• JSTS:Journal of Semiconductor Technology and Science
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• v.8 no.1
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• pp.46-50
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• 2008

The effect of physicochemical properties of solvents on the microstructure of polyvinyl carbazole (PVK) film for non-volatile polymer memory was investigated. For the solubilization of PVK molecules and the preparation of PVK films, four solvents with different physicochemical properties of the Hildebrand solubility parameter and vapor pressure were considered: chloroform, tetrahydrofuran (THF), 1,1,2,2-tetrachloroethane (TCE), and N,N-dimehtylformamide (DMF). The solubility of PVK molecules in the solvents was observed by ultravioletvisible spectroscopy. PVK molecules were observed to be more soluble in chloroform, with a low Hildebrand solubility parameter, than solvents with higher values. The aggregated size and micro-/nano-topographical properties of PVK films were characterized using optical and atomic force microscopes. The PVK film cast from chloroform exhibited enhanced surface roughness compared to that from TCE and DMF. It was also confirmed that the microstructure of PVK film has an effect on the performance of non-volatile polymer memory.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.12
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• pp.2019-2028
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• 1997

It has been well established that resistant force and wear that occur during rolling motion depend on several factors such as material type, hardness, subsurface microstructure, applied load, and speed. The purpose of this work is to investigate the effect of microstructure and the state of deformed layer on the rolling contact characteristics in dry and lubricated rolling contacts. The results of this work show that the rolling resistance behavior depends on the state of the deformed layer. Also, lubrication can reduce the plastic flow at the surface but may still have an effect on the subsurface strain. The cross-sectional view of the microstructure shows that surface traction has a difinite effect on the morphology of the surface region. That is, significant slip seems to have taken place between the ball than those of the dry rolling case. The surface generation effects were significantly less compared to the case of dry rolling contact.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1999.03b
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• pp.195-198
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• 1999

For the thixoforming process beside an existing solidus-liquidus interval, the reheating conditions to obtain the globular microstructure are very important. It relies on the control of globular microstructure of semi-solid alloys that contain non-dendritic particles. To obtain the globular microstructure in cross section of billet, the optimal design of the induction coil is necessary. Therefore, in this paper the optimal coil design to minimize electromagnetic end effect will be proposed. The results of coil design were also applied to the reheating process to obtain a fine globular microstructure. Finally, reheating data base of aluminum alloys for thixoforming and FEM model for induction heating based on the optimal coil design have been proposed.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2002.05a
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• pp.21-24
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• 2002

One of the factors influences on microstructure of semi-solid product is forging pressure. Generally, the more forging pressure makes the more fine microstructure in semi-solid compression test. The microstructure and mechanical properties were investigated according to the forging pressure. The applied pressure is 110MPa, 140MPa and 170MPa, respectively. Heat treatment conditions also influence to the microstructure and mechanical properties of semi-solid product. T6 heat treatment was performed and the evaluation of microstructure and mechanical properties was investigated according to the aging time in T6 heat treatment.

• Journal of Powder Materials
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• v.3 no.3
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• pp.188-195
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• 1996

In recent times the potential application of the high speed steel produced by HIP process for wear resistant and cutting materials are increasing. In this work the microstructure of Anval 30 produced by HIP process was investigated and the effect of WC, TiC addition on microstructure formation and wear properties were studied. After HIP process at 1150 $^{\circ}C$, the original feature of spherical raw powders was not removed and consequently, nonuniform microstructure was formed. However the WC added by simple powder mixture incereased the sinterbility of high speed steel and uniform microstructure formed. The wear characteristics of Anval 30 with carbide addition were tested at RT and $600^{\circ}C$. The uniform microstructure played an more important role in wear resistance as compared with the hardness.

• Journal of the Korean Society of Clothing and Textiles
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• v.20 no.3
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• pp.467-480
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• 1996

Interactions between PET POY and solvents were estimated by the changes in microstructure and surface morphology. Changes in microstructure and surface morphology by the solvent treatments were: an increase in crystallite size, a decrease in interplanar spacing, a change in degree of orientation of crystalline region, a change in surface characteristics.

• Journal of the Microelectronics and Packaging Society
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• v.12 no.1 s.34
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• pp.27-33
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• 2005

The effect of microstructure on alternating current-induced damage in 200 and 300 nm thick polycrystalline sputtered Cu lines on Si substrates has been investigated. Alternating currents were used to generate temperature cycles (with ranges from 100 to $300^{\circ}C$) and thermal strains (with ranges from 0.14 to $0.42\%$) in the Cu lines at a frequency of 10 kHz. Fatigue loading caused the development of severe surface roughness that was localized within individual grains which depends severely on grain orientations.

• Journal of the Korean Society for Heat Treatment
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• v.35 no.2
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• pp.57-65
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• 2022

In this study, the effect of the initial particle size distribution (PSD) of (K_0.5Na_0.5)NbO₃ powders on the microstructure of sintered ceramics was investigated. (K_0.5Na_0.5)NbO₃ powders with uni-, bi-, tri-, and quad-modal PSDs were obtained through a planetary ball-mill. For the specimens sintered at 1080℃, the growth of abnormal grains was promoted from the powders exhibiting quad- and tri-modal PSDs with a high content of large particles, resulting in a microstructure in which huge abnormal grains were predominant. However, as the number of peaks in PSD and the overall particle size decreased, the abnormal grain growth was suppressed and the grain growth of small particles started, resulting in a microstructure with a uniform grain size. For the specimens sintered at 1100℃, huge abnormal grains were not observed due to the decrease in the critical driving force for 2D nucleation even when powders with quad- and tri-modal PSDs were used. It was confirmed that when powder with unimodal PSD was used, a uniform microstructure that was not significantly affected by the sintering temperature could be obtained. The results of this study demonstrate that the microstructure of (K_0.5Na_0.5)NbO₃-based ceramics can be controlled by controlling the particle size of the initial powder.

• Korean Journal of Metals and Materials
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• v.50 no.6
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• pp.419-425
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• 2012

The purpose of this research was to develop a low Ni austenitic cast iron through replacing Ni by Cu and Mn because they are cheaper than Ni. The effect of the Cu content (6-12 wt%) on the microstructure characteristics was investigated in Fe-3%C-16%(Ni+Cu+Mn) cast iron. Contrary to general effect of the Cu on cast iron, the result of the microstructure analysis indicated that bainite and cementite were formed in high Cu content (>8 wt%Cu). A crystallized Cu-solution (Cu-Mn) phase and MnS in the Cu-solution were formed. The quantity of those phases increased as the Cu content increased. Consequently, the high Cu content in the composition ratio (Ni+Cu+Mn=16%) caused the formation of Cu-Mn/MnS and those phases decreased the effect of Cu and Mn on austenite formation. For this reason, bainite and cementite were formed in high Cu content.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.10a
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• pp.207-210
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• 2008

The effects of boron additions in steels have long been recognized as very important, mainly with respect to hardnability of heat treatable steels. we investigated the effect of the microstructure and mechanical properties with cooling condition after heat treatment of the boron-treated(${\fallingdotseq}8{\sim}18ppm$) low carbon(${\fallingdotseq}0.2%C$) low alloy steel. The specimens were austenitised for 10 min at $910^{\circ}C$, cooled for the various periods of time from 10 sec to 30 sec or with water after forming for 15 sec. After cooling, mechanical properties were measured by tensile test and hardness test. For analysis of microstructure, Optical were carried out.