• Journal of the Korea Institute of Building Construction
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• v.16 no.3
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• pp.219-227
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• 2016

Chloride ions ingress continuously in reinforced concrete through pores of it by $Cl^-$. Finally, it causes a localized corrosion of the rebar and then it generates cracks on concrete structures. Recently, new materials removing harmful anions have been developed. Layered double hydroxides(LDHs) has an excellent ability to remove harmful anions because various anions can be adsorbed in the interlayer space between divalent and trivalent cations. Thus, LDHs has been applied in various fields. Especially, LDHs is expected to be effective adsorbent binding chloride ions. In this study, $Ca/Al-NO_3$ and $Mg/Al-NO_3$ LDHs were prepared by using a co-precipitation method. $Ca/Al-NO_3$ and $Mg/Al-NO_3$ LDHs were compared and analyzed by using XRD, SEM analysis. Many nano size hexagonal crystals were observed by SEM. Experiments for binding chloride ions of LDHs were conducted by using potentiometric method. The experimental data were measured every 15 minutes. It was observed that the chloride ion content is reduced by increasing of LDHs mass fraction and the reaction rate of $Mg/Al-NO_3$ is faster than $Ca/Al-NO_3$. In future studies, binding chloride capacity in cement materials will be evaluated based on results of this study.

• Journal of the Korean Society of Radiology
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• v.4 no.4
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• pp.25-28
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• 2010

In this paper, the fabrication and feasibility study of clinical application with euripium doped gadollium oxide ($Gd_2O_3$:Eu) nano phosphor derived by low-temperature solution combustion method. From the fabricated phosphor, the photoluminescent characteristic and linearity as a function of phosphor film thickness were investigated to evaluate x-ray converstion properties. From the experimental results, the luminescent intensity was $2945pC/cm^2$-mR at $270{\mu}m$ $Gd_2O_3$:Eu film and this value is higher 1.2 time the conventional bulk phosphor, which is possible to imaging acquisition. And good linearity was shown at x-ray exposure range for clinical diagnostic application.

• Journal of the Korean Ceramic Society
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• v.41 no.10 s.269
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• pp.742-748
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• 2004

Isopropanol of low boiling point was used as a solvent to prepare Al-doped ZnO(AZO) thin films. A homogeneous and stable sol was made from Zn acetate a solute whose mole concentration was 0.7mol/$\iota$ and Al chloride as a dopant. Al-doped ZnO thin films were prepared by sol-gel method as a function of post-heating temperature from 500 to $700^{\circ}C$ and the optical and electrical properties were investigated. The c-axis orientation along (002) plane was enhanced with the increasing of post-heating temperature and the surface morphology of the films showed a homogeneous and nano-sized microstructure. The optical transmittance of the films post-heated below $650^{\circ}C$ was over $86\%$, but decreased at $700^{\circ}C$. The electrical resistivity of the thin films decreased from 73 to 22 $\Omega$-cm as the post-heating temperature increased up to $650^{\circ}C$, but increased greatly to 580 $\Omega$-cm at $700^{\circ}C$. XPS analysis indicated that the deterioration of electrical and optical properties was attributed to the precipitation of $Al_2O_3$ phase on the surface of AZO thin film. This result suggests that the optimum post-heating temperature to improve electrical and optical properties is $600^{\circ}C$.

• Textile Coloration and Finishing
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• v.28 no.1
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• pp.48-56
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• 2016

Improvement of heat sink technology related to the continuous implementation performance and extension of device-life in circumstance of easy heating and more compact space has been becoming more important issue as multi-functional integration and miniaturization trend of electronic gadgets and products has been generalized. In this study, it purposed to minimize of decline of the heat diffusivity by gluing polymer through compounding of inorganic particles which have thermal conductive properties. We used NH-9300 as base resin and used inorganic fillers such as silicon carbide(SiC), aluminum nitride(AlN), and boron nitride(BN) to improve heat diffusivity. After making film which was made from 100 part of acrylic resin mixed hardener(1.0 part more or less) with inorganic particles. The film was matured at $80^{\circ}C$ for 24h. Diffusivity were tested according to sorts of particles and density of particles as well as size and structure of particle to improve the effect of heat sink in view of morphology assessing diffusivity by LFA(Netzsch/LFA 447 Nano Flash) and adhesion strength by UTM(Universal Testing Machine). The correlation between diffusivity of pure inorganic particles and composite as well as the relation between density and morphology of inorganic particles has been studied. The study related morphology showed that globular type had superior diffusivity at low density of 25% but on the contarary globular type was inferior to non-globular type at high density of 80%.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.4
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• pp.288-294
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• 2012

The current growth of nano-industries has resulted in released nanoparticles entering into water and soil ecosystems via various direct or indirect routes. Physicochemical properties of nanoparticles differ from bulk materials, and nanomaterials influence the fates of nanoparticles and the interactions of living or non-living things in the environment. Microcosm analysis is a research methodology for revealing natural phenomena by mimicking part of an ecosystem under controlled conditions. Microcosm study allows for the integrated analysis of toxic effects and fates of nanoparticles in the ecosystem. Ecotoxicity studies of nanomaterials are steadily increasing, and microcosm studies of nanomaterials are currently beginning to surface. In this study, microcosm studies of nanomaterials in water and soil ecosystems were extensively investigated based on SCI(E) papers. We found that the microcosm studies have been reported in 12 instances, and mesocosm studies have been reported in only once until now. Advanced research was mostly evaluated at the microorganism level. But integrated analysis of nanotoxicity is required to research the interactions based of various species. Thus, our studies analysed the trend of microcosm studies on nanomaterials in water and soil ecosystems and suggested future directions of microcosm research of nanomaterials.

• Composites Research
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• v.26 no.5
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• pp.289-294
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• 2013

A thinner is used to improve the multi-walled carbon nano-tube (CNT) and carbon black (CB) dispersion in a polymer matrix and to make a soft electrode. The electrical and mechanical properties of the soft electrodes are investigated as functions of CNT, CB and thinner content. The optimal mixing condition for the electrode is thinner 80, CNT 3.5, CB 18 (phr) on the basis of matrix (KE-12). The specific resistance of that is 73 (${\Omega}{\cdot}cm$), and tensile strength, tensile modulus, and elongation of that is 0.45 MPa, 0.21 MPa, and 184%, respectively. Also, a simple structure of the actuator with an optimized electrode and elastomer is fabricated and its characteristic is evaluated. At the operating voltage 25 kV, the displacement of an elastomer KE-12 is 2.24 mm, and that of an elastomer KE-12 with thinner 50 (phr) is 4.05 mm. It shows a higher displacement compared to that of 3M 4910 which has similar modulus. The actuator made with elastomer and electrode of the same material (KE-12) may have advantages for fatigue life and application.

• Journal of the Mineralogical Society of Korea
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• v.22 no.1
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• pp.63-72
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• 2009

Carbon-coated lithium iron phosphate ($LiFePO_4/C$) composites are synthesized by the modified mechanical activation method (modified MA process) and studied by the Rietveld structural refinement. Rietveld indices of $LiFePO_4/C$ indicate good fitting with $R_p=8.14%,\;R_{wp}=11.1%,\;R_{exp}=9.09%,\;R_B=3.88%$, and S (GofF, Goodness of fit) = 1.2, respectively. $LiFePO_4/C$ with a space group Pnma shows a = 10.3229(3)${\AA}$, b = 6.0052(2) ${\AA}$, c = 4.6939(1) ${\AA}$, and V = 290.98(1) ${\AA}^3$ in dimension, indicating good agreements with those of previous works. Synthetic powders are nano-sized ($65{\sim}90nm$) homogeneous particles with high purity. Thus the modified MA method will be an efficient process to get a high quality cathode material for commercial lithium batteries.

• Korean Chemical Engineering Research
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• v.46 no.3
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• pp.626-632
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• 2008

The purpose of this study was to enhance gas exchange by producing hemosome, a hemoglobin microencapsulated with phospholipid of egg, and perfluorocarbone(PFC) emulsion solution. In the experiment, stable emulsion solution with 437 nm of mean particle size could be produced by Flusol-DA sonication, and shortening of emulsion time could be attained with higher stability as well. $0.8{\mu}m$ sized hemosome could be produced by microencapsulation of hemoglobin with phospholipid extracted from egg yolk. The pattern of oxygen saturation curve of hemosome was S shape, which is similar to that found in normal blood, and $P_{50}$ was measured to be 24 mmHg. The oxygen saturation in the mixed solution of hemosome and blood in 1:4(V/V%) ratio was similar to that of normal blood, and the same result was found in the mixed solution of PFC emulsion and blood in 1:4(V/V%) ratio.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.22 no.1
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• pp.57-63
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• 2012

$Al_2TiO_5$ ceramics were sintered by a solid-state reaction. LAS (${\beta}$-spodumene) and $Fe_2O_3$ were added to the $Al_2TiO_5$ composition for enhancement of sintering behavior such as mechanical strength and thermal shock resistance. The sintered body was much densified by addition of LAS and $Fe_2O_3$ because LAS formed the liquid-phase and $Fe_2O_3$ suppressed the grain growth. We have systematically investigated the sintering characteristics, microstructures, mechanical properties, and thermal shock resistance according to the change of the amount of additive. When the additive of LAS (20 wt%)-$Fe_2O_3$ was added to $Al_2TiO_5$, it confirmed that superior mechanical properties of the fracture strength of over 120 MPa and the thermal shock resistance of over $1,200^{\circ}C$ were achieved.

• Research in Plant Disease
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• v.20 no.2
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• pp.79-86
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• 2014

In order to seek more eco-friend, economic and safer quarantine method than current methyl bromide fumigation, the convergent treatment with 200 Gy of gamma irradiation and several chemicals such as nano-siver particles (NSS), sodium dichloroisocyanurate (NaDCC) was tried on the cuttings of lily in the packing of catonnage box for export. With 6 independent experiments of gamma irradiation on the three lily cultivars, cvs. Siberia, Le reve and Sorbonne, incidence and severity of lily leaf blight was investigated on leaves and petals at 8-d after infection. 200 Gy of gamma irradiation decreased at 13-25% of severity on the leaf of Sorbonne, but it increased at 2-5% of severity on the leaf of Siberia and Le reve. Chemical substitutes such as NSS and NaDCC were not effective to control of lily blight on cuttings. By 200 Gy of gamma irradiation treatment, chlorophyll contents were statistically significantly decreased at 12-d after irradiation and the longevities vaselife of fully open flower of Siberia and Sorbonne were increased at 0.4 to 1.2 days. In addition, the relative fresh weights of the gamma irradiated cuttings were severely dried compared to the non-irradiated control. On the other hands, the symptoms of phyto-toxicity of high dose gamma irradiation at 1 or 2 kGy on cv. Siberia were to be blight at the tip of bloom, bent necks of flower, and delayed the process of flowering.