• Imaging Science in Dentistry
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• v.44 no.3
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• pp.237-241
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• 2014

Fibromyxoma of the jaw is a rare benign mesenchymal odontogenic tumor with locally aggressive behavior. In the present report, a 13-year-old female patient presented to our university hospital with delayed eruption of some of her teeth. A panoramic radiograph taken at the initial examination revealed four pericoronal radiolucencies related to the four third molars. Thereafter, a magnetic resonance imaging (MRI) examination was performed. After the surgical removal of these molars, the microscopic examination diagnosed the four lesions as fibromyxomas. Here, we have discussed the clinical, panoramic radiography, MRI, and histopathological findings of the case.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.5 no.4
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• pp.95-101
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• 1985

In this study, impact fracture and Fatigue behaviors of SWS50 steel are investigated in terms of macroscopic view. Then the fundamental data needed to trace the relationship between macroscopic and microscopic views and the data for fracture control of steels manufactured in domestic are represented.

• Proceedings of the Korean Nuclear Society Conference
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• 1998.05b
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• pp.66-71
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• 1998

A study of treatment effects on laser surface melted Ni-base alloy 600, especially on precipitation behavior ad chemical composition changes on the grain boundary were conducted with microscopic equipments. Long-term aging treatment at 40$0^{\circ}C$ caused no considerable effects on the grain boundary properties. Cr-rich M$_2$$_3$C$_{6}$ and Cr$_{7}$C$_3$ carbides were precipitated and the resultant Cr depletion below 12 wt pct on some high angle grain boundaries was occurred by heat treatment at $600^{\circ}C$ for 24 hours. These results can imply that the resistance of intergranular stress corrosion cracking of heat treated alloy 600 might not be changed considerably in comparion with the as-LSM one.e.e.

• Korea-Australia Rheology Journal
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• v.12 no.3_4
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• pp.157-163
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• 2000

We develop a simple model which can describe and explain abnormal stress relaxation of ABS melt for which stress dose not exponentially decay. The relaxation behavior of ABS melt consists of two distinct relaxation modes. One is the relaxation of the matrix phase similar to the case of homopolymer melt. The other is manifested by the collection of butadiene rubber particles, named as the cluster, where the particles are connected through the interaction between grafted SAN and matrix SAN. The second mode of the relaxation is characterized by the relaxation time, which is a function of the average size and the microscopic state of the cluster. Experimental results reveal that it can be represented as the product of the average size of the clusters by a function of internal variable that represents the fraction of strained SAN chains inside the cluster.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.9
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• pp.1306-1313
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• 2004

This paper addresses a theoretical approach to calculate the amount of the stored energy during high strain-rate deformations using atomistic level simulation. The dynamic behavior of materials at high strain-rate deformation are of great interest. At high strain-rates deformations, materials generate heat due to plastic work and the temperature rise can be significant, affecting various properties of the material. It is well known that a small percent of the energy input is stored in the material, and most of input energy is converted into heat. However, microscopic analysis has not been completed without construction of a material model, which can simulate the movement of dislocations and vacancies. A major cause of the temperature rise within materials is traditionally credited to dislocations, vacancies and other defects. In this study, an atomistic material model for FCC such as copper is used to calculate the stored energy.

• KSTLE International Journal
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• v.2 no.1
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• pp.22-28
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• 2001

A resin bonded copper-graphite brush was investigated to evaluate the characteristics electrical signal transmission through a sliding contact as a function of the relative amount of graphite and copper in the brush. Particular attention was given to the correlation between electrical signal fluctuation and tribological properties in an electrical sliding contact system. A ring-on-block type tribotester was used for this experiment and the ring was made from pure copper. Results showed that a copper-graphite brush at a particular composition range exhibited the most stable frictional behavior with a minimum voltage drop. The amount of voltage drop at the friction interface was affected by the surface roughness, transfer film formation at the friction interface, and the real area of contact. Microscopic observations and the surface analysis showed a good agreement with the results from this experiment. The results also indicated that the electrical signal flunctuation was directly associated with the oscillation of the coefficient of friction during sliding by nanoscale variation of contacts at the friction interface.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.219-220
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• 2013

The phenomenology of liquid breakdown has been an area of interest for many years but is still not fully understood. Moreover, it was known that the behavior of magnetic nanoparticles in transformer oil could affect the dielectric breakdown voltage positively or negatively. In this study, we have imaged the magnetic nanoparticles in a transformer oil in-situ using an optical microscopic set-up and a microchannel according to the electric and magnetic fields applied. And we have calculated numerically dielectrophoresis and magnetophoresis forces, which must be the driving mechanisms to move magnetic nanoparticles in the fluid. It was found that when the electric field is applied the magnetic nanoparticles in the fluid experience an electrical force directed toward the place of maximum electric field strength. And when the external magnetic field is applied, the magnetic nanoparticles form long chains oriented along the direction of the field.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1995.11a
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• pp.240-243
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• 1995

The basic electrochemical and photochemical behavior of ultrathin mono- and hetero-type LB film of amphiphilic Ru bipyridine complex adsorbed on ITO electrode by the Langmuir- Blodgett(LB) method as monolayer and alternating multilayer state. With theoretical equation of cyclic voltammetry for redox species, the cyclic voltammogram were simulated successfully taking account the interaction parameters. We could fit almost all measured voltammograms with k$^{\circ}$=72s$\^$-1/, ${\alpha}$$\sub$a/=0.44, ${\alpha}$$\sub$c/=0.54, $\Gamma$$\sub$T/=1.4${\times}$10$\^$-10/, k=0.015s$\^$-1/ values. The AFM images of mono and hetero type LB film surfaces on ITO were also studied.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.207-208
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• 2006

Here, we discuss various thermodynamic factors that affect the design of nanomaterials based on block copolymers. It is well known that the ordering behavior is determined by composition, chain size N, and the ubiquitous Flory. However, the recent discovery of ordering upon heating, immisibility loops, and baroplasticity addresses a clear need for further microscopic interpretation of such. in order to help to design nanomaterials at aimed purposes. Employing a perturbed hard sphere chain model, the molecular factors such as self and cross-interactions, free space distribution, and directional interactions are incorporated in. It is shown that not only typical ordering phenomena, but also the recent observations just mentioned are all described through this unified way.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2006.05a
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• pp.77-80
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• 2006

Structural phase transformations of silicon during nanoindentation were investigated in detail at the atomic level. The molecular dynamics simulations of nanoindentation on the (100), (110) and (111) surface of single crystalline silicon were simulated, and this supported the theoretical prediction of the anisotropic behavior of structural phase transformations. Simulations showed that microscopic aspects of phase transformation varied according to the crystallographic orientation of the contact surface and were directly linked to the slip system.