• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.10
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• pp.1770-1774
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• 2007

In this paper we deal with a design of the evaluation system to assess the vehicle operational control algorithm for Personal Rapid Transit(PRT) system. PRT system is different from the conventional rail traffic system in such that the station is off-line so as to guarantee a very short headway. In this study we propose an evaluation system to assess the performance of the proposed vehicle control algorithm. The evaluation system is composed of virtual vehicles, central control system, virtual wayside facilities, monitoring equipments. The virtual vehicles are made up by the laptop computers and the central control system employs Power PC process of Motorola Inc. The wayside facilities are implemented by employing the PXI module of the National Instruments Corporation. In order to test the proposed evaluation system a test algorithm is used, which has been simulated in the combined simulation system between Labview Simulation Interface Toolkit and Matlab/Simulink.

• Journal of the Korean Operations Research and Management Science Society
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• v.23 no.1
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• pp.17-28
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• 1998

This study suggests a procedure for designing cellular manufacturing systems (CMS) which are combined with automated guided vehicles (AGVs) using a tandem configuration. So far most of the previous studies have dealt with conventional design problems not considering the layout and the characteristics of transporters used in CMS. A mathematical model is developed using the service time to perform material transfers as a suitable meassure. The service capacity of AGVs and space limitations are also reflected in this model. As the model can be shown strongly NP-hard, a heuristic algorithm is presented, in which each cell is temporarily formed using both the set covering model and similarity coefficients, and then locations of the cells are determined by means of tabu search and finally machine perturbations are carried out. An example problem is solved to demonstrate the algorithm developed.

• Journal of the Korean Society for Precision Engineering
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• v.31 no.9
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• pp.773-776
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• 2014

KTX (Korea Train eXpress) is the first high-speed train operated in Korea and its highest speed reaches 300 km/h. Korean high-speed trains are mostly operated on the railroads exclusively designed for high-speed trains, but the sections of Seoul~Gwangmyeong, nearby of Daejeon station and Dongdaegu are operated on the existing tracks having the speed less than 150 km/h. With this paper, we'd like to analyze the lateral force that occurs between the wheels and the rail when high-speed trains were operated on the existing track section to suggest an appropriate driving speed for high-speed trains. As the rigid wheel base of the high-speed train is 3m which is about 50% longer than normal vehicles, it works as an advantage for high-speed driving. However, as the lateral force becomes higher than normal vehicles when driving on curves, plans to reduce wear-outs on the wheels are required.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.3
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• pp.1152-1167
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• 2018

In this paper, I propose an application layer cooperative congestion control scheme for safety message broadcast in vehicular networks, called CMS, that adaptively controls a vehicle's safety message rate and transmit timing based on the channel congestion state. Motivated by the fact that all vehicles should transmit and receive an application layer safety message in a periodic manner, I directly exploit the message itself as a means of estimating the channel congestion state. In particular, vehicles can determine wider network conditions by appending their local channel estimation result onto safety message transmissions and sharing them with each other. In result CMS realizes cooperative congestion control without any modification of the existing MAC protocol. I present extensive NS-3 simulation results which show that CMS outperforms conventional congestion control schemes in terms of the packet collision rate and throughput, especially in a high-density traffic environment.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.33 no.2
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• pp.105-108
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• 2020

In this study, experiments and simulations were conducted for a 1,200-V-class trench Si insulated-gate bipolar transistor (IGBT) with a small cell pitch below 2.5 ㎛. Presently, as a power device, the 1,200-V-class trench Si IGBT is used for automotives including electric vehicles, hybrid electric vehicles, and industrial motors. We obtained a breakdown voltage of 1,440 V, threshold of 6 V, and state voltage drop of 1.75 V. This device is superior to conventional IGBTs featuring a planar gate. To derive its electrical characteristics, we extracted design and process parameters. The cell pitch was 0.95 ㎛ and total wafer thickness was 140 ㎛ with a resistivity of 60 Ω·cm. We will apply these results to achieve fine-pitch gate power devices suitable for electrical automotive industries.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.10
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• pp.4283-4287
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• 2011

This paper describes the characteristics of emissions and fuel economy of soft type hybrid vehicle (Hyundai Avante) and hard type hybrid vehicle(Toyoda, Prius) in a transient CVS-75 driving mode. Hybrid vehicles showed the better fuel economy and emission characteristics comparing the conventional gasoline vehicle. Especially, hard type hybrid vehicle showed the better fuel economy comparing soft type hybrid vehicle under 55 km/h periods in the CVS-75 mode.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.110-110
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• 2000

In this paper, an antilock brake system (ABS) for commercial vehicles is studied by considering the design of a fuzzy Logic controller with pulse width modulation (PWM). PWM method is used for generating solenoid valve inputs in order to cope with the chattering problem caused by the conventional on/off control The sliding mode observer is designed to estimate the vehicle longitudinal velocity and it is used to calculate the wheel slip ratio. The effectiveness of the proposed control algorithm was validated by simulations performed with a nonlinear 14-DOF vehicle model including the dynamics of the brakes.

• Journal of the korean Society of Automotive Engineers
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• v.13 no.5
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• pp.89-94
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• 1991

In the quantitative analysis of oxygenated exhaust emissions (unburned methanol, formal- dehyde) from methanol fueled vehicles, the oxygen contained in oxygenated exhaust gases lowers the FID (Flame Ionization Detector) response factor of conventional THC analyzer and leads to erroneous HC reading. For correct measurement of various HCs including oxygenated HCs emitted from FFV(Flexible Fuel Vehicle), first of all, the measurement technique of real HC emissions should be established. GC and HPLC-DNPH measuring methods specified by the EPA are used in this paper to analyze unburned methanol and formaldehyde components in the exhaust emissions. In emission test of FFV, unburned methanol and formaldehyde are emitted mostly during cold transient period, and it is shown that formaldehyde emission level is proportional to engine displacements. In view of the HC emission level, vehicle using M85 has 40% advantage over gasoline-fueled vehicle in OMHCE and has a good potential of a low emission vehicle.

• Journal of the Korean Society for Railway
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• v.6 no.1
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• pp.58-65
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• 2003

Wheel/Rail geometric constraint relationships, such as effective conicity and gravitational stiffness, strongly influence the lateral dynamics of railway vehicles. In general, these geometric contact characteristics are nonlinear functions of the wheelset lateral displacement. There is a need to develop a wheel/rail geometric contact simulation program for wheels and rails with arbitrary profiles for the prediction of the dynamic behavior of railway vehicles. An algorithm to simulate any combination of wheels and rails is employed and a GUI for easy analysis is constructed. The simulation program is applied to KTX which will run on both KTX and conventional rails, two rail standards having different rail profiles. The results show that the two rail systems have different geometric contact characteristic

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