• 한국기계가공학회지
• /
• 제20권6호
• /
• pp.17-25
• /
• 2021

In this study, the mechanical properties of railway-vehicle aluminum under frame was investigated based on the metal inert gas (MIG) welding conditions. An aluminum-alloy (6005A-T6) extruded material used in the lower panel of a railway vehicle was connected through MIG welding to determine the mechanical properties of MIG welds. Argon shielding gas and filler materials, such as ER5356 and ER4043, were used as consumable welding materials. For the welding conditions of the test specimen, welding frequencies of 2.5 and 4.5 Hz were applied using the SynchroPuls function, and the root faces were 1.0 and 1.5 mm. The mechanical properties of the MIG welds were determined through tensile, bending, and fatigue tests.

• ETRI Journal
• /
• 제43권6호
• /
• pp.1013-1023
• /
• 2021

In this study, we propose a practical path planning method that combines the A^* search algorithm and minimum snap trajectory generation. The A^* search algorithm determines a set of waypoints to avoid collisions with surrounding obstacles from a starting to a destination point. Only essential waypoints (waypoints necessary to generate smooth trajectories) are extracted from the waypoints determined by the A^* search algorithm, and an appropriate time between two adjacent waypoints is allocated. The waypoints so determined are connected by a smooth minimum snap trajectory, a dynamically executable trajectory for the quadrotor. If the generated trajectory is invalid, we methodically determine when intermediate waypoints are needed and how to insert the points to modify the trajectory. We verified the performance of the proposed method by various simulation experiments and a real-world experiment in a forested outdoor environment.

• Advances in aircraft and spacecraft science
• /
• 제9권1호
• /
• pp.1-15
• /
• 2022

This paper presents calibration of flush air data sensing systems during ascent period of a satellite launch vehicle. Aerodynamic results are numerically computed by solving three-dimensional time dependent compressible Euler equations over a payload shroud of a satellite launch vehicle. The flush air data system consists of four pressure ports flushed on a blunt-cone section of the payload shroud and connected to on board differential pressure transducers. The inverse algorithm uses calibration charts which are based on computed and measured data. A controlled random search method coupled with neural network technique is employed to estimate pitch and yaw angles from measured transient differential pressure history. The algorithm predicts the flow direction stepwise with the function of flight Mach numbers and can be termed as an online method. Flow direction of the launch vehicle is compared with the reconstructed trajectory data. The estimated values of the flow direction are in good agreement with them.

• 자동차안전학회지
• /
• 제14권1호
• /
• pp.14-19
• /
• 2022

Recently, automobile industries have developed ADAS, smart cars, connected cars, automated driving systems, which communicate with outsides of a vehicle not only in uni-directional way but also in bi-directional way. It is necessary to examine the electromagnetic immunity of vehicles equipped with those communication systems. The electromagnetic immunity tests are carried out in an electromagnetic semi anechoic chamber, which is cut off from the outside electromagnetically. In this study, additional test environments were designed and tested and as a result they are shown to be effective to create test environments in an experimental chamber for electromagnetic immunity tests of vehicles equipped with communication systems.

• 한국산업융합학회 논문집
• /
• 제26권6_1호
• /
• pp.985-991
• /
• 2023

This study proposes a solution to the voltage drop in electric vehicle chargers, due to the parasitic resistance and inductance of power cables when the chargers are separated by large distances. A method using multi-level electric vehicle chargers that can output power in stages, without installing an additional energy supply source such as a reactive power compensator or an energy storage system, is proposed. The voltage drop over the power cables, to optimize the charging scheduling, is derived. The obtained voltage drop equation is used to formulate the constraints of the optimization process. To validate the effectiveness of the obtained results, an optimal charging scheduling is performed for each period in a case study based on the assumed charging demands of three connected chargers. From the calculations, the proposed method was found to generate an annual profit of $20,800 for a $12,500 increase in installation costs.

• 한국정보통신학회논문지
• /
• 제25권2호
• /
• pp.280-285
• /
• 2021

VNDN 기술을 커넥티드 차량의 인포테인먼트 응용 서비스를 위한 통신 기술로 활용할 시 데이터가 통신의 주체가 되는 데이터중심네트워킹 기술 실현이 가능하며, 차량 보안 공격 및 해킹, 장거리 데이터 전송 시 성능 저하, 잦은 데이터 끊김 현상 등 현재의 호스트 중심 인터넷에 기반한 커넥티드 차량의 인포테인먼트 응용 서비스 기술이 갖는 한계를 극복 할 수 있다. VNDN 안에 지연에 매우 민감한 critical 정보 데이터를 RSU(Road Side Unit) 등에게 푸쉬 기반으로 전달해 주기 위한 Data 패킷 포워딩 이슈는 VNDN 기반 응용 서비스 실현을 위해 해결해야 할 이슈 중 하나이며, 이를 해결하기 위해 먼저 NDN 환경하에서 푸쉬 기반 데이터 트래픽을 지원해주기 위한 현존하는 포워딩 기법들을 포괄적으로 분석해 보고 각 기법 들을 성능 측면에서 비교 분석해 본다. 이를 통해 VNDN 환경하에서 보다 향상된 푸쉬 기반 중요 데이터 포워딩 기법 연구를 위한 사전 지식으로 활용되어질 수 있기를 기대한다.

• 대한인간공학회지
• /
• 제30권5호
• /
• pp.651-657
• /
• 2011

Objective: The aim of this study is to investigate the system to integrate and manage the in-vehicle interactions between the drivers and the in-vehicle mobile IT devices. Background: As the mobile IT technology is being used anywhere, the drivers are interacting with the mobile IT device on driving situations. The distraction of the driver's attention causes the car accidents. It is necessary to develop the HVI(Human Vehicle Interface System) to integrate and manage the in-vehicle interactions with IT devices. Method: The HVI System is designed not as the interfacing subject but as the supervising system to monitor the driver's status and support the driver to concentrate on the primary tasks. The HVI system collects the status information of the car and driver and estimate the driving workload. Results: The HVI system controls how to provide the output information based on the driving workload. We implemented the HVI system prototype and applied in the real vehicle with the HVI cell phone and the HVI car navigation system. Conclusion: Depending on the driving situations, the HVI system prevented the information output in dangerous situation and diversified the modality and the intensity of the output information. Application: We will extend the HVI system to be connected the other various IT devices and verity the effectiveness of the system through various experiments.

• 한국항행학회논문지
• /
• 제7권2호
• /
• pp.108-117
• /
• 2003

본 논문에서는 현재 도로상에서 이용되고 있는 루프감지기 체계와 호환성을 가지는 두 종류의 레이더 기술을 이용한 차량감지기를 개발하였다. 이 두 종류는 24 GHz의 FMCW 고도계와 도플러 속도계 기술을 이용하여 도로상의 차량의 길이와 속도정보를 알아낼 수 있는 비매설형의 차량감지기이다. 신호처리에는 DAQ 보드를 사용하였고, 응용소프트웨어인 LabView로 프로그래밍 하였다. 기존의 루프감지기와 연결된 교통정보 네트웍과의 호환성을 위해 RS-232C 표준인터페이스를 이용하여 VDS(Vehicle Detector System)로 차량 관련 데이터를 전송하였다. 속도와 차량길이 정보의 정확도에 있어서 기존 루프감지기를 실험장에 설치한 결과보다 약 10% 정도 향상되었음이 측정되었다.

• 한국정보통신학회논문지
• /
• 제13권11호
• /
• pp.2311-2316
• /
• 2009

최근 편의성, 안전성, 편리성 등의 키워드가 자동차 시장에서 새로운 화두로 등장하면서 자동차 시장에서 차량 내 전장부분의 중요성이 커지고 있다. 이에 따라 많은 전자기기의 사용이 필수적으로 요구되어지면서 전자기기들 간의 통신이 부각되어지고 있다. 차량 내부에서는 컨트롤러, 센서, 그리고 멀티미디어 기기인 오디오, 스피커, 비디오, 네비게이션 등 다양한 장치들이 CAN이나 MOST와 같은 차량 네트워크를 통해 연결되어 있다. 현재 차량 네트워크는 서로 각각의 목적에 따라 운용되고 관리되어 지고 있다. 본 논문에서는 MOST Network를 이용하여 최근의 키워드가 되고 있는 편의성, 안전성, 편리성 등을 고려한 지능형 자동차에 요구되는 Navigation을 구현하여 차량 내 CAN Network를 제어하는 시스템을 제시하고자 한다.

• 제어로봇시스템학회논문지
• /
• 제18권4호
• /
• pp.359-364
• /
• 2012

Real-Time Traversability should be analyzed from the equiped sensors' data in real time for autonomous outdoor navigation. However, it is difficult to find out such traversability that considers the terrain roughness and the vehicle dynamics especially in case of skid type vehicle. The traversability based on real time dynamic analysis was proposed to solve such problem but in navigation with strait driving path. To adapt the method into the navigation with curved driving path, a path following controller should be incorporated into the dynamic model even though it cause the real time problem. In this paper, a dynamic model is proposed to solve the real time problem in the traversability analysis based on real time dynamic simualtion. The dynamic model contains the control dummy which is connected to the vehicle body with a universal joint to follow the curved path without controller. Simulation and experimental results on $6{\times}6$ articulated unmanned ground vehicle demonstrate the method's effectiveness and applicability into the traversability analysis on terrain with bumps.