• Journal of the Korean Society for Precision Engineering
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• v.28 no.3
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• pp.330-338
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• 2011

Odometry is the critical factor to estimate the location of the robot. In the mobile robot with wheels, odometry can be performed using the information from the encoder. However, the information of location in the encoder is inaccurate because of the errors caused by the wheel's alignment or slip. In general, visual odometer has been used to compensate for the kinetic errors of robot. In case of using the visual odometry under some robot system, the kinetic analysis is required for compensation of errors, which means that the conventional visual odometry cannot be easily applied to the implementation of the other type of the robot system. In this paper, the novel visual odometry, which employs only the single camera toward the ground, is proposed. The camera is mounted at the center of the bottom of the mobile robot. Feature points of the ground image are extracted by using median filter and color contrast filter. In addition, the linear and angular vectors of the mobile robot are calculated with feature points matching, and the visual odometry is performed by using these linear and angular vectors. The proposed odometry is verified through the experimental results of driving tests using the encoder and the new visual odometry.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.348-356
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• 2004

In this paper, Analysis of parameters effecting on the derailment factor was conducted in oder to deduce technical requisites have to be reflected in design of Track and rolling-stocks because it is important to grasp the risk of derailment quantitatively. And then go far toward becoming practical study with that select two section of sharp curved track of actual train in service, incheon Metro Line 1 and make field research in condition of vehicles and track and analysis As a result of parameter study, the following conclusions were obtained. The radius of curve and Cant is in inverse proportion to the derailment factor, but as train operation velocity, standard deviation of alignment irregularity and the ratio lateral force : wheel load of the inside track increase, the derailment factor rise. In the investigation for the derailment safety of incheon Metro Line 1, the derailment factor was below 0.43 in both section R=200 and R=300, so that it proved safe compare with allowance limits 0.8, but it appeared that risk of the derailment in second transition curve is the highest among the entire curve.

• Journal of Korean Society of Steel Construction
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• v.20 no.1
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• pp.151-163
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• 2008

A formulation of three-dimensional model of articulated train-b ridge dynamic interaction has been made for the Korean eXpress Train (KTX). Semi-periodic profiles of rail irregularities consisting of elevation, alignment, cross and gauge irregularities have also been proposed using FRA maximum tolerable rail deviations. The effects of rail joints and sleeper step were also included. The resulting system matrices of train and bridge are very spare, and thus, are stored in one-dimensional arrays, yielding a time-efficient solution. A numerical algorithm for computing bridge-train response including an iterative scheme is also formulated. A program simulating train-bridge interaction and solving this problem using the new algorithm is implemented as new modules for the f inite element analysis software named XFINAS. Computed results using the new program are then checked by that of the validated 2-D bridge-train interaction model. This new 3D analysis provides more detailed train responses such as swaying, bouncing, rolling, pitching and yawing accelerations, which are useful inevaluating passenger riding comfort. Train operation safety and derailment could also be directly investigated by relative wheel displacements computed from this program.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.806-811
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• 2005

The robot to search and rescue is used in narrow space where human cannot approach. In case of this robot, it can overcome obstacles such as wrecks or stairs etc. Also, this robot can do various locomotion for each object. In this reason, an articulated robot has advantages comparing with one module robot. However, the existing articulated robot has limits to overcome vertical passages. For expanding contacted territory of robot, a novel mechanism is demanded. In this paper, the novel mechanism of articulated mobile robot is designed for moving level ground and vertical passages. This paper proposes to change wheel alignment. The robot needs two important motions for passing vertical passages like pipe. One is a motion to press wheels at wall for not falling into gravity direction. The other is a motion that wheels contact a vertical direction of wall's tangential direction for reducing loss of force. The mechanism of the robot focused that two motions can be acted to use just one motor. Length of each link of robot is optimized that wheels contact a vertical direction of wall's tangential direction through kinematic modeling of each link. The force of pressing wall of robot is calculated through dynamic modeling. This robot composes four modules. This mechanism is confirmed by dynamic simulation using ADAMS program. The articulated mobile robot is elaborated based on the results of kinematic modeling and dynamic simulation.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.27 no.1
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• pp.28-35
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• 2017

Recently, conventional hydraulic car lift systems face the technological limitations due to a lack of height control. The demand for height controllability is required in many tasks such as wheel alignment, and requires compensation for the structural deformation of the lift caused by irregular load distribution. In order to resolve this limitation of the conventional car lift, in this work, a new type of a hydraulic vehicle lift using a magneto-rheological (MR) valve system is proposed and analyzed. Firstly, the dynamic model of vehicle lift is formulated to evaluate control performance; subsequently, an MR valve is designed to obtain the desired pressure drop required in the car lift. Next, a proportional-integral-derivative (PID) controller is formulated to achieve accurate control of the lifting height and then computer simulations are undertaken to show accurate height control performances of the proposed new car lift system.

• Plant Journal
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• v.4 no.3
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• pp.66-72
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• 2008

The vibration of steam turbine is caused by Mass unbalance, Shaft misalignment, Oil whip and rubbing etc. But in turbine which is normally operated and maintained, the Mass unbalance component possesses the greatest portion. Our power plant has two steam turbines in capacity of 200 MW and 135 MW respectively and each turbine is supported by 6 journal bearings. However, we had many difficulties because the vibration amplitude of #3 and #4 Bearings was high during the start-up and operation mode change of steam turbine. But, with this study, we completely solved the vibration problem caused by the mass unbalance of #1 steam turbine. Until a recent date, #3 and #4 bearings which support high pressure turbine for #1 steam turbine had shown about $135{\mu}m$ in vibration amplitude (sometimes it increased to $221{\mu}m$ maximum. alarm: 6 mils, trip: 9 mils) at base load. After applying the study, they decreased to about $45{\mu}m$ maximum. It is a result from that we did not change the setting value of bearing alignment and only changed the assembly position of internal parts in Synchro clutch coupling rachet wheel which links between high pressure turbine and low pressure turbine, and increased the internal gap and machining of the Pawl cage surface. In the operation of steam turbine, if the vibration value increases by 1X, we should reduce the vibration of bearing by weight balancing. However, unless the vibration of bearing is declined by the balancing, we will have to disassemble and check the component and find the cause. In this study, we researched the way to lower mass unbalance that is 1X vibration component which has the greatest portion of vibration generated by steam turbine and we got good result by applying the findings of this study.

• The Bulletin of The Korean Astronomical Society
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• v.35 no.1
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• pp.36.2-36.2
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• 2010

The CQUEAN (Camera for QUasars in EArly uNiverse) is an optical CCD camera optimized for observation of high redshift objects. It is going to be attached to the cassegrain focus of 2.1m telescope at McDonald Observatory, USA. We are making a focal reducer for CQUEAN to secure a larger field of view. The focal reducer is composed of four spherical lens, and it reduces the focal length of telescope by one third. We designed the lens configuration, performed tolerance analysis, and estimated the optical performance with ZEMAX. The differences in optical performace with/without filters were also investigated. The result from ZEMAX shows that the system has ample margin of errors for median seeing of 1.2" at McDonald observatory. Even with aberration and alignment tolerance, the performance is better than the original requirement. The lenses are now being made, and the lens barrel and an adapter for assembly of the Andor CCD camera and the filter wheel is now under designing process. We expect that the manufacturing of the focal reducer system as well as its optical test will be finished by April 2010.

• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.232-235
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• 2008

The vibration of steam turbine is caused by Mass Unbalance, Shaft Misalignment, Oil Whip and Rubbing etc. but in turbine which is normally operated and maintained, the Mass Unbalance component possesses the greatest portion. Our power plant has two steam turbines in capacity of 200MW and 135MW respectively and each turbine is supported by 6 journal bearings. However, we had many difficulties because the vibration amplitude of No 3 and 4 Bearings was high during the start-up and operation mode change of steam turbine. But, with this study, we completely solved the vibration problem caused by the mass unbalance of No 1 steam turbine. Until a recent date, No 3 and 4 bearings which support high pressure turbine for No 1 steam turbine had shown about 135${\mu}$m in vibration amplitude (sometimes it increased to 221${\mu}$m maximum. alarm: 6mils, trip: 9mils) at base load. After applying the study, they decreased to about 40${\mu}$m maximum. It is a result from that we did not change the setting value of Bearing Alignment and only changed the assembly position of internal parts in Synchro Clutch Coupling Rachet Wheel which links between high pressure turbine and low pressure turbine, and increased the internal gap and machining of the Pawl stopper surface. In the operation of steam turbine, if the vibration value increases by 1X, we should reduce the vibration of bearing by weight balancing. However, unless the vibration of bearing is declined by the balancing, we will have to disassemble and check the component and find the cause. In this study, We researched the way to lower mass unbalance that is 1X vibration component which has the greatest portion of vibration generated by steam turbine and We got good result by applying the findings of this study.