• Applied Microscopy
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• v.43 no.2
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• pp.81-87
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• 2013

The influence of carbide formation on mechanical properties has been investigated in carburized steels. Through controlled diffusion and precipitation processes, the morphologies of carbides could be changed and then fine, networked, and spherical shapes at carburized layers were obtained. These morphological changes affected tensile and bending fatigue properties of the steel. The fine and the spherical carbides acted as resistance sites against crack propagation, which improved the mechanical properties. However, the networked carbides deteriorated the properties because the cracks propagated along the boundaries of them. These results indicate that the morphological control of carbides is one of important keys to improve the mechanical properties.

• Fashion & Textile Research Journal
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• v.13 no.2
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• pp.279-284
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• 2011

In this study, the process of preparation nonwoven with coated carbon nano fibers (CNFs) /poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) composite solution is described. The various contents of CNFs/PVDF-HFP composite coated nonwoven were prepared and characterized by morphological, mechanical, and electrical methods. Nonwovens are coated with CNFs/PVDF-HFP composite solution and decreased the pick up ratio with increasing CNFs contents in range from 0% to 16%. In the results of SEM images, it was clear that the CNFs were evenly distributed in coated nonwoven by SEM images, the existence of CNFs in coated nonwoven was confirmed regularly. The mechanical properties of various contents of CNFs/PVDF-HFP coated nonwoven were examined. The tensile linearity and compression linearity increased with increasing CNFs contents. The electrical properties of the CNFs/PVDF-HFP coated nonwoven increased with increasing CNFs contents.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.04a
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• pp.67-68
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• 2008

A simple bi-layer structure of organic light emitting diode (OLED) was used to study the characteristics of anode preparation. Indium tin oxide (ITO) anode surface treatment of OLEDs was performed to get the optimum condition for the ITO anode. The ITO surface was treated by $O_2$ or $O_2$ / Ar mixed gas plasma with different processing time. The electrical characteristics of OLED were improved by plasma treatment. The operating voltage of OLED with $O_2$ or $O_2$/Ar mixed gas plasma treated anodes decreases from 8.2 to 3.4 V and 3.2V, respectively. The $O_2$ /Ar mixed gas plasma treatment results in better electrical property.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.7
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• pp.49-54
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• 2010

The cryogenic ball milling was performed on carbon nanotubes (CNTs) at an extremely low temperature to increase the dispersion of CNTs. The effects of milling speed and time on the deagglomeration and structural changes of CNTs were studied. FESEM was used to analyze the dispersion and the change of particle size before and after milling process. Transmission electron microscopic (TEM) analysis was also investigated the effect of cryogenic ball milling on the morphological characteristics of CNTs. The structural changes by the cryogenic ball milling process were further confirmed by x-ray diffraction (XRD) and Raman spectroscopic analysis. The results showed that the agglomeration of CNTs was significantly reduced and amorphous structure was observed at high milling speed. However, the milling time has no great effect on the dispersion property and structural change of CNTs compared with milling speed.

• Proceedings of the Materials Research Society of Korea Conference
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• 2012.05a
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• pp.102.2-102.2
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• 2012

Different layers of zirconium nitride (ZrN) and hydroxyapatite (HA) coatings were prepared on cp Ti substrate for biomedical applications. The main idea is to improve the mechanical strength as well as the biocompatibility of the coating. ZrN is known for its high mechanical strength, corrosion resistance. HA is well known for its biocompatibility properties. Hence, in this study, both materials were coated on a cp Ti substrate with bottom layer with ZrN for good bonding with substrate and the top layer with HA for induce bioactivity. Middle layer was formed by a composite of HA and ZrN. Detail analyses of the layered coatings for its structural, morphological, topographical properties were carried out. Then the mechanical property of the layered coatings was analyzed by nanoindentation. Biomimetic growths of apatite on the functionally graded coatings were determined by simulated body fluid method. This study provides promising results to use this kind of coatings in biomedical field.

• Proceedings of the Korean Magnestics Society Conference
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• 2012.05a
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• pp.23-25
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• 2012

• Macromolecular Research
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• v.17 no.11
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• pp.863-869
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• 2009

The effect of a multiwalled carbon nanotube (MWCNT) dispersion on the electrical, morphological and rheological properties of polycarbonate (PC)/MWCNT composites was investigated, with and without pretreating the MWCNTs with hydrogen peroxide oxidation and lyophilization. The resulting PC/treated MWCNT composites showed higher electrical conductivity than the PC/untreated MWCNT composites. The morphological behavior indicated the treated composites to have greater dispersion of MWCNTs in the PC matrix. In addition, the electromagnetic interference shielding efficiency (EMI SE) of the treated composites was higher than that of the untreated ones. Rheological studies of the composites showed that the complex viscosity of the treated composites was higher than the untreated ones due to increased dispersion of the MWCNTs in the PC matrix, which is consistent with the electrical conductivity, EMI SE and morphological studies of the treated composites. The latter results suggested that the increased electrical conductivity and EMI SE of the treated composites were mainly due to the increased dispersion of MWCNTs in the PC matrix.

• Journal of Electrochemical Science and Technology
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• v.9 no.4
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• pp.330-338
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• 2018

The adhesion strength as well as the electrochemical properties of $LiNi_{0.4}Mn_{0.4}Co_{0.2}O_2$ electrodes containing various conductive carbons (CC) such as fiber-like carbon, vapor-grown carbon fiber, carbon nanotubes, particle-like carbon, Super P, and Ketjen black is compared. The morphological properties is investigated using scanning electron microscope to reveal the interaction between the different CC and the active material. The surface and interfacial cutting analysis system is also used to measure the adhesion strength between the aluminum current collector and the composite film, and the adhesion strength between the active material and the CC of the electrodes. The results obtained from the measured adhesion strength points to the fact that the structure and the particle size of CC additives have tremendous influence on the binding property of the composite electrodes, and this in turn affects the electrochemical property of the configured electrodes.

• Journal of the Korean Applied Science and Technology
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• v.24 no.2
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• pp.174-181
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• 2007

In this study, $SiO_2/poly(ethylene-co-vinyl$ alcohol)(EVOH) hybrid coating materials with gas barrier property could be produced using sol-gel method. The biaxially oriented polypropylene (BOPP) substrate with surface pretreatment was coated with the prepared hybrid sols containing various inorganic silicate component by a spin coating method. Crystallization behavior of the hybrids was investigated in terms of analysis of X-ray diffraction and cooling thermogram from DSC experiment. From the morphological observation of the $SiO_2/EVOH$ hybrid gel, it was confirmed that there existed an optimum content of inorganic silicate precursor, Tetraethylorthosilicate (TEOS), to produce hybrid materials with dense microstructure, exhibiting uniformly dispersed silica particles with average size below 100 nm. When TEOS was added at below or above the optimum content, particle clusters with large domain were observed, resulting in phase separation. This morphological result was found to be in good agreement with that of oxygen permeability of the hybrid coated films. In the case of film coated with hybrid prepared from addition of 0.01 - 0.02mol of TEOS, a remarkable improvement in barrier property could be obtained, however, with the addition of TEOS more than 0.04 mol, the barrier property was dramatically reduced because of phase separation and micro-crack formation on the film surface.

• Journal of Sericultural and Entomological Science
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• v.18 no.2
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• pp.101-105
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• 1976

The study was carried out to investigate the variations in the fibroin hydrolysis of leading silkworm varieties in Korea, and the relationship between the fibroin hydrolysis of the silkworm varieties with some characteristics and silk morphological property. The results obtained are summarized as follows: 1) The fibroin hydrolyzing ratio of both parent silkworm cocoons was reduced in the F$_1$hybrids. 2) A positive corelation (r=＋0.86) was approved between the mid-parent value and the F$_1$hybrid in the fibroin hydrolysis. 3) It was disclosed that the fibroin hydrolyzing ratio of Jam 103${\times}$Jam 104 was the lowest among the leading silkworm F$_1$hybrids. 4) The fibroin hydrolysis was affected by the silk morphological property, showing a positive corelation between the size of cocoon filament and the fibroin hydrolyzing ratio. 5) It was thought that the determination of the fibroin hydrolyzing ratio was useful as a marker for the selection of its related economical characters in silkworm breeding, because the fibroin hydrolysis of parents silkworm cocoons was heritable in their F$_1$hybrids.