• 천문학논총
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• 제30권2호
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• pp.401-403
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• 2015

We present the 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 ($z_s=0.245$) is severely distorted by a nearby elliptical galaxy ($z_l=0.08$), via gravitational lensing. The system is analysed by several methods, including surface brightness fitting, gravitational lens modeling, and spectral energy distribution fitting. From Galfit and Ellipse we measure basic parameters of the galaxy, such as the effective radius and the average surface brightness within it. gravlens yields the total mass inside the Einstein radius ($R_{Ein}$), and MAGPHYS gives us an estimate of the stellar mass inside $R_{Ein}$. By comparing these parameters, we confirm that the lens galaxy is an elliptical galaxy on the Fundamental Plane and calculate the stellar mass fraction inside $R_{Ein}$, and discuss the results with regards to the initial mass function.

• 한국멀티미디어학회논문지
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• 제15권11호
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• pp.1273-1283
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• 2012

본 논문에서는 참외 수확로봇을 위한 비전 기반 참외 위치인지 알고리즘을 제시하였다. 입력된 영상의 RGB값을 HSI값으로 변환 후 Hue 값을 이용하여 이진화를 수행한 후에 참외 영역을 추출하였다. 형태학적 필터링을 이용하여 잡음을 제거한 후에 경계선 검출과 convex hull 기법을 이용하여 최외각 정점을 검출하였다. RANSAC 알고리즘에 의하여 참외에 대한 타원 정합을 수행하고 참외의 중심점, 장축 및 단축의 길이, 회전각도에 대한 정보를 획득하였다. 참외 모델에 대한 다양한 시뮬레이션 실험에 의해 제안한 방법의 유효성을 검증하였고, 실제 참외에 적용시켜 제안한 방법의 타당성을 확인하였다.

• 한국정밀공학회지
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• 제18권9호
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• pp.171-178
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• 2001

The nonlinearity of a laser interferometer usually ranges from sub-nanometer to several manometers. This nonlinearity, which has periodic characteristics, limits the accuracy of the interferometer at the sub-nanometer level. The nonlinearity error of the one-frequency homodyne interferometer with quadrature fringe detection results from a number of factors including polarization mixing by imperfect optical elements, unequal gain of photo detectors, lack of quadrature between two signals and misalignment. In this paper, we described a method for measuring and compensating the nonlinearity of homodyne interferometer using the elliptical fitting technique with least-square method. Experimental results demonstrate that $^\pm$3.5 nm nonlinearity can be reduced to $^\pm$0.2 nm level.

• 천문학회보
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• 제38권2호
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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.

• 천문학회보
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• 제39권1호
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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.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 추계학술대회 논문집 학회본부 B
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• pp.615-617
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• 1998

This paper proposes a new segmentation method of human races from grey scale images with clutter using a racial template and elliptical structure of the human head. Face detection technique can be applied in many areas of image processing such as face recognition, composition and computer graphics. Until now, many researches about face detection have been conducted, and applications in more complicated conditions are increasing. The general case is more in a complicated background than in a simple one, and a image with not only one face. Research and development of face detection in such a general case are growing rapidly, and the necessity for that is increasing continuously. Sirohey proposed a face detection method using linearized elliptical equation. The method designed in this paper is improved to be applicable even in the more general cases like where the face is much smaller than the image size and with many faces in one image using template matching and elliptic fitting technique.

• 대한전기학회논문지:전력기술부문A
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• 제48권11호
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• pp.1472-1475
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• 1999

This paper proposes a new detection method of human faces in grey scale images with cluttered background using a facial template and elliptical structure of the human head. Face detection technique can be applied in many areas of image processing such as face recognition, composition and computer graphics, etc. Until now, many researches about face detection have been done, and applications in more complicated conditions are increasing. The existing technique proposed by Sirohey shows relatively good performance in image with cluttered background, but can apply only to image with one face and needs much computation time. The proposed method is designed to reduce complexity and be applied even in the image with several faces by introducing template matching as preprocess. The results show that the proposed method produces more correct detection rate and needs less computation time than the existing one.

• 천문학회보
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• 제42권2호
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• pp.46.2-46.2
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• 2017

We will present a discovery of an elliptical jellyfish galaxy in Abell 2670 (Sheen et al. 2017, ApJL, 840, L7). Our MUSE IFU spectra revealed a rotating gas disk in the center of the galaxy and long ionised gas tails emanating from the disk. Its one-sided tails and a tadpole-like morphology of star-forming blobs around the galaxy suggested that the galaxy is experiencing strong ram-pressure stripping in the cluster environment. Stellar kinematics with stellar absorption lines in the MUSE spectra demonstrated that the galaxy is an elliptical galaxy without any hint of a stellar disk. Then, the primary question would be the origin of the rich gas component in the elliptical galaxy. A plausible scenario is a wet merger with a gas-rich companion. In order to investigate star formation history of the system (the galaxy and star-forming blobs), we derived star-formation rate and metallicity from the MUSE spectra. Photometric UV-Optica-IR SED fitting was also performed using GALEX, SDSS, 2MASS and WISE data, to estimate dust and gas masses in the system. For a better understanding of star formation history and environmental effect of this galaxy, FIR/sub-mm follow-up observations are proposed.

• 천문학회보
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• 제42권1호
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• pp.30.2-31
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• 2017

Compact elliptical (cE) galaxies are in a rare class of stellar systems characterized by high stellar densities, small sizes, high velocity dispersion, and high metallicity corresponding to elliptical galaxies. cE galaxies have been observed around massive galaxies, so they could be formed under strong influences of tidal stripping and truncation. However, the recent discovery of isolated cE galaxies requires the need of new formation scenarios. We aim at finding cE galaxies in various environments using SDSS DR12, and studying stellar population of cEs as function of environments. Based on the typical properties of cE galaxies, we selected cE candidates by restricting that low-luminosity Mg > 19.5 mag, small sizes Re < 700 pc, and high velocity dispersions ${\sigma}$ > $60kms^{-1}$. Since effect radii of cE candidates are mostly smaller than the seeing size of SDSS photometry, we calculated the effective radius by fitting a Sersic profile. In addition, we assumed that host galaxies have brightness with Mr < -21 mag, and an environmental parameter is computed as distances between cE galaxies and host-galaxies. We found 112 cE galaxies at z < 0.05, which have high sersic indices (mean value is 5.2) similar to the typical massive elliptical galaxies. Mgb values of cE galaxies increase as the distances from the host galaxies decrease. Especially, for cEs close to the host galaxies (NcE; $D_{host}$ < 300 pc), the Mgb values are similar to those of massive elliptical galaxies, which is consistent with the previous studies. On the other hand, cE galaxies distant from the host galaxies (DcE; Dhost >300 pc) have lower Mgb values than the conventional cE. The Mgb values follow the ${\sigma}$-Mgb relation of elliptical galaxies, and are connected to its faint end. This can be explained as a result of different merger histories for differing environments. For example, NcE galaxies are formed by tidal stripping by massive galaxies as suggested by previous studies, but DcE galaxies could be linked with high-redshift spheroids (e.g. red nuggets) which have not evolved into present-day elliptical galaxies because of the environmental influences.

• 천문학회보
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• 제39권2호
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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.