• International Journal of Aeronautical and Space Sciences
• /
• v.10 no.1
• /
• pp.58-66
• /
• 2009

Formation controller for multiple spacecrafts is designed based on a decentralized approach. The objective of the proposed controller is to make each spacecraft fly to the desired waypoints, while keeping the formation shape of multiple spacecrafts. To design the decentralized formation controller, the output feedback linearization technique using error functions for goal convergence and formation keeping is utilized for spacecraft dynamics. The primary contribution of this paper is to proposed optimal controller for formation flying based on the decentralized approach. To design the optimal controller, eigenvalue assignment technique is used. To verify the effectiveness of the proposed controller, numerical simulations are performed for three-dimensional waypoint-passing missions of multiple spacecrafts.

• Journal of Astronomy and Space Sciences
• /
• v.30 no.1
• /
• pp.11-15
• /
• 2013

A collision-free formation reconfiguration trajectory subject to the linearized Hill's dynamics of relative motion is analytically developed by extending an algorithm for gravity-free space. Based on the initial solution without collision avoidance constraints, the final solution to minimize the designated performance index and avoid collision is found, based on a gradient method. Simple simulations confirm that satellites reconfigure their positions along the safe trajectories, while trying to spend minimum energies. The algorithm is applicable to wide range of formation flying under the Hill's dynamics.

• The Bulletin of The Korean Astronomical Society
• /
• v.36 no.2
• /
• pp.57.2-57.2
• /
• 2011

To study the formation and evolution of sub-galactic scale structures, we have added SPH (Smoothed Particle Hydrodynamics) method into an existing cosmological PMTree code, GOTPM. To follow the evolution of gas particles, we consider heating/cooling processes, star formation, and energy & metal feedback by supernova explosion. We have performed various tests for the new code and found that the results reproduce observed quantities or follow the known analytic solutions. We present a test simulation of isolated disk galaxy with a focus on whether the star formation reproduces the observed features.

• Journal of the Architectural Institute of Korea Planning & Design
• /
• v.34 no.4
• /
• pp.133-140
• /
• 2018

This study is change of the street space of the port city of Yokohama and the transformation process of the canal. modern port city Yokohama is a region that was responsible for the development of East-West maritime transport routes in Japan in the 17th century and the inland transportation through fishing villages and ports. it has also grown rapidly as a regional port and new port. In particular, through the revitalization of trade between foreign settlements and Japanese residents in the port area, the existing fishing area became a modern port city space. Yokohama went through the following process and grew into a modern port city. The construction of the port harbor and the maintenance of existing logistics functions, the formation of the central horizontal axis through maintenance of the fishing village, the construction of the logistics movement route to the inland area through the construction of the canal, the expansion of the horizon for fire prevention and fire restoration, The formation of a new settlement space according to the movement, the transformation of the existing religious axis by the combination of the elaboration and the introduction of modern transportation, and the spatial connection between the inland cities.

• Journal of Environmental Science International
• /
• v.29 no.4
• /
• pp.403-413
• /
• 2020

The purpose of this study is to understand the formation of internal wind paths of open space and its effect on meteorological factors and the generation of negative air ions. Various types of internal wind paths of open space were formed. Subsequently, changes in meteorological factors in each type were measured and the generated negative air ions were analyzed. The four key findings of the study are summarized as follows. First, the average wind speed formed inside the open space was analyzed such that the difference in wind speed was dependent on the difference in the composition of the wind path. Second, the negative air ion generation was observed to have the same trend as the average wind speed difference. Third, changes to the meteorological factors were more evident depending on the difference in wind path formation patterns. Solar radiation was expected to be highly affected by the physical structure (direction) of the target site. The relative humidity was found to show large difference depending on the different wind path type; however, this difference was significantly reduced when converting to absolute humidity. Fourth, it was found that the wind path formation type of open space affects meteorological factors through path analysis, and the changed meteorological factors affect the amount of generated negative air ions. Two conclusions can be obtained based on these results. First, the changes in internal wind speed formation of open space directly reduced the amount of generated negative air ions. Second, the changes in wind speed affect meteorological factors as well as the amount of generated negative air ions.

• The Bulletin of The Korean Astronomical Society
• /
• v.41 no.2
• /
• pp.39.2-40
• /
• 2016

The molecular gas surrounding an H II region is thought to be a place where star formation can be induced. Such triggered star formation can arise form the overpressurization of existing density enhancements or thought the collapse of a swept up layers of material. In this talk, We will discuss the results of a study of star-formation activity associated with the outer Galaxy ring-shaped H II regions KR 7, KR 81, KR 120 and KR 140 using archival Spitzer and WISE data along with the JHK observations. We used CO data cubes from the FCRAO and TRAO in order to define extent of the molecular cloud associated each HII region. Using the infrared data sets, We identified and classified YSO populations within each molecular cloud using measures such as the class I/II ratio and YSO spatial density. Along with this, one of the main question in the study of star formation is how protostar accrete material from their parent molecular clouds and observations of infall motions are needed to provide direct evidence for accretion. Combining our observation of the YSO population distribution with time scales associated with YSO evolution and HII expansion, we investigated the possible significance of triggered star formation in the molecular cloud surrounding each region.

• The Bulletin of The Korean Astronomical Society
• /
• v.38 no.1
• /
• pp.50.2-50.2
• /
• 2013

In the process of star formation, the density and temperature of associated material, which are the physical conditions for the molecular chemistry, vary dramatically. As a result, the connection between physical and chemical conditions has been used to trace the evolutionary stages in star formation. One chemical tracer for the physical conditions in star forming material is the [HCN]/[HNC] abundance ratio since the ratio strongly depends on the kinetic temperature in molecular clouds. Here we investigate the [HCN]/[HNC] abundance ratios in objects related to the massive star formation. For the investigation, we carried out $H^{13}CN$ and $HN^{13}C$ line observation toward objects in three different evolutionary stages of massive star formation: Infrared dark clouds (IRDCs), High-mass protostellar object (HMPOs), and Ultra-compact HII regions (UCHIIs). According to our observational results, both $H^{13}CN$ and $HN^{13}C$ lines have been detected toward 19 IRDCs, 25 HMPOs, and 31 UCHIIs. We will discuss about the [HCN]/[HNC] abundance ratios in different evolutionary stages of massive star formation and associate the results with the physical conditions of the targets.

• Korean Institute of Interior Design Journal
• /
• v.25 no.6
• /
• pp.127-138
• /
• 2016

As the dark side of society, Idle spaces, which occurred with the paradigm change due to rapid modernization and industralization, has been existing as a severed part in cities. But with the periodic change, interest in the existing place and regional regeneration, and the necessity of reconsidering about the idle spaces values of space, city environment, socio-culture, and economy was proposed. I estimated that the change of relational aesthetics aspect of modern arts resulted in the consideration of recognizing 'place' of art, through the study, it was revealed that the form of modern arts and change of enjoyment were related to space, and the fact that this had a relation with the rise of artistic regeneration of idle spaces. mutually communicative relationship formation and practical form of arts was deducted through the interpretation of relational aesthetics, Idle spaces and artistic regeneration space can be categorized into forms of experiential space, creative space, and cultural space, depending on the formation of relationship between author-art-audience. Through the comprehensive analysis, Artistic regeneration space by relationship formation is Vitalization of various forms of art and participation program eliminates the boundary between creation and enjoyment, and the space itself can be said to contain extensive, integral, and nonterritorialization meaning as a place of experiencing art. In other words, Artistic regeneration space of idle spaces forms a close relationship with the local society, and is placed within the context of daily domain as an open space, straying off from the existing separative and closed artistic space configuration. and artistic changeover of idle spaces is not only the appearance of space that simply fulfills function according to transfiguration of modern art, but signifies that art is coexisting with space as an indivisible relationship, and can be said to be the foothold of new relationship creation as the practical 'place' of art.

• The Bulletin of The Korean Astronomical Society
• /
• v.44 no.1
• /
• pp.69.2-69.2
• /
• 2019

Recent high resolution IR observations reveal that molecular clouds are filamentary and such a structure is ubiquitous over various star-forming environments, and it is clear that filaments play a crucial role in the formation of cores and stars. However, the formation process of dense cores in the filaments are still unknown. To investigate this issue in detail, we have carried out TRAO FUNS (TRAO survey of nearby Filamentary molecular clouds, the Universal Nursery of Stars) toward various star forming filamentary molecular clouds. In this presentation, we will report the first look results of filaments and dense cores in MCLD 123.5+24.9 and IC 5146, which are known as a quiescent, non-star-forming region and an active, high-mass star forming region, respectively. By comparing the kinematic properties of filaments and dense cores in different star forming environments, we verified the formation scenario of filaments and dense core, i.e., gravoturbulent fragmentation via supersonic motions.

• Journal of the Korean Society for Aviation and Aeronautics
• /
• v.24 no.2
• /
• pp.19-24
• /
• 2016

Positional stability analysis based on aerodynamic forces and induced moments of formation flight using two small aircraft models is presented. The aerodynamic force and moments of the trailing aircraft are analyzed in the aspect of flight stability. The induced moments with the change of local flow direction by wing-tip vortex from the leading aircraft can affect the flight positional stability of aircraft in closed formation flight. Aerodynamic forces and moments of trailing aircraft model are measured by 6-component internal balance at the 49 locations with vertical and lateral space between two aircraft models. Results are shown that the positional stability of trailing aircraft in formation flight can be analyzed by positional stability derivatives with vertical and lateral space. It is concluded that flying positions can be important factors for aircraft position stability due to induced aerodynamic force and moments with vertical and lateral spacing by the variation of flow pattern from the leading aircraft in formation flight.