• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.285-285
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• 2016

Resistive random access memory devices have been widely studied due to their high performance characteristics, such as high scalability, fast switching, and low power consumption. However, fluctuation in operational parameters remains a critical weakness that leads to device failures. Although the random formation and rupture of conducting filaments (CFs) in an oxide matrix during resistive switching processes have been proposed as the origin of such fluctuations, direct observations of the formation and rupture of CFs at the device scale during resistive switching processes have been limited by the lack of real-time large-area imaging methods. Here, a novel imaging method is proposed for monitoring CF formation and rupture across the whole area of a memory cell during resistive switching. A hybrid structure consisting of a resistive random access memory and a light-emitting diode enables real-time monitoring of CF configuration during various resistive switching processes including forming, semi-forming, stable/unstable set/reset switching, and repetitive set switching over 50 cycles.

• Journal of ILASS-Korea
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• v.3 no.3
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• pp.49-59
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• 1998

The vaporization characteristics and spray combustion processes in the high-pressure environment are numerically investigated. This study employ the high-pressure vaporization model together with the state-of-art spray submodels. The present high-pressure vaporization model can account for transient liquid heating, circulation effect inside the droplet forced convection, Stefan flow effect, real gas effect and ambient gas solubility in the liquid droplets. Computations are carried out for the evaporating sprays, the evaporating and burning sprays, and the spray combustion processes of the turbocharged diesel engine. Numerical results indicate that the high-pressure effects are quite crucial for simulating the spray combustion processes including vaporization, spray dynamics, combustion, and pollutant formation.

• The Bulletin of The Korean Astronomical Society
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• v.44 no.2
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• pp.41.2-41.2
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• 2019

The aim of this study is to demonstrate the subsurface origin of the complex observed evolution of the solar active region 10930 (AR10930) associated with merging and breakup of magnetic polarity regions at the solar surface. This is important for a comprehensive understanding of observed properties of the active region, because subsurface magnetic flux and subsurface dynamical processes are seamlessly connected to surface magnetic flux and surface dynamical processes, respectively. In other words, the solar surface does not behave as an impermeable boundary towards magnetic flux and dynamical processes. In this talk, we show a magnetohydrodynamic (MHD) model of merging and fragmentation in AR10930. We then discuss what physical processes could be involved in the characteristic evolution of an active region magnetic field that leads to the formation of a sunspot surrounded by satellite polarity regions.

• Proceedings of the Korea Association of Crystal Growth Conference
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• 1999.06a
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• pp.69-80
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• 1999

Computer simulations have played a central role in the development of out understanding of the atomic scale processes involved in crystal growth. The assumptions underlying computer modeling will be discussed and out recent work on modeling of the kinetic formation of thermodynamically unstable phases in alloys or mixtures will be reviewed. Our Monte Carlo computer simulations have reproduced the experimental results on the rapid recrystallization of laser-melted doped silicon. An analytical model for this phenomenon has been developed, and its applicability to other materials will be discussed.

• Proceedings of the KIEE Conference
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• 1989.11a
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• pp.505-508
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• 1989

A computer simulation code of UV preionized discharge KrF laser is developed, including time dependent circuit equations, boltzmann equations, and plasma kinetic equations for various atomic and molecular species. Rate constants for electron collision processes are calculated with a boltzmann equations as a function of E/N. In this study, we studied mainly the $KrF^*$ formation process, relaxation process, and the 248nm absorption process as a function of charging voltage.

• 제어로봇시스템학회:학술대회논문집
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• 1992.10a
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• pp.531-536
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• 1992

In GMA welding processes, monitoring and control of weld quality are extremely difficult problems. This paper describes a neural network-based method for monitoring and control of weld pool sizes. First, weld pool sizes are estimated via a neural estimator using multi-point surface temperatures, which are strongly related to the formation of weld pool, and then controlled using the estimated pool sizes. Two types of controllers using the pool size estimator are designed and tested. To evaluate the performance of the designed controllers, a series of simulation studies was performed.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.9 no.4
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• pp.365-370
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• 1999

Computer simulations have played a central role in the development of our understanding of the atomic scale processes involved in crystal growth. The assumptions underlying computer modeling will be discussed and our recent work on modeling of the kinetic formation of thermodynamically unstable phases in alloys or mixtures will be reviewed. Our Monte Carlo computer simulations have reproduced the experimental results on the rapid recrystallization of laser-melted doped silicon. An analytical model for this phenomenon has been developed, and its applicability to other materials will be discussed.

• Proceedings of the Optical Society of Korea Conference
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• 2008.02a
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• pp.397-398
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• 2008

We have developed simplified processes for the formation of insulators, cathode separators and bus electrodes in PMOLEDs. The insulators and cathode separators are patterned simultaneously by a single layer of image reversal photoresist. And, the bus electrodes of low resistance are formed by the cathode separator and cathode metal. Using these simplified processes, we fabricated 1.17" $96{\times}RGB{\times}96$ panels and analyzed their performance and reliability.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.11a
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• pp.484-488
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• 1997

BSCCO thin film is fabricated cia both processes of co-deposition and layer-by-layer deposition at an ultralow growth rate using ion beam sputtering method. The adsorption of Bi atom and the appearance of Bi-2212 phase shows large differance between both processes. It is found that the resident time of Bi vapor species on the surface of the substrate strongly dominates the film composition and the formation of the structure.

• Bulletin of the Korean Chemical Society
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• v.17 no.9
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• pp.781-786
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• 1996

Mass transport behavior of C60 films on electrodes with different thicknesses has been studied by an Electrochemical Quartz Crystal Microbalance (EQCM) during electrochemical reduction-oxidation processes in the presence of water. C60 films were found to be reduced in the presence of water and they remains quite stable. In thin films, the mass on electrode decreased after a complete cycle while X-ray Photoelectron Spectroscopy (XPS) study does not support the existence or formation of C60-epoxides during electrochemical reduction processes in the presence of water or oxygen.