• Journal of the Korea Institute of Military Science and Technology
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• v.24 no.2
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• pp.151-164
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• 2021

With the gradual increase in the ROK naval power, it is an undeniable fact that the time of operation in the ice-infested area will be necessary in the near future. Recently, cases of ice formation around Korean waters in wintertime have been frequently reported. However, in the case of the ROK naval vessels to date, it is a fact that the ice-strengthened perspective has not been considered from the design stage. In this study, the capability of operation in the ice-infested area of the ROK naval vessels, which did not take into account the ice-strengthened design, was reviewed through the evaluation of the vessel's structural integrity in accordance with the sea ice conditions.

• The Bulletin of The Korean Astronomical Society
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• v.46 no.2
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• pp.72.2-72.2
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• 2021

Cosmic reionization imprints its history on the sky map of the cosmic microwave background (CMB) polarization. Even though mild, the signature of the reionization history during its early phase (z>15) can also impact the CMB polarization. We forecast the observational capability of the LiteBIRD(Lite(Light) satellite for the studies of B-mode polarization and Inflation from cosmic background Radiation Detection), a truly cosmic-variance limited apparatus. We focus on the capability for such an apparatus to probe the partial optical depth of the CMB photons during z>15. We show that LiteBIRD is able to probe this quantity with a modest to high significance, enabling one to tell how efficient the cosmic reionization and star formation were at z>15.

• Bulletin of the Korean Space Science Society
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• 2008.10a
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• pp.26.3-26.3
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• 2008

This research develops a GPS-based formation-flying testbed (FFTB) for formation navigation and control. The FFTB is a simulator in which spacecraft simulation and modeling software and loop test capabilities are integrated for test and evaluation of spacecraft navigation and formation control technologies. The FFTB is composed of a GPS measurement simulation computer, flight computer, environmental computer for providing true environment data and 3D visualization computer. The testbed can be simulated with one to two spacecraft, thus enabling a variety of navigation and control algorithms to be evaluated. In a formation flying simulation, GPS measurement are generated by a GPS measurement simulator to produce pseudorange, carrier phase measurements, which are collected and exchanged by the flight processors and subsequently processed in a navigation filter to generate relative and/or absolute state estimates. These state estimates are the fed into control algorithm, which are used to generate maneuvers required to maintain the formation. In this manner, the flight processor also serves as a test platform for candidate formation control algorithm. Such maneuvers are fed back through the controller and applied to the modeled truth trajectories to close simulation loop. Currently, The FFTB has a closed-loop capability of simulating a satellite navigation solution using software based GPS measurement, we move forward to improve using SPIRENT GPS RF signal simulator and space-based GPS receiver

• The Bulletin of The Korean Astronomical Society
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• v.43 no.1
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• pp.47.2-47.2
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• 2018

In this talk, we will review extragalactic science cases with NISS and SPHEREx. With its capability to perform a low resolution spectroscopy over a wide area, NISS and SPHEREx can provide valuable information about the evolution of spectral shapes of galaxies in different environments over cosmic history. This talk will focus on the cases for the studies that are closely related to the galaxy evolution and formation.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.26-29
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• 2008

In the fields of electronics and displays where inkjet printing has demonstrated its capability to fabricate colorant subpixels of thin film transistor liquid crystal(TFT LCD) color filters and organic light emitting diode (OLED) displays, conducting tracks and TFTs, the production of satellite droplets is one of primary things to eliminate because they generally deteriorate the pattern quality. To understand the production mechanism of satellite droplets in this paper, driving waveforms such as monopolar and bipolar were employed and the influence of the pulse duration time were investigated in both experimental and numerical aspects.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2012.11a
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• pp.90-90
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• 2012

Catechol moiety has enough reducing capability of reducing metal ions. Catechol-grafted polymer is chemically synthesized and electrospun into nanofibers as templates for metal nanostructures. The metal nanostructures are spontaneously generated on the catechol-grafted polymer nanofibers under ambient conditions.

• Journal of Korea Foundry Society
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• v.17 no.4
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• pp.327-337
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• 1997

The current understanding of the mechanism of inoculation of the eutectic in commercial Fe-C-Si alloys using either silicon containing alloys or graphite has been discussed. The mechanism whereby inclusion formation within a cast iron melt is essential for inoculation effectiveness in ferro silicon inoculation has been reviewed. The role of graphitic inoculants has been presented, including the results of recent research that confirms the inoculating capability of graphite and demonstrates those factors which must be considered in evaluating inoculation effectiveness. Fading of inoculation, both ferro silicon and graphite, and the mechanism whereby this occurs, has also been discussed.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.169-172
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• 2005

Tiny camera module using in modern cellular phone requires precise assembly processes. Higher camera resolution and more functions such as zoom lens make the number of camera parts bigger. As market grows rapidly, automatic assembly process is required. However, diverse product line and short life cycle make it difficult. To attack this, a flexible and expandable lens assembly system is proposed. For the fast manufacturing line formation, modular concept is adopted. Also each module is designed to have intelligence to save system formation time. The assembly system is built up on the standard flat-form which provides vibration free base, air and electric supply, controllers, etc. Futhermore, the assembly cell has the capability of handling tiny, thin, or transparent parts which are very difficult to align with vision.

• Journal of Energy Engineering
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• v.7 no.2
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• pp.180-186
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• 1998

In this study, the effect of shear rate on the viscosity variation is examined to understand the flow characteristics of the mixture of bentonite and water. The variation of film thickness according to mixing ratio and viscosity is measured to characterize the film formation. And, the separation of dried film is studied according to film thickness. Specific surface area affecting on adsorption capability is measured using BET method. The viscosity decreases and the film thickness increases as the mixing ratio increases. The separation characteristic of dried film is suitable within a range of 40 to 150 ${\mu}{\textrm}{m}$ in film thickness and 5 to 10% in mixing ratio.

• The Bulletin of The Korean Astronomical Society
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• v.39 no.2
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• pp.77.2-77.2
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• 2014

Questions of how our Milky Way evolves through the interaction with its environment have been constantly raised. One particularly interesting question is how the metallicity would change as our Milky Way goes through collision with HVCs. Because of the possibility of HVCs providing fuel for star formation in the Galactic disk, we simulate the collision between HVCs and the Galactic disk. More specifically, we trace how the Galactic metallicity changes throughout the process of HVCs colliding with our Milky Way based upon a specific scenario that HVCs are primordial gas left-overs from an ancient galaxy formation. Such mixing between metal-rich gas (disk) and metal-poor HVC can be traced by running numerical simulations with the FLASH code due to its capability of tracking down the abundance change of a specific element such as carbon at each time step of the hydrodynamic evolution. As for now, we give how this mixing depends on model parameters that we choose such as collision speed, initial metallicities, temperature and so on.