• Conservation Science in Museum
• /
• v.12
• /
• pp.35-45
• /
• 2011

To keep relics excavated in the era of the Japanese Colonist's rule in the Korean Peninsula in order, the National Museum of Korea selected some of horse strap pendants (Haengyeob) that were excavated from Seobongchong, Sikrichong and Geumryeongchong, and it investigated conservation and production technique. The horse strap pendants selected were classified into three, that is to say, Oval and fish-tail shape, heart shape and atypical: At the results of microscopic observation, XRF and SEM-EDS analysis, base plate was made of iron, and top plate as well as pattern plate was made of iron, copper and silver. Both Oval and fish-tail shape and heart shape horse strap pendants had horse strap pendants having same production technique and sizes at all of three ancient tombs were made of iron and copper. The gold layer of horse strap pendants except the atypical one having no gold layer were made by amalgam gilding.

• Journal of Conservation Science
• /
• v.28 no.2
• /
• pp.101-112
• /
• 2012

The Donggwanwangmyo Shrine was built in the period of Joseon Dynasty in 1602. There are Clay Statues (Gwanwo, Jangbi, Woojanggun, Juchang, Jojaryoung and so on) enshrined in the inside of the main hall. Original color of these Clay Statues are deteriorated by inorganic pollutant like dust. And the origanal forms were damaged during several process of restorations and repaintings. This study carried out XRD, SEM-EDS, P-XRF and chromaticity measurement for characterization of pigments which painted on Clay Statues. As a result, cinnabar, hematite and red lead were used to paint in pigments for the red and brown colors. Light red pigment was made by gypsum with these minerals that make colors. Graphite and gold were used to color of black and gold pigment, respectively. Green pigment is identified of malachite, atacamite and glauconite. Blue pigment which is clearly painted on Clay Statues is interpreted a morden industrial pigment that were painted at repair work. White pigments are detected calcite, gypsum and silver white. Orpiment and litharge were used to color of yellow and light yellow pigment.

• Journal of the Korean Applied Science and Technology
• /
• v.31 no.1
• /
• pp.92-100
• /
• 2014

Hydrophobic magnesium hydroxide [$Mg(OH)_2$] was modified by hydrothermal method using non-ionic sorbitol surfactant with Span series. Mganesium chloride [$MgCl_2$] and sodium hydroxide [NaOH] were used for synthesis of $Mg(OH)_2$. Also non-ionic surfactant were added as a stabilizer, dispersant and surface modifier. Addition of non-ionic surfactant was favourable to obtain small sized $Mg(OH)_2$ particles with better dispersibility and hydrophobic property of $Mg(OH)_2$ particles. The obtained product were characterized by particle size analysis(PSA), scanning electron microscope(SEM), energy dispersive spectroscopy(EDS), x-ray diffraction(XRD) and fourier transform infrared spectroscopy(FT-IR). The results show that the product are prepared with this method has a well hydrophobic properties and dispersity compared with unmodified $Mg(OH)_2$ particles. The improve properties of surface modified $Mg(OH)_2$ particles were also verified by similarity synthesizing under slightly different conditions.

• Composites Research
• /
• v.33 no.4
• /
• pp.205-212
• /
• 2020

In this study, HfC was coated on two types of carbon/carbon composites coated with SiC by vacuum plasma spraying(VPS). The experiment was performed using a plasma wind tunnel with heat flux of 5.06 MW/㎡ for 120 s heat flux before and after the coating. The mass ablation rate was calculated through the mass change before and after the test, and the length change was measured by using calipers and high speed camera. The oxidation/ablation behavior were observed by FE-SEM with EDS analysis of the specimens cross section. The plasma wind tunnel test results showed that the coated specimens had low weight loss and length change, and high oxidation/ablation resistance. However, two types of the specimens tested under the same conditions were different in the ablation behavior and ablation rate, and it was evaluated that the cylindrical type had higher oxidation/ablation resistance.

• Resources Recycling
• /
• v.25 no.3
• /
• pp.3-10
• /
• 2016

The passive treatment was required a large area for the treatment of acid mine drainage (AMD), and pollutants were discharged with mine drainage by the increased flow rate in summer. This study was performed to improve the turbidity and to precipitate the pollutants quickly using coagulants and flocculants in AMD of abandoned mine sites that were difficult to build the passive treatment system. The coagulant PAC (Poly aluminium chloride) and flocculant PAM (Polyacrylamide) were selected to improve turbidity in W mine waters. We also tested the particle size analysis, ICP-OES and/or SEM-EDS for water and sludge samples.

• The Journal of the Korea Contents Association
• /
• v.13 no.9
• /
• pp.392-399
• /
• 2013

The purpose of this study is to identify the manufacturing possibility of non-cement mortar using blast furnace slag and alkali accelerator. In this experimental study, the blast furnace slag which is the by-product of the steel industry substitute for cement, and the potassium hydroxide(KOH), calcium hydroxide ($Ca(OH)_2$) and sodium hydroxide(NaOH) as stimulus were added to each specimen. And the analysis on reaction property of non-cement mortar was conducted by measurement such as flexural and compressive strength, XRD, EDS and SEM. From the test results, it can be founded that $SiO_2$ and CaO included in the blast furnace slag are released and make the calcium silicate hydrate like the hydration reaction of the cement. Also, the continued study is need to reduce emission of $CO_2$ because of major content in filed of the building construction.

• Resources Recycling
• /
• v.26 no.1
• /
• pp.16-21
• /
• 2017

This paper relates to the synthesis of a source powder for SiC crystal growth. ${\beta}-SiC$ powders are synthesized at high temperatures (>$1400^{\circ}C$) by a reaction between silicon powder and carbon powder. The reaction is carried out in a graphite crucible operating in a vacuum ambient (or Ar gas) over a period of time sufficient to cause the Si+C mixture to react and form poly-crystalline SiC powder. End-product characterizations are pursued with X-ray diffraction analysis, SEM/EDS, particle size analyzer and ICP-OES. The purity of the end-product was analyzed with the Korean Standard KS L 1612.

• Applied Chemistry for Engineering
• /
• v.30 no.1
• /
• pp.68-73
• /
• 2019

We prepared hydrophobic silica particles by a sol-gel process from tetraethyl orthosilicate (TEOS), followed by coupling the reaction with octyltrimethoxysilane (OTMS) or hexadecyltrimethoxysilane (HDTMS) under various reaction conditions. We confirmed the extent of silica surface modification with organic compounds by SEM-EDS, thermogravimetry and elemental analysis. The silica particles obtained after the hydrolysis reaction of TEOS in ethanol at $50^{\circ}C$ for 24 h and the coupling reaction with OTMS for 2 h at the same temperature displayed the optimum performance in terms of the dispersity in an organic solvent and the surface roughness of films composited with epoxy resins. The oxygen permeability of the composite film with modified-silica was 12% lower than that of using the film without modified-silica.

• Electronic Materials Letters
• /
• v.14 no.6
• /
• pp.755-765
• /
• 2018

In situ nitrogen doped hard carbon nanotubes (NHCNT) were fabricated by pyrolyzing tubular nitrogen doped conjugated microporous polymer. KOH activated NHCNT (K-NHCNT) were also prepared to improve their porous structure. XRD, SEM, TEM, EDS, XPS, Raman spectra, $N_2$ adsorption-desorption, galvanostatic charging-discharge, cyclic voltammetry and EIS were used to characterize the structure and performance of NHCNT and K-NHCNT. XRD and Raman spectra reveal K-NHCNT own a more disorder carbon. SEM indicate that the diameters of K-NHCNT are smaller than that of NHCNT. TEM and EDS further indicate that K-NHCNT are hollow carbon nanotubes with nitrogen uniformly distributed. $N_2$ adsorption-desorption analysis reveals that K-NHCNT have an ultra high specific surface area of $1787.37m^2g^{-1}$, which is much larger than that of NHCNT ($531.98m^2g^{-1}$). K-NHCNT delivers a high reversible capacity of $918mAh\;g^{-1}$ at $0.6A\;g^{-1}$. Even after 350 times cycling, the capacity of K-NHCNT cycled after 350 cycles at $0.6A\;g^{-1}$ is still as high as $591.6mAh\;g^{-1}$. Such outstanding electrochemical performance of the K-NHCNT are clearly attributed by its superior characters, which have great advantages over those commercial available carbon nanotubes ($200-450mAh\;g^{-1}$) not only for its desired electrochemical performance but also for its easily and scaling-up preparation.

• Resources Recycling
• /
• v.29 no.6
• /
• pp.98-103
• /
• 2020

In this study, the depression behavior of zinc sulfate on the sphalerite with the addition of potassium butyl xanthate was investigated to clear the relationship between zinc sulfate and xanthate in depression of sphalerite. As a result of the experiment, it was confirmed that the depress effect of zinc sulfate on the sphalerite declined with the increase of its addition amount. From the results of SEM-EDS and FT-IR analysis, it was found out that the amorphous precipitate of metal xanthate (Zn-BX) was formed in sphalerite concentrate, when the solubility product of [Zn+]·[BX] in the pulp solution exceeded 3.71×10-11, which is the solubility of Zn-butyl xanthate. It is considered that the Zn-butyl xanthate had a negative effect on the depression of sphalerite.