• The Bulletin of The Korean Astronomical Society
• /
• v.44 no.2
• /
• pp.63.2-63.2
• /
• 2019

Recent submillimeter observations of ALMA reveal that many protoplanetary disks contain substructures like gaps or rings. The disk-planet interaction is believed to be the most likely gap formation scenario, and most previous numerical work attempted to constrain the planet mass using the density profiles of gas in the gaps. Since the dust and gas distributions likely differ from each other in protoplanetary disks, however, perturbed rotational velocities that directly probe the gas would give a more reliable estimate to the planet mass. In this work, we run two-dimensional hydrodynamic simulations to measure the amplitudes and widths of rotational velocity perturbations induced by planets with different mass. We present the parametric relations of the gap widths and depths as functions of the planet mass and disk properties. We also apply our relations to HD 163296 to infer the masses of embedded planets.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.13 no.5
• /
• pp.1-7
• /
• 2014

In this paper the structural analysis of a planet carrier was carried out for the design optimization of a slewing reducer used in tower cranes. The stress changes of the planet carrier according to the tolerance of interference fit were investigated, and the strength was evaluated on the basis of the stress level. The analysis results showed that the tolerance of interference fit have an important influence on the stress level of the planet carrier. To guarantee the static safety of carrier, the tolerances of carrier pinhole and planet pin as well as loading level exerted on the planet carrier should be determined considered correctly.

• Journal of Institute of Control, Robotics and Systems
• /
• v.18 no.11
• /
• pp.989-996
• /
• 2012

The purpose of this paper is to analyze GPS (Global Positioning System) satellite orbital mechanics, and then to propose a novel long-term GPS satellite orbit prediction scheme including virtual planet perturbation. The GPS orbital information is a necessary prerequisite to pinpointing the location of a GPS receiver. When a GPS receiver has been shut down for a long time, however, the time needed to fix it before its reuse is too long due to the long-standing GPS orbital information. To overcome this problem, the GPS orbital mechanics was studied, such as Newton's equation of motion for the GPS satellite, including the non-spherical Earth effect, the luni-solar attraction, and residual perturbations. The residual perturbations are modeled as a virtual planet using the least-square algorithm for a moment. Through the modeling of the virtual planet with the aforementioned orbital mechanics, a novel GPS orbit prediction scheme is proposed. The numerical results showed that the prediction error was dramatically reduced after the inclusion of virtual planet perturbation.

• The Bulletin of The Korean Astronomical Society
• /
• v.37 no.2
• /
• pp.109.2-109.2
• /
• 2012

Current microlensing follow-up observations focus on high-magnification events because of the high efficiency of planet detection. However, central perturbations of high-magnification events caused by a planet can also be produced by a very close or a very wide binary companion, and the two kinds of central perturbations are not generally distinguished without time consuming detailed modeling (a planet-binary degeneracy). Hence, it is important to resolve the planet-binary degeneracy that occurs in high-magnification events. In this paper, we investigate caustic-crossing high-magnification events caused by a planet and a wide binary companion. From this study, we find that because of the different magnification excess patterns inside the central caustics induced by the planet and the binary companion, the light curves of the caustic-crossing planetary-lensing events exhibit a feature that is discriminated from those of the caustic-crossing binary-lensing events, and the feature can be used to immediately distinguish between the planetary and binary companions.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2009.10a
• /
• pp.602-605
• /
• 2009

This study is intended to analyze unscientific concepts shared by high school students regarding planet movement; produce a learning program to address these concepts; and investigate what impact the application of the program to planet observation and classroom lessons may have on their grasp of planet movement and their attitudes toward science at large. Application of the learning program developed in this study to teaching and learning courses led to the discovery that the program is a useful tool to enhance students' understanding of planet movement. These results suggest that a variety of programs including planet movement activities that may keep students interested in science should be continued. The above study results may be utilized in geoscience teaching and learning. It is deemed necessary to develop better learning programs and study teaching and learning methods regarding not only planet movement but also other spheres.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2012.04a
• /
• pp.518-521
• /
• 2012

N스크린 서비스는 하나의 디지털 컨텐츠를 TV, 스마트폰, 태블릿 PC나 노트북 등을 통해 일관성 있는 문맥으로 단절 없이 소비할 수 있는 환경을 마련해 준다. 현재 이 서비스는 TV와 모바일 기기의 스마트화, 클라우드 컴퓨팅의 확산, 홈 네트워킹의 발전, 모바일 웹을 위한 다양한 기술의 발전으로 그 발전 가능성이 매우 큰 서비스이다. 이런 N스크린 서비스는 단순한 연속적 상연 서비스를 넘어 다양한 기기를 동시에 사용하는 협업적 N스크린 서비스로도 진화할 것이다. 이런 환경에서 개발된 SK Planet hoppin 서비스는 TV, PC, 스마트폰, 태블릿 PC간의 연동을 통해, 기기 종류에 제약 없이 구매된 컨텐츠를 상영할 수 있는 통합 미디어를 구현하기 위해 개발되었다. 이를 위해 통신망으로 연결된 미디어 서버 및 hoppin 단말기를 위한 안드로이드 기반의 플랫폼을 개발하였으며, 크래들을 사용한 TV 연결을 통해 모바일 기기를 secondary 스크린으로도 사용될 수 있도록 했다. 이런 서비스는 현재 국내 유일의 형태이며 hoppin은 향후 협업적인 N스크린 서비스로 더욱 발전해 갈 수 있을 것이다.

• Journal of the Korean Society of Earth Science Education
• /
• v.13 no.3
• /
• pp.305-316
• /
• 2020

This study aimed to analyze the conception of an extra-solar planet perceived by university students. To conduct this, we developed an extra-solar planet education program and questionnaires which help to figure out changes between before and after the program, and then applied them to the targeted students. The results of the study are as follows. First, as to the conception of an extra-solar planet, participants understood it merely as a planet outside the solar system before they got training. However, they expanded it to the one revolving around a star that appears outside the solar system based on keywords after the training. Second, they gave brief responses regarding exploration strategies (e.g., observing the extra-solar planet by using the Doppler effect, dietary phenomenon, and gravitational lens) based on indirect experiences they encountered in the media. The responses indicated their lack of concept of the extra-solar planet exploration methods. However, their recognition of the extra-solar planet observation became concrete while students learned about the exploration of the extra-solar planet. Third, they were expanding the importance of the exoplanet observation simply beyond the discovery of extraterrestrial life to the creative process and research methods, including the solar system and the development of humanity. Fourth, they recognized that exoplanet education is necessary for curriculum as it will be able to bring about students' interest and curiosity as well as scientific knowledge if contents related to the extra-solar planet appear in the earth science curriculum.

• The Bulletin of The Korean Astronomical Society
• /
• v.35 no.1
• /
• pp.48.2-48.2
• /
• 2010

Korean-Japanese Planet Search Program has been carried out since 2005 to search for planets around intermediate-mass giant stars (1.5-5.0 solar masses) by an international collaboration between Korean and Japanese researchers. In this program, we have been carrying out a precise radial velocity survey of about 190 G-type giant stars (6.21.9 solar masses) giant stars. These results extend the planet mass distribution of massive intermediate-mass stars to higher and lower mass region, and may further constrain substellar system formation mechanisms. We report the recent results and current status of Korean-Japanese Planet Search Program.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.38 no.3
• /
• pp.187-196
• /
• 2020

In this study, collapsed building detection using UAV (Unmanned Aerial Vehicle) and PlanetScope satellite images was carried out, suggesting the possibility of utilization of heterogeneous sensors in object detection located on the surface. To this end, the area where about 20 buildings collapsed due to forest fire damage was selected as study site. First of all, the feature information of objects such as ExG (Excess Green), GLCM (Gray-Level Co-Occurrence Matrix), and DSM (Digital Surface Model) were generated using high-resolution UAV images performed object-based segmentation to detect collapsed buildings. The features were then used to detect candidates for collapsed buildings. In this process, a result of the change detection using PlanetScope were used together to improve detection accuracy. More specifically, the changed pixels acquired by the bitemporal PlanetScope images were used as seed pixels to correct the misdetected and overdetected areas in the candidate group of collapsed buildings. The accuracy of the detection results of collapse buildings using only UAV image and the accuracy of collapse building detection result when UAV and PlanetScope images were used together were analyzed through the manually dizitized reference image. As a result, the results using only UAV image had 0.4867 F1-score, and the results using UAV and PlanetScope images together showed that the value improved to 0.8064 F1-score. Moreover, the Kappa coefficiant value was also dramatically improved from 0.3674 to 0.8225.

• Journal of The Korean Astronomical Society
• /
• v.35 no.1
• /
• pp.35-40
• /
• 2002

Gaudi, Naber & Sackett pointed out that if an event is caused by a lens system containing more than two planets, all planets will affect the central region of the magnification pattern, and thus the existence of the multiple planets can be inferred by detecting additionally deformed anomalies from intensive monitoring of high magnification microlensing events. Unfortunately, this method has important limitations in identifying the existence of multiple planets and determining their parameters (the mass ratio and the instantaneous projected separation) due to the degeneracy of the resulting light curve anomalies from those induced by a single planet and the complexity of multiple planet lensing models. In this paper, we propose a new channel to search for multiple planets via microlensing. The method is based on the fact that the lensing light curve anomalies induced by multiple planets are well approximated by the superposition of those of the single planet systems where the individual planet-primary pairs act as independent lens systems. Then, if the source trajectory passes both of the outer deviation regions induced by the individual planets, one can unambiguously identify the existence of the multiple planets. We illustrate that the probability of successively detecting light curve anomalies induced by two Jovian-mass planets located in the lensing zone through this channel will be substantial. Since the individual anomalies can be well described by much simpler single planet lensing models, the proposed method has an important advantage of allowing one to accurately determine the parameters of the individual planets.