• Korean Journal of Mathematics
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• v.25 no.4
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• pp.537-554
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• 2017

In this paper, we study the surfaces foliated by ellipses in three dimensional Euclidean space ${\mathbf{E}}^3$. We prove the following results: (1) The surface foliated by an ellipse have constant Gaussian curvature K if and only if the surface is flat, i.e. K = 0. (2) The surface foliated by an ellipse is a flat if and only if it is a part of generalized cylinder or part of generalized cone.

• Proceedings of the IEEK Conference
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• 2003.07e
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• pp.2124-2127
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• 2003

This paper suggests user interface method with wearable computer by means of detecting gaze under HMD, head mounted display, environment. System is derived as follows; firstly, calibrate a camera in HMD, which determines geometrical relationship between monitor and captured image. Second, detect the center of pupil using ellipse fitting algorithm and represent a gazing position on the computer screen. If user blinks or stares at a certain position for a while, message is sent to wearable computer. Experimental results show ellipse fitting is robust against glint effects, and detecting error was 6.5％, and 4.25％ in vertical and horizontal direction, respectively.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.12
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• pp.1237-1244
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• 2015

A gerotor can be manufactured in a miniature size because it has a high discharge per cycle and a simple structure. Gerotors are widely used for the lubrication oil of an engine and as the hydraulic source of an automatic transmission. Recently, improvements in fuel efficiency and noise reduction have come to the fore in the automobile industry, and it has been necessary for better fuel efficiency to continuously improve the flow rate and noise of internal gear pumps through the optimal design of the gerotor and port shape. In this study, gerotors were generated based on the equations derived for a lobe shape with multiple profiles (ellipse 1-elliptical involute-ellipse 2). The ranges of the design parameters were considered to prevent a cusp and loop. In addition, the optimal lobe shape was obtained by determining the influence of the lobe shape on the performances (flow rate, irregularity, etc.), according to the values of the design parameters.

• Journal of Korea Water Resources Association
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• v.44 no.4
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• pp.327-338
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• 2011

This study examined the quantification problem of a storm shape using the concept of equivalent ellipses. The equivalent ellipses of a storm event were estimated at every time step with respect to the several thresholds of rainfall intensity, which was also examined in terms of their size and number. In addition, the average equivalent ellipse was decided, and the confidence intervals of major axis, minor axis, and rotational angle were calculated to evaluate if the average equivalent ellipse could be the representative one. As results, the following results could be derived. First of all, the number of equivalent ellipses and the size of equivalent ellipses increase as the threshold increase. Secondly, the appropriate ratio of major and minor axises of equivalent ellipse is 2 : 1. Finally, the average rotational angle estimated with respect to several threshold rainfall intensities were all found not to be statistically different from that of all representative rotational angles.

• Tribology and Lubricants
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• v.28 no.3
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• pp.136-141
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• 2012

In this paper, we investigated the friction characteristics of $W100^{\circ}{\o}L25m$ ellipse type surface pattern, on bearing steel. These characteristics are researched by utilizing a pin-on-disk wear test machine, under various velocities and other conditions. The reduction of friction is a necessary requirement for the improved efficiency of industrial parts. As the speed increases, there is a decrease in the effect of the dimple of friction characteristic in low velocity, with substantially little change to density. Conversely, as the load increases, the test direction of ellipse type dimple pattern, resulting in a difference in the texture of these two components. At a dimple density of 7.5% the friction characteristic is easily demonstrated, with a consistent change in both speed and load.

• Journal of Biosystems Engineering
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• v.36 no.5
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• pp.377-383
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• 2011

This study proposed the new method of discerning the assembled parts and presuming the position of central point in a Cowl Cross Bar (CCB) using a Charge-Couple Device (CCD) camera attached to a robot in the auto assembly line. Three control points of an ellipse were decided by three reference points, which were equally distanced. The radii of these reference points were determined by the size of the object, and the repeated presumption secured the precise determination. The comparison of the central point of ellipse presumed by Randomized Hough Transform (RHT) with the part information stored in a database was used for determining the faulty part in an assembly. The method proposed in this study was applied for the real-time inspection of elliptical parts, such as bolt, nut hole and so on, connected to a CCB using a CCD camera. The findings of this study showed that the precise decision on whether the parts are inferior or not can be made irrespective of the lighting condition of industrial site and the noises of the surface of the part. In addition, the defect decision on the individual elliptic parts assembled in a CCB showed more than 98% accuracy within a 500-millisecond period at most.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.772-777
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• 2003

A vision-based tool position estimation system for the inspection and maintenance manipulator working inside the steam generator bowl of nuclear power plants can help human operators ensure that the inspection probe or plug are inserted to the targeted tube. Some previous research proposed a simplified tube position verification system that counts the tubes passed through during the motion and displays only the position of the tool. In this paper, by using a general camera calibration approach, tool orientation is also estimated. In order to reduce the computation time and avoid the parameter bias problem in an ellipse fitting, a small number of edge points are collected around the large section of the ellipse boundary. Experiment results show that the camera calibration parameters, detected ellipses, and estimated tool position are appropriate.

• The KIPS Transactions:PartB
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• v.15B no.2
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• pp.81-86
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• 2008

This paper discusses the problem of partial object recognition in image databases. We propose the method to reconstruct and estimate partially occluded shapes and regions of objects in images from overlapping and cutting. We present the robust method for recognizing partially occluded objects based on symmetry properties, which is based on an ellipse of objects. Our method provides simple techniques to reconstruct occluded regions via a region copy using the symmetry axis within an object. Since our method relies on reconstruction of the object based on the symmetry rather than statistical estimates, it has proven to be remarkably robust in recognizing partially occluded objects in the presence of scale changes, rotation, and viewpoint changes.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.37 no.8
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• pp.67-75
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• 2000

In this paper, we proposed a new method to find dive parameters of an ellipse from the optical Hough transform (HT) results. The method employs the HT for detection of a straight line and the one-dimensional analysis of the resultant parameter domain. Using this algorithm, we simulated about the ellipses with different positions, and obtained the information of the ellipse with 94% accuracy in the worst case. To compare the simulation results with the experimental ones, we performed optical experiments using a HT Computer Generated Hologram (CGH) filter. Through the experiments, we showed that our results were very similar to the simulation results.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.11
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• pp.1161-1169
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• 2003

In this paper, ADE(Axially Displaced Ellipse) Gregorian dual reflector antennas, which are the special form of Gregorian dual reflector antennas, were analyzed. In the procedure of antenna analysis, the aperture field distribution was obtained by using the geometrical optics and their far-field radiation characteristics were analyzed by using the aperture field method. The analysis results such as antenna efficiency, HPBW(Half Power Beam Width), FNBW(First Null Beam Width), and FSL(First Sidelobe Level) were presented as functions of edge taper and size of main reflector and subreflector. From the results in this paper, we could confirm that ADE reflector antennas have the different radiation characteristics from the classical dual reflector antennas.