• Proceedings of the Korean Society of Precision Engineering Conference
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• 1993.10a
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• pp.601-606
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• 1993

The natural frequency measurement of passenger car tire under the load and rotation are studied. In order to obtain theoretical natural frequency and mode shape, the plane vibration of a tire is modeled to that of circular beam. By using the Tickling method based on Hamilton's principle, theoretical results are determined by considering tension force due to tire inflation pressure, rotational velocity and tangential, radial stiffness. Modal parameters varying the inflation pressure, load, rotational velocity are determined experimentally by using frequency response function method. The results show that experimental conditions are parameter for shifting of natural frequency.

• Interaction and multiscale mechanics
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• v.4 no.1
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• pp.1-16
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• 2011

The inverse problem about the theoretical analysis of a drill string bending in a channel of an inclined bore-hole with localized geometrical imperfections is studied. The system of ordinary differential equations is first derived based on the theory of curvilinear flexible elastic rods. One can then use these equations to investigate the quasi-static effects of the drill string bending that may occur in the process of raising, lowering and rotation of the string inside the bore-hole. The method for numerical solution of the constructed equations is described. With the proposed method, the phenomenon of the drill column movement, its contact interaction with the bore-hole surface, and the frictional seizure can be simulated for different combinations of velocities, directions of rotation and axial motion of the string. Geometrical imperfections in the shape of localized smoothed breaks of the bore-hole axis line are considered. Some numerical examples are presented to illustrate the applicability of the method proposed.

• Journal of Sensor Science and Technology
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• v.26 no.4
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• pp.259-265
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• 2017

Magnetometer calibration must be performed before the use of three-axis magnetometers to ensure the accuracy of orientation estimation. Recently, one of the most popular calibration approaches is the ellipsoid fitting technique due to its high performance in calibration. To date, in fact, performances of the existing ellipsoid fitting methods have been evaluated with full range rotation data. However, in case of the calibration of magnetometers attached to vehicles, ships, and planes, it is very difficult to collect the full range rotation data since their allowable ranges in terms of roll and pitch are limited to small. This constraint may result in serious performance degradation of some ellipsoid fitting algorithms. Therefore, to be practical, this paper proposes a weighted least square-based magnetometer calibration method that is robust in roll-pitch limited conditions. Furthermore, the proposed method is a linear approach and thus is free from the well-known initial value issue in nonlinear approaches. Experimental results show the superiority of the proposed method to other ellipsoid-fitting calibration methods.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.5
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• pp.132-139
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• 2008

To meet demand of big capacity and high speed rotation for washing machine, more stress from bending and twisting are complexly loaded onto the shaft supporting the horizontal drum, causing problems in fracture strength and fatigue life. Also, Vibration occurs due to the frequency of the rotating parts. But, shaft has various design factors such as diameter and distance between bearings according to configuration of shaft, the optimal values can't be easily determined. Using a design of experiment (DOE) based on the FEM (Finite Element Method), which has several advantages such as less computing, high accuracy performance and usefulness, this study was performed investigating the interaction effect between the various design factor as well as the main effect of the each design factor under bending, twist and vibration and proposed optimum design using center composition method among response surface derived from regression equation of simulation-based DOE.

• IE interfaces
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• v.24 no.3
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• pp.258-266
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• 2011

In this paper, we deal with a problem improving the productivity of a discrete production line for filling a printer cartridge with toner. We develop a new technology for controlling the weight of toner which must be filled in a cartridge and reform the current line based on our new control technology to result in more than 35% improvement of productivity as well as the control accuracy. In detail, first, we find a bottleneck process, the toner-filling process which gives the current production cycle times. Second, we divide the processing time of the bottleneck into several work elements and find the rotation time of an AC servomotor to be further reduced. Third, in order to reduce the rotation time, we develop a mathematical control-time model for determining the rotation time. Finally, we reform the current line partially as required by the change of the new control method.

• Structural Engineering and Mechanics
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• v.2 no.3
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• pp.257-267
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• 1994

Motions of an unsymmetric rigid body on a rigid floor subjected to earthquake excitations with special attention to coefficient of friction are investigated. Motions of a body in a plane are classified (Ishiyama 1980) into six types, i.e. (1) rest, (2) slide, (3) rotation, (4) slide rotation, (5) translation jump, (6) rotation jump. Based upon the theoretical and experimental research work special attention is paid to the sliding of a body. The equations of motions and the behavior of coefficient of friction in the time of floor excitation are studied. One of the features of this investigation is the introduction and estimation of the "time dependent" coefficient of friction. It has been established that the constant kinetic coefficient of friction $${\mu}(kin){\sim_\sim}0.8{\mu}(stat)$$ does not give the appropriate results. The method for the estimation of the friction coefficient variation during the time is given.

• Proceedings of the IEEK Conference
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• 2000.07a
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• pp.446-449
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• 2000

A direct RTI(Rotation and translation invariant) fingerprint identification is proposed using the GCMs(generalized complex moments) and Gabor filter-based features from the grey level fingerprint around core point. The core point is located as reference point for the translation invariant matching. And its symmetry axis is detected for the rotation invariant matching from its neighboring region centered at the core point. And then, fingerprint is divided into non-overlapping blocks with respect to the core point and, in contrast to minutiae-based method using various processing steps, features are directly extracted from the blocked grey level fingerprint using Gabor filter, which provides information contained in a particular orientation in the image. The Proposed fingerprint identification is based on the Euclidean distance of the corresponding Gabor features between the input and the template fingerprint. Experiments are conducted on 300 ${\times}$ 300 fingerprints obtained from the CMOS sensor with 500 dpi resolution, and the proposed method could obtain 97% identification rate.

• Proceedings of the IEEK Conference
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• 2000.09a
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• pp.901-904
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• 2000

A direct authentication from gray-scale image, instead of the conventional multi-step preprocessing, is proposed using Gabor filter-based features from the gray-scale fingerprint around core point. The core point is located as a reference point for the translation invariant matching. And its principal symmetry axis is detected for the rotation invariant matching from its neighboring region centered at the core point. And then fingerprint is divided into non-overlapping blocks with respect to the core point and features are directly extracted form the blocked gray level fingerprint using Gabor filter. The proposed fingerprint authentication is based on the Euclidean distance between the corresponding Gabor features of the input and the template fingerprints. Experiments are conducted on 300${\times}$300 fingerprints obtained from a CMOS sensor with 500 dpi resolution, and the proposed method could lower the False Reject Rate(FRR) to 18.2% under False Acceptance Rate(FAR) of 0%.

• Journal of Institute of Control, Robotics and Systems
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• v.16 no.4
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• pp.339-345
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• 2010

This paper introduces GP(Genetic Programming) based robust corner detectors for scaled and rotated images. Various empirical algorithms have been studied to improve computational speed and accuracy including approaches, such as the Harris and SUSAN, FAST corner detectors. These techniques are highly efficient for well-defined corners, but are limited to corner-like edges which are often generated in rotated images. It is very difficult to detect correctly edges which have characteristics similar to corners. In this paper, we have focused the above challenging problem and proposed Genetic Programming-based automated generation of corner detectors which is robust to scaled and rotated images. The proposed method is compared to the existing corner detectors on test images and shows superior results.

• Journal of Korea Entertainment Industry Association
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• v.14 no.7
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• pp.651-658
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• 2020

The basic medical subjects are essential for the understanding of the major in the department of health science and are very important. Anatomy is one of the fundamental areas of medical education. On the other hand, the application of new teaching method is being attempted in various fields. Station rotation model, one of the blended learning, is also one of the popular teaching method. Station rotation model allows students to rotate through stations on a fixed schedule, where at least one of the stations is an online learning station. This study investigate the satisfaction of students when applying station rotation model to anatomy class. Each station in the station rotation model consisted of VR application learning, online problem solving, model observation and oral test. After applying station rotation model (2 weeks) to the 'Functional anatomy and Practice' course taken by 37 students of the'Department of Occupational Therapy'at H University, this study conducted a satisfaction survey compare with lecture class for students taking the course. At the result, station rotation model was significantly higher than lecture class in both understanding, interest, concentration and diversity degree. Based on these results, I suggest applying the station rotation model to the anatomy class because it also showed high satisfaction in that.