• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.4
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• pp.371-378
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• 2015

Range extenders, which are power generation systems driven by small engines, extend the driving distance and time of electric vehicles (EVs) through continuous charging of batteries. The currently used range extenders with gasoline engines pose limitations with regard to the realization of high-power compact systems, owing to their complex structure and low energy density. In contrast, micro gas turbine (MGT) range extenders (MGT power packs) possess high power and low weight, and can therefore be significantly reduced in size despite increase in speed. In this study, an MGT power pack for the range extenders of EVs was developed using a turbo-prop micro turbine, an alternator for passenger vehicles and electric batteries. The operating characteristics of the MGT power pack were measured through a series of experiments conducted under electrical no-load and load conditions. Their power generation performance and efficiency were measured under various electrical loads and power transmission gear ratios. From the results, electrical load was found to have no influence on power generation performance. The maximum electrical power output was 0.8 kW at a core turbine speed of 150 krpm, and the application of 3:1 reduction gear to the turbine output shaft increased the power to 1.5 kW by 88%. This implies that the test results demonstrated stable power generation performance of the MGT power pack regardless of vehicle load changes, thus revealing its feasibility for use with the range extenders of EVs.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.12
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• pp.8700-8706
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• 2015

The first driving device of the power bogies for the Korean high-speed railway vehicle consists of the traction motor (TM) and the motor reduction gears unit (MRU). Although TM and MRU are the mechanically integrated structures, their time between overhauls (TBO) have two separate intervals due to different technical requirements(i.e. TBO of MRU: $1.8{\times}10^6km$, TBO of TM: $2.5{\times}10^6km$). Therefore, to reduce the unnecessary number of preventive maintenances, it is important to evaluate the optimal TBO with a viewpoint of reliability-center maintenance towards cost-effective solution. In this study, derived from the field data in maintenance, fault tree analysis and failure rate of the subsystem considering criticality of the components are evaluated respectively. To minimize the conventional total maintenance cost, the same optimal TBO of the components is derived from genetic algorithm considering target reliability and improvement factor. In this algorithm, a chromosome which comprised of each individual is the minimum preventive maintenance interval. The fitness function of the individual in generation is acquired through the formulation using an inverse number of the total maintenance cost. Whereas the lowest common multiple method produces only a four percent reduction compared to what the existing method did, the optimal TBO of them using genetic algorithm is $2.25{\times}10^6$km, which is reduced to about 14% comparing the conventional method.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.5
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• pp.516-521
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• 2016

In this study, we investigated the operation of railroad fire fighting vehicles against fires on trains in a long railway tunnel. In recent years, long railway tunnels (more than 10 km in length) have been built and the number of such tunnels, such as the Geumjeong tunnel (20.3 km in length) on the Gyeongbu high speed line, Solan tunnel (16.7 km in length) on the Yeongdong line and Yulhyeon tunnel (50.3 km in length) on the Suseo high speed line which is scheduled to be opened in the second half of 2016, is increasing. Significant damage is to be expected, due to the increased evacuation time and limited accessibility of fire services when the train is stopped by an urgent fire in the tunnel. Special fire fighting vehicles capable of running on rails have been developed and operated in overseas advanced countries. Therefore, a fire-response system using Unimog vehicles, which can run on road and rail, instead of road vehicles, is necessary. The characteristics of the railway tunnel and thermal environmental change caused by a train fire in a tunnel were analyzed in this study. Also, the operational requirements of the railroad fire fighting vehicles were evaluated by taking into account the specifications of the railroad fire fighting vehicles under development.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2007.11a
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• pp.313-318
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• 2007

Interior permanent magnet synchronous motor(IPMSM) has become a popular choice in electric vehicle applications, due to their excellent power to weight ratio. This paper proposes maximum torque control of IPMSM drive using adaptive fuzzy neural network controller and artificial neural network(ANN). This control method is applicable over the entire speed range which considered the limits of the inverter's current and voltage rated value. For each control mode, a condition that determines the optimal d-axis current $i_d$ for maximum torque operation is derived. This paper considers the design and implementation of novel technique of high performance speed control for IPMSM using Adaptive-FNN controller and ANN controller. The hybrid combination of neural network and fuzzy control will produce a powerful representation flexibility and numerical processing capability. Also, this paper reposes speed control of IPMSM using Adaptive-FNN and estimation of speed using ANN controller. The back propagation neural network technique is used to provide a real time adaptive estimation of the motor speed. The proposed control algorithm is a lied to IPMSM drive system controlled Adaptive-FNN and ANN controller, the operating characteristics controlled by maximum torque control are examined in detail. Also, this paper proposes the analysis results to verify the effectiveness of the Adaptive-FNN and ANN controller.

• Journal of the Korea Institute of Military Science and Technology
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• v.19 no.4
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• pp.551-558
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• 2016

We analyzed wind speed over South Korea for HALE UAV(High Altitude Long Endurance Unmaned Aerial Vehicle) flight safety. Annual variation of wind speed at 200 hPa showed that winter season was stronger than summer. According to latitude, wind speeds in January and August were found to be $52{\sim}74m\;s^{-1}$ and $15{\sim}26m\;s^{-1}$, respectively. Wind speed was stronger(weaker) at lower latitudes than higher latitudes in winter(summer). Frequency(%) of wind speed less than threshold value($18m\;s^{-1}$) for the operation date was investigated. The days showing the frequency greater than 60 % in all altitudes of surface ~ 50 hPa showed the range of 1 ~ 33 days at 7 stations. Operation date was the longest period at Gosan. The appropriate date of HALE UAV operation at Gosan and Osan is considered as the middle of July ~ middle of August and end of July ~ early August, respectively. These results can be used to determine the operation date of HALE UAV.

• Journal of IKEEE
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• v.8 no.1 s.14
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• pp.108-116
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• 2004

In this paper, the measurement system of speed and distance of vehicles using laser is implemented and verified through the outdoor test. The implemented system consists of a laser module and a control/speed-computation module. The Former is composed of a optics part, a transmit/receive part, and a LDC(Laser Detection and Counter), and the latter is a control part that controls the laser module and a speed computation part that calculates velocity of vehicles using a microcontroller. The algorithm to compute speed has been developed to consider characteristics of laser and surrounding conditions. The implemented system has been tested and verified on the high way, and the result shows stability of the system and accuracy of the algorithm.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.11 no.3
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• pp.124-132
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• 2012

There is high probability of children's traffic accidents. Because their physical, mental attribute are weak. Major part of the accidents happen during walking. Above all, jaywalking is the biggest traffic accident reason. Many traffic accidents take place on the road to school or near the home area. So Ministry of Public Administration and Security legislated children safeguard zone since 1995. But a study are inadequate the safety facilities on the effectiveness verification in the school zone. Therefore, this study aims to analyze the effectiveness of safety facilities. The vehicle speed is a direct correlation traffic accident. So in this study, the MOE(Measure of Effectiveness) is average travel speed in the school zone. The results shows that hump, rised pedestrian crossing has an effect.

• Journal of the Korean Institute of Gas
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• v.24 no.6
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• pp.55-60
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• 2020

As research and development of eco-friendly vehicles are expanding worldwide, additional devices of vehicles are reduced or deleted to increase the mileage, or research is being conducted to reduce weight. Among them, the multi-stage transmission that was applied to the internal combustion engine vehicle was deleted and replaced with a reducer, and the initial driving power is secured by increasing the torque through the control of the motor output value. However, since frequent motor speed change can result in a load increase, this study attempts to develop a compact and lightweight manual two-stage reducer with a general reducer structure. Therefore, a two-speed transmission with two gear ratio was designed by inserting a large gear and a small gear in a structure with a parallel shaft to connect the gears with a V-belt in the form of a parallel shaft reducer, and setting the gear ratio of the low and high gears respectively. In addition, power performance according to the rotational speed and load of the transmission was checked through a test, and the heat generation characteristics generated during driving were checked to verify the validity of the transmission.

• Design & Manufacturing
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• v.16 no.4
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• pp.34-39
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• 2022

Sustained economic development around the world is accelerating resource depletion. Research and development of secondary batteries that can replace them is also being actively conducted. Secondary batteries are emerging as a key technology for carbon neutrality. The core of an electric vehicle is the battery (secondary battery). Therefore, in this study, the temperature change by the heat source of the hammer and the rotational speed (rpm) of the abrasive disc of the Classifier Separator Mill (CSM) was repeatedly calculated and analyzed using the heat flow simulation STAR-CCM+. As the rotational speed (rpm) of the abrasive disk increases, the convergence condition of the iteration increases. Under the condition that the inlet speed of the Classifier Separator Mill (CSM) and the heat source value of the disc hammer are the same, the disc rotation speed (rpm) and the hammer temperature are inversely proportional. As the rotational speed (rpm) of the disc increases, the hammer temperature decreases. However, since the wear rate of the secondary battery material increases due to the strong impact of the crushing rotational force, it is determined that an appropriate rpm setting is necessary. In CSM (Classifier Separator Mill), it is judged that the flow rate difference is not significantly different in the direction of the pressure outlet (Outlet 1) right above the classifier wheel with the fastest flow rate. Because the disc and hammer attachment technology is adhesive, the attachment point may deform when the temperature of the hammer rises. Therefore, it is considered necessary to develop high-performance adhesives and other adhesive technologies.

• International Journal of Highway Engineering
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• v.14 no.5
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• pp.165-177
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• 2012

PURPOSES: The number of traffic accidents in 2010 was 226,978 in Korea, a high percentage of which up to 12.61% was due to drunk driving. As it is expected that the number of traffic accidents will increase because of the drastic increase of the number of vehicle registrations and the prevalent drinking cultures, it is necessary to understand the driving characteristics of drunken drivers to lower the increasing rate. METHODS: This study, therefore, comparatively analyzes the two groups - one group before drinking and the other after drinking - based on the graph, and implements the correlation in each scenario(1,2,3). scenario 1. appearance of jaywalkers; scenario 2. appearance of an illegal left-turning car; and scenario 3. appearance of a vehicle and a person as obstacles to the driver after an accident. RESULTS: The comparative analysis of speed shows that the group after drinking was 50km/h faster than the group before drinking in Scenario 1, 20km/h in Scenario 2, and 15km/h in Scenario 3 respectively. In the comparative analysis of acceleration, the average level of the group after drinking was 0.15 higher than that of the group before drinking in Scenario 1, 0.30 in Scenario 2, and 0.15 in Scenario 3. In the comparative analysis of deceleration, the average level of the group after drinking was about 0.4 lower than that of the group before drinking in Scenario 1, 0.35 in Scenario 2, and 0.2 in Scenario 3 respectively. In the comparative analyses, the item of speed, acceleration and deceleration was of significance for each group in Scenarios. CONCLUSIONS: The comparative analysis demonstrated that there is a difference between the group before drinking and the group after drinking. In the analysis of correlation in each group, it was proved that the drunken group was of significance.