• International Journal of Automotive Technology
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• 제7권2호
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• pp.179-185
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• 2006

Airbag deployment has been responsible for huge death, incidental injuries and broken bones due to low crash severity and wrong deployment decision. This misfortune has led the authorities and the industries to pursue uniquely designed airbags incorporating crash-sensing technologies. This paper provides a thorough discussion underlying crash sensing algorithm approaches for the subject matter. Unfortunately, most algorithms used for crash sensing still have some problems. They either deploy at low severity or fail to trigger the airbag on time. In this work, the crash-sensing algorithm is studied by analyzing the data obtained from the variables such as (i) change of velocity, (ii) speed of the vehicle and (iii) acceleration. The change of velocity is used to detect crash while speed of the vehicle provides relevant information for deployment decision. This paper also demonstrates crash severity with respect to the changing speed of the vehicle. Crash sensing simulations were carried out using Simulink, Stateflow, SimMechanics and Virtual Reality toolboxes. These toolboxes are also used to validate the results obtained from the simulated experiments of crash sensing, airbag deployment decision and its crash severity detection of the proposed system.

• 한국융합학회논문지
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• 제10권11호
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• pp.327-333
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• 2019

차량의 변속기어가 체결된 주행 상태에서 가속페달을 방치하는 경우 연료차단 주행이 시작된다. 적극적인 연료차단 주행을 활용하면 차량 연비가 개선된다. 본 연구에서는 차량의 속도, 가속도, 도로구배를 입력데이터로 사용하여 연료차단 주행 여부를 예측할 수 있는 딥러닝 기법을 제안하였다. 약 12km 정도의 도로주행을 통해 측정한 9600개의 데이터에 은닉층 3~10개, 매개변수 10~20개의 딥러닝 연산법을 적용하여 연료차단 주행여부를 예측하였다. 연산 결과, 렐루함수를 활성화함수로 적용하고 은닉층 7개, 매개변수 10개인 경우 정확도 84.5% 수준으로 예측할 수 있었다. 입력데이터인 속도, 가속도, 도로구배의 변화율이 연료소모율 데이터의 변화율에 비해 큰 것이 오차의 원인으로 판단된다. 따라서 입력데이터 정규화 과정을 통해 정확도를 높일 수 있을 것으로 예상된다. 본 연구의 특징은 차량의 연료분사 인젝터나 OBD 데이터를 사용하지 않고 GPS 등에서 쉽게 측정할 수 있는 데이터에 딥러닝을 적용한 방식이다. 또한 연산량이 적어 본 연구에서 제안한 방식으로 친환경 경제운전에 적용하기 용이할 것으로 기대된다.

• International Journal of Automotive Technology
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• 제8권1호
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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.

• 오토저널
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• 제13권1호
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• pp.35-45
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• 1991

A linear quarter model of a vehicle suspension system is built and simulated. Especially the so-called sensitivity analysis is conducted in order to show its applicability to design problems, and sensitivity function is determined in the frequency domain. The change of frequency response function is predicted, which depends on the design parameter variation and the property is verified by computer simulation. Typical performance measures, namely, sprung mass acceleration, suspension deflection, and tire deflection are examined. The vehicle model is analyzed for ist performance sensitivity as a function of the system's feedback gains. The variable feedback gains are selected as the spring and damping coefficients. Frequency response, RMS response, and performance index of the performance evaluation variables are considered and three-dimensional and contour plots of response surfaces are formed to examine output sensitivity to suspension feedback. Performance trade-offs over the entire frequency spectrum are identified from the FRF, and that between ride quality and handling characteristics are examined from the RMS responses.

• Journal of Mechanical Science and Technology
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• 제19권6호
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• pp.1253-1267
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• 2005

Misalignment can be an important problem in the integration of GPS/INS. Observability analysis of the alignment errors in the integration of low-grade inertial sensors and multi-antenna GPS is presented in this paper. A control-theoretic approach is adopted to study the observability of time-varying error dynamics models. The relationship between vehicle motions and the observability of the errors in the lever arm and relative attitude between GPS antenna array and IMU is given. It is shown that alignment errors can be made observable through maneuvering. The change of acceleration makes the components of the relative attitude error that are orthogonal to the direction of the acceleration change observable. The change of angular velocity makes the components of the lever arm error that are orthogonal to the direction of the angular velocity observable. The motion of constant angular velocity has no influence on the estimation of the lever arm.

• 대한기계학회논문집A
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• 제40권9호
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• pp.801-805
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• 2016

플러그인 하이브리드 전기자동차는 내연기관과 전기모터를 동력원으로 사용하며 주행 상황에 따라 다양한 주행 모드을 갖는다. 주행 모드에는 전기모터로만 주행하는 EV 모드(전기주행), 내연기관으로 주행하는 엔진 운전 모드, 두 개의 동력원을 이용하는 HEV 모드(하이브리드 주행)가 있다. 특히 병렬형 구조를 갖는 하이브리드 전기자동차는 모드변환에 따라 엔진 클러지가 접합되거나 해제되는데, 클러치 접합 시 나타나는 충격은 차량의 승차감에 영향을 주기 때문에 중요하다. 본 논문에서는 플러그인 하이브리드 전기자동차의 성능 시뮬레이터를 MATLAB/Simulink를 이용하여 개발하고, 시뮬레이션 결과를 통해 엔진 클러치 접합 시 나타나는 충격 특성을 분석하였다.

• 한국안전학회지
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• 제23권2호
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• pp.72-80
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• 2008

In a case of an automobile collision, vehicle damage and injury of the driver and the passenger occur. The scale of the collision which is effected by the extent of vehicle damage and the injury of the passenger, depends on the delta-V. Based on the photograph interpretation o the actual case of accidents in the Seoul and the Incheon area, this study measured the depth of crush and calculated the delta-V. Through verifying the correlation of the depth of crush and the change of velocity, relative equation was evaluated and compared with the prior study results to prove that they are almost identical. Thus, the depth of crush can be used as an index of the degree of impact, which can be utilized as the change of velocity to evaluate the level of injury done to the passengers. However, the period of hospitalization and diagnostics claimed by the injured proves to have no correlation with the delta-V and the extent of vehicle damage, this is due to the non-objective way of diagnosis and the anamnesis of the injured. This study established the absolute limit harmlessness and the choosing limit harmlessness, allowing the appraisal for Yes or No of the injury or the harmlessness based on the prior studies. Moreover, utilizing the relative equation formed between the depth of crush and the delta-V, each case of collision was compared and evaluated in comparison to the limit harmlessness to prove that the 90.4% of the so-called 'claiming-to-be-injured' were exaggerating or fabricating.

• 드라이브 ㆍ 컨트롤
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• 제15권4호
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• pp.74-80
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• 2018

A damper is a hydraulic device designed to absorb or eliminate shock impulses which is acting on the sprung mass of vehicle. It converting the kinetic energy of the shock into another form of energy, typically heat. In a vehicle, a damper reduce vibration of car, leading to improved ride comfort and running stability. Therefore, a damper is one of the most important components in a vehicle suspension system. Conventionally, the design process of vehicle suspensions has been based on trial and error approaches, where designers iteratively change the values of the design variables and reanalyze the system until acceptable design criteria are achieved. Therefore, the ability to tune a damper properly without trial and error is of great interest in suspension system design to reduce time and effort. For this reason, a many previous researches have been done on modeling and simulation of the damper. In this paper, we have conducted optimal design process to find optimal design parameters of damping force which minimize a acceleration of sprung mass for a given suspension system using genetic algorithm.

• International Journal of Automotive Technology
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• 제6권2호
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• pp.141-148
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• 2005

In order to reduce the time and costs of improving the performance of vehicle suspensions, the techniques for optimizing damping and air spring characteristic were proposed. A full vehicle model for a bus is constructed with a car body, front and rear suspension linkages, air springs, dampers, tires, and a steering system. An air spring and a damper are modeled with nonlinear characteristics using experimental data and a curve fitting technique. The objective function for ride quality is WRMS (Weighted RMS) of the power spectral density of the vertical acceleration at the driver's seat, middle seat and rear seat. The objective function for handling performance is the RMS (Root Mean Squares) of the roll angle, roll rate, yaw rate, and lateral acceleration at the center of gravity of a body during a lane change. The design variables are determined by damping coefficients, damping exponents and curve fitting parameters of air spring characteristic curves. The Taguchi method is used in order to investigate sensitivity of design variables. Since ride and handling performances are mutually conflicting characteristics, the validity of the developed optimum design procedure is demonstrated by comparing the trends of ride and handling performance indices with respect to the ratio of weighting factors. The global criterion method is proposed to obtain the solution of multi-objective optimization problem.

• 한국도로학회논문집
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• 제13권2호
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• pp.49-56
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• 2011

교통사고 원인분석 및 사고예방을 위해서는 교통사고 유발요인에 대한 이해가 필요하다. 기존 연구에서는 기하구조, 운전자 특성 등의 요인을 고려하여 연구를 진행하였다. 그러나, 운전자 특성요인 분석에 사용된 자료는 검지기에서 측정된 집계된 속도로써, 속도 변화량을 이용한 사고분석연구에는 한계가 존재한다. 따라서, 본 연구에서는 차량의 속도변화 등의 수집이 용이한 센서를 이용하여 자료를 수집하였다. 가속도자료 및 기하구조 특성을 나타내는 변수를 설정하고, 사고자료와 매칭을 통해 사고개연성이 높은 잠재적 변수로의 적합성을 평가하였다. T-test, 이항 로지스틱 회귀분석을 사용했으며, T-test 결과로써 도출된 변수를 이항 로지스틱 회귀분석의 독립변수에 적용하고, 사고발생 유 무를 종속변수로 설정하였다. 분석결과, 5개의 변수가 사고발생에 영향을 주는 변수로 도출되었다. 또한, 도출된 모형은 사고발생구간의 예측에 적용할 수 있는 타당성을 확보하는 것으로 분석되었다. 본 연구에서 도출된 위험 운전행태 변수 및 모형은 프로브차량에 설치하여 활용할 수 있는 장치 등에 적용시켜 사고위험도 및 안전성 평가에 활용할 수 있을 것으로 기대된다.