• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.11
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• pp.1309-1315
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• 2014

The switch for a maglev vehicle should be designed such that the vehicle safely changes its track without touching the guiderail. In particular, a medium-to-low-speed EMS -type maglev train relies heavily on a U-type electromagnet where it generates levitation force and guidance force simultaneously. Therefore, it is necessary to evaluate the safety of the vehicle whenever it passes the switch, as it lacks active control of the guidance force. Furthermore, when the vehicle passes a segmented switch, which is a group of curves made up of connected lines with a small radius of curvature, it may come into mechanical contact with the guiderail owing to the excessive lateral displacement of the electromagnet. The goal of this study is to analyze the influence of a segmented switch on the safety of major design-related variables for achieving improved running safety. We propose a three-dimensional multibody dynamics model composed of two cars with one body. Using the proposed model, we perform a simulation of the lateral air gap, which is one of the measurements of the running safety of the vehicle when it passes the switch. The analyzed design variables are the length between short span girder, the articulation angle, the length between two centers of a fixed girder at its ends, and the number of girders. On the basis of the effects of the considered design variables, we establish an optimized design of a switch with improved safety.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.10
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• pp.345-353
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• 2020

On conventional railway lines, trains with different speeds are operated. Therefore, trains moving on curved sections with cants must accept various ranges of balanced cants, cant deficiency, and cant excess, which is essential for the comfort and safety of train operation. In this study, the correlation between the curve radius, cant, and train speed on a track was analyzed to check the cant range that satisfies the criteria of train types, operation speed, cant deficiency, and cant excess. Also, the range of setting the cant by the curve radius and balanced cant were calculated by a regression analysis of train speed according to the frequency of operation in the case of mixed trains. The results could make it possible to improve the speed of the operation route, reduce the loss of ride quality, reduce the risk of derailing caused by cant deficiency, and minimize the load deflection by excess cant. This will ensure the safety of trains running on curves and improve the efficiency of track maintenance.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.3
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• pp.317-326
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• 2016

In this study, running stability and ride quality analyses, applying the 'ISO 3888 (double lane change)' and 'ISO 2631-1' (mechanical vibration and shock) tests, were performed for the suspension optimization of the Korean personal rapid transit (PRT) vehicle. The suspension optimization results for running stability and ride quality were derived by applying the multiresponse surface method. From the comparisons of the optimization results for different ratios of the objective functions of running stability and ride quality, we derived the best objective function ratio of 3.9-to-6.1 to improve both the running stability and the ride quality. With the optimized results, the suspension stiffness became 30.68 N/mm, between the value of the $S_2$ and $S_3$ models, and the damping coefficient equaled that of the $D_1$ model. When compared with the suspension of the current PRT vehicle, the roll angle, yaw rate, sideslip angle, and ride comfort were improved by 0.37, 0.37, 2.8, and 5, respectively.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.39-45
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• 2008

A levitation rail is placed on the top of track structure to operate Maglev vehicles and a part of track that link up with a sleeper is applied repeated load in Maglev vehicles operation. This paper aimed to verify validity of design for levitation rail, through the fatigue analysis about load which is applied to levitation rail in Maglev vehicles operation and impact load occurring in an emergency landing. Load conditions applied design load(23kN/m) in normal operation and skid drop load(24kN/m) in vehicle drop. And boundary conditions are consider bolt fixing and welding. Through static analysis, weak point and maximum stress of levitation rail could be obtained. S-N(stress-life) method was used in oder to predict fatigue life, and Goodman relationship was applied to consider a effect of mean stress. Also damage was calculated by using Miner's. As a result of fatigue analysis, levitation rail had a fatigue life which was more than requirement ($10^6$cycle) in all analysis conditions. Assumption that $10^8{\sim}10^9$cycles is infinite life, all analysis conditions had infinite life except a case under drop load and bolt fixing($1.21{\times}10^6$).

• Journal of Korean Society of Forest Science
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• v.100 no.2
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• pp.154-164
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• 2011

This study was conducted to develop the semi-crawler type mini-forwarder that can be operated comfortable small-scale logging operation in the steep terrain and also used at a variety of operations such as the civil work in erosion control and forest-road. Considering the minimum turning radius and the width of forest operation road, the total length, width and loading capacity of the semi-crawler type mini-forwarder is 5,750 mm, 1,900 mm and $2.5m^{3}$, respectively. The maximum engine power is 96ps at 3600 rpm. Selected hydraulic pumps are consists of two main pumps and two sub-main pumps. Main hydraulic pumps are utilized to running motor of the front wheel and rear crawler. Sub-main pumps are utilized to the actuation parts such as steering, crane, out-rigger and dump cylinder. The transmission was adapted as the HST (Hydro-Static Transmission) system. The driving parts are designed and manufactured as the front wheel type and the rear crawler type. The steering type was manufactured as the ackerman type. Driving control parts type was designed and manufactured as driver's seat type of normal cars. It is also attached on auxiliary equipments such as winch, log grapple and out-rigger. The traveling speed of the semi-crawler type mini-forwarder in forest road was 5.3 km/hr to 7.7 km/hr.

• Journal of Advanced Marine Engineering and Technology
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• v.17 no.5
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• pp.44-53
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• 1993

In this paper, we discuss on the control algorithm to make the wheeled inverse pendulum type mobile robot move in two dimensional plane. The robot considered in this paper has two independently driven wheels in same axel which suport and move it-self, and is assumed to have the fyro type sensor to know the inclination algle of the body and rotary encoders to know wheel's rotation angular velocity. The control algorithm is divided into three parts. The first part is for the posture and velocity control for forward-backward direction, the second is the steering control, and the last part is for the control of total system to track the given trajectory. We handle the running velocity control of the robot as part of the posture control to keep the balance because the posture relates deeply with the velocity and can be controlled by the velocities of the wheels. The control problem is analyzed as the tracking control, and the controller is realized with the state feedback and feed-forward of the reference velocity. Constructing the control system which contained one intergrator in forward path, we also realized the control system without observer for the estimation of the accumulated errors in the inclination angle of the body. To prevent the robot from being unstable state by sudden variation of the reference velocity when it starts and stops, or changes velocity, the reference velocity of which acceleration is slowly changing, is ordered to the robot. To control its steering, we give the different reference velocities for both wheels which are calculated from the desired angular velocity of the body. Finally, we presents the experimental results of the experimental robot Yamabico Kurara in which the proposed control algorithm had been implemented.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.555-560
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• 2003

Korean High Speed Train(KHST) has been tested on the high speed test line in Osung site of Korea High Speed Rail Construction Authority (KHRC). since it was developed as G7 Project Plan In 2002. This paper introduces the dynamic test devices in KHST and shows the comparison between the results of test and theoretical computing results which derive from the new model for KHST dynamic behavior. Previous computer simulation model for KHST was developed to review wether the vehicle system was satisfied with the dynamic performance requirements during the design procedure. But It should be applied the results of the parts test for suspension elements in order to compare between the results of computation and real test. Using VAMPIRE Program made by AEA Technology in UK. the new model also was modified. This paper shows that the static wheel loads calculated from new model is similar to test results. For test on high speed line, we prepared the test devices for evaluating the dynamic performances. which was consisted of the accelerometers( based on Kisler Co.) and the data aquisition systems (based on National instrument Co.), and test program coded by LabView 6i program. These lest devices and programs are flexible to extension the channels for adding sensors and connect to the ethernet network. The acceleration of car bodies, bogie frames and axle boxes were compared between the results of computation and test at 150km/. This paper shows that the results of test were high in high frequency band range but similar frequency band range. It might be considered that these differences were caused by the test which did not performed at constant speed for comparison analysis. Also. It will be able to understand the differences and make better results through a lot of tests planed in future.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.4
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• pp.1523-1531
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• 2011

Multi-axle driving vehicle are favored for military use in off road operations because of their high mobility on extreme terrains and obstacles. Especially, Military Vehicle needs an ability to driving on hills of 60% angle slope. This paper presents the improvement of the ability of hill climbing for 6WD/6WS vehicle through the optimal tire force distribution method. From the driver's commands, the desired longitudinal force, the desired lateral force, and the desired yaw moment were obtained for the hill climbing of vehicle using optimal tire force distribution method. These three values were distributed to each wheel as the torque based on optimal tire force distribution method using friction circle and cost function. To verify the performance of the proposed algorithm, the simulation is executed using TruckSim software. Two vehicles, the one the proposed algorithm is implemented and the another the tire's forces are equivalently distributed, are compared. At the hill slop, the ability to driving on hills is improved by using the optimum tire force distribution method.

• The Transactions of the Korean Institute of Power Electronics
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• v.16 no.5
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• pp.494-502
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• 2011

Bimodal tram is designed to run on a dedicated path in automatic mode using a magnetic track system in order to realize a combination of the accessibility of a bus and the constant regularity of a railroad. This paper presents design and test results of the series hybrid propulsion system of the bimodal tram on both test track and public road, which uses CNG (Compressed Natural Gas) engine and Lithium polymer battery pack. This paper describes the real-time data measuring equipment for the series hybrid propulsion system of the bimodal tram. Using this measurement equipment, the performance of the prototype vehicle's driving on test track and public road was verified and the fuel consumption and the efficiency of CNG engine have been investigated.

• Journal of the Korean Geotechnical Society
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• v.23 no.6
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• pp.115-126
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• 2007

The tilting-train is very attractive to the railroad users in the world because it runs with high speed in curved track using pre-existing infrastructure. The tilting-train has a unique allowable speed and mechanism expecially in curved track. Therefore, it should be evaluated in terms of the stability of the train operation and roadbed. In this study, when the tilting-train is being operated with the allowable speed, the behavior of the roadbed is evaluated by examining the settlement and bearing capacity of the roadbed. Additionally, the stability of the roadbed is estimated in the condition of soft roadbed influenced by the weather effects and cyclic train loading. The numerical results show that the roadbed settlements satisfy the allowable settlement when Young's moduli of the upper roadbed and in-situ soil are more than $2,300t/m^2\;and\;3,300t/m^2$, respectively, in the continuous welded rail (CWR) and $3,800t/m^2\;and\;4,600t/m^2$, respectively, in the rail joint.