• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.663-667
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• 2005

Surface modified carbon nanotubes were applied into the epoxy composites to investigate its tribological property. Carbon nanotubes reinforced epoxy composites were fabricated by casting. Effects to the tribological property of loading concentrations and types of surface modification of carbon nanotubes were investigated under sliding condition using linear reciprocal sliding wear tester. The results show that the small amount of carbon nanotubes into the epoxy exhibited lower weight loss than the pure epoxy. It is concluded that the effect of an enormous aspect ratio of carbon nanotubes surface area which wider than conventional fillers that react as interface for stress transfer. As increased the contents of carbon nanotubes, the weight loss from the wear test was reduced. And the surface modified carbon nanotubes show better tribological property than as produced carbon nanotubes. It is due that a surface modification of carbon nanotubes increases the interfacial bonding between carbon nanotubes and epoxy matrix through chemical bonding. Changes in worn surface morphology are also observed by optical microscope and SEM for investigating wear behaviors. Carbon nanotubes in the epoxy matrix near the surface are exposed, because it becomes the lubricating working film on the worn surface. It reduces the friction and results in the lower surface roughness morphology in the epoxy matrix as increasing the contents of the carbon nanotubes.

• Bulletin of the Korean Chemical Society
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• v.34 no.10
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• pp.2883-2888
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• 2013

To enhance the power conversion efficiency of dye-sensitized solar cell (DSSC), the surface of titanium dioxide ($TiO_2$) photoelectrode was modified by hydroxylation treatment with $NH_4OH$ solution at $70^{\circ}C$ for 6 h. The $NH_4OH$ solutions of various concentrations were used to introduce the hydroxyl groups on $TiO_2$ surface. As the concentration of $NH_4OH$ was increased, the short-circuit current density ($J_{SC}$) value and conversion efficiency of solar cells were increased because the amount of adsorbed dye molecules on $TiO_2$ surface was increased. As a result of the surface modification to introduce hydroxyl groups, the concentration of adsorbed dye on the $TiO_2$ surface could be improved up to 32.61% without the changes of morphology, surface area and pore volume of particles. The morphology, the specific surface area, the pore volume and the chemical states of $TiO_2$ surface were characterized by using FE-SEM, $N_2$ adsorption-desorption isotherms and XPS measurements. The amount of adsorbed dye and the performance of fabricated cells were analyzed by using UV-Vis absorption spectroscopy and solar simulator.

• Korean Journal of Oriental Medicine
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• v.12 no.3 s.18
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• pp.117-130
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• 2006

The purpose of this study was to introduce the differential standard of Mok-Hyaeng Radix species. We established the classificatory standard according to the external and internal morphology and the pattern in 4 kinds of Mok-Hyaeng Radix. The results follow: 1. On the external morphology, Radix of Vladimiria souliei had a sticky material in the head of roots and it was yellowish white in the cut surface. It attached to teeth during chewing. Radix of Aucklandia lappa (=Saussurea lappa) was dark grayish brown and was grayish brown in the cut surface. It had special odor and was not attache to teeth chewing it. On the other hand, Radix of Inula helenium was dark brown. In the cut surface, cortical layer was different from wood layer. Radix of Aristolochia contorta was yellowish brown. In the cut surface, it was not smooth and cortical layer was different from wood layer. 2. On the internal morphology, Radix of Vladimiria souliei had many fascicular fibers and scattered large oil chambers in the bast ray, xylem ray, and parenchyma. On Radix of Aucklandia lappa (=Saussurea lappa), it was difficult to find out the trace when the cork layer was exfoliated. The cambium formed circle and the large oil chambers were scattered in the phloem and xylem. On the other hand, external cortical layer of Radix of Inula helenium was detached and cambium was formed to indistinct circle and large oil chambers were scattered in the phloem and xylem. On Radix of Arustolochia contorta, the large oil chambers were scattered in the surface later, bast part was relatively broad and cambium formed circle. 3. On the TLC pattern, Radix of Aristolochia contorta, Inula helenium, Aucklandia lappa, and Vladimiria souliei were chromogenic to violet and purple according to sulfuric acid colour pattern, especially faint on Aristolochia contorta. 4. On the pattern analysis of HPLC, we compared the content and the pattern of constunolide and dehydrocostus lactone, Radix of Aucklandia lappa was similar to Radix of Vladimiria souliei and Radix of Aristolochia contorta was similar to Radix of Inula helenium. On the total HPLC component pattern, constunolide and dehydrocostus lactone were similar in all four types, but it showed the Rf 5-6 peak was only in Radix of Aristolochia contorta, not in Radix of Inula helenium, Aucklandia lappa, and Vladimiria souliei. It is considered the results of this study will be furnished the basis to succeeding studies and it is needed to extensive comparative study for the same genus-degree of relatedness.

• Journal of the Korea Institute of Military Science and Technology
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• v.14 no.5
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• pp.897-903
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• 2011

The objective of this study is to investigate the thermal behavior on material surface and the variation in the surface morphology of aluminum 6061 alloy by the Nd:YAG pulsed-laser irradiation. First, we predicted the surface temperature variation during pulsed-laser irradiation by using the two dimensional finite element analysis. When the pulsed-laser of 133 mJ energy and 5 ns pulse duration is irradiated on the surface of aluminum alloy, the material surface is thought to be melting because the surface temperature rises steadily up to about $660^{\circ}C$ exceeding the melting point. Also, the experimental results show that the solidification microstructure has been developed clearly after surface melting. Second, the diameter of melted zone was analysed by finite element analysis and measured by OM(Optical Microscopy). It increased logarithmically with increase in the number of laser irradiation. In addition, AFM(Atomic Force Microscopy) measurement showed an increase in the average surface roughness during pulsed-laser irradiation.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2002.05a
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• pp.46-46
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• 2002

It is well known that thin film growth and surface morphology can be substantially modified by ion-bombardment during the deposition. This is particularly important in case of thin-film deposition at low temperatures where the film growth occurs under highly nonequilibrium conditions. An attractive way to promote crystalline growth and surface morphology is deposition of additional energy in to the surface of the growing film by bombardment with hyperthermal particles. We were deposited crystalline Ti and TiN thin films on Si substrate by magnetron sputtering method with grid. Its thin films were highly smoothed and dense as increasing grid bias. In order explore the benefits of a bombardment of the growing film with high energetic particles. Ti and TiN films were deposited on Si substrates by an unbalanced magnetron sputter source with attached grid assembly for energetic ion extraction. Also, we have studied the variation of the plasma states by Langmuir probe and Optical Emission Spectroscopy (OES). The epitaxial orientation. microstructual characteristics. electrical and surface properties of the films were analyzed by XRD. SEM. Four point probe and AFM.

• Korean Journal of Plant Taxonomy
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• v.40 no.2
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• pp.105-107
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• 2010

This study was carried out to find specific characters of the seed morphology and anatomy of Korean Eranthis in Ranunculaceae. As a result, E. byunsanensis differs with E. stellata on the basis of presence of unicellular hairs on the seed surface. E. stellata has no unicellular hairs on its seed surface. On the other hand, E. byunsanensis bears such unicellular hairs derived from epidermal cells of the seed surface. Besides other morphological characters used when it was published as a new species, the presence of unicellular hairs on the seed surface strongly supports it as an endemic species of Korea. In addition, to compare the seed morphology of E. pinnatifida and E. pungdoensis, for which mature seeds were not available at this time, an additional study should be conducted in near future.

• Journal of the Korea Convergence Society
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• v.7 no.6
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• pp.193-198
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• 2016

The texture of electrodeposits varies with deposition conditions. Texture of electrodeposits is also related to microstructure, surface morphology and mechanical properties. When the electrodeposits annealed, the recrystallization texture may be different from the original deposition texture. The surface morphology, the microstructure and the initial and recrystallization textures of copper electrodeposits vary with deposition conditions. The texture, microstructure, surface morphology and mechanical properties of electrodeposits are known to vary with electrolysis conditions, such as bath composition, over potential, pH, current density, bath temperature, etc. The (111) and (110) textures of copper electrodeposits can be obtained from copper sulfate bath. In this study, copper electrodeposits with (111) and (110) textures are obtained from a copper sulfate bath, and the change from (111) to (110) textures of copper electrodeposits can be explained.

• Korean Journal of Materials Research
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• v.20 no.8
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• pp.412-417
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• 2010

Mo thin films were used for the back electrode because of the low resistivity in the Mo/$CuInGaSe_2$ contact in chalcopyrite solar cells. $1\;{\mu}m$ thick Mo thin films were deposited on soda lime glass by varying the Ar pressure with the dc-magnetron sputtering process. The effects of the Ar pressure on the morphology of the Mo back electrode were studied and the relationships between the morphology and electro-optical properties, namely, the resistivity as well as the reflectance of the Mo thin films, were investigated. The resitivity increased from $24\;{\mu}{\Omega}{\cdot}cm$ to $11833\;{\mu}{\Omega}{\cdot}cm$; this was caused by the increased surface defect and low crystallinity as the Ar pressure increased from $3{\times}10^{-3}$ to $3{\times}10^{-2}\;Torr$. The surface morphologies of the Mo thin films changed from somewhat coarse fibrous structures to irregular and fine celled structures with increased surface cracks along the cell boundaries, as the Ar pressure increased from $3{\times}10^{-3}$ to $3{\times}10^{-2}\;Torr$. The changes of reflectances in the visible light range with Ar pressures were mainly attributed to the surface morphological changes of the Mo thin films. The reflectance in the visible light range showed the highest value of 45% at $3{\times}10^{-3}\;Torr$ and decreased to 18.5% at $3{\times}10^{-2}\;Torr$.

• Korean Journal of Chemical Engineering
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• v.35 no.11
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• pp.2241-2255
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• 2018

RSM methodology was applied to present mathematical models for the fabrication of polyvinylidene fluoride (PVDF) dual-layer hollow fibers in membrane distillation process. The design of experiments was used to investigate three main parameters in terms of polymer concentration in both outer and inner layers and the flow rate of dope solutions by the Box-Behnken method. According to obtained results, the optimization was done to present the proper membrane with desirable properties. The characteristics of the optimized membrane (named HF-O) suggested by the Box-Behnken (at the predicted point) showed that the proposed models are strongly valid. Then, a morphology study was done to modify the fiber by a combination of three types of a structure such as macro-void, sponge-like and sharp finger-like. It also improved the hydrophobicity of outer surface from 87 to $113^{\circ}$ and the mean pore size of the inner surface from 108.12 to 560.14 nm. The DCMD flux of modified fiber (named HF-M) enhanced 62% more than HF-O when it was fabricated by considering both of RSM and morphology study results. Finally, HF-M was conducted for long-term desalination process up to 100 hr and showed stable flux and wetting resistance during the test. These stepwise approaches are proposed to easily predict the main properties of PVDF dual-layer hollow fibers by valid models and to effectively modify its structure.

• Journal of Microbiology and Biotechnology
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• v.17 no.10
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• pp.1721-1726
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• 2007

Comparative morphology among species of the genus Calostoma, including C. cinnabarina, C. ravenelii, and C. japonicum, was investigated by scanning electron microscopy and atomic force microscopy. Spore morphology of C. cinnabarina and C. ravenelii showed no dramatic differences by light microcopy and scanning electron microscopy. To differentiate these species, atomic force microscopy was employed. Quantitative analysis of the surface roughness of basidiospores revealed subtle differences in height fluctuation at the nanometer scale between the species of Calostoma. Basidiospores of C. cinnabarina had a relatively rougher surface than those of C. ravenelii at $2.0{\times}2.0\;{\mu}m^2$ scan areas.