• Plant Journal
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• v.13 no.1
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• pp.30-36
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• 2017

During the start-up of 500 MW class coal-fired power plant, abnormal shaft vibration was occurred on bearings installed on both side of high and intermediate pressure steam turbine. Shaft vibration was analyzed to investigate the reason and find the resolution, based on well-known theory in this study. Typical vibration characteristics which occur when rotating parts contact with stationary parts were observed at the analysis of frequency, amplitude and phase angle. The reason of abnormal vibration was assumed to be rub and internal parts wear was observed during repair period. As a result of applying low speed turning and balancing for resolution of abnormal vibration, balancing was more effective for rub removal. So balancing could be excellent resolution in the case of abnormal vibration which is similar to this study.

• Journal of Institute of Control, Robotics and Systems
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• v.18 no.4
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• pp.365-370
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• 2012

Most path planning algorithms for a marine robot in the ocean environment have been developed without considering the robot's heading angle. As a result, the robot has a difficulty in following the path correctly. In this paper, we propose a limit-cycle circle set that applies to the $Theta^*$ algorithm. The minimum turning radius of a marine robot is calculated using a limit-cycle circle set, and circles of this radius is used to generate a configuration space of an occupancy grid map. After applying $Theta^*$ to this configuration space, the limit-cycle circle set is also applied to the start and end nodes to find the appropriate path with specified heading angles. The benefit of this algorithm is its fast computation time compared to other 3-D ($x,y,{\theta}$) path planning algorithms, along with the fact that it can be applied to the 3-D kinematic state of the robot. We simulate the proposed algorithm and compare it with 3-D $A^*$ and 3-D $A^*$ with post smoothing algorithms.

• Journal of the Korean Institute of Intelligent Systems
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• v.11 no.5
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• pp.367-372
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• 2001

This paper proposes a hierachically structured navigation algorithm for multiple mobile robots under unknown dynamic environment. The proposed algorithm consists of three basic parts as follows. The first part based on the fuzzy rule generates the turning angle and moving distance of the robot for goal approach without obstacles. In the second part, using both fuzzy and neural network, the angle and distance of the robot to avoid collision with dynamic and static obstacles are obtained. The final adjustment of the weighting factor based on fuzzy rule for moving and avoiding distance of the robots is provided in the third stage. Some simulation results show the effectiveness of the proposed algorithm.

• Journal of the Korean Institute of Intelligent Systems
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• v.13 no.2
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• pp.180-185
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• 2003

This paper proposes an intelligent navigation algorithm for multiple mobile robots under unknown dynamic environment. The proposed algorithm consists of three basic parts as follows. The first part based on the fuzzy rule generates the turning angle and moving distance of the robot for goal approach without obstacles. In the second part, using both fuzzy and neural network, the angle and distance of the robot to avoid collision with dynamic and static obstacles are obtained. The final adjustment of the weighting factor based on fuzzy rule for moving and avoiding distance of the robots is provided in the third stage. The experiments which demonstrate the performance of the proposed intelligent controller is described.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.4
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• pp.125-134
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• 2003

In this study, Mooney-Rivlin 1st model and Mooney-Rivlin 3rd model are adopted as strain energy density functions of the rubber compounds of a radial tire. It is shown that the FE analysis using Mooney-Rivlin models for rubber compounds may provide good approximations by employing the appropriate strain range of experimental stress-strain data in a way to describe the stress-strain relationship accurately. Especially, Mooney-Rivlin 3rd model gives an accurate stress-strain relationship regardless of the fitting strain range used within the strain of 100%. The static nonlinear FE analysis of a tire inflation is performed by employing an axisymmetric model, which shows that the outside shapes of the tire before and after inflating the tire agree well with those of the real tire. Additionally, the deformations at crown center and turning point on sidewall, distribution of belt cord force, interlaminar shear strain are predicted in terms of variation of belt cord angle which is known as the most influential factor in inflation behavior of a tire.

• Journal of Navigation and Port Research
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• v.36 no.8
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• pp.613-618
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• 2012

For the tug-barge simulation, captive model test(Horizontal Planar Motion Mechanism) of the barge model is carried out. From the result of HPMM test, a resistance coefficient, maneuvering coefficients of the barge are obtained. A mathmatical model of the barge is validated by turning simulations with different angle of towing line applied a simple towing line model and the tactical diameter compared to sea trial data. As a result, the tactical diameter of the barge is smaller as the angle of towing line is bigger. The tactical diameter from simulations is smaller than that from sea trial data, may be caused by increased displacement of the barge.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.5
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• pp.3060-3070
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• 2015

Recently, novice driver or weak drivers was difficult to understand the movement characteristics of the car and are immature sense of width and length of the car according to various each driver's sex and age, model. To complement this problem, the use of rear sensor and the camera is increased. And the parking assistance system that improves the convenience of parking the driver is being developed. Accordingly, parking guide system is needed to reflect the difference in the steering angle and correct the error distance. In this study, it is proposed that the turning radius during backward by complementing the existing Ackerman Jentaud type. And it develops more accurate parking guideline to be able to generat algorithm by applying the formula to propose a steering wheel angle sensor value derived through the handle.

• Journal of the Korean Society for Precision Engineering
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• v.11 no.2
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• pp.182-188
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• 1994

This expermintal study is intended to investigate he development of flank wear in turning os SUS304 which is used in industrial applications and is acknowledged as a machining difficult material. In cutting process, change of velocity, change of feed, and change of depth of cut were investigated about the effect of flank wear, and slenderness ratio is also investigated. The variations of unit cutting force with the change of rake angle and the change of uncut chip area are observed. The friction angles are calculated for the change friction force and observed. The friction angles are calculated for the change friction force and normal forcd on the different rake angles. From this experimental study, the following results can be said. 1. Under the high cutting speed condition, the flaank wear is affected by the feed and depth of cut, but the influence of feed and depth of cut to the flank wear is reduced when the velocity is low. 2. The smaller slenderness ratio is, the shorter the tool life results in high cutting speed, and the lower cutting speed is, the lower the effect of slenderness ratio to the flank wear is. 3. Using the characteristics of force-RMS, the flank wear of a tool can be detected. There are almost no differences between the RMS characteristics of cutting force and feed force.

• Journal of the Society of Naval Architects of Korea
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• v.61 no.1
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• pp.29-43
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• 2024

The present study concerns a feasibility study for applying principal component analysis to ship dynamics in maneuver. Using the four degrees of freedom standard modular model for ship dynamics maneuver simulations of large angle zigzag tests with rudder deflection angle variations are conducted. The datasets of ship motion, hydrodynamic force, and moment during the maneuver are acquired to identify the principal modes. The covariance matrix of obtained ship dynamics variables shows a strong linear correlation between the motion, hydrodynamic force, and moment, except the surge force. Four eigenvectors of the covariance matrix are selected as the principal modes of ship dynamics. Using the principal modes, ship motion in turning circle and zigzag tests is reconstructed, showing good agreement with the original data.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.51-56
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• 2011

The train travels on the track and, thus, the rear wheels precisely follow the paths of the front wheels. On the contrary, in the vehicles running on the road like automobiles, buses and trucks, the front wheels try to drag the rear ones toward them and across the inside of the curve. Off-tracking is defined as the radial offset between the path of the centerline of the front axle and the path of the centerline of the following axle. In the case of the bimodal tram with AWS(all wheel steering), the off-tracking decrease but the rear swing-out values increase because of the rear steering at the reverse phase angle. Thus, in order to determine the swept path width, maximum road width at the minimum turning radius, off-tracking and swing-out should be considered for the bimodal tram. In this paper, trajectory simulations were carried out for the various condition such as front steering, front and rear steering and suppression of swing-out to optimize the swept path width.