• Journal of the Korea institute for structural maintenance and inspection
• /
• v.16 no.2
• /
• pp.75-86
• /
• 2012

This paper presents some research results on the shrinkage characteristics and frost resistance before and after cracking of FR-ECC(Fire Resistance-Engineered Cementitious Composite). Also, a waterstop performance and exfoliating resistance of multi-layer lining specimens using FR-ECC and flexural performance of beam member by repaired FR-ECC are estimated in this paper. Experimental results indicate that the plastic shrinkage crack and length change ratio of FR-ECC have been reduced as compared with that of the existing repair mortar, and that its crack resistance on the dry shrinkage is improved under the confining stress. As well as FR-ECC has been great in the frost resistance and its tensile properties under the cracked state have been not reduced by freezing and thawing reaction. In addition, beam member by repaired FR-ECC have been increased in the flexural properties such as initial crack moment, yeild moment, and its crack width has been controled in a stable by the frexural failure.

• Journal of the Korean institute of surface engineering
• /
• v.51 no.4
• /
• pp.243-248
• /
• 2018

All solid state thin film batteries with two types of cell structure, Pt / $LiCoO_2$ / LiPON / Cu and Pt / $LiCoO_2$ / LiPON / $LiCoO_2$ / Cu, are prepared and their electrochemical performances are investigated to evaluate the effect of $LiCoO_2$ interlayer at the interface of LiPON / Cu. The crystallinity of the deposited $LiCoO_2$ thin films is confirmed by XRD and Raman analysis. The crystalline $LiCoO_2$ cathode thin film is obtained and $LiCoO_2$ as the interlayer appears to be amorphous. The surface morphology of Cu current collector after cycling of the batteries is observed by AFM. The presence of a 10 nm-thick layer of $LiCoO_2$ at the interface of LiPON / Cu enhances the interfacial adhesion and reduces the interfacial resistance. As a result, Li plating / stripping at the interface of LiPON / Cu during charge/discharge reaction takes place more uniformly on Cu current collector, while without the interlayer of $LiCoO_2$ at the interface of LiPON / Cu, the Li plating / stripping is localized on current collector. The thin film batteries with the interlayer of $LiCoO_2$ at the interface of LiPON / Cu exhibits enhanced initial coulombic efficiency, reversible capacity and cycling stability. The thickness of the anode current collector Cu also appears to be crucial for electrochemical performances of all solid state thin film batteries.

• Journal of the Korean Applied Science and Technology
• /
• v.19 no.2
• /
• pp.103-107
• /
• 2002

Diphosphine dinuclear gold(I) complexes were synthesized from the reaction of bridged diphosphines and gold ions. As a bridged diphosphine, 1,2-bis(diphenylphosphino)metbane (dppm) or 1,1'-Bis(diphenylphosphino) ferrocene (dppf) was introduced. As anionic ligands, CI was first coordinated to Au, resulting in (diphosphine)$(AuCl)_{2}$. Then, the ligand, SPh, was substituted for Cl in the chloride complex to give (diphosphine)$(AuSPh)_{2}$. As a result, three digold complexes, (dppm)$(AuCl)_{2}$. (I), (dppf)$(AuCl)_{2}$. (II), and (dppf)$(AuSPh_{2}$. (III) were prepared in this study. The thermal properties were investigated at first hand to confirm that the gold complexes were in fact formed. The digold complexes were decomposed above $200^{\circ}C$ while the ligand, dppm or dppf, melts under $180^{\circ}C$ The photoluminescence (PL) spectra of the spin-coated thin films showed the maximum peak at 590, 595, and 540nm for the complex, I, II, and III, respectively. These complexes were found to give the orange color phosphorescence. Therefore, these digold complexes can be candidates for orange-red phosphorescent materials in organic electroluminescent devices (OELD). Further studies on application of the complexes as a dopant in an emitting layer are in progress in our laboratory.

• Korean Journal of Metals and Materials
• /
• v.48 no.11
• /
• pp.995-1002
• /
• 2010

This study investigated the effect of process temperature on the alloying process during synthesis of $Sm_2Fe_{17}$ powder from ball-milled samarium oxide ($Sm_2O_3$) powders and a solid reducing agent of calcium hydrides ($CaH_2$) using iron nanopowder (n-Fe powder) by a reduction-diffusion (R-D) process. The $n-Fe-Sm_2O_3-CaH_2$ mixed powders were subjected to heat treatment at $850{\sim}1100^{\circ}C$ in $Ar-H_2$ for 5 h. It was found that the iron nanopowders in the mixed powders are sintered below $850^{\circ}C$ during the R-D process and the $SmH_2$ is synthesized by a reduced Sm that combines with $H_2$ around $850^{\circ}C$. The results showed that $SmH_2$ is able to separate Sm and $H_2$ respectively depending on an increase in process temperature, and the formed $Sm_2Fe_{17}$ phase on the surface of the sintered Fe nanopowder agglomerated at temperatures of $950{\sim}1100^{\circ}C$ in this study. The formation of the $Sm_2Fe_{17}$ layer is mainly due to the diffusion reaction of Sm atoms into the sintered Fe nanopowder, which agglomerates above $950^{\circ}C$. We concluded that nanoscale $Sm_2Fe_{17}$ powder can be synthesized by controlling the diffusion depth using well-dispersed Fe nanopowders.

• Journal of the Society of Cosmetic Scientists of Korea
• /
• v.36 no.1
• /
• pp.89-92
• /
• 2010

In the previous study, we reported the antioxidative activity, antiaging activity, antibacterial activity and moisturizing effect of cream containing Persicaria hydropiper L. extract. In this study, the components of Persicaria hydropiper L. extract were analyzed by TLC and HPLC. Aglycone fractions obtained from the deglycosylation reaction of ethyl acetate fraction among the Persicaria hydropiper L. extract, showed 2 bands and 2 peaks in TLC and HPLC experiments, respectively. Two components were identified as quercetin and kaempferol. TLC chromatogram of ethyl acetate fraction of Persicaria hydropiper L. extract revealed 6 bands and HPLC chromatogram showed 7 peaks, which were identified as quercetin, hyperin, isoquercitrin, quercitrin, kaempferol. In conclusion, with the antioxidative activity, antiaging activity, antibacterial activity and moisturizing effect reported previously, component analysis of Persicaria hydropiper L. extracts could be applicable to new cosmeceuticals.

• Journal of Powder Materials
• /
• v.26 no.1
• /
• pp.40-44
• /
• 2019

Tungsten trioxide ($WO_3$) is a promising candidate as a photocatalyst because of its outstanding electrical and optical properties. In this study, we prepare $WO_3$ thin films by electrodeposition and characterize the photocatalytic degradation of methylene blue using these films. Depending on the voltage conditions (static and pulse), compact and porous $WO_3$ films are fabricated on a transparent ITO/glass substrate. The morphology and crystal structure of electrodeposited $WO_3$ thin films are investigated by scanning electron microscopy, atomic force microscopy, and X-ray diffraction. An application of static voltage during electrodeposition yields a compact layer of $WO_3$, whereas a highly porous morphology with nanoflakes is produced by a pulse voltage process. Compared to the compact film, the porous $WO_3$ thin film shows better photocatalytic activities. Furthermore, a much higher reaction rate of degradation of methylene blue can be achieved after post-annealing of $WO_3$ thin films.

• Molecules and Cells
• /
• v.42 no.9
• /
• pp.637-645
• /
• 2019

Effector-triggered immunity (ETI) is an effective layer of plant defense initiated upon recognition of avirulence (Avr) effectors from pathogens by cognate plant disease resistance (R) proteins. In rice, a large number of R genes have been characterized from various cultivars and have greatly contributed to breeding programs to improve resistance against the rice blast pathogen Magnaporthe oryzae. The extreme diversity of R gene repertoires is thought to be a result of co-evolutionary history between rice and its pathogens including M. oryzae. Here we show that Pii is an allele of Pi5 by DNA sequence characterization and complementation analysis. Pii-1 and Pii-2 cDNAs were cloned by reverse transcription polymerase chain reaction from the Pii-carrying cultivar Fujisaka5. The complementation test in susceptible rice cultivar Dongjin demonstrated that the rice blast resistance mediated by Pii, similar to Pi5, requires the presence of two nucleotide-binding leucine-rich repeat genes, Pii-1 and Pii-2. Consistent with our hypothesis that Pi5 and Pii are functionally indistinguishable, the replacement of Pii-1 by Pi5-1 and Pii-2 by Pi5-2, respectively, does not change the level of disease resistance to M. oryzae carrying AVR-Pii. Surprisingly, Exo70F3, required for Pii-mediated resistance, is dispensable for Pi5-mediated resistance. Based on our results, despite similarities observed between Pi5 and Pii, we hypothesize that Pi5 and Pii pairs require partially distinct mechanisms to function.

• Korean Journal of Environmental Agriculture
• /
• v.39 no.4
• /
• pp.289-296
• /
• 2020

BACKGROUND: There is a need for a revolutionary method to overcome the problem of biochar, which has relatively low adsorption capacity for existing anion pollutants, along with collectively recycling fallen leaves, a kind of forest by-product. Therefore, the objective of this study was to prepare iron-decorated biochar derived from fallen leaves (Fe-FLB), and to evaluate their adsorption properties to Congo red (CR) as anionic dye. METHODS AND RESULTS: The adsorption properties of CR by fallen leaves biochar (FLB) and Fe-FLB were performed under various conditions such as initial CR concentration, reaction time, pH and dosage with isotherm and kinetic models. In this study, Fe-FLB prepared through iron impregnation and pyrolysis of fallen leaves contained 56.9% carbon and 6.3% iron. Congo red adsorption by FLB and Fe-FLB was well described by Langmuir model and pseudo second order model and the maximum adsorption capacities of FLB and Fe-FLB were 1.1 mg/g and 25.6 mg/g, respectively. In particular, it was found that the adsorption of CR was occurred by chemical adsorption process by the outer boundary layer of Fe-FLB. CONCLUSION: Overall, the production of Fe-FLB using fallen leaves and using it as an anion adsorbent is considered to be a way to overcome the problem of biochar with relatively low anion adsorption in addition to the reduction effect of waste.

• Korean Journal of Metals and Materials
• /
• v.49 no.7
• /
• pp.549-556
• /
• 2011

This study aimed to evaluate the performance of diffusion barriers in order to prevent fuel-cladding chemical interaction (FCCI) between the metallic fuels and the cladding materials, a potential hazard for nuclear fuel in sodium-cooled fast reactors. In order to prevent FCCI, Zr or V metal is deposited on the ferritic-martensitic stainless steel surface by physical vapor deposition with a thickness up to $5{\mu}m$. The diffusion couple tests using uranium alloy (U-10Zr) and a rare earth metal such as Ce-La alloy and Nd were performed at temperatures between 660~800$^{\circ}C$. Microstructural analysis using SEM was carried out over the coupled specimen. The results show that significant interdiffusion and an associated eutectic reaction ocurred in the specimen without a diffusion barrier. However, with the exception of the local dissolution of the Zr layer in the Ce-La alloy, the specimens deposited with Zr and V exhibited superior eutectic resistance to the uranium alloy and rare earth metal.

• Journal of Powder Materials
• /
• v.28 no.1
• /
• pp.31-37
• /
• 2021

This study explores reducing the oxygen content of a commercial Ti-48Al-2Cr-2Nb powder to less than 400 ppm by deoxidation in the solid state (DOSS) using Ca vapor, and investigates the effect of Ca vapor on the surface chemical state. As the deoxidation temperature increases, the oxygen concentration of the Ti-48Al-2Cr-2Nb powder decreases, achieving a low value of 745 ppm at 1100℃. When the deoxidation time is increased to 2 h, the oxygen concentration decreases to 320ppm at 1100℃, and the oxygen reduction rate is approximately 78% compared to that of the raw material. The deoxidized Ti-48Al-2Cr-2nb powder maintains a spherical shape, but the surface shape changes slightly owing to the reaction of Ca and Al. The oxidation state of Ti and Al on the surface of the Ti-48Al-2Cr-2Nb powder corresponds to a mixture of TiO2 and Al2O3. As a result, the peaks of metallic Ti and Ti suboxide intensify as TiO2 and Al2O3 in the surface oxide layer are reduced by Ca vapor deposition.