• 제어로봇시스템학회:학술대회논문집
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• 1995.10a
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• pp.368-371
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• 1995

This paper describes dynamic analysis and attitude control of a large spacecraft with flexible appendages in gravitational field. The effect of attitude control and vibration control of flexible appendages in gravitational field has been clarified. We demonstrate some simulations in gravitational field for some cases, and suggest the effects of gravitational torque, parameters of flexible appendages, attitude control and vibration control of flexible appendages.

• Journal of The Korean Astronomical Society
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• v.19 no.1
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• pp.11-14
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• 1986

It is shown in this paper that the astigmatic property of single gravitational lens in static bounded gravitational field can be retained, if n-gravitating body as a whole acts simultaneously as gravitational lens.

• Journal of The Korean Astronomical Society
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• v.19 no.2
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• pp.63-68
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• 1986

In this paper we deal with the orientation and the deformation of the circular light bundle passing in a static bounded gravitational field. The properties of caustic of the gravitational lens are discussed.

• Publications of The Korean Astronomical Society
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• v.30 no.2
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• pp.401-403
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• 2015

We present the results of the analysis of FLS 1718+59, a galaxy-galaxy gravitational lens system in the Spitzer First Look Survey (FLS) field. A background galaxy ($z_s=0.245$) is severely distorted by a nearby elliptical galaxy ($z_l=0.08$), via gravitational lensing. The system is analysed by several methods, including surface brightness fitting, gravitational lens modeling, and spectral energy distribution fitting. From Galfit and Ellipse we measure basic parameters of the galaxy, such as the effective radius and the average surface brightness within it. gravlens yields the total mass inside the Einstein radius ($R_{Ein}$), and MAGPHYS gives us an estimate of the stellar mass inside $R_{Ein}$. By comparing these parameters, we confirm that the lens galaxy is an elliptical galaxy on the Fundamental Plane and calculate the stellar mass fraction inside $R_{Ein}$, and discuss the results with regards to the initial mass function.

• The Bulletin of The Korean Astronomical Society
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• v.36 no.1
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• pp.47.2-47.2
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• 2011

Gravitational waves from the pulsar glitch can be detected by next generation gravitational wave observatories. We investigate characteristics of the modes that can emit the gravitational waves excited by three different types of perturbations satisfying conservation of total rest mass and angular momentum. These perturbations mimic the pulsar glitch theories i.e., change of moment of inertia due to the star quakes or angular momentum transfer by vortex unpinning at crust-core interface. We carry out numerical hydrodynamic simulations using the pseudo-Newtonian method which makes weak field approximation for the dynamics, but taking all forms of energies into account to compute the Newtonian potential. Unlike other works, we found that the first and second strongest modes that give gravitational waves are $^2p_1$ and $H_1$ rather than$^2f$. We also found that vortex unpinning model excites the inertial mode in quadrupole moment quite effectively. The inertial mode may evolve into the non-axisymmetric r-mode.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.89.2-89.2
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• 2012

We present our analysis of a newly discovered galaxy-galaxy gravitational lens system in the First Look Survey (FLS) field. This object shows a highly distorted background galaxy (z=0.245) image by a nearby elliptical galaxy (z=0.08), which can be interpreted as a result of gravitational lensing. We model the lens with elliptical isothermal sphere model, and present the mass and potential distribution of the system.

• Bulletin of the Korean Chemical Society
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• v.33 no.2
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• pp.711-713
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• 2012

• Advances in materials Research
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• v.12 no.2
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• pp.101-118
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• 2023

The purpose of this paper is to study the effects of magnetic field and gravitational field on fiber-reinforced thermoelastic medium with memory-dependent derivative. Three-phase-lag model of thermoelasticity (3PHL) is used to study the plane waves in a fiber-reinforced magneto-thermoelastic material with memory-dependent derivative. A gravitating magneto-thermoelastic two-dimensional substrate is influenced by both thermal shock and mechanical loads at the free surface. Analytical expressions of the considered variables are obtained by using Laplace-Fourier transforms technique with the eigenvalue approach technique. A numerical example is considered to illustrate graphically the effects of the magnetic field, gravitational field and two types of mechanical loads(continuous load and impact load).

• The Bulletin of The Korean Astronomical Society
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• v.38 no.2
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• pp.52.1-52.1
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• 2013

We present new analyses of FLS 1718+59, a galaxy-galaxy gravitational lens system in the Spitzer First Look Survey (FLS) Field. A background galaxy (z = 0.245) is severely distorted by a nearby elliptical galaxy (z = 0.08), which can be interpreted as a result of gravitational lensing. We analyze this system by multiple methods, including ELLIPSE fitting, gravitational lens modeling, and surface brightness fitting. From this analysis, we obtain parameters of the lens galaxy using varying approaches and compare them. In the future, we will conduct SED fitting for the lens galaxy and estimate the stellar mass, and compare this with the total mass of the lens to check the M-L relation.

• Publications of The Korean Astronomical Society
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• v.32 no.1
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• pp.251-255
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• 2017

Submillimetre and millimetre-wave surveys with Herschel and the South Pole Telescope have revolutionised the discovery of strong gravitational lenses. Their follow-ups have been greatly facilitated by the multi-wavelength supplementary data in the survey fields. The forthcoming Euclid optical/near-infrared space telescope will also detect strong gravitational lenses in large numbers, and orbital constraints are likely to require placing its deep survey at the North Ecliptic Pole (the natural deep field for a wide class of ground-based and space-based observatories including AKARI, JWST and SPICA). In this paper I review the current status of the multi-wavelength survey coverage in the NEP, and discuss the prospects for the detection of strong gravitational lenses in forthcoming or proposed facilities such as Euclid, FIRSPEX and SPICA.