• Journal of Astronomy and Space Sciences
• /
• v.36 no.4
• /
• pp.265-281
• /
• 2019

We present new BVRI light curves of UY UMa with no O'Connell effect and a flat bottom secondary eclipse. Light curve synthesis with the Wilson-Devinney code gives a new solution, which is quite different from the previous study: UY UMa is an A-subtype over-contact binary with a small mass ratio of q = 0.21, a high inclination of 81°.4, a small temperature difference of ΔT=18°, a large fill-out factor of f = 0.61, and a third light of approximately 10% of the total systemic light. The absolute dimensions were newly determined. Seventeen new times of minimum light have been calculated from our observations. The period study indicates that the orbital period has intricately varied in a secular period increase in which two cyclical terms with periods of 12^y.0 and 46^y.3 are superposed. The secular period increase was interpreted to be due to a conservative mass transfer of 2.68 × 10^-8 M_⊙/yr from the less massive to the more massive star. The cyclical components are discussed in terms of double-light time contributions from two additional bound stars. The statistical relations of Yang & Qian (2015) among the physical parameters of 45 deep, low mass ratio contact binaries were revisited by using the physical parameters of UY UMa and 25 Kepler contact binaries provided by Şenavci et al. (2016).

• Journal of The Korean Astronomical Society
• /
• v.55 no.1
• /
• pp.1-9
• /
• 2022

We present the photometric properties of V608 Cas from detailed studies of light curves and eclipse timings. The light curve synthesis indicates that the eclipsing pair is an overcontact binary with parameters of ∆T = 155 K, q = 0.328, and f = 26%. We detected the third light ℓ₃, which corresponds to about 8% and 5% of the total systemic light in V and R bands, respectively. Including our 6 timing measurements, a total of 38 times of minimum light were used for a period study. It was found that the orbital period of V608 Cas has varied in some combination of an upward parabola and two periodic variations. The continuous period increase with a rate of +3.99 × 10^-7 d yr^-1 can be interpreted as a mass transfer from the secondary component to the primary star at a rate of 1.51 × 10^-7 M_⊙ yr^-1. The periods and semi-amplitudes of the two periodic variations are about P₃ = 16.0 yr and P₄ = 26.3 yr, and K₃ = 0.0341 d and K₄ = 0.0305 d, respectively. The most likely explanation of both cycles is a pair of light-traveling time effects operated by the possible presence of third and fourth components with estimated masses of M₃ = 2.20 M_⊙ and M₄ = 1.27 M_⊙ in eccentric orbits of e₃ = 0.66 and e₄ = 0.52. Because the contribution of ℓ₃ is very low compared to the estimated masses of two circumbinary objects, they can be inferred as very faint compact objects.

• Journal of Astronomy and Space Sciences
• /
• v.23 no.4
• /
• pp.319-326
• /
• 2006

We present light curves of a short period binary system BL Eridani. The light curves were observed with VRI filters by a 50cm wide field robotic telescope at Siding Spring Observatory (SSO), equipped with a 2K CCD camera, which was developed by Korea Astronomy and Space Science Institute (KASI), and Yonsei University Observatory(YUO). The photometric observations were made on 6 nights by automatic operation mode and remote observation mode at SSO and KASI in Korea, respectively. We obtained new VRI CCD light curves and new 5 times of minima, and analyzed the light corves with the Wilson & Deviney (1971) binary 2005 version and derived the new photometric solutions. The mass ratio q=0.48 in this study shows different value with earlier investigators. According to the model analysis, it is considered that the BL Eri system is currently undergoing contact stage of the two binary components, rather than near-contact stage.

• The Journal of Engineering Geology
• /
• v.15 no.3
• /
• pp.337-348
• /
• 2005

Jurassic granite from Pocheon area were tested to investigate the effect of microcracks on mechanical properties of the granite. Three oriented core specimens were used for uniaxial compressive tests and each core specimen are perpendicular to the axes'R'(rift plane),'c'(grain plane) and'H'(hardway plane), respectively Among vacious elastic constants, the variation of Poisson's ratio as function of the directions was examined. From the related chart between ratio of failure strength and Poisson's ratio, H-specimen shows the highest range in Poisson's ratio and Poisson's ratio decreases in the order of C-specimen and R-specimen. The curve pattern is nearly linear in stage $I\simIII$ but the slope increases abruptly in stage H-3. As shown in the related chart, diverging point of a curve is formed when ratio of failure strength is $0.92\sim0.96$ Stage IV -3 is out of elastic region. The behaviour of rock in the four fracturing stages was analyzed in term of the stress-volumetric strain me. From the stress increment-volumetric strain equations governing the behaviour of rock, characteristic material constants, a, n, Q, m and $\varepsilon_v^{mcf}$, were determined. Among these, inherent microcrack porosity$(a, 10^{-3})$ and compaction exponent(n) in the microcrack closure region(stage I ) show an order of $a^R(3.82)>a^G(3.38)>a^H(2.32)\;and\;n^R(3.69)>n^G(2.79)>n^H(1.99)4, respectively. Especially, critical volumetric microcrack strain($\varepsilon_v^{mcf}$) in the stage W is highest in the H-specimen, normal to the hardway plane. These results indicate a strong correlation between two major sets of microcracks and mechanical properties such as Poisson's ratio and material constants. Correlation of strength anisotropy with microcrack orientation can have important application in rock fracture studies.

• Radiation Oncology Journal
• /
• v.8 no.1
• /
• pp.1-6
• /
• 1990

In the present study, a perfluorchemical emulsion (Fluosol-DA $20\%$) did not alter $D_o\;and\;D_q$ values on cell survival curve, indicating that the lack of a direct effect of Fluosol-DA $20\%$ on cellular radiosensitivity in vitro. The effect of Fluosol-DA $20\%$ injection in combination with carbogen breathing was determined on the hypoxic cell fraction in SCK tumors. The hypoxic cell fraction in control SCK tumors was 0.39. This value decreased to 0.05 when the mice were i.v. injected with 12 ml/kg of Fluosol-DA $20\%$ in a carbogen atomosphere. The measured mean and median $PO_2$ values with a microelectrode in the control tumors was 9 mmHg and 4 mmHg, respectively. The treatment of the SCK tumors in the host mice with injected Fluosol-DA $20\%$ in combination with carbogen breathing increased the mean and median $PO_2$ values to 67 mmHg and 62 mmHg, respectively. Using carbogen breathing alone caused a moderate increase of tumor $PO_2$. But Fluosol-DA $20\%$ injection alone caused little change $PO_2$ in the tumor. It was concluded that the combination of Fluosol-DA injection and carbogen breathing is an effective means to improve oxygenation of tumors.

• Journal of The Korean Astronomical Society
• /
• v.55 no.4
• /
• pp.123-130
• /
• 2022

We present the analysis of a planetary microlensing event OGLE-2019-BLG-0362 with a shortduration anomaly (~0.4 days) near the peak of the light curve, which is caused by the resonant caustic. The event has a severe degeneracy with ∆𝜒² = 0.9 between the close and the wide binary lens models both with planet-host mass ratio q ≃ 0.007. We measure the angular Einstein radius but not the microlens parallax, and thus we perform a Bayesian analysis to estimate the physical parameters of the lens. We find that the OGLE-2019-BLG-0362L system is a super-Jovian-mass planet $M_p=3.26^{+0.83}_{-0.58}M_J $ orbiting an M dwarf $M_h=0.42^{+0.34}_{-0.23}M_{\odot}$ at a distance $D_L=5.83^{+1.04}_{-1.55}kpc$. The projected star-planet separation is ${\alpha}_{\bot}= 2.18^{+0.58}_{-0.72}AU$, which indicates that the planet lies beyond the snow line of the host star.