• Nuclear Engineering and Technology
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• v.30 no.2
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• pp.99-111
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• 1998

Chemical composition of the insoluble residue in a simulated spent PWR fuel(SIMRJEL) were studied. SIMFUELS were prepared by adding calculated amount of FP(fission product) elements with a burnup of 3.6% FIMA(fission per initial metal atom) to uranium in nitrate solution, evaporating the mixed solution to dryness, calcining at 90$0^{\circ}C$ in a stream of 4% H$_2$ + 96% He, and heating the pellet at 140$0^{\circ}C$ under high and low oxygen potentials. Insoluble residue was obtained from the dissolution of the SIMFUEL with HNO$_3$(1 : 1). The chemical composition of the SIMFUELs and the insoluble residues was determined by EPMA(electron probe microanalysis), XPS(X-ray photoelectron spectroscopy) and by XRD (X-ray diffraction) measurements. All of the insoluble residues suspended and precipitated were composed mainly of Mo, Ru with a small amount of Zr, Rh, Pd and Cd. The amount of insoluble residue(<1 wt.%) and a Mo/Ru ratio decreased with increasing oxygen potential. Formation of the zirconium molybdate precipitate, ZrMo$_2$O$_{7}$(OH)$_2$($H_2O$)$_2$, was observed in the residues. The possible role of Mo on the phase formation was discussed in regard to oxygen potential.l.

• Korean Chemical Engineering Research
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• v.46 no.4
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• pp.697-700
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• 2008

The underpotential deposited Bi on Pt($Bi_{upd}/Pt$) anode for formic acid fuel cells (FAFCs) was developed using multi-layered preparation method for better electrocatalytic utilization of Pt. The electron probe microanalysis (EPMA) result indicated that $Bi_{upd}$ remains through the catalyst layer during stability test. In performance test, the multilayered $Bi_{upd}$ on Pt black showed superior performance by approximately 200 mV at current density of $150mA/cm^2$ compared with PtRu black anode catalyst. Based on preparation condition of $Bi_{upd}/Pt$ black, carbon supported $Bi_{upd}/Pt/C$ electrode was prepared and it showed enhanced performance and stability.

• Analytical Science and Technology
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• v.22 no.5
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• pp.395-406
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• 2009

The determination of iodine in the spent nuclear fuel and the volatile behavior during its acid dissolution have been studied by NAA(neutron activation analysis) and electron probe microanalysis (EPMA). Simulated spent fuels (SIMFUELs) were dissolved in $HNO_3$(1+1) at $90^{\circ}C$ for 8 hours. The iodine remained in a dissolver solution after dissolution, and that condensed in dissolution apparatus and trapped in the adsorbent by volatilization during the dissolution were determined, respectively. The condensed iodine was recovered by the redistillation with $HNO_3$(1+1) after transfer of the dissolver solution. The iodines in the dissolver and redistilled solution were separated by solvent extraction followed by ion exchange or precipitation method and determined by RNAA (radiochemical neutron activation analysis). The ion exchange column and filtration kit used for the isolation of iodine, which were prepared with a polyethylene tube, were used as an insert in the pneumatic tube for neutron irradiation. The iodine volatilized during the dissolution of SIMFUELs was collected in a trapping tube containing Ag-silica gel (Ag-impregnated silica gel) adsorbent, and the distribution of iodine trapped in the adsorbents were determined by EPMA. The adsorbing characteristics shown with the SIMFUELs were compared with those shown with a real spent fuel from the nuclear power plant.

• International Journal of Korean Welding Society
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• v.1 no.1
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• pp.58-62
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• 2001

The surface of AC8A Ah alloy was modified by adding the Cu powder using a Plasma Transferred Arc (PTA) welding process. Under the optimum fabricating conditions, the modified surface of AC8A Ah alloy was observed to possess the sound microstructure with a minimum porosity. Hardness and wear resistance properties of the as-fabricated alloy were compared with those of the 76 heat-treated one. In case of the as-fabricated alloy, the hardness of the modified layer was twice that of the matrix region. Although significant increase in the hardness of the matrix region was observed after T6 heat treatment, the hardness of the modified layer was not observed to change. The wear resistance of the modified layer was significantly increased compared to that of the matrix region. The microstructure of a weld zone and the matrix region were investigated using the optical microscope, scanning electron microscope (SEM), electron probe microanalysis (EPMA), and transmission electron microscope (TEM). The primary and eutectic silicon in the weld zone were finer and more curved than in the matrix region, while some precipitates has had been found therein. According to the TEM observation, the predominant precipitate present in the weld zone was the $\theta$'phase, which is precipitated during cooling by rapid solidification in PTA welding process. Improvement of hardness and wear properties in the weld zone in the as-fabricated condition can be explained based on the presence of $\theta$’precipitates and fine primary and eutectic silicon distribution.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.9
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• pp.589-593
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• 2014

AlNO multi-layer thin films on aluminum substrates were prepared by DC reactive magnetron sputtering method. $Al_2O_3$/AlNO(LMVF)/AlNO(HMVF)/Al/substrate of 4 multi-layer has been prepared in an Ar and ($N_2+O_2$) gas mixture, and $Al_2O_3$ of top layer is anti-reflection layer on double AlNO(LMVF)/AlNO(HMVF) layers and Al metal of infrared reflection layer. In this study, the roughness and surface properties of AlNO thin films were estimated by field emission scanning electron microscopy(FE-SEM). The grain size of AlNO thin films increased with increasing sputtering power. The composition of thin films has been systematically investigated using electron probe microanalysis(EPMA). The optical properties with wavelength spectrum were recorded by UV-Vis-NIR spectrophotometry at a range of 200~1,500 nm. The absorptance of AlNO films shows the increasing trend with swelling ($N_2+O_2$) gas mixture in HMVF and LMVF deposition. The excellent optical performance showed above 98% of absorptance in visible wavelength region.

• Journal of the Korean Society for Heat Treatment
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• v.27 no.6
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• pp.281-287
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• 2014

Microstructural and mechanical characteristics of Al-6Si-2Cu alloy for engine mount bracket prepared by gravity casting (as-cast) and die-casting (as-diecast) process have been investigated. For the microstructural characterization, the inductively coupled plasma mass spectrometry (ICP-MS), optical microscope (OM), scanning electron microscope (SEM) and electron probe microanalysis (EPMA) analyses are conducted. For the intermetallic phases, the X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS) are also conducted with quantitative and qualitative analysis. Micro Vickers hardness and static tensile test are achieved in order to measure mechanical properties of alloys. Secondary dendrite arm spacing (SDAS) of as-cast and as-diecast show 37um and 18um, respectively. A large amount of coarsen eutectic Si, $Al_2Cu$ intermetallic phase and Fe-rich phases are identified in the Al-6Si-2Cu alloy. Mechanical properties of gravity casting alloy are much higher than those of die-casting alloy. Especially, yield strength and elongation of gravity casting alloy show 2 times higher than die-casting alloy. After shot peening, shot peening refined the surface grains and Si particles of the alloys by plastic deformation. The surface hardness value shows that shot peening alloy has higher value than unpeening alloy.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.12
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• pp.820-824
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• 2014

TiNOx multi-layer thin films on aluminum substrates were prepared by DC reactive magnetron sputtering method. 4 multi-layers of $TiO_2$/TiNOx(LMVF)/TiNOx(HMVF)/Ti/substrate have been prepared with ratio of Ar and ($N_2+O_2$) gas mixture. $TiO_2$ of top layer is anti-reflection layer on double TiNOx(LMVF)/TiNOx(HMVF) layers and Ti metal of infrared reflection layer. In this study, the crystallinity and surface properties of TiNOx thin films were estimated by X-ray diffraction(XRD) and field emission scanning electron microscopy(FE-SEM), respectively. The grain size of TiNOx thin films shows to increase with increasing sputtering power. The composition of thin films has been investigated using electron probe microanalysis(EPMA). The optical properties with wavelength spectrum were recorded by UV-Vis-NIR spectrophotometry at a range of 200~1,500 nm. The TiNOx multi-layer films show the excellent optical performance beyond 9% of reflectance in those ranges wavelength.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.12 no.2
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• pp.68-72
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• 2002

The $\beta$-$FeSi_2$ and $\alpha$-$FeSi_2$ single crystals were synthesized by chemical vapour transport (CVT) using iodine as a transporting agent from the commercially available $FeSi_2$ powder. The $FeSi_2$ powder together with iodine were sealed in an evacuated quartz ampoule and the ampoule then being placed in two-zone electrical furnace for growing crystal. The CVT of $FeSi_2$ with iodine yielded $\beta$-$FeSi_2$ and $\alpha$-FeSi$_2$ single crystals at deposition temperature of 750 and $950^{\circ}C$ respectively. The source temperature was $1050^{\circ}C$ in both cases. The crystals of the $\alpha$-FeSi$_2$ phase were typically plate shaped with dimensions of about $10\times 10 \textrm{mm}^2$, whereas the crystals of orthorhombic $\beta$-$FeSi_2$ phase grew predominantly in the fonts of thin needle of about 10 mm in length. The composition of$\alpha$-FeSicrystal determined by electron probe microanalysis (EPMA) resulted in Si-rich $FeSi_{2.58}$ . 57. Furthermore, the CVT $\beta$-$FeSi_2$ crystal was found to be transformed to the high temperature $\alpha$-$FeSi_2$phase above $930^{\circ}C$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.2
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• pp.154-161
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• 1998

The effects of melting temperature and holding time on the critical current density($J_c$) of $YBa_2Cu_3O_x$ based superconducting bulk fabricated by MPMG process were investigated. The amount of the formed $Y_2BaCuO_5$ phases increased with the melting temperature. However, the value of critical current density was highest at 1120 $^{\circ}C$. With this proper melting temperature, the effect of holding time on the critical characteristics was also investigated. In the case of Ag addition, the volume of the formed $Y_2BaCuO_5$ phase when the amount of Ag addition was 10 wt% and 20 wt% was observed to be highest at 20 minute and 40 minute respectively. But in the specimen without Ag, volume of $Y_2BaCuO_5$ phase increased as the holding time increased. The proper melting temperature and the holding time obtained were 1120 $^{\circ}C$ and 20 minute. The long holding time was not effective for the $J_c$ improvement as well as the formation of $Y_2BaCuO_5$.

• Journal of Korean Society for Atmospheric Environment
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• v.24 no.5
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• pp.594-603
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• 2008

A single particle analytical technique, named low-Z particle electron probe X-ray microanalysis, was applied to characterize four samples collected at an underground shopping area connected to Dongdeamun subway station, in January and May 2006. Based on the analysis of their chemical compositions of the samples, many distinctive particle types are identified and the major chemical species are observed to be soil-derived particles, iron-containing particles. sulfates. nitrates, and carbonaceous particles. which are encountered both in coarse and fine fractions. Carbonaceous particles exist in carbon-rich and organic. Soil derived particles such as aluminosilicates, AlSi/C, $CaCO_3\;and\;SiO_2$ are more frequently encountered in spring samples than winter samples. Nitrate- and sulfate-con taming particles are more frequently encountered in winter samples, and those nitrate- and sulfate-containing particles mostly exist in the chemical forms of $Ca(CO_3,\;NO_3),\;Ca(NO_3,\;SO_4),\;(Na,\;Mg)NO_3\;and\;(Mg,\;Na)(NO_3,\;SO_4)$. Fe-containing particles which came from nearby subway platform are in the range of about 10% relative abundances for all the samples. It is observed that nitrate- and sulfate-containing particles and carbonaceous particles are much more frequently encountered in indoor aerosol samples than in outdoor aerosols, implying that $NO_x,\;SO_x$, and VOCs at the underground shopping area were more partitioned into aerosol phase.