• Journal of Astronomy and Space Sciences
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• v.21 no.3
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• pp.209-220
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• 2004

Some methods have been presented to get optimal formation trajectories in the step of configuration or reconfiguration, which subject to constraints of collision avoidance and final configuration. In this study, a method for optimal formation trajectory-planning is introduced in view of fuel/time minimization using parameter optimization technique which has not been applied to optimal trajectory-planning for satellite formation flying. New constraints of nonlinear equality are derived for final configuration and constraints of nonlinear inequality are used for collision avoidance. The final configuration constraints are that three or more satellites should be placed in an equilateral polygon of the circular horizontal plane orbit. Several examples are given to get optimal trajectories based on the parameter optimization problem which subjects to constraints of collision avoidance and final configuration. They show that the introduced method for trajectory-planning is well suited to trajectory design problems of formation flying missions.

• Proceedings of the Korea Contents Association Conference
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• 2003.05a
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• pp.454-460
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• 2003

while they cannot overcome the limitation that arises in the process of representing the 3D real world to the 2D plane. Also, there exists requirements on performance to support realtime navigation capability.In this paper, therefore, we propose a cell loading algorithm for navigating virtual space that can support realtime visualization according to the multimedia objects in variety and the change of the view point by user, and that can accommodate the capacity imposed in the process of navigation regardless of the number of objects.

• KIEAE Journal
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• v.15 no.4
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• pp.61-68
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• 2015

[Purpose] Recently, skyscrapers have sharply increased throughout the world, including South Korea. Although a skyscraper has its own merit such as the landmark of a city, it also has various problems like massive energy consumption. This study is aimed to establish the concept of environment-friendly skyscraper and propose a plan to realize skyscraper after analyzing the architectural, facility and environmental friendly elements of skyscrapers. [Method] This study lists up skyscrapers over 40 floors and 200 meters high. Upon 10 constructed buildings, it analyzes their basic plans and the green building technologies applied to them and suggests effective and environment-friendly architectural plan. [Result] This study examined the distinctions of the layout, shape, facade, and floor plan plane of 10 skyscrapers and found out specific techniques to be used for the use plan of natural energy, plan for saving resources and reducing wastes and a plan for environmental architecture and system.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.1
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• pp.57.1-57.1
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• 2017

As an upgrade we report the current ASTE ultra-wideband corrugated horn design. The length of the feedhorn gets shortened from 12.5 mm to 11 mm, and it shows better side lobe level at the far-field patterns compared with the previous design. We looked into possible quasi-optical solution to match the feedhorn beam to the optics of the current ASTE telescope, starting from frequency-independent solution using two ellipsoidal mirrors to which wideband performance of the feedhorn naturally fits. We used a commercial physical optics package (GRASP) with an user-defined optimizer to give physical constraints to evaluated optical designs for highest efficiency.

• Journal of the Optical Society of Korea
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• v.19 no.3
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• pp.303-310
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• 2015

An image-space telecentric lens for an intra-oral 3D scanner was designed and fabricated for dental application. Since a telecentric function can provide the same results regardless of image plane position, it helps to realize a more accurate image for an intra-oral scanner. The performance of the designed lens meets the required properties for HD resolution. In particular, lateral color is corrected within 1 pixel. This system achieves depth of focus of more than 3 mm. For user convenience, the developed system consists of a prism part and an imaging part. Both parts are optimized to reduce the front size and weight of the system. In order to make the parallax sights, parallax angle was determined to be 8 degrees between two optical systems.

• Journal of The Korean Astronomical Society
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• v.56 no.2
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• pp.169-185
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• 2023

The GMT-Consortium Large Earth Finder (G-CLEF) is the first instrument for the Giant Magellan Telescope (GMT). G-CLEF is a fiber feed, optical band echelle spectrograph that is capable of extremely precise radial velocity measurement. G-CLEF Flexure Control Camera (FCC) is included as a part in G-CLEF Front End Assembly (GCFEA), which monitors the field images focused on a fiber mirror to control the flexure and the focus errors within GCFEA. FCC consists of an optical bench on which five optical components are installed. The order of the optical train is: a collimator, neutral density filters, a focus analyzer, a reimager and a detector (Andor iKon-L 936 CCD camera). The collimator consists of a triplet lens and receives the beam reflected by a fiber mirror. The neutral density filters make it possible a broad range star brightness as a target or a guide. The focus analyzer is used to measure a focus offset. The reimager focuses the beam from the collimator onto the CCD detector focal plane. The detector module includes a linear translator and a field de-rotator. We performed thermoelastic stress analysis for lenses and their mounts to confirm the physical safety of the lens materials. We also conducted the global structure analysis for various gravitational orientations to verify the image stability requirement during the operation of the telescope and the instrument. In this article, we present the opto-mechanical detailed design of G-CLEF FCC and describe the consequence of the numerical finite element analyses for the design.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1999.04a
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• pp.129-136
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• 1999

This research proposes an effective analytical methodology for vertical vibration of three dimensional frame structures including slabs. The consideration of slabs, although allows more precise results, requires large amount of computer time and memory space due to the use of plane stress elements. In consideration of these problems, a method to properly manage nodal points and degrees of freedom is proposed based on matrix condensation technique. Also studied is the use of substructure method to obtain fast and reliable results with simple input data when they are applied to conventional building structures.

• The Bulletin of The Korean Astronomical Society
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• v.35 no.1
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• pp.76.2-76.2
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• 2010

We report the extended far-ultraviolet (FUV) halo of NGC 891 above the galactic plane. The FUV intensity distribution is well described by two exponential components, one with the scale height of ~0.34 kpc and the other of ~2.3 kpc. The extraplanar FUV halo is traceable up to > 5 kpc. The FUV halo is attributable to scattered-off starlight by extraplanar dust. Using Monte-Carlo radiative transfer simulations, the FUV intensity distribution along the minor axis is found to be well modeled with two dust comonents. Its implications are discussed.

• Journal of The Korean Astronomical Society
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• v.31 no.2
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• pp.127-140
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• 1998

With a large format near-infrared camera at the 2.2-m telescope on Mauna Kea Observatory, we performed J K near-infrared observations for the metal rich globular cluster NGC6712. This cluster lies near the galactic plane and therefore suffers heavy reddening. We present the near-infrared color-magnitude diagram and also derive the metallicity ([Fe/H] ${\~}-0.96{\pm}0.27$) as well as its distance modulus ((m - M) ${\~}13.42{\pm}0.12$).

• The Bulletin of The Korean Astronomical Society
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• v.44 no.1
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• pp.84.1-84.1
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• 2019

722 open clusters in the Sim open cluster catalogue show the outermost structure of open clusters. The catalogue is based on the proper motion and parallax of the stars. These results reveal the hidden structures of weak membership signals in the field star contamination. It contains the tidal tails, flattened structure along the galactic plane, interacting double clusters and very poor and spread clusters. We will show these interesting structures.