• The Bulletin of The Korean Astronomical Society
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• v.44 no.1
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• pp.33.3-33.3
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• 2019

Automatic, yet reliable methods to find and classify barred galaxies are going to be more important in the era of large galaxy surveys. Here, we introduce a new approach to classify barred galaxies by analyzing the butterfly pattern that Buta & Block (2001) reported as a bar signature on the potential map. We make it easy to find the pattern by moving the ratio map from a Cartesian coordinate to a polar coordinate. Our volume-limited sample consists of 1698 spiral galaxies brighter than Mr = -15.2 with z < 0.01 from the Sloan Digital Sky Survey/DR7 visually classified by Ann et al. (2015). We compared the results of the classification obtained by four different methods: visual inspection, ellipse fitting, Fourier analysis, and our new method. We obtain, for the same sample, different bar fractions of 63%, 48%, 36%, and 56% by visual inspection, ellipse fitting, Fourier analysis, and our new approach, respectively. Although automatic classifications detect visually determined, strongly barred galaxies with the concordance of 74% to 86%, automatically selected barred galaxies contain different amount of weak bars. We find a different dependence of bar fraction on the Hubble type for strong and weak bars: SBs are preponderant in early-type spirals, whereas SABs are in late-type spirals. Moreover, the ellipse fitting method often misses strongly barred galaxies in the bulge-dominated galaxies. These explain why previous works showed the contradictory dependence of the bar fraction on the host galaxy properties. Our new method has the highest agreement with visual inspection in terms of the individual classification and the overall bar fraction. In addition, we find another signature on the ratio map to classify barred galaxies into new two classes that are probably related to the age of the bar.

• The Transactions of the Korea Information Processing Society
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• v.4 no.12
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• pp.3200-3210
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• 1997

In image processing we encounter some tasks to detect ellipse or to discriminate the curves. LSM is well used to fit curves to ellipse but it can fail to fit correctly when fitting to defected one. To overcome this problem, we propose Modified LSM. Only 2-parameters among 5-paramaters are to be determined by LSM, while 3-parameters are to be calculated by the constrain that the curve must pass 3 given points. Those 3 points are selected by operator so as to have elliptic feature. Such proposed MLSM shows better result than genunal LSM in case when the ellipse is severely defected. and is proved to be good method for determing the human dentition.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.4
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• pp.388-393
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• 2019

As a fiiting method to data with outliers, RANSAC(RANdom SAmple Consensus) based algorithm is widely used in fitting of line, circle, ellipse, etc. CUDA is currently most widely used GPU with massive parallel processing capability. This paper proposes an efficient CUDA implementation of multiple planes fitting using RANSAC with 3d points data, of which one set of 3d points is used for one plane fitting. The performance of the proposed algorithm is demonstrated compared with CPU implementation using both artificially generated data and real 3d heights data of a PCB. The speed-up of the algorithm over CPU seems to be higher in data with lower inlier ratio, more planes to fit, and more points per plane fitting. This method can be easily applied to a wide variety of other fitting applications.

• Journal of Korea Society of Industrial Information Systems
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• v.19 no.4
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• pp.41-52
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• 2014

In this paper, O-ring size measurement algorithm based on a small machine vision inspection equipment which can replace a expensive and large machine vision inspection equipment is presented. The small machine vision inspection equipment acquires a image from a CCD camera shooting a measurement plane which located on a back light and the proposed size measurement algorithm is apply to the image. For improvement of size measurement accuracy, camera lens distortion correction and perspective distortion correction are conducted by software technique. Consider O-ring's shape, ellipse fitting model is applied. In order to increase the reliability of ellipse fitting, RANSAC algorithm is applied.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.05a
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• pp.909-912
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• 2012

An automated cell tracking system is automatically to analyze and track changes of cell behaviors in time-lapse cell images acquired from microscope in the cell culture. In this paper, we proposed and developed an ellipse fitting based algorithm for separating very small size overlapping cells in a cell image consisted of thousands or ten thousands cells. We were extracted contours of clusters and divided them into line segments and then produced their fitted ellipses for each line segment. By experimentations, our algorithm was separated clusters with average 91% precision for two overlapping cells and average 84% precision for three overlapping cells respectively.

• The Bulletin of The Korean Astronomical Society
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• v.39 no.2
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• pp.70.1-70.1
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• 2014

We analyze a newly discovered galaxy-galaxy scale gravitational lens system, FLS 1718+59 in the Spitzer First Look Survey (FLS) field. A background galaxy (z = 0.245) is severely distorted by a foreground galaxy (z = 0.08), via gravitational lensing. We analyze this system by several methods, including surface brightness fitting (Galfit and Ellipse), gravitational lens modeling (gravlens), and spectral energy distribution fitting (Magphys). From Galfit and Ellipse we measure properties of the lens galaxy, such as the effective radius and the average surface brightness inside it, the ellipticity, and the position angle. gravlens gives us the total mass inside the Einstein radius ($R_{Ein}$), and Magphys provides us an estimate of the stellar mass inside $R_{Ein}$. By comparing these obtained parameters, we confirm that the lens galaxy is an elliptical galaxy on the Fundamental Plane, and calculate the stellar mass function inside $R_{Ein}$, and discuss the implications of the results regarding the initial mass function.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.2
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• pp.43.4-44
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• 2017

Bar fractions depend on the properties of host galaxies. However, the observational studies did not provide consistent tendency. We investigated the bar fractions and their dependence on properties of host galaxies using three bar classifications: visual inspection, ellipse fitting method and Fourier analysis from a volume-limited sample of 1,698 disk galaxies brighter than Mr=-15.2 within z = 0.01 from the Sloan Digital Sky Survey (SDSS) Data Release 7 (DR7). We found two causes to make the discrepancy in previous studies. One is caused by the difficulty in automatically identifying bars for bulge-dominated galaxies. In particular, ellipse fitting methods could miss early-type barred galaxies when a large bulge weakens the transition between a bar and disk. The other is caused by the difference in the correlation between the bar types and host morphology for strong bars and weak bars. Strong bars are preponderant in early-type spirals which are red, bulge-dominated and highly concentrated, whereas weak bars are frequent in late-type spirals which are blue, disk-dominate and less-concentrated. Therefore, how much weak bars they contain affects the trend of bar fraction on host galaxy properties. We also discuss the effect of host properties on the formation, evolution, and destruction of bars.

• The Bulletin of The Korean Astronomical Society
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• v.38 no.2
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• pp.52.1-52.1
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• 2013

We present new analyses of FLS 1718+59, a galaxy-galaxy gravitational lens system in the Spitzer First Look Survey (FLS) Field. A background galaxy (z = 0.245) is severely distorted by a nearby elliptical galaxy (z = 0.08), which can be interpreted as a result of gravitational lensing. We analyze this system by multiple methods, including ELLIPSE fitting, gravitational lens modeling, and surface brightness fitting. From this analysis, we obtain parameters of the lens galaxy using varying approaches and compare them. In the future, we will conduct SED fitting for the lens galaxy and estimate the stellar mass, and compare this with the total mass of the lens to check the M-L relation.

• The Bulletin of The Korean Astronomical Society
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• v.39 no.1
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• pp.36.2-36.2
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• 2014

We present results of the analysis of FLS 1718+59, a galaxy-galaxy gravitational lens system in the Spitzer First Look Survey (FLS) Field. A background galaxy (z = 0.245) is severely distorted by an elliptical galaxy (z = 0.08), by gravitational lensing. We analyze this system by several methods, including Ellipse and Galfit fitting, gravitational lens modeling (gravlens), and SED fitting. Properties of the lens galaxy can be obtained: from Galfit we measure the effective radius and the average surface brightness inside it, and from gravlens we estimate the total mass inside the Einstein radius (lensing mass). We use these parameters to check that the lens galaxy is located on the Fundamental Plane. Also, we conduct SED fitting for the lens galaxy and estimate the stellar mass, and compare this with the lensing mass of the lens galaxy to check the M-L relation.

• 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.