• Journal of the Korea Convergence Society
• /
• v.11 no.6
• /
• pp.59-67
• /
• 2020

Expressway is the main link in promoting the national economic development, which plays a vital part in improving the regional economy and people's living standards, therefore, it is of great significance to accelerate the construction of expressways. However, because it is difficult for the existing system to identify the information of special vehicles quickly, leading to the cumbersome flow of special vehicles passing through the toll station of expressways [1], which brings a certain burden to the work of expressway administrators. The surge in the number of private cars also increased the traffic pressure of toll stations, especially the free expressways traffic policy implemented by the State during holidays, resulting in more frequent traffic jams at high-speed intersections. According to this situation, a intelligent system was created to ameliorate the difficult situation of special vehicle identification on expressways, reduce the congestion at high-speed intersections, and improve the efficiency of staff by data-based means.

• Proceedings of the KSR Conference
• /
• 2011.10a
• /
• pp.663-669
• /
• 2011

Since railway vehicle's improvements on speed and weight has caused interior noise, the passenger's convenience fell dramatically. Therefore many on-going researches are dedicated to reduce interior noise. In this study the analytical prediction of interior noise reduction has done through filling up the empty space using form and to modify the floor structure, which contributes highly with interior noises. Using Statistical Energy Analysis(SEA), the interior noise of the vehicles without the form filling on the floor structure and the vehicles with form filling and also a modified structure has been predicted. The selected percentage of form filling was 0, 50, 100% and through this research the analysis of noise reduction by form filling has been made. When floor structure has been filled with form, approximately 2 dB of noise reduction was observed and the difference of noise reduction level with 50 and 100% form filling was predicted to be very little. Through this study, the expectation of interior noise reduction in high speed trains is considered high.

• International Journal of Fluid Machinery and Systems
• /
• v.5 no.2
• /
• pp.91-99
• /
• 2012

The Fighter aircraft transmission system consists of a light weight, High Speed Flexible Coupling (HSFC) known as Power Take-Off shaft (PTO) for connecting Engine gearbox (EGB) with Accessory Gear Box (AGB). The HSFC transmits the power through series of specially contoured metallic annular thin flexible plates whose planes are normal to the torque axis. The HSFC operates at high speed ranging from 10,000 to 18,000 rpm. The HSFC is also catered for accommodating larger lateral and axial misalignment resulting from differential thermal expansion of the aircraft engine and mounting arrangement. The contoured titanium alloy flexible plates are designed with a thin cross sectional profile to accommodate axial and parallel misalignment by the elastic material flexure. This paper investigates the effect of misalignment on the transmission characteristics of the HSFC couplings. A mathematical model for the HSFC coupling with misalignment has been developed for analyzing the torque transmission and force interaction characteristics. An extensive testing has been conducted for validating characteristics of the designed coupling under various misalignment conditions. With this the suitability of the model adapted for the design iteration of HSFC development is validated. This method will reduce the design iteration cycles of HSFC and can be extended for the similar development of flexible couplings.

• Journal of Power Electronics
• /
• v.11 no.4
• /
• pp.449-455
• /
• 2011

Electric drive vehicles (EDV) have received much attention recently because of their environmental and energy benefits. In an EDV, the motor drive system directly influences the performance of the propulsion system. However, the available DC voltage is limited, which limits the maximum speed of the motors. At high speeds, the inverter voltage increases if the square wave (SW) voltage (six-step operation) is used. Although conventional direct torque control (DTC) has several advantages, it cannot work in the six-step mode required in high-speed applications. In this paper, a single-mode seamless DTC for AC motors is proposed. In this scheme, the trajectory of the reference flux changes continuously between circular and hexagonal paths. Therefore, the armature voltage changes smoothly from a high-frequency switching pattern to a square wave pattern without torque discontinuity. In addition, because multi-mode controllers are not used, implementation is more straightforward. Simulation results show the voltage pattern changes smoothly when the motor speed changes, and consequently, torque control without torque discontinuity is possible in the field weakening area even with a six-step voltage pattern.

• Proceedings of the KSR Conference
• /
• 2008.11b
• /
• pp.380-386
• /
• 2008

The development of a new railway vehicle is under progress through the Next Generation High-Speed Rail Development Project in Korea. Its aim is to develope fundamental technology of the vehicle that can run over 400km/h. The new distributed traction bogie system, 'HEMU'(High-speed Electric Multiple Unit), will be used and is different from that of previously developed high speed railway vehicles. Previous vehicles adopted push-pull type system, which means one traction-car drives rest all of the vehicle. Due to the difference, investigation on dynamic behavior and its safety evaluation are necessary, as a part of verification of the design specification. In the paper, current progresses of researches are presented. And the High-Speed Railway vehicle system is evaluated for a dynamic characteristic simulation. Proper dynamic models including air-suspension system, wheel-rail, bogie and car-body is developed according to the vehicle simulation scenario. The basic platform for the development of dynamic solver is prepared using nodal, modal coordinate system and wheel-rail contact module. Operating scenario is prepared using commercial dynamic analysis program and used for development of dynamic model, which contains many parts such as carbodies, bogies and suspension systems. Furthermore, international safety standard is applied for final verification of the system. Finally, the reliability of the dynamic model will be verified with test results in the further researches. This research will propose a better solution when test results shows a problem in the parts and elements. Finally, the vehicle that has excellent performance will be developed, promoting academic achievement and technical development.

• Proceedings of the KIEE Conference
• /
• 2006.07b
• /
• pp.653-654
• /
• 2006

This paper proposes a new linear magnetic damper for absorbing shock from a crash accident involving high speed vehicles. The magnetic damper is composed of a conductive plate, a yoke and permanent magnets which are constructed to a Halbach array to improve the damping force. In order to calculate the damping force, finite element analysis(FEA) using J-Mag, a commercial FEA tool, is performed and the results are validated by the experiment. Also, the design optimization of the plate generating the eddy current causing the damping force performed to obtain the most efficient damping force. Finally, the specifications and the performance of the proposed magnetic damper are represented.

• 한국전산유체공학회:학술대회논문집
• /
• 2001.05a
• /
• pp.72-77
• /
• 2001

The computational efficiency of an shape optimization procedure is highly dependent upon the proper selection of shape representation methods and design variables. In this study, shape functions, Bezier and NURBS(non-uniform rational B-splines) curves are selected as configuration generation methods and their efficiencies on the nose shape design of high-speed air vehicles, are compared. The effects of the number of control points, weighting factors and the optimization methods when utilizing the NURBS curves, are investigated. By implementing Bezier and NURBS curves, shapes having lower drag than the optimization case utilizing the shape functions, were obtained, hence it was demonstrated that these curves have better capability in representing the configuration. Efforts will be given to improve the convergence behavior when utilizing the NURBS, hence to reduce the number of Navier-Stokes analysis calculations.

• Journal of Institute of Control, Robotics and Systems
• /
• v.14 no.6
• /
• pp.603-607
• /
• 2008

This paper proposes a fast acquisition method using INS velocity and multiple correlators for high speed vehicles. In order to reduce acquisition time in GPS receiver, the method utilizes inertial velocity information and multiple correlators. Search range of the Doppler frequency is reduced by using INS velocity and the number of cells at one search can be increased by using multiple correlators. By using both multiple correlators and the INS velocity in the acquisition, search space can be greatly reduced. Experimental results show that the method gives faster signal acquisition performance than the conventional method.

• Journal of Institute of Control, Robotics and Systems
• /
• v.18 no.3
• /
• pp.251-257
• /
• 2012

Unmanned ground vehicles have important military, reconnaissance, and materials handling application. Many of these applications require the UGVs to move at high speeds through uneven, natural terrain with various compositions and physical parameters. This paper presents a framework for high speed autonomous navigation based on the integrated real time traversability. Specifically, the proposed system performs real-time dynamic simulation and calculate maximum traversing velocity guaranteeing safe motion over rough terrain. The architecture of autonomous navigation is firstly presented for high-speed autonomous navigation. Then, the integrated real time traversability, which is composed of initial velocity profiling step, dynamic analysis step, road classification step and stable velocity profiling step, is introduced. Experimental results are presented that demonstrate the method for a $6{\times}6$ autonomous vehicle moving on flat terrain with bump.

• Proceedings of the KSR Conference
• /
• 2009.05b
• /
• pp.473-479
• /
• 2009

Dynamic analysis is necessary for the High-Speed Railway vehicle which aims to run on max 400km/h. Especially, dynamic simulation using CAE(Computer Aided Engineering) can help to reduce the time of development of the High-Speed Railway vehicles. Also, it helps to reduce prices and improve the quality such as safety, stability and ride. There are many dynamic software for a railway vehicle, such as Vampire and ADAMS-Rail. There are limitations for each software and difficulties to analyze overall dynamics for entire railway system. To overcome these limitations, in this study, a program which can simulate entire railway vehicles was developed. This program is easy to use because it was developed using C++, which is object-oriented programming language. In addition, the basic platform for the development of dynamic solver is prepared using the nodal, modal coordinate system with a wheel-rail contact module. Rigid, flexible and large deformable body systems can be modeled by a user according to the characteristic of a desired system. Its reliability is verified by comparison with a commercial analysis program.