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Ivan L. Andronov,Yonggi Kim,Young-Hee Kim,Joh-Na Yoon,Lidia L. Chinarova,Mariia G. Tkachenko 한국우주과학회 2015 Journal of Astronomy and Space Sciences Vol.32 No.2
We present a by-product of our long term photometric monitoring of cataclysmic variables. 2MASS J18024395 +4003309 = VSX J180243.9 +400331 was discovered in the field of the intermediate polar V1323 Her observed using the Korean 1-m telescope located at Mt. Lemmon, USA. An analysis of the two-color VR CCD observations of this variable covers all the phase intervals for the first time. The light curves show this object can be classified as an Algol-type variable with tidally distorted components, and an asymmetry of the maxima (the O’Connell effect). The periodogram analysis confirms the cycle numbering of Andronov et al. (2012) and for the initial approximation, the ephemeris is used as follows: Min I. BJD = 2456074.4904+0.3348837E . For phenomenological modeling, we used the trigonometric polynomial approximation of statistically optimal degree, and a recent method “NAV” (“New Algol Variable”) using local specific shapes for the eclipse. Methodological aspects and estimates of the physical parameters based on analysis of phenomenological parameters are presented. As results of our phenomenological model, we obtained for the inclination i=90°, M1=0.745M◉, M2=0.854M◉, M=M1+M2=1.599M◉, the orbital separation a=1.65·109m=2.37R◉ and relative radii r1=R1/a=0.314 and r2=R2/a=0.360. These estimates may be used as preliminary starting values for further modeling using extended physical models based on the Wilson & Devinney (1971) code and it's extensions
In-vitro instrumental stimulation of oral breakdown of rice gels with different amylose contents
Yonggi Kim,suyong lee 한국산업식품공학회 2017 학술대회 및 심포지엄 Vol.2017 No.11
In-vitro food mastication has been simulated by incorporating size reduction process, followed by incubation with human saliva. However, they do not suffice to simulate the actual oral breakdown process where disruption by mastication (chewing) and wetting/lubrication by salivation take place simultaneously. In this study, in-vitro oral digestion of rice gels with different amylose contents was simulated by instrumentally performing mastication and salivation. The hardness of artificial saliva-treated rice gels was distinctly lowered with increasing chewing cycles and the rice gels with high amylose contents showed the highest degradation rate. When the rice gels were subjected to non-destructive tomographic analysis, the high amylose rice gels were clearly shown to be favorably fragmented into smaller pieces by chewing, followed by the low and intermediate amylose samples. These results could be explained by their cohesive texture rather than hardness. Therefore, this study may help understanding the changes in the physical properties of cereal-based foods during oral digestion.
THEORETICAL LINE PROFILES OF THE MAGNETIC COMPACT STARS
KIM YONGGI The Korean Astronomical Society 1996 Journal of The Korean Astronomical Society Vol.29 No.suppl1
Using a phenomenological model for the accretion onto the magnetic white dwarf, we calclliated some optical line profiles from the magnetosphere of such systems. Line profiles of these systems seem to be produced in the magnetosphere of the compact star due to the reemission of X-ray produced near the stellar surface. Some results of our new calculation and the analysis of these results will be presented. Our results show that the model used here can reproduce the observed optical line profiles and open the possiblity to determine the parameters of individual systems.
POORLY STUDIED ECLIPSING BINARIES IN THE FIELD OF DO DRACONIS: V454 DRA AND V455 DRA
Kim, Yonggi,Andronov, Ivan L.,Andrych, Kateryna D.,Yoon, Joh-Na,Han, Kiyoung,Chinarova, Lidia L. The Korean Astronomical Society 2020 Journal of The Korean Astronomical Society Vol.53 No.2
We report an analysis of two poorly studied eclipsing binary stars, GSC 04396-00605 and GSC 04395-00485 (recently named V455 Dra and V454 Dra, respectively). Photometric data of the two stars were obtained using the 1-m Korean telescope of the LOAO operated by KASI while monitoring the cataclysmic variable DO Dra in the frame of the Inter-Longitude Astronomy (ILA) project. We derived periods of 0.434914 and 0.376833 days as well as initial epochs JD 2456480.04281 and JD 2456479.0523, respectively, more accurate than previously published values by factors 9 and 6. The phenomenological characteristics of the mean light curves were determined using the New Algol Variable (NAV) algorithm. The individual times of maxima/minima (ToM) were determined using the newly developed software MAVKA, which outputs accurate parameters using "asymptotic parabola" approximations. The light curves were approximated using phenomenological and physical models. In the NAV algorithm, the phenomenological parameters are well determined. We derived physical parameters using the Wilson-Devinney model. In this model, the best-fit parameters are highly correlated, thus some of them were fixed to reasonable values. For both systems, we find evidence for the presence of a cool spot and estimate its parameters. Both systems can be classified as overcontact binaries of EW type.