• 제어로봇시스템학회:학술대회논문집
• /
• 1997.10a
• /
• pp.1330-1333
• /
• 1997

In this paper, the optimal torque shaping is obtained for 3-axis rotation of a spacecraft. The true optimal 3-axis rotation of rigid spaeraft is first investigated via parameter optimization method with prescribed switching times. Input torque shape of the troque generating device mounted on the central hub is optimized using fourier Series expansion so that the spacecraft may slew while minimizing the vibration energy of flexible modes. Numerical results show that proposed method suggests a reference trahectory for open-loop control, and also verify that it can minimize the vibratory modes of the spacecraft during/after the rest-to-rest maneuver.

• 제어로봇시스템학회:학술대회논문집
• /
• 2003.10a
• /
• pp.762-766
• /
• 2003

In this paper, we present a new approach to solve the problem of estimating the camera 3-D location and orientation from a matched set of 3-D model and 2-D image features. An iterative least-square method is used to solve both rotation and translation simultaneously. Because conventional methods that solved for rotation first and then translation do not provide good solutions, we derive an error equation using roll-pitch-yaw angle to present the rotation matrix. To minimize the error equation, Levenberg-Marquardt algorithm is introduced with uniform sampling strategy of rotation space to avoid stuck in local minimum. Experimental results using real images are presented.

• Journal of the Korean Society for Railway
• /
• v.9 no.3 s.34
• /
• pp.277-281
• /
• 2006

The center pivot in the power car of KTX carries the traction force of the motor bogie to the carbody. The damage to the center pivot due to failure of swivel joint causes a serious hazard of the train. To prevent the hazard, information on the relative motion between bogie and carbody is necessary. In this paper, a method to measure the relative rotation of the center pivot is proposed and an actual test to verify the method and safety is conducted. The test results show that the rotation of the center pivot is within the allowable limit and the damage due to the relative motion doesn't take place.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.38A no.3
• /
• pp.224-239
• /
• 2013

An exact performance analysis of an ML detector for a 2-dimensional rotation-transform aided QPSK system operating over an impulsive noise environment is presented using Rieman integrals of a two-dimensional Gaussian Q-function over Voronoi cells. A set of interesting features of the Voronoi cells is also characterised systematically. An optimum rotation angle yielding the minimum BER is also studied. The differences between the proposed exact method and the previous approximate analysis method are investigated in terms of the corresponding BERs and the derived optimum angles.

• Proceedings of the KIEE Conference
• /
• 1999.07g
• /
• pp.2821-2823
• /
• 1999

In this paper we proposed an algorithm for rotation-invariant pattern recognition and rotated angle estimation between two patterns by employing selective template matching. Generally template matching has been used in determining the location of pattern but template matching requires a number of calculating correlation. To reduce the number of correlation we used steady-state genetic algorithm which is effective in optimization problem. We apply this method to distinguish specific pattern from similar coin patterns and estimate rotated angle between patterns. Our result leads us to the conclusion that proposed method performed faster than classical template matching

• Journal of Sensor Science and Technology
• /
• v.22 no.6
• /
• pp.393-399
• /
• 2013

We propose a method of sensing the rotation and distance of a camera by using a fisheye lens system as a vision sensor. We estimate the rotation angle of a camera with a modified correlation method by clipping similar regions to avoid symmetry problems and suppressing highlight areas. In order to eliminate the rectification process of the distorted points of a fisheye lens image, we introduce an offline process using the normalized focal length, which does not require the image sensor size. We also formulate an equation for calculating the distance of a camera movement by matching the feature points of the test image with those of the reference image.

• Korean Journal of Remote Sensing
• /
• v.24 no.6
• /
• pp.641-644
• /
• 2008

In order to improve a camera rotation calculation based on the bundle adjustment in Chon's camera motion (Chon and Shankar, 2007, 2008), this paper introduces a method calculating the camera rotation. It estimates a unit vector in the optical axis of a camera through the angles between the optical axis and vectors passing a camera position and ground control points (GCP). The camera position is estimated by using the inner product method proposed by Chon. The horizontal and vertical unit vectors of the camera are determined by using Yakimovsky and Cunningham's camera model (CAHV) (1978).

• Journal of the Korean Society for Nondestructive Testing
• /
• v.34 no.6
• /
• pp.447-456
• /
• 2014

In this paper, a new damage-detection method based on structural vibration is proposed. The essence of the proposed method is the detection of abrupt changes in rotation. Damage-induced rotation (DIR), which is determined from the modal flexibility of the structure, initially occurs only at a specific damaged location. Therefore, damage can be localized by evaluating abrupt changes in rotation. We conducted numerical simulations of two damage scenarios using a 10-story cantilever-type building model. Measurement noise was also considered in the simulation. We compared the sensitivity of the proposed method to localize damage to that of two conventional modal-flexibility-based damage-detection methods, i.e., uniform load surface (ULS) and ULS curvature. The proposed method was able to localize damage in both damage scenarios for cantilever structures, but the conventional methods could not.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.25 no.1
• /
• pp.197-208
• /
• 1998

This study was carried out to compare the amount of the maxillary bone remodeling and tooth displacement in each three maxillary superimposition methods, Ricketts, Best-fit, Structural method. Forty cases of the lateral cephalometric radiographs from 27 boys and 13 girls who had been treated to correct anterior cross-bite were selected for the study. The initial radiographs were taken at about 8-year-old and the second radiographs were taken in about 3.3 years later. Followings were the results: 1. With the Structural method, backward movement was shown in PNS, while forward movement was observed in ANS and point A. With the Ricketts method, however, all structures were shown significant backward movement comparing with Structural method(P<0.05). With the Best-fit method, the amount of horizontal movement was similar to that of the Structural method(P>0.05). 2. The palate seemed to be moved downward with Structural method, but there was no measured downward remodeling on nasal floor with Ricketts and Best-fit method(P<0.05). 3. Comparing with Structural method, Ricketts and Best-fit method significantly underestimated the eruption of the teeth by 20% to 30% (P<0.05). 4. The Structural method showed the anteroinferior rotation (43%) and posteroinferior rotation(57%) of the palatal plane, while the Best-fit method showed mostly anterosuperior rotation(87%), but no change was found in the Ricketts method. 5. With the Structural method, there was a statistically significant correlation between the amount of the rotation of the palatal plane and that of N-S line(r=0.86). 6. The measured angles of the long axis of the incisors and molars showed no significant difference in each 3 methods(P>0.05).

• Journal of Korean Association for Spatial Structures
• /
• v.13 no.2
• /
• pp.57-66
• /
• 2013

There are a number of construction methods to build spatial structures such as erection method, Element method, Block method, Sliding method, Lift-up method and Push-up method. These methods are uneconomical and low accuracy, and require long construction duration because of a need of a scaffold or a tower crane to build spatial roof frame. In this study, the construction method to erect a truss structure was proposed as an economical and easy installation method. The proposed method has end hinges of keel truss and winches with horizontal cable. This method makes safe and accurate production and reduces construction duration because trusses are built on the floor or supporter. The goal of this study is to verify the validity of construction method by building scale model using the proposed method.