• 자동차안전학회지
• /
• 제7권2호
• /
• pp.32-38
• /
• 2015

A sine with dwell test is well known as a test scenario for evaluation of performance of electronic stability control(ESC) on passenger vehicles and heavy commercial vehicles. However, when it comes to ESC for medium commercial vehicles, the test scenario has not been established yet. In this paper, the sine with dwell test was modified considering characteristics of medium commercial vehicles. The three main modifications of the original test scenario are the steering angle level, steering frequency, and loading condition of the vehicle. These modifications are derived from simulation study for different medium commercial vehicles. From simulation study, it was shown that the ESC system for medium commercial vehicle is objectively evaluated by the proposed test scenario. A clear improvement on vehicle stability was seen in the results when ESC system was used.

• 한국자동차공학회논문집
• /
• 제22권7호
• /
• pp.63-69
• /
• 2014

Domestic automobile companies have adopted drum type brake system for commercial vehicles. However recently those companies have been applying disc-brake system to solve vehicle control-instability and inefficient heat discharge performance of conventional drum brake system for a medium commercial vehicle. Because the kinetic energy of a running commercial vehicle is relatively high, the brake system should discharge lots of heat energy while braking. A ventilated type brake disc has been used to increase heat discharge performance of a brake system. The vent structure of a disc highly affects cooling efficiency. This paper compares thermal characteristics of three types of vent structure in JASO C421 braking condition. It is found that the slant bend type disc has the lowest temperature and thermal stress distributions in the braking condition.

• 대한기계학회논문집A
• /
• 제39권2호
• /
• pp.235-240
• /
• 2015

디지털 기기의 발달과 더불어 능동안전시스템 또한 비례적으로 발달됨에 따라 4.5 톤 이상 중대형상용차에도 능동안전시스템에 대한 요구가 대두되고 있다. 승용차량과 달리 중대형 상용차량 경우 카메라 장착 위치가 상대적으로 높아 차선 인식에 불리한 조건을 가지고 있다. 본 논문에서는 공간영역처리 기반 중 하나인 소벨 에지(Sobel Edge) 추출과 허프 변환(Hough Transform) 기법과 색 변환보정 기법으로 국내 도로 환경에 맞는 차선 인식에 대한 방법을 제시하고, 영상을 통한 전방의 차량을 인식하는 객체 인식 기법 중에 Haar-like 기법, Adaboost 기법, SVM 기법, Template Matching 기법 등을 적용 및 분석을 통하여 검출 오류를 줄이기 위한 전방 차량 인식 방법을 제안한다. 성능검증을 위해서 실차평가를 실시하였으며, 차선 인식에 대해 98% 이상의 높은 인식률을 얻었다.

• 한국자동차공학회논문집
• /
• 제23권4호
• /
• pp.371-379
• /
• 2015

This paper represents the structural design of the light weight axle beam for medium duty commercial vehicle using hot press. To reduce the weight of the axle, axle beam of solid type was replaced by hollow type which was made by hot press. According to the change of axle beam structure and manufacturing method, we have to investigate the structural strength and fatigue performance. To verify the axle beam performance, the structural analysis was carried out by simplified axle beam model and various design parameters that are axle beam height, thickness and width. From the analysis results, the light weight axle beam structure was founded and applied the full model analysis. This study will be used as a guidance in development of the light weight axle for medium duty commercial vehicle.

• 한국자동차공학회논문집
• /
• 제13권2호
• /
• pp.10-15
• /
• 2005

This study was initiated to evaluate the cooling performance of CAC (charged air cooler) and radiator in the engine room of a mini bus. So we had firstly to predict the mass flow rate coming from radiator grille and front bum per opening using computational fluid dynamics (CFD) simulation based on 3D configuration. And simulations were carried out for different cooling module layout and bum per opening hole size on sam e vehicle operating condition. Simulation results show that CAC cooling performance at reverse protecting plate-applying model was much efficient than that of the bum per opening hole size-increasing model in IMTD point of view. Part of the CFD simulation results was com pared to with experimental data. It was confirm ed that the CFD approach using STAR-CD based on pursuing no-com promise solution could provide design engineers with useful design information in the early design stage of vehicle development.

• 한국자동차공학회논문집
• /
• 제6권3호
• /
• pp.154-160
• /
• 1998

Ride quality of medium truck became a very important factor in the suspension design, to the demand of more comfortable ride of passengers. This study describes how to determine and evaluate design parameters related to the chassis suspension system with time and frequency analysis. The spring stiffness and damping force of the chassis suspension system were obtained by observing the vertical acceleration PSD. The simulation was carried out on various road profiles, which was suggested by ISO. The pitching motion of the medium size truck was observed to improve the ride quality. A computer simulated truck model was constructed using DADS, a commercial dynamic analysis software, in order to simulate the truck motions. From the analyzed process of suspension parameters, it was concluded that the spring and the shock absorbers affect the pitching of the vehicle. In order to validate the computer simulated truck model, a physical prototype was constructed and tested.

• 한국IT서비스학회지
• /
• 제15권4호
• /
• pp.25-39
• /
• 2016

The drone is an unmanned aerial vehicle which has no human pilot. Drones can be classified into military drones, commercial drones, and personal drones by usage. Also, drones can be classified from large-sized to nano-sized drone by size and autonomous, remote controlled drone by control type. Especially, military drones can be classified into low-altitude drones, medium-altitude, and high-altitude drones by altitude. Recently, the drone industry is one of the fast growing industries in the world. As drone technologies have become more advanced and cost-effective, Korean government has set its goal to become a top-level country in drone business. However, the government's strict regulation for drone operations is one of the biggest hurdles for the development of the related technologies in Korea and other countries. For example, critical problems for drone delivery can be classified into technical issues and institutional issues. Technical issues include durability, conditional awareness, grasp and release mechanisms, collision avoidance systems, drone operating system. Institutional issues include pilot and operator licensing, privacy rules, noise guidelines, security rules, education for drone police. This study analyzes the trends of the drone industry from the viewpoint of technology and regulation. Also, we define the business areas of drone utilization. Especially, the drone business types or models for public sector are proposed. Drone services or functions promoting public interests need to be aligned with the business reference model of Korean government. To define ten types of drone uses for public sector, we combine the business types of government with the future uses of drones that are proposed by futurists and business analysts. Future uses of drones can be divided into three sectors or services. First, drone services for public or military sectors include early warning systems, emergency services, news reporting, police drones, library drones, healthcare drones, travel drones. Second, drone services for commercial or industrial services include parcel delivery drones, gaming drones, sporting drones, farming and agriculture drones, ranching drones, robotic arm drones. Third, drone services for household sector include smart home drones.

• 한국추진공학회:학술대회논문집
• /
• 한국추진공학회 2008년도 제31회 추계학술대회논문집
• /
• pp.72-77
• /
• 2008

발사체 RCS는 발사체의 롤, 피치, 요방향의 자세제어뿐만 아니라 상단의 자세제어를 담당하는 핵심부품으로서 발사체의 임무요구조건에 따라 하이드라진을 이용한 단일추진제, UDMH/NTO를 이용한 이원추진제, 그리고 소형발사체의 경우 GN2를 이용한 냉가스시스템 등으로 분류된다. 본 연구에서는 해외 상용발사체를 중심으로 발사체에 대한 간략한 소개 및 RCS에 적용되는 최신 기술, 개발현황 등에 대해 기술하였다.

• 대한교통학회지
• /
• 제28권6호
• /
• pp.43-54
• /
• 2010

최근 화물수요모형에 화물자동차 투어행태를 반영하기 위한 접근방법이 제시되었다. 화물자동차 이동을 투어기반 접근방법으로 모형화 하기 위해서는 화물자동차 투어와 투어유형에 대한 이해가 필요하다. 본 연구는 화물자동차 투어유형을 왕복형 투어와 체인형 투어로 구분하여 이들 투어유형 선택행태를 분석하였다. 투어유형 선택행태를 분석하기 위한 방법으로는 의사결정나무(decision tree)와 로짓모형(logit model)을 이용하였다. 분석결과 화물자동차 투어유형을 분류하는 설명변수로 화물적재율, 평균화물량, 총화물량이 선정되었으며, 의사결정나무와 로짓모형이 유사한 결과를 도출하였다. 또한 소형과 중형 화물자동차의 투어유형을 분류하는 설명변수가 큰 차이를 보이지 않음에 따라 화물자동차 투어를 계획함에 있어 화물을 어떻게 적재할 것인지가 가장 중요한 것으로 나타났다. 의사결정나무와 로짓모형의 예측력을 비교한 결과는 의사결정나무가 로짓모형에 비해 상대적으로 우수한 결과를 보였는데, 이는 화물자동차 투어유형을 분류함에 있어 로짓모형과 같이 설명변수의 선형적 결합에 의한 분류 보다는 의사결정나무와 같이 다수 설명변수들의 규칙조합으로 분류하는 것이 효과적임을 나타낸다.

• 한국항공우주학회지
• /
• 제44권8호
• /
• pp.668-674
• /
• 2016

본 논문에서는 우주개발 중장기 계획에 따라 2020년 이후 한국형발사체의 후속으로 계획된 정지궤도위성 발사체와 대형 위성 발사체의 개발 방향에 대한 논의와 이를 구현하기 위해 요구되는 발사체 기술들에 대해 전망한다. 차세대 발사체는 고성능화뿐 아니라 저비용 및 고신뢰도를 목표로 세계 위성 발사 서비스 시장에서 경쟁할 수 있는 발사체로 개발되어야 하며, 이를 위해 75톤 급 케로신/액체산소 로켓 엔진 등 한국형발사체를 통해 확보된 발사체 기술 기반 및 개발 성과를 활용하고 발전시키는 방향으로 개발되는 것이 바람직하다.