• Journal of Institute of Control, Robotics and Systems
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• v.3 no.1
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• pp.32-39
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• 1997

One of the most important performance criteria in tuning the gain of position loop controller for CNC machining center is the contour error. In this papre we analyze contour error in the linear and circular interpolations for the axis-matched and mismatched cases. To have small contour errors, it is necessary to set the P gain for each axis to be same. And the D gain should be much smaller than the P gain. Baded on the analysis in the frequency domain, we propose a gain tuning method for the P and PD controllers. We show that the PD controller is better than the P controller. The effectiveness of this method is demonstrated by experiments.

• Journal of Ocean Engineering and Technology
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• v.34 no.2
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• pp.89-96
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• 2020

In this study, the Norbury-Fraenkel family of vortex rings is analyzed using a contour dynamics method for the stream function, which significantly reduces the numerical burden in the calculation. The stream function is formulated as the integral along the contour of the vorticity core. The integration over the logarithmic-singular segment is evaluated analytically, and the positions of the nodal points of the contour are calculated directly. The shapes of the cores and the dividing stream surfaces are found based on the mean core radius. Compared with other studies, the proposed method is verified and found to be more efficient.

• Journal of Biomedical Engineering Research
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• v.13 no.2
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• pp.115-124
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• 1992

An algorithm has been proposed for the automatic detection of optimal epiand endocardial left ventricular borders from 2-D short axis echocardiogram which is degraded by noise and echo drop out. For the implementation of the algorithm, we modified Ballard's Generalized Hough Transform which can be applicable only for deterministic object border, and newly proposed Fuzzy Hough Transform method. The algorithm presented here allows detection of object whose exact shapes are unknown. The algorithm only requires an approximate model of target object based on anatomical data. To detect the approximate epicardial contour of left ventricle, Fuzzy Hough Transform was applied to the echocardiogram. The optimal epicardial contour was founded by using graph searching method which contains cost function analysis process. Using this optimal epicardial contour and average thickness imformation of left ventricular wall, the approximate endocardial line was founded, and graph searching method was also used to detect optimal endocardial contour.

• Advances in aircraft and spacecraft science
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• v.1 no.4
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• pp.399-408
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• 2014

The flowfields inside a contour and a conical nozzle exhausting into a straight cylindrical supersonic diffuser are computed by solving numerically axisymmetric turbulent compressible Navier-Stokes equations for stagnation to ambient pressure ratios in the range 20 to 34. The diffuser inlet-to-nozzle throat area ratio and exit-to-throat area ratio are 21.77, and length-to-diameter ratio of the diffuser is 5. The flow characteristics of the conical and contour nozzle are compared with the help of velocity vector and Mach contour plots. The variations of Mach number along the centre line and wall of the conical nozzle, contour nozzle and the straight supersonic diffuser indicate the location of the shock and flow characteristics. The main aim of the present analysis is to delineate the flowfields of conical and contour nozzles operating under identical conditions and exhausting into a straight cylindrical supersonic diffuser.

• Proceedings of the IEEK Conference
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• 2000.11d
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• pp.85-88
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• 2000

We present a new approach to analyzing the dynamic false contour noise of AC plasma display panels (PDP), which is known to degrade the image quality severely. Compared with the existing methods that consider only the amount of light emission from PDP during 1 field time, the proposed approach uses the impulse response model of the human vision system and estimates how the human beings actually feel as the function of time. Experimental results using various benchmark sub-field scan algorithms are included.

• Journal of Fashion Business
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• v.10 no.4
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• pp.29-44
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• 2006

This study was aimed at giving help to the people intending to change hair fashion feeling for making their own hair style design and also providing the academic guide line to the cosmetic circles for developing new hair design and promoting sales by producing hair styles following the results from the statistical analysis based on the theoretical study on the face contour groups & hair fashion feeling groups. The researching methods were composed of following 3 steps ; prior theoretical research, statistical analysis, and hair style production. At first, the prior theoretical research was accomplished by analysis of literatures, magazines and internet sites about face contour, total & hair fashion feelings, hair style productions. Second, the prior statistical analysis were done about hairstyle images & their charateristics based on fashion feelings, and characteristics of fashion feeling group. And the third, hair style productions were done coordinated by face contours(oval, circle, long, square, reverse triangle) and hair fashion feelings(natural, sexy, sophisticate, ethnic, romantic pretty, elegance, sporty, avant garde) following the statistical results. But owing to the limitations to change hair length and color, these changes are modified by wigs and photoshop 7.0 program. So we could know there was no confirmed hair fashion feeling of one's best, but one could change one's hair fashion feeling and express one's beauty if one could adjust one's hair styles properly to one's face contour. This study would be very helpful to the people trying to change their own hair fashion feeling and be useful to the cosmetic circles for developing new design and promoting sales by comprehending hair design market and also be valuable to develop the methodology of 3 step research.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.12 no.3
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• pp.17-24
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• 2003

One of the most important performance criteria related to the gain tuning of controller for CNC machining center is the contour error. This study analyzed circular error by the axis-matched and mismatched cases. To reduce ellipse and radius error, it is necessary to set the gain for each axis to be same bandwidth and high response. Based on the analysis in the frequency domain, we simulate feed system by mathematical model and then predict bandwidth of each axis. For analysis of structure vibration while the each axis is moving, we try the various of measuring method and position loop is improved by jerk limit.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.49 no.2
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• pp.8-17
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• 2012

In this paper we proposes a new framework to obtain 3D shape information of thin film rapidly. The conventional equipments based on reflectometry are not suitable for obtaining 3D overall shape information of thin film rapidly since they require more than 30 minutes to measure the absolute thickness for 170 points. The proposed framework is based on an image analysis method that extracts contour lines from interference fringes images using Canny edge detector. The absolute thickness for contour lines are measured and then a height map from the contour lines is obtained by interpolation using Borgefors distance transformation. The extracted height map is visualized using the DirectX 3D terrain rendering method. The proposed framework can provide 3D overall shape information of thin film in about 5 minutes since relatively small number of real measurement for contour lines is required.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.10a
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• pp.171-172
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• 2009

• Journal of the Korean Statistical Society
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• v.17 no.1
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• pp.24-29
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• 1988

The asymptotic distribution of the sample partial autocorrelation terms after lag p of an AR(p) model has been shown by Dixon(1944). The derivation is based on multivariate analysis and looks tedious. In this paper we present an interesting contour-integral derivation.