This study classified outer-ring galaxies using 25,308 galaxies within z=0.05 from the SDSS DR7, which are larger than Rpet>6 arcsec and whose minor-to-major axis ratio (b/a)<0.6. We selected 531 galaxies that have ring-like structures by visual inspection of the color images of 25,308 galaxies; these galaxies with ring-like structures served as a primary sample from which we selected 90 outer-ring galaxies. The final sample of 69 outer-ring galaxies was selected by examining the photometric properties of the candidate galaxies. Their properties were determined by conducting surface photometry on their u, g, r, i, and z images. The frequency of the outer-ring galaxies was found to be 0.3% of the local galaxies. We examined the environment of the outer-ring galaxies using two measures of environment, namely, the projected distance to the nearest-neighbor galaxy and the local background density. We did not observe any notable difference between outer-ring and other galactic environments.

Abstract
요 약
서 론
연구 방법 및 절차
    데이터 선정
    자료 처리
    연구 결과
    등광도지도
    광도윤곽, 타원율, 위치각
분석 및 논의
    외부고리 은하의 개수 비율
    외부고리 은하의 환경
    5-band 광도 윤곽(luminosity profile)
결론 및 토의
References

• 장훈휘(한국교원대학교 지구과학교육과) | Hunhwi Chang (Department of Earth Science Education, Korea National University of Education)
• 손정주(한국교원대학교 지구과학교육과) | Jungjoo Sohn (Department of Earth Science Education, Korea National University of Education) Corresponding author
• 안홍배(부산대학교 과학교육학부) | Hongbae Ahn (Department of Science Education, Pusan National University)