Jungbeom Kim

Tensile properties and microstructure of microalloyed CuAlNiX shape memory alloys

Abstract The effects of microalloying additions (0.3Ti, 3Ti-0.2Mn, and 0.3Ti-0.6Zr) to a β Cu-13Al-3Ni shape memory alloy on the tensile properties, shape recovery capacity and microstructure were investigated. It was found that the tensile properties,(σt, σf and ϵf) lie roughly on a straight line according to a Hall-Petch relationship. The highest fracture stress (903 MPa) and fracture strain (8.6%) were obtained in the Cu-13.4Al-3.05Ni-0.24Ti-0.63Zr alloy. Fractography revealed a change from the intergranular to the transgranular fracture mode. Grain boundary cracking was markedly suppressed by the microalloying additions and the fracture model lso changed from brittle to ductile with decreasing grain size of the β phase. The investigated alloys were fully martensitic consisting of internally faulted M18R and internally twinned N2H types.

Microstructure and properties of grain-refined Cu-Zn-Al-X shape memory alloys

This work was concerned with the effects of adding the microalloying elements of nickel, silicon, zirconium and titanium to the Cu-25Zn-4Al (wt%) shape memory alloy on the microstructure and properties

Coordinated implementation and processing of a unified chassis control algorithm with multi-central processing unit

Abstract This paper proposes a multi-core architecture for implementation of a unified chassis control (UCC) algorithm on a field programmable gate array (FPGA) which operates as a multi-core process. The proposed multi-core architecture aims to reduce the operating load and maximize the reliability for improving the performance of the UCC system. The proposed multi-core architecture supports distributed control with analytical and physical redundancy capabilities. The UCC algorithm used in this research consists of three parts: a supervisor, a main controller, and fault detection/isolation/tolerance control (FDI/FTC). These three components are implemented and evaluated with the multi-core process environment with the FPGA. An electronic control unit is configured by three MicroBlaze processors with FPGA, and a control area network (CAN) is also implemented for hardware-in-the-loop (HILS) evaluation. Three types of multi-core architectures, i.e. distributed processing, triple voting, and hybrid operation, are implemented to investigate the performance and reliability. A vehicle simulator and brake HILS are used to evaluate the proposed multi-core architectures. From the test results, it is shown that all of the proposed multi-core systems have better performance and improved reliability compared with the single core system. In particular, the hybrid operation architecture shows better reliability and performance compared with the other two multi-core architectures, distributed processing and triple voting.

Accuracy Improvement of DGPS for Low-Cost Single-Frequency Receiver Using Modified Flächen Korrektur Parameter Correction

A differential global positioning system (DGPS) is one of the most widely used augmentation systems for a low-cost L1 (1575.42 MHz) single-frequency GPS receiver. The positioning accuracy of a low-cost GPS receiver decreases because of the spatial decorrelation between the reference station (RS) of the DGPS and the users. Hence, a network real-time kinematic (RTK) solution is used to reduce the decorrelation error in the current DGPS system. Among the various network RTK methods, the Flachen Korrektur parameter (FKP) is used to complement the current DGPS, because its concept and system configuration are simple and the size of additional data required for the network RTK is small. The FKP was originally developed for the carrier-phase measurements of high-cost GPS receivers; thus, it should be modified to be used in the DGPS of low-cost GPS receivers. We propose an FKP-DGPS algorithm as a new augmentation method for the low-cost GPS receivers by integrating the conventional DGPS correction with the modified FKP correction to mitigate the positioning error due to the spatial decorrelation. A real-time FKP-DGPS software was developed and several real-time tests were conducted. The test results show that the positioning accuracy of the DGPS was improved by a maximum of 40%.

Development of Control Algorithm for Intersection Safety System Using the Fusion of V2X and Environmental Sensors

This paper describes the development and verification of control algorithms for V2X and environmental sensor integrated intersection support and safety systems. The objective of the research is to develop core technologies for effective fusion of V2X and environmental sensors and to develop new safety function for intersection safety. One of core technologies is to achieve the improvement of GPS accuracy, and the other is to develop the algorithm of a vehicle identification which matches all data from V2X, vehicle sensors and environmental sensors to specific vehicles. A intersection optimal pass (IOP) algorithm is designed based on these core technologies. IOP recommends appropriate speed to pass the intersection in the consideration of traffic light signal and preceeding vehicle existence. Another function is developed to prevent a collision avoidance when car crash caused by traffic violation of surrounding vehicles is expected. Finally all functions are implemented and tested in three test vehicles. It is shown that IOP can support convenient and comfortable driving with recommending optimal pass speed and collision avoidance algorithm can effectively prevent collision caused by traffic sign violation of surrounding vehicles.