It is difficult to distinguish the pure signal produced by an orbiting planetary companion around giant stars from other possible sources, such as stellar spots, pulsations, or certain activities. Since 2003, we have obtained radial (RV) data from evolved stars using the high-resolution, fiber-fed Bohyunsan Observatory Echelle Spectrograph (BOES) at the Bohyunsan Optical Astronomy Observatory (BOAO). Here, we report the results of RV variations in the binary star HD 135438. We found two significant periods: 494.98 d with eccentricity of 0.23 and 8494.1 d with eccentricity of 0.83. Considering orbital stability, it is impossible to have two companions in such close orbits with high eccentricity. To determine the nature of the changes in the RV variability, we analyzed indicators of stellar spot and stellar chromospheric activity to find that there are no signals related to the significant period of 494.98 d. However, we calculated the upper limits of rotation period of the rotational velocity and found this to be 478–536 d. One possible interpretation is that this may be closely related to the rotational modulation of an orbital inclination at 67–90 degrees. The other signal corresponding to the period of 8494.1 d is probably associated with a stellar companion orbiting the giant star. A Markov Chain Monte Carlo (MCMC) simulation considering a single companion indicates that HD 135438 system hosts a stellar companion with 0.57+0.017 −0.017 M⊙ with an orbital period of 8498 d.

This paper is written as a follow-up observations to reinterpret the radial velocity (RV) of HD 36384, where the existence of planetary systems is known to be ambiguous. In giants, it is, in general, difficult to distinguish the signals of planetary companions from those of stellar activities. Thus, known exoplanetary giant hosts are relatively rare. We, for many years, have obtained RV data in evolved stars using the high-resolution, fiber-fed Bohyunsan Observatory Echelle Spectrograph (BOES) at the Bohyunsan Optical Astronomy Observatory (BOAO). Here, we report the results of RV variations in the M giant HD 36384. We have found two significant periods of 586 d and 490 d. Considering the orbital stability, it is impossible to have two planets at so close orbits. To determine the nature of the RV variability variations, we analyze the HIPPARCOS photometric data, some indicators of stellar activities, and line profiles. A significant period of 580 d was revealed in the HIPPARCOS photometry. H𝛼 EW variations also show a meaningful period of 582 d. Thus, the period of 586 d may be closely related to the rotational modulations and/or stellar pulsations. On the other hand, the other significant period of 490 d is interpreted as the result of the orbiting companion. Our orbital fit suggests that the companion was a planetary mass of 6.6 𝑀J and is located at 1.3 AU from the host.

We have been conducting a exoplanet search survey using Bohyunsan Observatory Echelle Spectrograph (BOES) for the last 18 years. We present the detection of exoplanet candidate in orbit around HD 18438 from high-precision radial velocity (RV) mesurements. The target was already reported in 2018 (Bang et al. 2018). They conclude that the RV variations with a period of 719 days are likely to be caused by the pulsations because the Lomb-Scargle periodogram of HIPPARCOS photometric and Hα EW variations for HD 18438 show peaks with periods close to that of RV variations and there were no correlations between bisectors and RV measurements. However, the data were not sufficient to reach a firm conclusion. We obtained more RV data for four years. The longer time baseline yields a more accurate determination with a revised period of 803 ± 5 days and the planetary origin of RV variations with a minimum planetary companion mass of 21 ± 1MJup. Our current estimate of the stellar parameters for HD 18438 makes it currently the largest star with a planetary companion.

PURPOSES : This study aimed to develop data conversion of NGII HD maps to OpenDRIVE format for virtual road implementation for autonomous-driving verification. METHODS : A method of defining the reference line of OpenDRIVE on the centerline of an NGII HD map is proposed. According to the construction characteristics of the NGII HD map, the optimal conversion method through parametric cubic polynomials was used in the form of piecewise and clamped cubic polynomials. RESULTS : The study focused on curved roads that may cause problems when converting HD map data into OpenDRIVE formats. As a result of data conversion, a reference line was defined to precisely follow the alignment of NGII HD maps drawn based on MMS data, and a lively virtual road was reproduced through road lane width and lane expression. CONCLUSIONS : A virtual road in the same environment as a real road, which is one of the important factors in verifying autonomous driving technology through virtual driving simulation, was constructed. The piecewise-polynomial normal was 0.008 m on average, and as a result of calculating the distance between the endpoint coordinates of the road object and the endpoint coordinates of the converted road object on the NGII HD map, the difference between the two points was 0.163 m on average. The clamped cubic polynomials normal was observed to be an average of 0.170 m.

It has been established that the acoustic mode parameters of the Sun and Sun-like stars vary over activity cycles. Since the observed variations are not consistent with an activity-related origin, even Sun-like stars showing out-of-phase changes of mode frequencies and amplitudes need to be carefully studied using other observational quantities. In order to test whether the presumed relations between the global seismic parameters are a signature of the stellar activity cycle, we analyze the photometric light curve of HD 49933 for which the rst direct detection of an asteroseismic signature for activityinduced variations in a Sun-like star was made, using observations by the CoRoT space telescope. We nd that the amplitude of the envelope signicantly anti-correlates with both the maximum frequency of the envelope and the width of the envelope unless super are-like events completely contaminate the light curve. However, even though the photometric proxy for stellar magnetic activity appears to show relations with the global asteroseismic parameters, they are statistically insignicant. Therefore, we conclude that the global asteroseismic parameters can be utilized in cross-checking asteroseismic detections of activity-related variations in Sun-like stars, and that it is probably less secure and efective to construct a photometric magnetic activity proxy to indirectly correlate the global asteroseismic parameters. Finally, we seismically estimate the mass of HD 49933 based on our determination of the large separation of HD 49933 with evolutionary tracks computed by the MESA code and nd a value of about 1:2M and a sub-solar metallicity of Z = 0:008, which agrees with the current consensus and with asteroseismic and non-asteroseismic data.

We report the detection of exoplanet candidates in orbits around HD 60292 and HD 112640 from a radial velocity (RV) survey. The stars exhibit RV variations with periods of 4953 days and 6136 days, respectively. These detections are part of the Search for Exoplanets around Northern Circumpolar Stars (SENS) survey using the ber-fed Bohyunsan Observatory Echelle Spectrograph installed at the 1.8-m telescope of the Bohyunsan Optical Astronomy Observatory in Korea. The aim of the survey is to search for planetary or substellar companions. We argue that the periodic RV variations are not related to surface inhomogeneities; rather, Keplerian motions of planetary companions are the most likely interpretation. Assuming stellar masses of 1:7  0:2M⊙ (HD 60292) and 1:8  0:2M⊙ (HD 112640), we obtain minimum planetary companion masses of 6:5  1:0MJup and 5:0  1:0MJup, and periods of 495:4  3:0 days and 613:2  5:8 days, respectively.

Detecting exoplanets around giant stars sheds light on the later-stage evolution of planetary systems. We observed the M giant HD 18438 and the K giant HD 158996 as part of a Search for Exoplanets around Northern circumpolar Stars (SENS) and obtained 38 and 24 spectra from 2010 to 2017 using the high-resolution Bohyunsan Observatory Echelle Spectrograph (BOES) at the 1.8m telescope of Bohyunsan Optical Astronomy Observatory in Korea. We obtained precise RV measurements from the spectra and found long-period radial velocity (RV) variations with period 719.0 days for HD 18438 and 820.2 days for HD 158996. We checked the chromospheric activities using Ca ii H and H lines, HIPPARCOS photometry and line bisectors to identify the origin of the observed RV variations. In the case of HD 18438, we conclude that the observed RV variations with period 719.0 days are likely to be caused by the pulsations because the periods of HIPPARCOS photometric and H EW variations for HD 18438 are similar to that of RV variations in Lomb-Scargle periodogram, and there are no correlations between bisectors and RV measurements. In the case of HD 158996, on the other hand, we did not find any similarity in the respective periodograms nor any correlation between RV variations and line bisector variations. In addition, the probability that the real rotational period can be as longer than the RV period for HD 158996 is only about 4.3%. Thus we conclude that observed RV variations with a period of 820.2 days of HD 158996 are caused by a planetary companion, which has the minimum mass of 14.0 MJup, the semi-major axis of 2.1 AU, and eccentricity of 0.13 assuming the stellar mass of 1.8 M⊙. HD 158996 is so far one of the brightest and largest stars to harbor an exoplanet candidate.

This study proposes that general users will produce UHD image contents or game background image. UHD realistic image gives reality with a 4K ultra high‐definition large screen. However, UHD contents are relatively lacked. In order to produce UHD contents, 4K images are needed. As shooting equipment is expensive, HD image is converted through upscale or pull down. Accordingly, in this study, we propose to take 4K definition static image with general camera to produce UHD contents, and to insert sound and effects and to sync using editing program. For experiment, we used 15 seconds' length image in 3840x2160 and 4096x2304 resolution respectively. In the experiment, it was found that image quality and volume increased and sense of reality changed according to definition and high frame rate. As another experiment, we used 15 seconds' length HD image in 3840x2160 resolution using high frame rate method. In the experiment, it was found that image quality, volume and sense of reality were changed according to high frame rate.

Requirements for contents service providing a sense of realism based on high quality and high resolution have increased since HD (High definition) and 3D technologies have emerged. Recently, high frame rate (HFR) and multi-channel audio-based contents with 4K resolution have been produced since UHDTV which can display 4 times as many pixels as Full HD on a screen has been released. Also high performance graphic rendering technology using high resolution large display, high-speed transmission technology etc have been continuously researched to improve gamers' level of satisfaction providing greater immersion in game field. The necessity to implement UHDTV game based on high resolution large display has been raised to provide greater immersion and presence. Therefore, the research examines changes in display environment to implement high quality games using UHDTV.

In an attempt to optimize the magnetic properties of (Nd, Dy)-Fe-B sintered magnets, hydrogenation and post-sintering heat treatment processes were investigated at various hydrogenation temperatures and heat treatment temperatures. The coercivity of (Nd, Dy)-Fe-B sintered magnets hydrogenated at increased to about 1.2 kOe without any detrimental effect on the remanence. Moreover, the coercivity of the magnets was enhanced further by a consecutive and step heat treatment. These results eventually leaded to the reduction of the Dy content in a high coercive (> 30 kOe) (Nd, Dy)-Fe-B sintered magnets, as much as 10%.

Through time-series CCD photometry using a 155mm refractor, we found a new δ Scuti type variable star, HD 235428, near a known bright δ Scuti type star, DQ Cep. We performed follow-up observations using a 61cm telescope at Sobaeksan Optical Astronomy Observatory. Four frequencies have been derived by multiple-frequency analysis, which are 15.804, 5.498, 15.351 and 24.516cycle day−1 , respectively. V-amplitude of HD 235428 is ΔV = 0.026.