• Journal of the Korean Chemical Society
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• v.50 no.1
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• pp.32-36
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• 2006

films of gold nanoparticles were formed on indium tin oxide (ITO) by an electrodeposition method from an aminosilicate stabilized gold colloid solution. The thin films were examined by cyclic voltammetry (CV), scanning electron microscopy (SEM), UV-visible, and energy dispersive X-ray spectroscopy (EDXS). The surface coverage of gold nanoparticles on the thin film was estimated to 1.2 nanomole/cm2. An anthraquinone-2, 6-disulfonic acid, disodium salt (AQDS) self-assembled layer was generated by immersing gold thin film into 1mM of AQDS in 0.1M HClO4 solution for over 20 hours. As a result, a new absorbance peak from the multi-layers (AQDS/thin film of gold /ITO) was obtained about at 690 nm. Also, the surface plasmon absorption of multi-layers was measured by UV-Visible spectrometer along with chronoamperometry by applying the various potentials from +0.5V to -0.5V. The maximum surface plasmon absorption band at 550 nm was decreased by applying negative potentials. The change of absorbance was correlated with the surface coverage of the AQDS indicating the pseudo-capacity surface state of the AQDS layer was coupled to the energy level of the plasmonband by applied negative potentials.

• Carbon letters
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• v.28
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• pp.31-37
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• 2018

This paper examines a simple one-step and catalyst-free method for synthesizing carbon nanoparticles from aliphatic alcohols and n-hexane with linear molecule formations by using a stable solution plasma process with a bipolar pulse and an external resistor. When the external resistor is adopted, it is observed that the current spikes are dramatically decreased, which induced production of a more stable discharge. Six aliphatic linear alcohols (methanol-hexanol) containing carbon with oxygen sources are studied as possible precursors for the massive production of carbon nanoparticles. Additional study is also carried out with the use of n-hexane containing many carbons without an oxygen source in order to enhance the formation of carbon nanoparticles and to eliminate unwanted oxygen effects. The obtained carbon nanoparticles are characterized with field emission-scanning electron microscopy, energy dispersive X-ray spectroscopy, and Raman spectroscopy. The results show that with increasing carbon ratios in alcohol content, the synthesis rate of carbon nanoparticles is increased, whereas the size of the carbon nanoparticles is decreased. Moreover, the degree of graphitization of the carbon nanoparticles synthesized from 1-hexanol and n-hexane with a high carbon (C)/oxygen (O) ratio and low or no oxygen is observed to be greater than that of the carbon nanoparticles synthesized from the corresponding materials with a low C/O ratio.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.363-363
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• 2008

The development of dry etching process for sapphire wafer with plasma has been key issues for the opto-electric devices. The challenges are increasing control and obtaining low plasma induced-damage because an unwanted scattering of radiation is caused by the spatial disorder of pattern and variation of surface roughness. The plasma-induced damages during plasma etching process can be classified as impurity contamination of residual etch products or bonding disruption in lattice due to charged particle bombardment. Therefor, fine pattern technology with low damaged etching process and high etch rate are urgently needed. Until now, there are a lot of reports on the etching of sapphire wafer with using $Cl_2$/Ar, $BCl_3$/Ar, HBr/Ar and so on [1]. However, the etch behavior of sapphire wafer have investigated with variation of only one parameter while other parameters are fixed. In this study, we investigated the effect of pressure and other parameters on the etch rate and the selectivity. We selected $BCl_3$ as an etch ant because $BCl_3$ plasmas are widely used in etching process of oxide materials. In plasma, the $BCl_3$ molecule can be dissociated into B radical, $B^+$ ion, Cl radical and $Cl^+$ ion. However, the $BCl_3$ molecule can be dissociated into B radical or $B^+$ ion easier than Cl radical or $Cl^+$ ion. First, we evaluated the etch behaviors of sapphire wafer in $BCl_3$/additive gases (Ar, $N_2,Cl_2$) gases. The behavior of etch rate of sapphire substrate was monitored as a function of additive gas ratio to $BCl_3$ based plasma, total flow rate, r.f. power, d.c. bias under different pressures of 5 mTorr, 10 mTorr, 20 mTorr and 30 mTorr. The etch rates of sapphire wafer, $SiO_2$ and PR were measured with using alpha step surface profiler. In order to understand the changes of radicals, volume density of Cl, B radical and BCl molecule were investigated with optical emission spectroscopy (OES). The chemical states of $Al_2O_3$ thin films were studied with energy dispersive X-ray (EDX) and depth profile anlysis of auger electron spectroscopy (AES). The enhancement of sapphire substrate can be explained by the reactive ion etching mechanism with the competition of the formation of volatile $AlCl_3$, $Al_2Cl_6$ or $BOCl_3$ and the sputter effect by energetic ions.

• Journal of Dental Rehabilitation and Applied Science
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• v.34 no.1
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• pp.1-9
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• 2018

Purpose: The purpose of this study is to investigate the effect of the titanium implant soaked in saline after RBM and acid etched surface treatment on the initial osseointegration by comparing the removal torque and the surface analysis compared to the titanium implant with only RBM and acid etched surface treatment. Materials and Methods: The control group was RBM and acid etched surface treated implants (RBM + HCl), and the test group was implants soaked in saline for 2 weeks after RBM and acid etched surface treatment (RBM + HCl + Sal). The control and test group implants were placed in the left and right tibiae of 10 rabbits, respectively, and at the same time, the insertion torque (ITQ) was measured. After 10 days, the removal torque (RTQ) was measured by exposing the implant site. FE-SEM, EDS, Surface roughness and Raman spectroscopy were performed for the surface analysis of the new implant specimens used in the experiments. Results: There was significant difference in insertion torque and removal torque between control group and experimental group (P = 0.014 < 0.05). Surface roughness of experimental group is higher than control group. Conclusion: Saline soaking after RBM and acid etched surface treatment of titanium implants were positively affect the initial osseointegration as compared to titanium implants with only RBM and acid etched surface treatment.

• Applied Chemistry for Engineering
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• v.31 no.2
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• pp.220-225
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• 2020

Hair is made of proteins containing various amino acids. Ultraviolet (UV) radiation is believed to be responsible for the most damaging effects of sunlight, and also plays an important role in hair aging. The purpose of this study was to investigate the changes in morphological and chemical structures after ultraviolet B (UVB) irradiation of human hair. The UVB-irradiated hair showed characteristic morphological and structural changes, compared to those of the normal hair. The result from a scanning electron microscope (SEM) equipped with an energy dispersive X-ray diffractometer (EDX) showed that the scale of UV-irradiated hair appeared to be rough and the amount of oxygen element was higher than that of the normal hair. Fluorescence and three dimensional (3D) topographical images were obtained by a confocal laser scanning microscope (CLSM). In 3D images, the green emission intensity of normal hair was much higher than that of fluorescing UVB-irradiated hair. The intensity of green emission reflects the intrinsic fluorescence of hair protein. Also, a fluorescent imaging method using fluorescamine reagent was used to identify the free amino groups resulting from a peptide bond breakage in UVB-irradiated hair. Strong blue fluorescence of UVB-irradiated hair, which indicates a very high level of amino groups, was observed by CLSM. Therefore, the fluorescamine as an extrinsic fluorescence could provide a useful tool to identify the peptide bond breakage in UVB-irradiated hair. Infrared image mapping was also employed to assess the cross-sections of normal and UVB-irradiated specimens to examine the oxidation of disulfide bonds. The degree of peak areas with strong absorbance for the disulfide mono-oxide was spread from the outside to the inside of hair. The spectroscopic techniques used alone, or in combination, launch new possibilities in the field of hair cosmetics.

• Polymer(Korea)
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• v.38 no.1
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• pp.74-79
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• 2014

Microfibrillated cellulose (MFC) was chemically modified with two different silane coupling agents (3-aminopropyltriethoxysilane and 3-mercaptopropyltriethoxysilane) and lauroyl chloride. The surface modification of MFC was confirmed by infrared spectroscopy (FTIR), energy dispersive X-ray spectroscopy (EDX), and contact angle measurements. Composite paper was successfully prepared with surface modified MFC and polyamide (PA) fiber. The surface modification of MFC not only prevented aggregation of MFC but also improved adhesive property between PA fiber and surface modified MFC. It was impossible to prepare papers of only PA fiber because there is no binder to connect PA fibers. That is, surface modified MFC as a binder in PA fiber played a crucial role in making composite paper. Composite paper with silane modified MFC showed higher tensile strength and modulus than composite paper with lauroyl moiety modified MFC. The structure, morphology, and mechanical properties of composite paper were analyzed by scanning electron microscope (SEM) and universal testing machine (UTM).

• Resources Recycling
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• v.30 no.2
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• pp.68-74
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• 2021

This study investigated formaldehyde (HCHO) removal by preparing porous supports using domestic low-grade silica coated with Co-ZSM5 and Cu-ZSM5 as the catalysts. First, the sample of the raw material for the support contained 90% silica with quartz crystal phase, which was confirmed as low-grade silica. According to Energy-dispersive X-ray spectroscopy (EDS) and Fourier-transform infrared spectroscopy (FT-IR) analyses, the catalysts, Co-ZSM5 and Cu-ZSM5, were successfully coated on the surface of the porous silica supports. During the removal test of HCHO using the prepared Co-ZSM5 and Cu-ZSM5 coated beads, depending on the reaction temperature, the Co-ZSM5 coated beads exhibited higher removal efficiencies (>97%) than the Cu-ZSM5 beads at 200 ℃. The higher efficiency of the Co-ZSM5 coating may be attributed to its superior surface activity properties (BET surface area and pore volume) that lead to the favorable HCHO decomposition. Therefore, Co-ZSM5 was determined to be the suitable catalyst for removing HCHO as a coating on a porous support fabricated using domestic low-grade silica.

• Journal of Korean Tunnelling and Underground Space Association
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• v.19 no.4
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• pp.589-609
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• 2017

This study carried out the density and energy dispersive X-ray spectroscopy and particle size analysis which are the physical characteristics of coal dust by collecting samples of coal dust in the five domestic mines to control the coal dust through ventilation in the workplace for coal mining in the country. This will contribute to a more comfortable working environment by understanding the physical characteristics of the coal dust which is derived from any hard coal produced domestically. In particular, the result of PSA analysis showed that the size of coal dust sample for this study ranged from $0.007{\sim}88.614{\mu}m$ were the particles less than $3.5{\mu}m$, the size range responsible for pneumoconiosis. To observe the flow of coal dust collected on the wind speed, the fallout of coal dust produced by the wind tunnel for the wind was measured and the particle size analysis of coal dust fallout was carried out. In addition, airborne dust is measured according to the mine velocity by using a multi-stage Anderson sampler in the mine where fine dust is generated in a large amount and the wind speed is found out to control the coal dust below $3.5{\mu}m$. In addition, natural ventilation pressure of A mine was calculated to prevent over design of the main fan.

• Applied Microscopy
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• v.41 no.2
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• pp.139-145
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• 2011

Parthenocissus tricuspidata is an epiphyte that lacks a main axial stem, but develops adhesive disks along the stem for climbing support. In this study, scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) were utilized to examine the brick wall surface and the adhesive disks of P. tricuspidata that attached to the surface successfully. The study was mainly focused the outermost layers of both structures before and after adhesion to find out whether there has been some structural and/or physical interactions between the two. The adhesive disks adhered firmly to the brick wall by secreting adhesive materials that help them for a tight attachment to the surface. The rough wall surface appeared facilitating better attachment of the adhesive disks by infiltrating the materials into those spaces leading to some degree of interactions at the interface. EDS analysis on the outermost layers of the adhesive disks that were separated from the substrates was also consistent with the SEM data on the interaction between the adhesive disks and the substrate surface. EDS analysis of the brick wall surface and the adhesive disks demonstrated similar elements of O, Si, Fe, Al, K, Mg, and Na in their components.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.23 no.4
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• pp.167-172
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• 2013

Titanium dioxides nanoparticles coated aluminum oxide powders were fabricated by pulsed laser deposition (PLD) with Nd : YAG laser at 266 nm. The Pulse laser energy is 100 mJ/pulse. During the irradiation of the focused laser on the $TiO_2$ target, Ar gas is supplied into the chamber. The gas pressure is varied in a range of $1{\times}10^{-2}$ to 100 Pa. Titanium dioxides nanoparticles deposited aluminum oxide powders were characterized by using energy dispersive X-ray spectroscopy (EDX), high resolution transmission electron microscopy (HR-TEM), in order to understand the effect of Ar background gas on surface morphology and properties of the powders. The coated $TiO_2$ nanoparticles had nanosized spherical shape and the crystallite sizes of 10~30 nm. The morphology of coated $TiO_2$ nanoparticles is not affected by gas pressure. However, the particle size and crystallinity slightly increased with the increase of gas pressure. According to this technique, the size and crystallinity of nanoparticles can be easily controlled by controlling pressure during the laser irradiation.