• 제어로봇시스템학회:학술대회논문집
• /
• 1996.10b
• /
• pp.268-272
• /
• 1996

Error correction effect for maladjusted stereo cameras with calibrated pixel distance parameter is presented. The camera calibration is a necessary procedure for stereo vision-based depth computation. Intra and extra parameters should be obtain to determine the relation between image and world coordination through experiment. One difficulty is in camera alignment for parallel installation: placing two CCD arrays in a plane. No effective methods for such alignment have been presented before. Some amount of depth error caused from such non-parallel installation of cameras is inevitable. If the pixel distance parameter which is one of intra parameter is calibrated with known points, such error can be compensated in some amount. Such error compensation effect with the calibrated pixel distance parameter is demonstrated with some experimental results.

• Journal of The Korean Society of Integrative Medicine
• /
• v.5 no.2
• /
• pp.11-17
• /
• 2017

Purpose : The aim of this study was to verify differences in cervicocephalic joint position sense error after different sustained sitting postures in healthy young adults. Methods : Twenty-five healthy adults(12 men, 13 women) participated in this study. Repositioning errors of neck movement were observed in participants during joint repositioning tasks. During 2 test days with a 1-week interval, the participants performed forward head posture and upright sitting posture in random order. Both head-to-neutral(HTN) and head-to-target(HTT) tasks were performed on each day. On the first day, the participants sat slouched or upright for 10 minutes. Then, they sat upright and moved their heads at a self-selected speed with their eyes-closed to pre-determined neutral and target positions as accurately as possible. The participants noticed that when they reached a pre-determined position, the errors between pre-determined neutral and target positions and current position was recorded. The tasks consisted of flexion, extension and lateral bending. On the second day, the same test was performed after another sitting posture for 10 minutes. Repositioning error values were collected by using a smart phone-based inclinometer. The mean value for three trials was used for data analysis. A paired t-test was used for statistical analysis. Results : Significant differences in joint repositioning errors were found between the repositioning error after different sitting postures on the sagittal plane for both the HTN and HTT tasks (P<.05). No significant differences in errors on the coronal plane were found (P>.05). Conclusion : Cervicocephalic joint position sense can be affected by sitting postures, especially on the sagittal plane.

• Journal of information and communication convergence engineering
• /
• v.6 no.3
• /
• pp.320-322
• /
• 2008

We present efficient algorithms for solving the piecewise-cubic approximation problems in the plane. Given a set D of n points in the plane, we find a piecewise-cubic polynomial curve passing through only the points of a subset S of D and approximating the other points using the uniform metric. The goal is to minimize the size of S for a given error tolerance $\varepsilon$, called the min-# problem, or to minimize the error tolerance $\varepsilon$ for a given size of S, called the min-$\varepsilon$ problem. We give algorithms with running times O($n^2$ logn) and O($n^3$) for both problems, respectively.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1994.10a
• /
• pp.515-518
• /
• 1994

Holographic interferometry is a useful whole-field nondestructive testing for measuring deformations and vibrations of engineering structure. A diverging beam is used as a light source int the most of holographic interferometer practically. For a relatively small object the optical arrangement using a collimated light source has no difficulty in use technically, but for a large object it is difficult to use a collimated beam. In this study we calculate the error of measured displacement from the sensitivity vector dominated by the geometry of optical arrangement for holographic interferometer and show the result obtained with 2-D plots. A Plane surface and a cylindrical surface were chosen as objects to be calculated and computer analysis was carried out for the cases of a diverging beam and a collimated one.

• Journal of KIISE:Computer Systems and Theory
• /
• v.36 no.1
• /
• pp.21-25
• /
• 2009

In this paper, we study the problem to fit a piecewise-quadratic polynomial curve to points in the plane. The curve consists of quadratic polynomial segments and two points are connected by a segment. But it passes through a subset of points, and for the points not to be passed, the error between the curve and the points is estimated in $L^{\infty}$ metric. We consider two optimization problems for the above problem. One is to reduce the number of segments of the curve, given the allowed error, and the other is to reduce the error between the curve and the points, while the curve has the number of segments less than or equal to the given integer. For the number n of given points, we propose $O(n^2)$ algorithm for the former problem and $O(n^3)$ algorithm for the latter.

• Smart Structures and Systems
• /
• v.3 no.2
• /
• pp.173-188
• /
• 2007

The general solution for two-dimensional magneto-electro-elastic media in terms of four harmonic displacement functions is proposed analytically. The expressions of specific solutions of magneto-electro-elastic plane problems with specific body forces are derived. Finally, based on the general solution in the case of distinct eigenvalues and the specific solution for density functionally gradient media, two kinds of beam problems with body forces depending only on the z or x coordinate are solved by the trial-and-error method.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.3 no.3
• /
• pp.541-546
• /
• 1999

The head-related transfer function (HRTF), which expresses the acoustic process from the sound source to the human ears in the free field, contains critical informations which the location of the source can be traced. It also makes it possible to realize multi-dimensional acoustic system that can approximately generate non-existing sound source. The use of non-individual, common HRTF brings performance degradation in localization ability such as front-back judgment error, elevation judgment error. In this paper, we have reduced the error on vertical plane by increasing the spectral notch level. The performance of the proposed method was Proved through subjective test that it is Possible to improve the ability to locate stationary/moving source.

• Transactions of Materials Processing
• /
• v.24 no.1
• /
• pp.28-36
• /
• 2015

After a short review of the iterative optimal blank method, a new method of measuring the shape error for stamped parts with 3D contour lines, which is an essential component of the optimal blank design, is proposed. When the contour line of the target shape does not exist in a plane, but exists in 3D space, especially when the shape of the target contour line is very complicated as in the real automotive parts, then the measurement of the shape error is critical. In the current study, a method of shape error measurement based on the minimum distance is suggested as an evolution of the radius vector method. With the proposed method, the optimal blank shapes of real automotive parts were found and compared to the results of the radius vector method. From the current investigation the new method is found to resolve the issues with the radius vector method.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.63 no.1
• /
• pp.99-107
• /
• 2014

In this paper, a landmark based localization system using a Kinect sensor is proposed and evaluated with the implemented system for precise and autonomous navigation of low cost robots. The proposed localization method finds the positions of landmark on the image plane and the depth value using color and depth images. The coordinates transforms are defined using the depth value. Using coordinate transformation, the position in the image plane is transformed to the position in the body frame. The ranges between the landmarks and the Kinect sensor are the norm of the landmark positions in body frame. The Kinect sensor position is computed using the tri-lateral whose inputs are the ranges and the known landmark positions. In addition, a new matching method using the pin hole model is proposed to reduce the mismatch between depth and color images. Furthermore, a height error compensation method using the relationship between the body frame and real world coordinates is proposed to reduce the effect of wrong leveling. The error analysis are also given to find out the effect of focal length, principal point and depth value to the range. The experiments using 2D bar code with the implemented system show that the position with less than 3cm error is obtained in enclosed space($3,500mm{\times}3,000mm{\times}2,500mm$).

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.15 no.1
• /
• pp.107-116
• /
• 1997

This study is concerned about the comparison of accuracy between the plane table survey and the transit survey in the boundary survey. Up to the present, the plane table survey is used for the boundary survey in Korea the plane table survey usually causes both human and mechanical observational errors large enough. In this study, both the plane table survey and the transit survey using total station were used and the same points were measured from the same station. As the results, the positional error has 2~20 cm in plan table survey and 0~2 cm in the transit survey. Thus the transit survey is considerably accurate compared to the plane table survey in the boundary survey.