• Korean Journal of Materials Research
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• v.33 no.4
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• pp.124-129
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• 2023

This study assessed the influences of fluorine introduced into DLC films on the structural and mechanical properties of the sample. In addition, the effects of the fluorine incorporation on the compressive stress in DLC films were investigated. For this purpose, fluorinated diamond-like carbon (F-DLC) films were deposited on cobalt-chromium-molybdenum substrates using radio-frequency plasma-enhanced chemical vapor. The coatings were examined by Raman scattering (RS), Attenuated total reflectance Fourier transform infrared spectroscopic analysis (ATR-FTIR), and a combination of elastic recoil detection analysis and Rutherford backscattering (ERDA-RBS). Nano-indentation tests were performed to measure hardness. Also, the residual stress of the films was calculated by the Stony equation. The ATR-FTIR analysis revealed that F was present in the amorphous matrix mainly as C-F and C-F₂ groups. Based on Raman spectroscopy results, it was determined that F made the DLC films more graphitic. Additionally, it was shown that adding F into the DLC coating resulted in weaker mechanical properties and the F-DLC coating exhibited lower stress than DLC films. These effects were attributed to the replacement of strong C = C by feebler C-F bonds in the F-DLC films. F-doping decreased the hardness of the DLC from 11.5 to 8.8 GPa. In addition, with F addition, the compressive stress of the DLC sample decreased from 1 to 0.7 GPa.

• Clean Technology
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• v.16 no.1
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• pp.19-25
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• 2010

In this work, the conversion of crystalline cellulose into polyols in the presence of hydrogen was examined over noble metal (Pt, Ru, Ir, Rh, and Pd) catalysts supported on activated carbon. For comparison, Pt/${\gamma}-Al_2O_3$ and Pt/H-mordenite were also investigated. Several techniques: $N_2$ physisorption, X-ray diffraction(XRD), inductively-coupled plasma-atomic emission spectroscopy (ICP-AES), temperature-programmed reduction with $H_2$ ($H_2$-TPR) and CO chemisorption were employed to characterize the catalysts. The cellulose conversion was not strongly dependent on the types of the catalyst used. Pt/AC showed the highest yields to polyols among activated carbon-supported noble metal catalysts, viz. Pt/AC, Ru/AC, Ir/AC, Rh/AC and Pd/AC.

• Journal of the Korean institute of surface engineering
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• v.56 no.6
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• pp.401-411
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• 2023

This study investigates the synthesis, characterization, and application of zinc oxide (ZnO) nanoparticles for corrosion resistance and stress corrosion cracking (SCC) mitigation in high-temperature and high-pressure environments. The ZnO nanoparticles are synthesized using plasma discharge in water, resulting in rod-shaped particles with a hexagonal crystal structure. The ZnO nanoparticles are applied to Alloy 600 tubes in simulated nuclear power plant atmospheres to evaluate their effectiveness. X-ray diffraction and X-ray photoelectron spectroscopy analysis reveals the formation of thermodynamically stable ZnCr₂O₄and ZnFe₂O₄ spinel phases with a depth of approximately 35 nm on the surface after 240 hours of treatment. Stress corrosion cracking (SCC) mitigation experiments reveal that ZnO treatment enhances thermal and mechanical stability. The ZnO-treated specimens exhibit increased maximum temperature tolerance up to 310 ℃ and higher-pressure resistance up to 60 bar compared to non-treated ZnO samples. Measurements of crack length indicate reduced crack propagation in ZnO-treated specimens. The formation of thermodynamically stable Zn spinel structures on the surface of Alloy 600 and the subsequent improvements in surface properties contribute to the enhanced durability and performance of the material in challenging high-temperature and high-pressure environments. These findings have significant implications for the development of corrosion-resistant materials and the mitigation of stress corrosion cracking in various industries.

• Transactions of the Korean hydrogen and new energy society
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• v.35 no.3
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• pp.336-344
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• 2024

In this study, a Ni_0.9Co_0.05Mn_0.05(OH)₂ precursor used as an anode active material using a black powder leaching solution of a recycled lithium ion battery was prepared through coprecipitation synthesis with co-precipitation time, NH₄OH concentration, pH, and stirring time as variables. The characteristics of the prepared powder were analyzed by X-ray diffraction (XRD), scanning electron microscope (SEM), particle size analysis (PSA), and inductively coupled plasma optical emission spectroscopy (ICP-OES). It was confirmed that the single crystal thickness of the LiNi_1-x-yCo_xMn_yO₂ (NCM) precursor changes depending on the NH₄OH concentration and reaction pH value, and thicker single crystals are formed at 2 M NH₄OH compared to 1 M and at pH 10.8-11.8 compared to pH 11.8-12.0. NCM precursor particles increased with coprecipitation time, and it was confirmed that the 72 hours NCM precursor had the largest particle size. Through ICP-OES analysis, it was confirmed that the NCM precursor was synthesized with the target composition of Ni²⁺:Co²⁺:Mn²⁺=90:5:5.

• Journal of Nutrition and Health
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• v.39 no.8
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• pp.762-772
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• 2006

This study was conducted to investigate dietary intakes, serum concentrations, and urinary excretions of iron (Fe), zinc (Zn), copper (Cu), manganese (Mn), selenium (Se), molybdenum (Mo), and chromium (Cr) of Korean young adult women. A total of 19 apparently healthy young adult women aged in their twenties or thirties participated voluntarily. One-tenth of all foods they consumed for 3 consecutive days were collected, all urine excreted for the same 3 days was gathered, and fasting venous blood was withdrawn for the trace mineral analyses. Of the food, blood, and urine samples, the contents of Zn, Cu, Mn, Se, Mo, and Cr were analyzed by inductively coupled plasma-mass spectroscopy (ICP-MS) and that of Fe by inductively coupled plasma-atomic emission spectroscopy (ICP-AES) after wet digestion. The intake of Fe, $6.94{\pm}2.18mg$, did not meet the estimated average requirement (EAR) for Korean women aged 20-29 years old. On the contrary, the intakes of Zn ($9.35{\pm}4.95mg$), Cu ($1.18{\pm}0.26mg$), and Mn ($3.69{\pm}0.69mg$) were sufficient for each respective EAR. However, some of the subjects did not take the EAR for Zn. The Se intake, $41.93{\pm}9.28{\mu}g$, however, was almost similar to the EAR for Se. Although there are no references for Mo and Cr, the intakes of these minerals ($134.0{\pm}49.1\;and\;136.5{\pm}147.9{\mu}g$, respectively) seemed to be excessively sufficient. Serum Fe concentration, $88.7{\pm}36.8{\mu}g/dL$, seemed to be a little bit lower than its reference median but within its normal range. Approximately one-fourth of the subjects were in anemic determined by Hb and Hct and below the deficiency serum level of Fe, $60{\mu}g/dL$. In addition, serum Se concentration, $3.73{\pm}0.60{\mu}g/dL$, was also below its reference median and normal range. However, serum concentrations of Zn ($99.6{\pm}30.6{\mu}g/dL$) and Mo ($0.25{\pm}0.10{\mu}g/dL$) were fairly good compared to each reference median. The status of Cu could be determined as good although its serum concentration ($91.6{\pm}14.6{\mu}g/dL$) was slightly below its reference median. Since there are no decisive reference values, it was not easy to evaluate serum concentrations of Mn ($0.93{\pm}0.85{\mu}g/dL$) and Cr ($8.60{\pm}7.25{\mu}g/dL$). But Mn and Cr status seemed to be adequate. Urinary Fe excretion, $4.48{\pm}1.98{\mu}g/dL$, was pretty much lower than its reference and that of Se, $2.45{\pm}1.17{\mu}g/dL$, was also lower than its average. On the other hand, those of Zn ($42.95{\pm}20.47{\mu}g/dL$) and Cu ($5.68{\pm}1.50{\mu}g/dL$) were flirty good. In case of Mn, urinary excretion, $0.31{\pm}0.09{\mu}g/dL$, was much greater than its reference. Urinary excretions of Mo ($7.48{\pm}2.95{\mu}g/dL$) and Cr ($1.37{\pm}0.41{\mu}g/dL$) were very higher compared to each reference. The results of this study revealed that Korean young adult women were considerably poor in Fe status, a bit inadequate in Se status, partly inadequate in Zn status, and flirty good in Cu, Mn, Mo and Cr status. However, there was a problem of excessive intakes of Mo and Cr. It, therefore, should be concerned to increase the intakes of Fe, Se and Zn but to decrease Mo and Cr consumption for young adult women.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.239-240
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• 2008

As semiconductor devices are scaled down for better performance and more functionality, the Cu-based interconnects suffer from the increase of the resistivity of the Cu wires. The resistivity increase, which is attributed to the electron scattering from grain boundaries and interfaces, needs to be addressed in order to further scale down semiconductor devices [1]. The increase in the resistivity of the interconnect can be alleviated by increasing the grain size of electroplating (EP)-Cu or by modifying the Cu surface [1]. Another possible solution is to maximize the portion of the EP-Cu volume in the vias or damascene structures with the conformal diffusion barrier and seed layer by optimizing their deposition processes during Cu interconnect fabrication, which are currently ionized physical vapor deposition (IPVD)-based Ta/TaN bilayer and IPVD-Cu, respectively. The use of in-situ etching, during IPVD of the barrier or the seed layer, has been effective in enlarging the trench volume where the Cu is filled, resulting in improved reliability and performance of the Cu-based interconnect. However, the application of IPVD technology is expected to be limited eventually because of poor sidewall step coverage and the narrow top part of the damascene structures. Recently, Ru has been suggested as a diffusion barrier that is compatible with the direct plating of Cu [2-3]. A single-layer diffusion barrier for the direct plating of Cu is desirable to optimize the resistance of the Cu interconnects because it eliminates the Cu-seed layer. However, previous studies have shown that the Ru by itself is not a suitable diffusion barrier for Cu metallization [4-6]. Thus, the diffusion barrier performance of the Ru film should be improved in order for it to be successfully incorporated as a seed layer/barrier layer for the direct plating of Cu. The improvement of its barrier performance, by modifying the Ru microstructure from columnar to amorphous (by incorporating the N into Ru during PVD), has been previously reported [7]. Another approach for improving the barrier performance of the Ru film is to use Ru as a just seed layer and combine it with superior materials to function as a diffusion barrier against the Cu. A RulTaN bilayer prepared by PVD has recently been suggested as a seed layer/diffusion barrier for Cu. This bilayer was stable between the Cu and Si after annealing at $700^{\circ}C$ for I min [8]. Although these reports dealt with the possible applications of Ru for Cu metallization, cases where the Ru film was prepared by atomic layer deposition (ALD) have not been identified. These are important because of ALD's excellent conformality. In this study, a bilayer diffusion barrier of Ru/TaCN prepared by ALD was investigated. As the addition of the third element into the transition metal nitride disrupts the crystal lattice and leads to the formation of a stable ternary amorphous material, as indicated by Nicolet [9], ALD-TaCN is expected to improve the diffusion barrier performance of the ALD-Ru against Cu. Ru was deposited by a sequential supply of bis(ethylcyclopentadienyl)ruthenium [Ru$(EtCp)_2$] and $NH_3$plasma and TaCN by a sequential supply of $(NEt_2)_3Ta=Nbu^t$ (tert-butylimido-trisdiethylamido-tantalum, TBTDET) and $H_2$ plasma. Sheet resistance measurements, X-ray diffractometry (XRD), and Auger electron spectroscopy (AES) analysis showed that the bilayer diffusion barriers of ALD-Ru (12 nm)/ALD-TaCN (2 nm) and ALD-Ru (4nm)/ALD-TaCN (2 nm) prevented the Cu diffusion up to annealing temperatures of 600 and $550^{\circ}C$ for 30 min, respectively. This is found to be due to the excellent diffusion barrier performance of the ALD-TaCN film against the Cu, due to it having an amorphous structure. A 5-nm-thick ALD-TaCN film was even stable up to annealing at $650^{\circ}C$ between Cu and Si. Transmission electron microscopy (TEM) investigation combined with energy dispersive spectroscopy (EDS) analysis revealed that the ALD-Ru/ALD-TaCN diffusion barrier failed by the Cu diffusion through the bilayer into the Si substrate. This is due to the ALD-TaCN interlayer preventing the interfacial reaction between the Ru and Si.

• Journal of Environmental Health Sciences
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• v.42 no.6
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• pp.450-464
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• 2016

Objectives: This study developed and validated reference materials (RMs) to analyze metal compounds in blood. Methods: We referred to KoNEHS (Korea National Environmental Health Survey) to estimate concentrations of blood metals (cadmium, Cd; lead, Pb; mercury, Hg) and applied analytical methods (inductively coupled plasma - mass spectroscopy, ICP-MS, for Cd and Pb; graphite furnace - atomic absorption spectrometry, GF-AAS, for Cd and Pb; and direct mercury analyzer, DMA, for Hg). Homogeneity and stability tests were carried out. In addition, certified values and uncertainties of RMs were calculated through internal and external experiments. All RMs were developed and assessed in various forms according to element, analytical method, and two types of concentration levels high concentration for occupational exposure and low concentration for environmental exposure. Results: All samples showed acceptable homogeneity, except for low concentration of Cd in the GF-AAS method. Short- and long-term stabilities were satisfied by ANOVA testing. In the inter-laboratory comparison, robust medians were lower than the certified values of all RMs (robust median/reference value; $1.301/1.327{\mu}g/L$ for Cd, ICP-MS, low concentration; $3.152/3.388{\mu}g/L$ for Cd, ICP-MS, high concentration; $1.219/1.301{\mu}g/L$ for Cd, GF-AAS, low concentration; $3.074/3.321{\mu}g/L$ for Cd, GF-AAS, high concentration; $14.473/14.516{\mu}g/L$ for Pb, ICP-MS, low concentration; $50.069/50.114{\mu}g/L$ for Pb, ICP-MS, high concentration; $12.881/14.147{\mu}g/L$ for Pb, GF-AAS, low concentration; $47.015/47.591{\mu}g/L$ for Pb, GF-AAS, high concentration; $4.059/4.218{\mu}g/L$ for Hg, DMA, low concentration; $11.474/11.181{\mu}g/L$ for Hg, DMA, high concentration). Conclusion: This study demonstrates procedures for developing and validating RMs for biomonitoring in the field of the environmental health.

• Korean Journal of Materials Research
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• v.24 no.12
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• pp.671-676
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• 2014

It is known that bones get damaged by accidents and aging. Since the discovery of Bioglass, various kinds of ceramics have been also found to bond to living bone; some of these ceramics are already being clinically used as bone-repairing materials. In the present study, antibacterial calcium silicate gel ($Ag-30CaO{\cdot}70SiO_2$ gel) was prepared by sol-gel method in order to control the microstructure, which is related to the dissolution rate and induction period of apatite formation in body environment. In addition, biological $Ag-30CaO{\cdot}70SiO_2$ is tested. This was done to impart antimicrobial activity to the $30CaO{\cdot}70SiO_2$. Ag ion was added during sol-gel synthesis to replace the $H_2O$ added during the making of the $30CaO{\cdot}70SiO_2$ gel, which has silver solutions of various concentration. After the sol-gel process, 1N-$HNO_3$ solution was used to wash the gel when synthesizing the gel, in order to maintain the porous structure and remove PEG, water soluble polymers. Then, the apatite forming ability of the sol-gel derived CaO-$SiO_2$ gels was investigated using simulated body fluid (SBF), which had almost the same ion concentration as that of human blood plasma. The gels were analyzed by FT-IR spectroscopy, SEM observation, XRD, and fluorescent microscopy. The apatite was successfully created even after washing the gel; apatite is present in an amorphous state, and was found to affect the concentration of the Ag ion in cells in MC3T3 live & dead assay results. From these results, it is suggested that a good material that can be used to repair defects of nature bone is $Ag-30CaO{\cdot}70SiO_2$ gel.

• Journal of the Korean Institute of Gas
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• v.9 no.4 s.29
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• pp.17-25
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• 2005

The dealuminated and alkali/alkaline-earth metal exchanged Y-zeolites were prepared as a catalyst. Elemental compositions and structures of the prepared catalysts were analyzed by the various spectroscopic techniques such as inductively coupled plasma-atomic emission spectroscopy(ICP-AES), X-ray fluorescence(XRF) and X-ray diffraction(XRD), and the desorption behaviors of adsorbed species on the catalyst surfaces were investigated via NO-TPD experiment. Comparing with the composition of the starting material of NaY zeolite, the magnitudes of Si/Al ratio in catalytic materials were increased after dealumination. The Si/Al ratio of catalytic materials after dealumination followed by Cs and Ba cation exchange were additionally decreased. Dealumination to catalysts induced a destruction of basic frame due to a detachment of aluminum, which results in reducing framework structure, while increasing non-framework structure. This phenomenon becomes more serious with increasing time of steam treatment and even more significant for the cation exchanged catalysts. In NO-TPD experiments, the desorption peaks of NO which indicates an activity point of catalysts shifted to the low temperature region after dealumination and cation exchange. The desorption peaks of the NO-TPD profiles taken after steam treatment also shifted to the low temperature region as the steam treatment time increased. In dealuminated and cation exchanged Y-zeolites, the catalytic activities were more influenced by exchanged cation and the formation of non-framework structure.

• Journal of the Korean Vacuum Society
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• v.16 no.2
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• pp.79-90
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• 2007

Prototype of $800{\ell}$ vacuum web coater (Vic Mama) consisting of ion source with low energy less than 250 eV for high speed surface modification and 4 magnetron sputter cathodes was designed and constructed. Its performance was evaluated through fabricating the adhesiveless flexible copper clad laminate (FCCL). Pumping speed was monitored in both upper noncoating zone pumped down by 2 turbo pumps with 2000 l/sec pumping speed and lower surface modification and sputter zone vacuumed by turbo pumps with 450 1/sec and 1300 1/sec pumping speed respectively. Ion current density, plasma density, and uniformity of ion beam current were measured using Faraday cup and the distribution of magnetic field and erosion efficiency of sputter target were also investigated. With the irradiation of ion beams on polyimide (Kapton-E, $38{\mu}m$) at different fluences, the change of wetting angle of the deionized water to polyimide surface and those of surface chemical bonding were analyzed by wetting anglometer and x-ray photoelectron spectroscopy. After investigating the deposition rate of Ni-Cr tie layer and Cu layer was investigated with the variations of roll speed and input power to sputter cathode. FCCL fabricated by sputter and electrodeposition method and characterized in terms of the peel strength, thermal and chemical stability.