• KSII Transactions on Internet and Information Systems (TIIS)
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• 제14권2호
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• pp.610-630
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• 2020

A large number of people suffered from traffic accidents each year, so people pay more attention to traffic safety. However, the traditional methods use laser sensors to calculate the vehicle distance at a very high cost. In this paper, we propose a method based on deep learning to calculate the vehicle distance with a monocular camera. Our method is inexpensive and quite convenient to deploy on the mobile platforms. This paper makes two contributions. First, based on Light-Head RCNN, we propose a new vehicle detection framework called Light-Car Detection which can be used on the mobile platforms. Second, the planar homography of projective geometry is used to calculate the distance between the camera and the vehicles ahead. The results show that our detection system achieves 13FPS detection speed and 60.0% mAP on the Adreno 530 GPU of Samsung Galaxy S7, while only requires 7.1MB of storage space. Compared with the methods existed, the proposed method achieves a better performance.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 춘계학술대회 논문집
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• pp.99-108
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• 2007

The bi-modal tram guided by the magnetic guidance system has two car-bodies and three axles. Each axle of the vehicle has an independent suspension to lower the floor of the car and improve ride quality. The turning radius of the vehicle may increase as a consequence of the long wheel base. Therefore, the vehicle is equipped with the All-Wheel-Steering(AWS) system for safe driving on a curved road. Front and rear axles should be steered in opposite directions, which means a negative mode, to minimize the turning radius. On the other hand, they also should be steered in the same direction, which means a positive mode, for the stopping mode. Moreover, only the front axle is steered for stability of the vehicle upon high-speed driving. In summary, steering angles and directions of the each axle should be changed according to the driving environment and steering mode. This paper proposes an appropriate AWS control algorithm for stable driving of the bi-modal tram. Furthermore, a multi-body model of the vehicle is simulated to verify the suitability of the algorithm. This model can also analyze the different dynamic characteristics between 2WS and AWS.

• 전기학회논문지
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• 제62권2호
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• pp.196-200
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• 2013

In this paper, the design of PRT vehicle power supply system is discussed. Since there is no power feeding line facilities in PRT system under development, the PRT vehicle must have its own energy storage device on board. For the energy storage device, ultra-capacitor bank is applied due to its fast charging capability and long life time. Charging the Ultra-capacitor bank is performed by wireless inductive power transfer system. The capacitor bank is charged up in less than 10 seconds when the vehicle is traveling by passenger stations. In this paper the design of the ultra-capacitor bank and the wireless inductive power transfer system for the PRT vehicle are discussed. Tests are conducted for the both system and the result shows the efficiency of the wireless inductive power transfer system is higher than 80%.

• 한국분무공학회지
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• 제23권4호
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• pp.234-243
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• 2018

Since September 2017, a small diesel vehicle certification test mode has been enhanced from NEDC to WLTC. The main reason for the change of the certification test mode is that the certification test mode of the emission control standard of the diesel vehicle does not sufficiently reflect various driving patterns of the actual roads. Several automakers have developed after-treatment systems such as LNT, SCR, and DPF to meet enhanced emissions regulations. In this study, four small diesel cars were selected for sale in Korea, and the exhaust gas measurement test was performed in the WLTC mode, which reflects the driving characteristics of the actual roads. As a result of test, LNT vehicle exceeded Euro 6 NOx regulation and SCR vehicle satisfied Euro 6 NOx regulation. In addition, both LNT and SCR systems showed high NOX emission characteristics due to speed, RPA and Vxa. For the PN, all test vehicles were fitted with a DPF and met the Euro 6 PN regulations, with similar PN emissions results in LNT and SCR system.

• 한국산학기술학회논문지
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• 제19권11호
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• pp.529-535
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• 2018

레인지 익스텐더 전기자동차는 소형의 발전용 엔진이 가장 효율이 좋은 특정 운전영역에서 기동하여 배터리를 충전시키며 주행거리를 연장하는 메커니즘으로 주행한다. 본 연구에서는 저가이면서 제어 로직이 간단한 시스템을 개발하기 위하여 기존 쓰로틀바디시스템을 대체하는 스텝모터방식 흡입공기량 공급시스템을 개발하여 기존 base 엔진에 적용하고, 흡입공기량 증대를 통한 성능 개선을 위해 흡 배기다기관의 길이 변경 효과를 실험적으로 살펴보았다. 실험결과, 하나의 스텝모터로 작동하는 Type B의 흡입공기량조절장치가 Type A보다 전 운전영역에서 성능이 높았으나 유동저항의 증가로 base 엔진보다는 성능이 낮았다. 이를 개선하기 위해 흡기매니폴드에 140mm 어댑터를 장착한 경우와 새로 설계된 70mm 길이의 배기 매니폴드를 적용한 경우 2200rpm과 4300rpm 두 속도조건에서 엔진성능이 향상됨을 확인할 수 있었다. 최적 설계된 엔진을 대상으로 레인지 익스텐더 전기자동차에 적용 가능하도록 발전기 부하를 연결하여 2단 속도로 고정밀 운전제어를 구현하였으며 그 결과, 1단 2200rpm과 2단 4300rpm 운전조건에서 ${\pm}2.5%$ 이내의 속도변화율을 나타내었고, 1단 속도에서 2단 속도로 상승 시 610rpm/s의 목표속도 추종성 결과를 얻었다.

• 한국철도학회논문집
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• 제15권4호
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• pp.343-351
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• 2012

차세대 고속열차(HEMU-430X)는 연구 지원과 많은 연구 기관의 노력으로 다년간 개발 중인 한국형 고속열차이다. 열차 모델을 다물체 동역학 해석 모델로 개발하여 차량-궤도 안전성 해석을 수행하였다. 이를 통해 국제 철도 안전 기준인 UIC code 518 OR에 따라 탈선 평가와 횡압의 제한 값을 확인하였다. 국제 기준에 따른 안전성 평가를 통하여 앞으로 본선 운전에 필요한 안전 확보 기본 자료를 생성하였으며 최고 속도에서의 안전성을 확인하였다.

• 한국산학기술학회논문지
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• 제14권9호
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• pp.4149-4155
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• 2013

더 빠른 절삭속도와 이송속도를 위한 고속가공은 표면품위와 재료제거율의 증가를 초래한다. 이 논문은 고속가공을 위한 정면밀링커터를 사용한 가공에서 획득된 진동특성에 관한 절삭조건의 영향을 연구하였다. 이 논문에서, 직교배열 테이블에 기초한 다구찌 실험계획법은 고속 정면밀링커터를 사용한 진동특성을 연구하기 위해 적용되었다. 실험조건은 직교배열 $L_{27}(3^{13})$ 을 사용하였다. 실험의 계획과 분석은 S/N비(신호 대 잡음비)와 분산분석을 이용하여 진동에 관한 절삭조건의 영향을 연구하기 위해 수행되었다. 절삭 파라미터 즉 이송속도, 챔퍼길이, 절삭속도 그리고 절삭깊이는 진동 특성치를 고려하여 최적화 되었다.

• 대한교통학회지
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• 제26권3호
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• pp.85-95
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• 2008

고속도로 교통사고 발생의 주요 원인인 과속을 줄이기 위하여 경찰청에서는 많은 예산을 들여 과속단속카메라를 설치 운영하고 있다. 지점식 과속단속카메라의 경우 GPS 탑재장치에 의해 위치가 노출되어 과속단속 실적이 떨어지며, 과속단속카메라가 설치되지 않은 차로나 구간에서 캥거루 주행 등 회피거동에 의해 과속억제 효과 또한 감소하고 있다. 운전자의 회피거동으로 인하여 긴 내리막 구간, 터널, 교량 등에서 과속예방효과나 교통사고 감소효과는 제한적일 수밖에 없다. 따라서 중요 시설이나 위험구간에서 차량들의 속도를 일정하게 유지시켜 교통사고 예방효과를 높이기 위한 대안으로 구간과속단속의 필요성이 높아지고 있다. 따라서, 본 연구에서는 우리나라 고속도로에 최초로 도입된 구간과속단속시스템의 효과평가를 위하여 시스템 적용 전 후 교통류특성과 관련된 자료를 수집하여 비교.분석하였고, 그 결과, 시스템 설치 후 속도저감 효과 및 해당 구간의 교통류 안정적 흐름을 보이는 것으로 나타나 구간과속단속 운영구간에 있어서 교통안전성 제고와 교통사고 감소효과가 있는 것으로 파악되었다.

• 한국도로학회논문집
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• 제14권6호
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• pp.183-190
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• 2012

PURPOSES : The fundamental diagram provides basic information necessary in the analysis of traffic flow and highway operation. When traffic flow is congested, the density-flow points in the fundamental diagram are widely scattered and move in a stochastic manner. This paper investigates the pattern of density-flow point transitions and identifies car-following behaviors underlying the density-flow transitions. METHODS : From a microscopic analysis of 722 fundamental diagrams of NGSIM data, a total of 20 transition patterns of fundamental diagrams are identified. Prominent features of the transition patterns are explained by the behavior of the leader and follower. RESULTS : It is found out that the average speed and the speed difference between the leader and the follower critically determine the density-flow transition pattern. The density-flow path is very sensitive to the values of vehicle speed and spacing especially at low speed and high density such that most fluctuations in the fundamental diagram in the congested regime is due to the noise of speed and spacing variations. CONCLUSIONS : The result of this study suggests that the average speed, the speed difference between the leader and the follower, and the random variations of speed and spacing are dominant factors that explain the transition patterns of a fundamental diagram.

• Environmental Engineering Research
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• 제25권3호
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• pp.366-373
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• 2020

The autonomous vehicles (AVs) could make a positive or negative impact on reducing mobile emissions. This study investigated the changes of mobile emissions that could be caused by large-scale adoption of AVs. The factors of road capacity increase and speed limit increase impacts were simulated using a conceptual modeling approach that combines a hypothetical speed-emission function and a traffic demand model using a virtual transportation network. The simulation results show that road capacity increase impact is significant in decreasing mobile emissions until the market share of AVs is less than 80%. If the road capacity increases by 100%, the mobile emissions will decrease by about 30%. On the other hand, driving speed limit increase impact is significant in increasing mobile emissions, and the environmentally desirable speed limit was found at around 95 km/h. If the speed limit increases to 140 km/h, the mobile emissions will increase by about 25%. This is because some vehicles begin to bypass the congested routes at high speeds as speed limit increases. Based on the simulation results, it is clear that the vehicle platooning technology implemented at reasonable speed limit is one of the AV technologies that are encouraging from the environmental point of view.