• Journal of the Korean Crystal Growth and Crystal Technology
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• v.21 no.3
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• pp.124-128
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• 2011

Electrospun webs have been widely investigated for applying to drug delivery system (DDS) because of their high specific surface area and high porosity. In this study, the composite webs of PLA (poly(lactic acid)) and $TiO_2$ were fabricated by melt-electro-spinning method for applying to drug delivery system. The morphologies of PLA/$TiO_2$, webs were observed using scanning electron microscope (SEM) and field emission transmission electron microscope (FE-TEM). The crystal structures of PLA/$TiO_2$ composite webs were confirmed by X-ray diffractometer (XRD).

• Advances in aircraft and spacecraft science
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• v.1 no.1
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• pp.1-14
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• 2014

Physico-chemical changes of the plasma modified titanium alloy [Ti-6Al-4V] surface were studied with respect to their crystallographic changes by X-Ray Diffraction (XRD) and Scanning Electron Microscope (SEM).The plasma-treatment of surface was carried out to enhance adhesion of high performance nano reinforced epoxy adhesive, a phenomenon that was manifested in subsequent experimental results. The enhancement of adhesion as a consequence of improved spreading and wetting on metal surface was studied by contact angle (sessile drop method) and surface energy determination, which shows a distinct increase in polar component of surface energy. The synergism in bond strength was established by analyzing the lap-shear strength of titanium laminate. The extent of enhancement in thermal stability of the dispersed nanosilica particles reinforced epoxy adhesive was studied by Thermo Gravimetric Analysis (TGA), which shows an increase in onset of degradation and high amount of residuals at the high temperature range under study. The fractured surfaces of the joint were examined by Scanning electron microscope (SEM).

• Journal of the Korean Geotechnical Society
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• v.28 no.6
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• pp.53-61
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• 2012

The purpose of this study is to understand the mechanism of cementation of soil induced by bacteria. In order to understand the mechanism of cementation of soft soils treated with bacteria, six types of specimens(Not treated, Normal concentration bacteria treatment, High concentration bacteria treatment, Supernatant high concentration bacteria treatment, Double high concentration bacteria treatment, and 25% Specimen high concentration bacteria treatment) were made. Scanning Electron Microscope (SEM), EDX and X-ray diffraction (XRD) analyses were performed on the soft silt and loose sand specimens. Compared with the normal bacteria concentration treated specimen, a clearer cementation between particles was observed in the 25% specimen high bacteria concentration treated specimen. On the basis of the preliminary results, it appears that microbial cementation can occur in the soft soil.

• Journal of the Korean institute of surface engineering
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• v.40 no.4
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• pp.185-189
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• 2007

A scanning electron microscope (SEM) is a complex system, consisting of many sophisticated components. For a systematic characterization, a $2^4$ full factorial experiment was conducted. The SEM components examined include condenser lens 1 and 2 (denoted as A and B, respectively), and Objective lens (coarse and fine-denoted as C and D respectively). A statistical analysis was conduced to investigate factor effects and variations In response surfaces. Among four factors, main effect analysis revealed that A and D were Identified as the dominant factor. Moreover, B showed conflicting effect against C. The $R^2$ of statistical regression model constructed was about 69.6%. The model generated 3D response surface plots facilitated understanding of complex tactor effects.

• Environmental Engineering Research
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• v.24 no.1
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• pp.24-30
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• 2019

The present study explores the applicability of response surface methodology (RSM) in conjunction with central composite design (CCD) matrix to statistically optimize ettringite crystallization process for the removal of sulphate from landfill leachate. A three factor-five coded level CCD with 20 runs, was performed to estimate the best fitted model. The RSM results indicated that the fitted quadratic regression model could be appropriate to predict sulfate removal efficiency. The pH was identified as the most dominant parameter affecting sulphate removal. 61.6% of maximum sulphate removal efficiency was obtained at pH of 11.06 for a 1.87 of $Ca/SO_4$ and 0.51 of $Al/SO_4$ molar ratios. The operating cost for ettringite crystallization at optimized conditions was calculated to be 0.52 $/$m^3$. The significance of independent variables and their interactions were tested by analysis of variance. Scanning electron microscope (SEM) and SEM coupled with energy dispersive X-Ray spectroscopy results confirmed the formation of ettringite crystal and were used to describe its morphology features.

• Proceedings of the KACD Conference
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• 2001.11a
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• pp.561.1-561
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• 2001

The aim of this study was to examine the localization of bacteria in the apices of roots with refractory apical periodontitis by a scanning electron micrscopy(SEM), and to identify the extra-radical bacteria using a immunohistological method. Eleven teeth were prepare for immunostaining and 4 for SEM. Immunostaining was performed with LSAB method and specific antisera against 18 bacteria selected for this study. Specimens for SEM observations were dried using a t-butyl alcohol freeze dryer and coated with gold-palladium.(omitted)

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1862-1865
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• 2005

We have a plan to design a controller for electron beam manufacturing system. At first, we designed a controller for SEM. The controller consists of five parts (power source, beam controller, scanning controller, optic controller and main controller). Beam controller supplies pulse wave for generating high voltage and can monitor the status of high voltage instrument through emission current. Optic controller controls focus, spot size and image shift. Main controller transmits variables from operating program to each part and monitors the status of peripheral device.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.2
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• pp.303-310
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• 2008

We fabricated hydrogenated amorphous silicon(a-Si:H) 140 nm thick film on a $180\;nm-SiO_2/Si$ substrate with an inductively-coupled plasma chemical vapor deposition(ICP-CVD) equipment at $250^{\circ}C$. Moreover, 30 nm-Ni film was deposited with a thermal-evaporator sequently. Then the film stack was annealed to induce silicides by a rapid thermal annealer(RTA) at $200{\sim}500^{\circ}C$ in every $50^{\circ}C$ for 30 minuets. We employed a four-point tester, high resolution X-ray diffraction(HRXRD), field emission scanning electron microscope(FE-SEM), transmission electron microscope(TEM), and scanning probe microscope(SPM) in order to examine the sheet resistance, phase transformation, in-plane microstructure, cross-sectional microstructure evolution, and surface roughness, respectively. We confirmed that nano-thick high resistive $Ni_3Si$, mid-resistive $Ni_2Si$, and low resistive NiSi phases were stable at the temperature of <300, $350{\sim}450^{\circ}C$, and >$450^{\circ}C$, respectively. Through SPM analysis, we confirmed the surface roughness of nickel silicide was below 12 nm, which implied that it was superior over employing the glass and polymer substrates.

• Korean Journal of Acupuncture
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• v.21 no.4
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• pp.43-51
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• 2004

Objectives : In order to ensure safe acupuncture treatment, the quality of the needle tip is essential. But, there have not been so many studies about the quality of the acupuncture needle tip. For this reason we have been already reported about the quality of acupuncture needle tip in Korea using scanning electron microscope(SEM) in 2002, 2003. In order to compare than other society, we investigated the current condition of the tips of the acupuncture needles sold in Europe. Methods : We obtained the needles made by 7 companies, which are sold currently in Europe, and selected 50 pieces out of 100 pieces from each company by randomized methods. And then we observed the tip of each needle using a scanning electron microscope at ${\times}800$ magnification. Results and Discussion : We found that needles had several defects such as scratch marks on the surface, metallic scuff, lumps and irregularities of the needle tips, stubbed or malformed tips, tips of point off-center, peeled off coated tips, same as Korean needles. There was much difference on the quality of needles among the manufacturers, and some needles seem to need thorough quality control. Allowing for the high price, the quality of some needle in Europe generally are better than that of Korean needles. But some Korean needles hold a top position than European ones in quality. We want a good industrial standard to be made in acupuncture manufacturing fields in the near future, because the safety is not less valuable than the efficacy in medicine.

• The Korean Journal of Malacology
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• v.29 no.2
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• pp.97-103
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• 2013

In the present study, we monitored the early development of Saccostrea kegakia subtropical oyster species distributing on rocky intertidal off the northern Jeju Island using scanning electron microscope (SEM). The female oyster collected in early August, 2012 were fully mature exhibiting relatively small eggs ($46.5{\pm}1.4{\mu}m$ in diameter) in the gonad, while testis of the mature male oysters were filled with fully developed sperms of 36.9 ${\mu}m$ in length. The fertilized eggs developed into 2-cell stage with polar body after 1 hr 20 min of fertilization, then followed by Morula stage (3 hr 20 min), Blastula stage (4 hr 50 min), Gastrula stage (7 hr), and trochophore larvae stage (9 hr 30 min). The observed early development of S. kegaki in this study was similar the early development of other oysters, although size of the fertilized eggs were somewhat smaller.