스의 영상에서의 번호판의 길이를 초기조건으로 설정하여 본 연구의 계산 알고리즘을 적용하면 저속 추돌 속도를 정확하게 산정할 수 있다. 직선 추돌사고에는 본 연구의 결과가 그대로 적용되지만 각도를 두고 추돌하는 경우에는 별도의 고려가 필요하다.

• 자동차안전학회지
• /
• 제10권2호
• /
• pp.6-12
• /
• 2018

Optimized section shape of aluminum bumper backbeam for enhancing the front high speed crashworthiness was investigated. Front body analysis model of a convertible vehicle was built up and parameter studies were carried out with changing the inner rib shape and the section thickness distribution. First an inner rib shape displaying most efficient structural performance was selected. Next, for the selected section the effect of section thickness combination was examined. Also, a light weighed backbeam section displaying crash performance over the current design was suggested. Finally RCAR front low speed impact analyses were carried out for the optimized models.

• 한국자동차공학회논문집
• /
• 제12권4호
• /
• pp.191-197
• /
• 2004

This paper presents experimental results for human drivers' driving patterns and an Adaptive Cruise Control(ACC) strategy. Analyses have shown that female drivers' driving characteristic values such as time-gap and minimum clearance are larger than those of male drivers'. Human drivers tend to have more clearance margins at high speed than at low speed. At low speed, drivers are much more sensitive to the desired clearance than at high speed. A multi-vehicle detection method is presented to improve ride quality of an ACC. Simulation results have shown that the proposed ACC can provide superior performance compared to the ACC strategy which uses a single-vehicle detection method.