• 제목/요약/키워드: Car-following model

검색결과 73건 처리시간 0.029초

다양한 연속 교통류 구현을 위한 확률파장전파모형의 개발 (A Study on Stochastic Wave Propagation Model to Generate Various Uninterrupted Traffic Flows)

  • 장현호;백승걸;박재범
    • 대한교통학회지
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    • 제22권4호
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    • pp.147-158
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    • 2004
  • SWP(Stochastic Wave Propagation: 확률파장전파) 모형은 Cellular Automata(CA) 이론을 기반으로한 간략한 차량모형을 이용하여 개별차량의 확률적 형태와 혼잡의 전파를 모사하고, 통계물리학을 기반으로 교통류를 거시적으로 해석한다. SWP모형은 이산적 시공간 구조와 정수형 자료를 이용한 프로그램 지향적 모형구조를 가지며 연산수행속도가 빨라 대규모 가로망의 실시간 시뮬레이션을 가능하게 하였다. 그러나 비현실적인 충돌회피과정으로 인한 자연발생적 혼잡(Spontaneous jam)의 형성 때문에 미시적으로는 혼잡내에서 잠금현상(Lockup)이 발생하여 혼잡내 차량의 저속을 설명할 수 없고, 거시적으로는 혼잡의 밀도와 전파속도를 설명하기 어렵다는 한계를 가지고 있다. 본 연구에서는 비현실적인 차량의 정지과정을 보다 현실적으로 모사하기 위한 정지조작규칙(SMR: Stopping Maneuver Rule)과 혼잡내에서 차량의 낮은 가속을 설명하기 위한 저가속규칙(LAR: Low Acceleration Rule)을 기존의 SWP모형인 NaSch모형에 추가하였다. 이를 통해 미시적으로 보다 현실적인 차량의 정지과정을 모사하면서 혼잡내에서 잠금현상을 방지하고, 거시적으로 혼잡의 밀도와 전파속도를 설명함으로써 보다 다양하게 연속 교통류를 구현하는 모형을 구축하였다.

QFT 기법을 이용한 승용디젤엔진 공연비 제어 알고리즘 설계 연구 (Robust Air-to-fuel Ratio Control Algorithm of Passenger Car Diesel Engines Using Quantitative Feedback Theory)

  • 박인석;홍승우;신재욱;선우명호
    • 한국자동차공학회논문집
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    • 제21권3호
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    • pp.88-97
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    • 2013
  • This paper presents a robust air-to-fuel ratio (AFR) control algorithm for managing exhaust gas recirculation (EGR) systems. In order to handle production tolerance, deterioration and parameter-varying characteristics of the EGR system, quantitative feedback theory (QFT) is applied for designing the robust AFR control algorithm. A plant model of EGR system is approximated by the first order transfer function plus time-delay (FOPTD) model. EGR valve position and AFR of exhaust gas are used as input/output variables of the plant model. Through engine experiments, parameter uncertainty of the plant model is identified in a fixed engine operating point. Requirement specifications of robust stability and reference tracking performance are defined and these are fulfilled by the following steps: during loop shaping process, a PID controller is designed by using a nominal loop transmission function represented on Nichols chart. Then, the frequency response of closed-loop transfer function is used for designing a prefilter. It is validated that the proposed QFT-based AFR control algorithm successfully satisfy the requirements through experiments of various engine operating points.

자율주행자동차의 안전한 차량 추종을 위한 RSS 모형의 안전거리 비교 (Comparison of RSS Safety Distance for Safe Vehicle Following of Autonomous Vehicles)

  • 박성호;박상민;홍윤석;류승규;윤일수
    • 한국ITS학회 논문지
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    • 제17권6호
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    • pp.84-95
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    • 2018
  • 자율주행 과실 여부 판단 위한 방법으로 수학적인 모형인 responsibility-sensitive safety(RSS)를 제시된 이후로 자율주행 관련 산업으로부터 많은 관심을 받고 있다. 하지만, 이러한 수학적 모형이 자율주행자동차가 관련된 교통사고 발생 시 책임소재를 명확히 하는 데 활용될 수 있는 지에 대한 종합적인 검토는 부족한 실정이다. 본 연구에서는 RSS 모형의 적용성과 활용을 위해서 추가적으로 해결되어야 할 사항에 대하여 분석하였다. 결론적으로 RSS 모형을 활용하기에는 모형식 자체 및 수용성 등에 한계가 있으며, RSS 모형을 실무적으로 사용하려고 한다면 자율주행자동차의 반응시간을 정의하고, 자율주행자동차별로 적절한 기술수준에 따라서 반응시간 값을 측정하고 관리할 필요가 있는 것으로 판단된다.

종방향 자율주행의 미지 고장 재건을 위한 순환 최소 자승 기반 적응형 슬라이딩 모드 관측기 개발 (Development of a RLS based Adaptive Sliding Mode Observer for Unknown Fault Reconstruction of Longitudinal Autonomous Driving)

  • 오세찬;송태준;이종민;오광석;이경수
    • 자동차안전학회지
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    • 제13권1호
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    • pp.14-25
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    • 2021
  • This paper presents a RLS based adaptive sliding mode observer (A-SMO) for unknown fault reconstruction in longitudinal autonomous driving. Securing the functional safety of autonomous vehicles from unexpected faults of sensors is essential for avoidance of fatal accidents. Because the magnitude and type of the faults cannot be known exactly, the RLS based A-SMO for unknown acceleration fault reconstruction has been designed with relationship function in this study. It is assumed that longitudinal acceleration of preceding vehicle can be obtained by using the V2V (Vehicle to Vehicle) communication. The kinematic model that represents relative relation between subject and preceding vehicles has been used for fault reconstruction. In order to reconstruct fault signal in acceleration, the magnitude of the injection term has been adjusted by adaptation rule designed based on MIT rule. The proposed A-SMO in this study was developed in Matlab/Simulink environment. Performance evaluation has been conducted using the commercial software (CarMaker) with car-following scenario and evaluation results show that maximum reconstruction error ratios exist within range of ±10%.

수입자동차 리콜 수요패턴 분석과 ARIMA 수요 예측모형의 적용 (Analysis of the Recall Demand Pattern of Imported Cars and Application of ARIMA Demand Forecasting Model)

  • 정상천;박소현;김승철
    • 산업경영시스템학회지
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    • 제43권4호
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    • pp.93-106
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    • 2020
  • This research explores how imported automobile companies can develop their strategies to improve the outcome of their recalls. For this, the researchers analyzed patterns of recall demand, classified recall types based on the demand patterns and examined response strategies, considering plans on how to procure parts and induce customers to visit workshops, recall execution capacity and costs. As a result, recalls are classified into four types: U-type, reverse U-type, L- type and reverse L-type. Also, as determinants of the types, the following factors are further categorized into four types and 12 sub-types of recalls: the height of maximum demand, which indicates the volatility of recall demand; the number of peaks, which are the patterns of demand variations; and the tail length of the demand curve, which indicates the speed of recalls. The classification resulted in the following: L-type, or customer-driven recall, is the most common type of recalls, taking up 25 out of the total 36 cases, followed by five U-type, four reverse L-type, and two reverse U-type cases. Prior studies show that the types of recalls are determined by factors influencing recall execution rates: severity, the number of cars to be recalled, recall execution rate, government policies, time since model launch, and recall costs, etc. As a component demand forecast model for automobile recalls, this study estimated the ARIMA model. ARIMA models were shown in three models: ARIMA (1,0,0), ARIMA (0,0,1) and ARIMA (0,0,0). These all three ARIMA models appear to be significant for all recall patterns, indicating that the ARIMA model is very valid as a predictive model for car recall patterns. Based on the classification of recall types, we drew some strategic implications for recall response according to types of recalls. The conclusion section of this research suggests the implications for several aspects: how to improve the recall outcome (execution rate), customer satisfaction, brand image, recall costs, and response to the regulatory authority.

충돌회피를 위한 가속도를 고려한 차선 변경 시스템 개발 (Development of Lane Change System considering Acceleration for Collision Avoidance)

  • 강현구;이동휘;허건수
    • 한국자동차공학회논문집
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    • 제21권2호
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    • pp.81-86
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    • 2013
  • This paper presents the lane change system for collision avoidance. The proposed algorithm for the collision avoidance consists of path generation and path following. Using a calculated TTC (Time to Collision), partial braking is operated and collision avoidance path is generated considering relative distance, velocity and acceleration. Based on the collision avoidance path, desired yaw angle and yaw rate are calculated for the automated path following. The lateral controller is designed by a Lyapunov function approach using 3 D.O.F vehicle model and vehicle parameters. The required steering angle is determined from wheel velocity, longitudinal and lateral velocity in order to follow the desired yaw angle and yaw rate. This system is developed MATLAB/Simulink and its performance is evaluated using the commercial software CarSim.

더블허들 모형을 이용한 전통시장 재방문객의 농산물 구입결정 요인에 관한 연구 (A Study on Purchasing Agricultural Products of Re-visitors In Traditional Market Using Double Hurdle Model)

  • 이향미
    • 농촌계획
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    • 제21권2호
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    • pp.137-147
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    • 2015
  • In this study, consumers who have experience of visiting Jeongsun Arirang Market has been selected as samples to understand the characteristics of agricultural products purchase. For this, double hurdle model was used in order to resolve sample selection problem and obtain consistent estimator. The key points are the following. First, as the age increases(up to 59.8 years), chances of purchasing the products at traditional market increase as income increases. Second, when the residence area is outside of Gangwon-province, the purchase amount of the products increased compared to those from visitors within the Gangwon province. Also, visitors who use public transportations purchase less products compared to those who use their own car. Third, probability of agricultural products increase as the visitors consider positive effect the product purchase leads to the local farmers. Fourth, if the visitors consider the quality of the agricultural products, probability of purchasing agricultural product at the site increases. However, if the visitors consider the freshness of the agricultural products, the purchase amount rather drops. Fifth, the probability of purchase increases as visitors consider the brand of traditional market.

Dental Serveyor의 사용법에 관한 연구(I) (A Study on the Usage of Dental Serveyor(I))

  • 김원수
    • 대한치과기공학회지
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    • 제15권1호
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    • pp.63-72
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    • 1993
  • The following results were come out after the careful study on the rational application of dental surveyor in the clinic 1. The adequate path of placement satisfying guiding plane, retention non-interference and esthetics. 2. The location of clasp arm and the accurate under cut position and amount of clasp tip can be judged. 3. In case that the model needs to be mounted to the surveyor, the exactly same location can be attained by the means of the tripoding. 4. The unnecessary undercut areas in the path of placement and removal car be corrected. 5. The surveyor is essential in manufacturing dental prosthesis and it can also carry out all sorts of prospective designs In terms of the diagnosis and treatment.

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철도안전법 시행지침 16조의 충격가속도 평가를 위한 객차의 데이터 필터링 연구 (Study on the Collision Acceleration Data Filtering of the Passenger Trailer for the Article 16 of the Rolling Stock Crashworthiness Regulations)

  • 조현직;김운곤;구정서;송달호
    • 한국철도학회:학술대회논문집
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    • 한국철도학회 2008년도 춘계학술대회 논문집
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    • pp.820-825
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    • 2008
  • In the article 16 of the domestic rolling stock crashworthiness regulations, the collision acceleration level during collision accidents should remain under the maximum 7.5g and the average 5g. By the way, the accelerations obtained in crash simulations and tests contain many kinds of high frequency components due to numerical oscillations or noisy signals. So, this paper aims to develop reliable post-processing methods to filter high frequency oscillations and extract the rigid body motions of passenger rail cars. For this study we used the 1-dimensional dynamic model of KHST (Korean high-speed train), and evaluated acceleration data at the driver's area in the first power car and the passenger area in the following trailer.

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A Systolic Parallel Simulation System for Dynamic Traffic Assignment : SPSS-DTA

  • Park, Kwang-Ho;Kim, Won-Kyu
    • 지능정보연구
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    • 제6권1호
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    • pp.113-128
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    • 2000
  • This paper presents a first year report of an ongoing multi-year project to develop a systolic parallel simulation system for dynamic traffic assignment. The fundamental approach to the simulation is systolic parallel processing based on autonomous agent modeling. Agents continuously act on their own initiatives and access to database to get the status of the simulation world. Various agents are defined in order to populate the simulation world. In particular existing modls and algorithm were incorporated in designing the behavior of relevant agents such as car-following model headway distribution Frank-Wolf algorithm and so on. Simulation is based on predetermined routes between centroids that are computed off-line by a conventional optimal path-finding algorithm. Iterating the cycles of optimization-then-simulation the proposed system will provide a realistic and valuable traffic assignment. Gangnum-Gu district in Seoul is selected for the target are for the modeling. It is expected that realtime traffic assignment services can be provided on the internet within 3 years.

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