• Bulletin of the Korean Space Science Society
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• 1998.10a
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• pp.17.2-17
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• 1998

• Bulletin of the Korean Space Science Society
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• 2002.05b
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• pp.17.2-17
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• 2002

• Journal of Astronomy and Space Sciences
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• v.11 no.2
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• pp.196-207
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• 1994

Data on 27 W UMa systems having a asymmetric light curve so called O'Conell effect have been collected. Investigated 27 W UMa systems were classified into 12 positive and 15 negative type according to the shape of its asymmetric light curve. A list of members of the group, their current observational statue, and their physical and evolutional relationship to asymmetric W UMa type binaries are discussed.

• Bulletin of the Korean Space Science Society
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• 2003.10a
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• pp.76-76
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• 2003

근접 식쌍성들의 극심시각의 체계적인 측광관측을 위하여 충북대학교 41동 옥상에 반자동 소형망원경 관측시스템을 구축하였다(이충욱 등 2003). 이 연구는 그 관측시스템을 이용하여 2002년 10월부터 2003년 9월까지 관측한 결과를 소개한다. 관측한 근접 식쌍성들은 Kreiner, Kim & Nha (2001)가 제시한 1,140개의 천체들 중에서 선택하였다. 관측성들에 대한 식 부근의 광도곡선과 새롭게 구한 극심시각들을 제시한다. 또한, 관측 과정에서 부수적으로 발견된 W UMa형 쌍성의 광도곡선을 제시한다.

• Bulletin of the Korean Space Science Society
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• 2003.10a
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• pp.22-22
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• 2003

1998년 12월부터 1999년 5월까지 총 10일간 소백산천문대의 61cm 망원경과 PM512 CCD 카메라를 이용하여 W UMa형 접촉 식쌍성 AM Cnc의 CCD 측광관측을 수행하여 BVI 광도곡선을 완성하였다. 새로운 광도곡선으로부터 주극심시각 2점, 부극심시각 3점을 얻었다. 이 관측치를 포함하여 AH Cnc의 관측된 모든 극심시각을 수집하여 분석한 결과, 영년 주기 증가를 보이고, 변화 원인을 질량이 큰 별에서 질량이 작은 별로의 보존적 질량이동에 의한 것으로 해석하였다. 영년주기 증가율은 3.18$\times$$10^{-7}$ day/year이다. 새로운 BVI 광도곡선을 WD 쌍성 모델의 접촉모드(Mode 3)로 분석하여 측광해를 산출하였고, 측광해의 결과는 질량비 0.159, 궤도경사각 86$^{\circ}$, 접촉도(fill-out factor) 49%등으로 계산되었다. 측광해를 Sandquist & Shetrone(2003)의 연구결과와 비교하면 질량비와 궤도경사각은 거의 같고, 접촉도는 약간 작은 값이다. 작은 값이다.

• Journal of Astronomy and Space Sciences
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• v.5 no.1
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• pp.73-79
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• 1988

New differential photoelectric observations in UBV system of the W UMa-type eclipsing binary SW Lac presented. The data were obtained on 4 nights from October in 1987 using the 61cm reflector at Sobaeksan Astronomical Observatory. These light curves are compared with recent published light curves in order to check the light curve variations and magnitude difference of minimum light phases. Four times of minimum light are deduced and the orbital period variation of SW Lac has been discussed.

• Journal of Astronomy and Space Sciences
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• v.23 no.4
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• pp.311-318
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• 2006

High-precision photometric observations were performed in BVI bandpasses using Am robotic telescope at Mt. Lemmon Observatory for two binary stars, which are reclassified as W UMa-type systems from ROTSE(Robotic Optical Transient Search Experiment) follow-up observations and show peculiar light variations. In order to analyze W UMa-type eclipsing binaries systematically, the light curve analysis script using 2005 version of Wilson-Devinney binary code is constructed. The orbital inclinations of GSC2S84-1731 and GSC2576-0319 are $43.^{\circ}5\;and\;57.^{\circ}6$ from light-curve analysis, respectively. Spot model is applied to explain the asymmetric light curve for GSC2S84-1731 and the spot parameters are derived.

• Journal of the Korean earth science society
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• v.27 no.6
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• pp.695-700
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• 2006

We present B, V, I time series CCD photometry for the variable star TU UMi to classify its variable type. The observations were performed using 61cm telescope equipped with 2K CCD camera at Sobaeksan Optical Astronomy Observatory (SOAO). Judging from the amplitude ratio $({\Delta}i/{\Delta}v)$ and color variation $({\Delta}(b-v),\;{\Delta}(v-i))$. TU UMi should be a W UMa type eclipsing binary. We obtained two primary times of minimum lights (HJD 2453848.0446, HJD 2453848.2309) from our observations and determined new orbital elements (Min I=HJD 2452500.1344+0.37708907${\times}$E) for TU UMi.

• Journal of Astronomy and Space Sciences
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• v.16 no.1
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• pp.21-30
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• 1999

We perform CCD observations in VRI filters for AK Her during 3 nights in Feb 1997 and Mar 1998 at Mt. Sobaek National Observatory, and obtained 236 images in V, 198 in R, and 197 in I filter. From the data, we construct light curves which contain a pair primary and secondary minima and (O-C) diagram. We analyzed the obtained light curves of AK Her using the Wilson-Devinney code. From the analyses, we find that AK Her is more likely detached or semi-detached than contact system. From the (O-C) diagram, we find that the (O-C) residuals increases out of accordance with the expectation of Borkovits & Hegedus since 1990. However, we cannot identify cause of the periodic variation of the (O-C) residuals.

• Journal of Astronomy and Space Sciences
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• v.17 no.1
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• pp.19-32
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• 2000

A total of 1,018 observations (509 in B, 509 in V) of the eclipsing binary VW Cep was made during 7 nights from April through May in 1999 at Sobaeksan Optical Astronomy Observatory, using the CCD camera attached to the 61cm telescope. A time of minimum light of HJD2451327.2282 was determined from our data, and we constructed BV light curves with the data. Using, Wilson-Devinney’s binary model, we analized the light curves. The absolute dimension of $M_1=0.95M_\odot,M_2=0.33M_\odot,R_1=1.02R_\odot,R_2=0.66R_\odot$ of the VW Cep system were derived from our light curve solution and Kaszas et al. (1998) spectroscopic results.