• Journal of Astronomy and Space Sciences
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• v.30 no.4
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• pp.291-298
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• 2013

The concept of the satellite formation flight is area where it is actively study with expandability and safety compare to existing satellite. For execution of duty with more safety issue, it needs to consider hot topic of space debris for operation of formation flight. In this paper, it suggests heuristic algorithm to have avoidance maneuver for space debris towards operating flight formation. Indeed it covers, using common software, operating simulation to nearest space environment and not only to have goal of avoidance but also minimizing the usage of fuel and finding optimization for maximizing cycle of formation flight. For improvement on convergence speed of existing heuristic algorithm, it substitute to hybrid heuristic algorithm, PSOGSA, and the result of simulation, it represents the satisfaction of minimum range for successful avoidance maneuver and compare to not using avoidance maneuver, it keeps more than three times of formation maintenance performance. From these, it is meaningful results of showing several success goals like simple avoidance collision and fuel usage and decreasing number of times of maintaining formation maneuver.

• International Journal of Aeronautical and Space Sciences
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• v.14 no.2
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• pp.183-192
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• 2013

This paper presents formation reconfiguration using impulsive control input for spacecraft formation flying. Spacecraft in a formation should change the formation size and/or geometry according to the mission requirements and space environment. To modify the formation radius and geometry with respect to the leader spacecraft, the follower spacecraft generates additional control inputs; the two impulsive control inputs are general control type of the spacecraft system. For the impulsive control input, Lambert's problem is modified to construct the transfer orbit in relative motion, given two position vectors at the initial and final time. Moreover, the numerical simulation results show the transfer trajectories to resize the formation radius in the radial/along-track plane formation and in the along-track/cross-track plane formation. In addition, the maneuver characteristics are described by comparing the differential orbital elements between the reference orbit and transfer orbit in the radial/along-track plane formation and along-track/cross-track plane formation.

• Journal of Astronomy and Space Sciences
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• v.37 no.1
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• pp.51-60
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• 2020

This study designs and analyzes satellite formation flying concepts for the Small scale magNetospheric and Ionospheric Plasma Experiments (SNIPE) mission, that will observe the near-Earth space environment using four nanosats. To meet the requirements to achieve the scientific objectives of the SNIPE mission, three formation flying concepts are analyzed: a cross-shape formation, a square-shape formation, and a cross-track formation. Of the three formation flying scenarios, the cross-track formation scenario is selected as the final scenario for the SNIPE mission. The result of this study suggests a relative orbit control scenario for formation maintenance and reconfiguration, and the initial relative orbits of the four nanosats meeting the formation requirements and thrust limitations of the SNIPE mission. The formation flying scenario is validated by calculating the accumulated total thrust required for the four nanosats. If the cross-track formation scenario presented in this study is applied to the SNIPE mission, it is expected that the mission will be successfully accomplished.

• Journal of The Korean Association For Science Education
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• v.8 no.1
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• pp.23-32
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• 1988

This paper was made for the purpose of analyging primary school child's concept formation about Euclidian space. Using clinical method, this research was executed to 360 children at a primary school in Inchon city. Research results according to the problem were as following: (1) The concept formation about Euclidion space is later than that of Piaget's research. (2) The vertical concept formation is faster than the horizontal that. (3) Sex Difference of concept formation about Euclidian space is as follews; boy's concept formation is almost three time as fast as girl's

• The Bulletin of The Korean Astronomical Society
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• v.46 no.1
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• pp.29.3-29.3
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• 2021

Globular clusters (GCs) form at the very early stage of galaxy formation, and thus can be used as an important clue indicating the environment of the galaxy formation era. Although various GC formation scenarios have been suggested, they have not been examined in the cosmological context. Here we introduce the 'particle tagging method' in order to investigate the formation scenarios of GCs in a galaxy cluster. This method is able to trace the evolution of GCs that form in the dark matter halos which undergo the hierarchical merging events in galaxy cluster environments with an effective computational time. For this we use dark matter merger trees from the cosmological N-body simulation. Finally, we would like to find out the best GC formation scenario which can explain the observational properties of GCs in galaxy clusters.

• Journal of Astronomy and Space Sciences
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• v.8 no.1
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• pp.1-10
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• 1991

The dust formation processes in novae are investigated with close attention to recent infrared observations. Using mainly the classical nucleation theory, we have calculated the time scales of dust formation and growth in the environments of novas. Those time scales roughly the typical observations. We have classified the dust-forming novae into three classes according to their explosion properties and the thermodynamic properties of dust grains. Oxygen grains form much later than carbon grains because of their thermodynamic properties. The effect of grain formation to the efficiency of stellar winds to drive the material outward is tested with newly obtained Planck mean values of dust grains.

• The Bulletin of The Korean Astronomical Society
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• v.44 no.1
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• pp.75.3-75.3
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• 2019

Understanding how ram pressure stripping (RPS) affects the star formation activity of cluster galaxies is one of the important issues in astrophysics. To examine whether we can identify any discernible trend in the star formation activity of galaxies undergoing ram pressure stripping, we study the star formation properties of galaxies in the Virgo cluster for which high-resolution HI images are available. We first classify galaxies in the Extended Virgo Cluster Catalog into different stages of RPS based on their HI morphology, HI deficiency, and location in phase space. We then examine various star formation activity indicators of these galaxies, which include starburstiness, g - r color, and WISE [3.4]-[12] color. No noticeable enhancement in star formation was identified for galaxies undergoing early or active stripping. Our results suggest that star formation activity at best seems to be enhanced locally in such galaxies, making it challenging to detect with integrated photometry. With the combination of HI deficiencies and locations in phase space, we were instead able to capture the overall quenching of star formation activity with increasing degree of ram pressure stripping, which agree with previous studies.

• Korean Institute of Interior Design Journal
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• v.17 no.3
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• pp.148-155
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• 2008

The following research focuses on the formation method of digital space by organistic line extension among various digital formation methods. The paper reflects on the meaning and concept of today's digitalism which enables the application of complex organistic system on space through advanced technology. It also explores the concept of a line in topology which differs in assumptive meaning from traditional Euclidian geometry. The findings of the research are that first, digital space is not optimized, but is a tentative formation in process. A digital space encompasses characteristics such as infinity, possibility, potential, asymmetry, and the force of virtuality such characteristics are expressed through a moving surface constantly changing with direction. Second, a digital space formed by line extension is inseparable and durable since no measurement or dimension is predetermined. Furthermore, its sense of direction and flexibility gives it a feeling of a living organism. Third, a Euclidian methodology called 'NURBS' is being developed to express such a dynamic digital space; this is reflected through three elements, control point, weights, and knots to effectively reflect the characteristics of virtuality. The opportunities of digital space are infinite, and the possibilities of formation methods likewise vast.

• KIEAE Journal
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• v.15 no.3
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• pp.65-74
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• 2015

Purpose: This study is to propose a methodology for the formation of space according to the integration of structural concept and architectural concerns in the contemporary era. Beginning with researching on the theoretical fundamentals about surface-structure, it introduces several architectural examples to analyze its own structural form and spatial characteristics, and finally simulates a model for the formation of space through a real work. Method: The study is partially based on the Executive Architectural Project for 'Village of Spring' in Seocheon, which was planned in 2008 to suggest a strategic settlement layout for urban regeneration, and completed in 2012. Making architectural vocabularies permeated into surface-structure, throughout the design process of initially pursued concepts to the design development stage, we could encounter a new type of innovative space formation. It shows that the structure is one of most useful means for the realization of architectural concepts, and a design itself. Result: The expected result of the study intends to enhance the relationship between spatial formation and surface-structure, also ultimately to produce a structural system as 'space generator' to fulfill the social needs and its requirements.

• The Bulletin of The Korean Astronomical Society
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• v.44 no.1
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• pp.40.1-40.1
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• 2019

We utilize times since infall of cluster galaxies obtained from Yonsei Zoom-in Cluster Simulation (YZiCS), the cosmological hydrodynamic N-body simulations, and star formation rates from the SDSS data release 10 to study how quickly late-type galaxies are quenched in the cluster environments. In particular, we confirm that the distributions of both simulated and observed galaxies in phase-space diagrams are comparable and that each location of phase-space can provide the information of times since infall and star formation rates of cluster galaxies. Then, by limiting the location of phase-space of simulated and observed galaxies, we associate their star formation rates at z ~ 0.08 with times since infall using an abundance matching technique that employs the 10 quantiles of each probability distribution. Using a flexible quenching model covering different quenching scenarios, we find the star formation history of satellite galaxies that best reproduces the obtained relationship between time since infall and star formation rate at z ~ 0.08. Based on the derived star formation history, we constrain the quenching timescale (2 - 7 Gyr) with a clear stellar mass trend and confirm that the refined model is consistent with the "delayed-then-rapid" quenching scenario: the constant delayed phase as ~ 2.3 Gyr and the quenching efficiencies (i.e., e-folding timescale) outside and inside clusters as ~ 2 - 4 Gyr (${\propto}M_*^{-1}$) and 0.5 - 1.5 Gyr (${\propto}M_*^{-2}$), Finally, we suggest: (i) ram-pressure is the main driver of quenching of satellite galaxies for the local Universe, (ii) the quenching trend on stellar mass at z > 0.5 indicates other quenching mechanisms as the main driver.