• Korean Chemical Engineering Research
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• v.55 no.6
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• pp.861-867
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• 2017

In order to improve the capacity and cycling stability of Ni-rich NCA cathode materials for lithium ion batteries, the boron and cobalt were doped in commercial $Li_{1.06}Ni_{0.91}Co_{0.08}Al_{0.01}O_2$ (NCA) powders. Commercial NCA particles are mixed composites such as secondary particles of about $5{\mu}m$ and $12{\mu}m$, and the particle size was decreased by doping boron and cobalt. The initial discharge capacities of the boron and cobalt doped NCA-B and NCA-Co were found to be 214 mAh/g and 200 mAh/g, respectively, which are higher values than that of the raw NCA cathode material. In particular, NCA-Co exhibits the best discharge capacity of 157 mAh/g after 20 cycles, which is probably due to the enhanced diffusion of lithium ion by crystal growth along with the c-axis direction.

• Transactions of the Korean hydrogen and new energy society
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• v.11 no.4
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• pp.189-202
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• 2000

$AB_2$ type Zr-based Laves phases alloys have been studied for potential application as a negative electrode in a Ni-MH battery. The $AB_2$-type electrodes have a much higher energy density than $AB_5$-type electrodes per weight, however they have some disadvantages such as poor activation behavior and cycle life etc. Nonetheless, the $AB_2$-type electrodes have been studied very extensively due to their high energy density. In this study, in order to develop the cycle life, the Mn of $AB_2$ alloy composition was substituted partially by Mo. The alloys were melted by arc furnace and remelted 4-5 times for homogeneity. The alloy powder was used below 200-325 mesh for experiments. The structures and phases of the alloys were analyzed by XRD, SEM and EDS, and measured the curve of a pressure-composition isotherms. The electrodes were prepared by cold pressing of the copper-coated(25 wt%) alloy powders, and tested by a half cell. The results are summarized as follows. The cycle life was improved with the increase of Mo amount in $Zr_{1-x}Ti_xV_{0.4}Ni_{1.2}Mn_{0.4}Mo_y$(x=0.3, 0.4) and the activation was faster, whereas the discharge capacity decreased.

• Korean Journal of Metals and Materials
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• v.46 no.4
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• pp.209-216
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• 2008

Super austenitic stainless steels shows the high PRE (Pitting Resistance Equivalent) number and the good corrosion resistance. This work controlled the Co contents in Fe-31Cr-1.7Mo-27Ni-0.25N alloys to elucidate the effect of cobalt contents on the biocompatibility and corrosion resistance. Increasing Co contents, the hardness of the annealed alloys tends to be reduced. In aged alloys, cobalt decreased the increments of hardness by aging treatment. Cobalt decreased the critical pitting temperature (CPT) in 6% $FeCl_3$ + 1% HCl solution, but improved the anodic polarization behavior in Hanks' balanced salt solution and artificial saliva solution. Repassivation rate in artificial body solutions was improved by increasing cobalt contents, but didn't show the linear relationship to PRE number of the alloys. The experimental alloys showed the non-cytotoxicity because of its high corrosion resistance.

• Journal of the Microelectronics and Packaging Society
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• v.29 no.4
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• pp.71-75
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• 2022

In this research, Fe-Ni alloy films were electrodeposited on stainless steel (SS304 and SS430) and Ti plates to investigate the effects of surface conditions of cathode on deposits. The Ti plates were electropolished in 3 M H₂SO₄-methanol electrolytes at various conditions before electrodeposition, and unpolished Ti and the optimized specimen, polished at 10 V for 8 min, were used as cathode. The anomalous codeposition, the phenomenon which more active Fe is reduced preferentially, occurred on all substrate, however, there were differences in composition of all deposits. As the results of potential monitoring during electrodeposition, it was confirmed that the larger overpotential was applied to the deposition cell when using Ti cathode, leading to high Fe content of deposits from unpolished Ti due to increase in nucleation of Fe. Also, it was founded that the polished Ti can reduced deposition overpotential.

• Journal of Conservation Science
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• v.35 no.5
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• pp.440-452
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• 2019

This research has analyzed SI, the traditional steel, and SIHS(SI + HS), SICS(SI + CS), and SINiS(SI + NiS), the materials that were produced through welding and reprocessing three modern steel- HS, CS, and NiS- that have different carbon content. The purpose of the analyzation was to improve the definition of the multi-layered pattern that appears in the forging process. In observing modified structures on the commissures of three modern steel that have different carbon component to the SI, SINiS produced the most significant multi-layered pattern as well as the excellent welding quality. The excellent welding quality was due to the content of nickel which helped the forge welding process with other materials. There was no significant difference in crystal grain per materials, and SICS showed the highest hardness. At the measurement of EPMA for commissures of the materials, SINiS showed the highest definition of the multi-layered pattern due to the nickel and carbon content. The results above showed that the carbon steel with nickel content is the best material for the most definite multi-layered pattern, expressed from the multi-layered structure which is a characteristic of traditional forge welding technology. It is expected that the result of this research can be utilized as the technical data in further researches regarding the relics excavated from ancient welding process and their multi-layered structure and patterns.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.3
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• pp.576-584
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• 2020

The extruder screw material is mainly SKD11, but the recent development of synthetic resins have increased the occurrence of chemical corrosion and wear. To solve this issue, high chromium cast iron is needed because of its good abrasion resistance and corrosion resistance, but its use is avoided because of its poor machinability. In this study, to improve the machinability of high chrome cast iron, 0, 0.5, 1.0, 1.5% of nickel, which has excellent workability, was added to high chromium cast iron with a composition of Fe-23Cr-2.5C-1.2Si-1.08Mn-0.48Mo-0.3V, and annealed after casting. Subsequently, the effect of nickel on the machinability and corrosion resistance was analyzed using a turning test and coin polarization test, and compared with SKD11. After casting using a high-frequency vacuum induction furnace, the annealing treatment was performed at 750 ℃ for five hours and then reheated at 1100 ℃ for five hours. A turning test after annealing at 750 ℃ showed that the machinability was improved remarkably when the nickel content was over 1.0%. In the potentiodynamic polarization test in a 5% NaCl solution, the corrosion resistance decreased with increasing nickel content in the as-cast and annealing treatment. On the other hand, after reheating, the corrosion resistance was best with a 1.5% nickel content.

• Journal of Energy Engineering
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• v.19 no.4
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• pp.221-227
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• 2010

In this study, we consider gas generation characteristics on pyrolysis of eco-fuel which were made by mixing of Pitch Pine and Lauan sawdust as biomass and polyethylene, polypropylene, polystyrene as municipal plastic wastes with catalyst in fixed bed reactor. From the result of higher heating value(HHV) measurement and of ultimate analysis, the heating value of plastic wastes and a hydrogen content in plastic sample are higher than biomass. An activation energy was reduced by a catalyst addition. However the catalyst content influence over 5 wt% was insignificant. The yield of hydrogen from gasification of biomass containing plastic wastes such as polyethylene, polypropylene and polystyrene were obtained higher than that of sole biomass. The high temperature and mixture ratio of catalyst conditions induced to high hydrogen yield in most of the samples. As the influence of catalyst, the hydrogen yield by catalytic reaction was higher than non-catalytic reaction. We confirmed that Ni-$ZrO_2$ catalyst is more active in increasing the hydrogen yield in comparison with that of carbonate catalyst. The maximum hydrogen yield was 65.9 vol.%(Pitch Pine / polypropylene / 20 wt.% Ni-$ZrO_2$(1:9) at $900^{\circ}C$).

• Journal of Korea Soil Environment Society
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• v.3 no.2
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• pp.41-51
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• 1998

The research was conducted to measure the heavy metal pollution of soils and vegetations adjacent to the closed Daeseong coal mine in Keumsan, Chungnam. The studied area was divided into two sites ; the coal-bearing polluted and the non-polluted without coal. The samples of the weathered soils and vegetations(Miscnthus sinenis(MS) and Pinus rigida(PR)) were collected from both area. Cr, Mo, Ni, and Fe concentrations were high in the polluted soils, whereas Co, Sc, and Zn concentrations were high in the non-polluted soils. In the vegetations, Co, Cr, Sc, and Fe concentrations in the roots of MS and PR growing on the polluted sites were higher than the above-ground. However, on the non-polluted sites, Mo and Ni concentrations had an opposite trend. In the above-ground parts, high heavy metal concentrations (except Cr) were shown in MS of the non-polluted sites, whereas in the roots, heavy metal concentrations (except Zn) were high in the polluted sites. In the average heavy metal concentrations of two plants, most elements (except Zn) were lower in the plants than the soils. Comparing with vegetations and adjacent forest soils, heavy metal concentrations of the MS were similar to those of soil concentrations relative to the PR, suggesting that absorptions of the elements were higher in the MS than the PR.

• Korean Journal of Agricultural and Forest Meteorology
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• v.7 no.4
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• pp.265-273
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• 2005

Chemical properties and heavy metal concentrations of forest soils of four abandoned coal mine lands affected by coal mining activities in the Mungyeong area were investigated to provide basic information for revegetation of abandoned coal mine lands. Soil pH in abandoned coal mine lands ranged from 5.30 to 6.76 it in the control site was 5.23. Contents of organic matter and total N in abandoned coal mine lands were $4.46\~7.19\%\;and\;0.07\~0.15\%$, respectively. Available P contents were 6.54 for A (Samchang), 6.52 for B (Bongmyeong),3.94 fur C (Kabjung), 5.45 mg/kg for D (Danbong coal mine land) and 5.25 mg/kg for the control site, which had a positive correlation with soil pH. Contents of exchangeable Ca, Mg, K and Na in abandoned coal mile lands averaged 196.1, 88.7, 88.2 and $10.2cmol^+/kg$, with a range of $132.1\~242.1,\;24.2\~138.\; 64.9\~120.8\;and\;8\~12.2cmol^+/kg$, respectively. Those of the control site were 192.8, 95.8, 104 and $21.2 cmol^+/kg$, respectively. Heavy metals such as Al, As, Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn of forest soil in abandoned coal mine lands have a larger content than those of the control site. Al, Mn and fb content was especially high in abandoned coal mine lands. The Al content of forest soil in abandoned coal mine lands ranged from 397 to 917 ppm, which was considered to be high enough to inhibit tree growth. Therefore, it is suggested that soils of abandoned coal mine lands contaminated by mining activities need to be properly treated for remediation of environmental problems.

• Journal of Nutrition and Health
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• v.25 no.2
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• pp.123-131
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• 1992

Concentrations of 5 major minerals(Na, K, Ca, P, Mg) and 3 trace elements(Mn, Mo, Ni) were measured in human milk samples collected from 21 highly selected healty lactating women at 2-5 days and at 1, 2, 4, 6 and 12 weeks postpartum. Significant decrease in contents of the major minerals and trace elements were found with time postpartum. Sodium contents decreased from 293.01ug/N at 2-5 days to 194.27ug/N at 12 weeks. Potassium contents also decreased from 436.18ug/N in colostrum to 358.51ug/N in matured milk at 12 weeks. The Ca/P ratios of colostrum transitional and matured milk were 3.39, 281 and 2.45 respecti-vely. Mean manganese levels of colostrum and transitional were 0.024ug/N and those of matured milk were 0.014ug/N. Molybdenum concentrations in the breast-milk collected at 1, 2, 4 weeks were higher than those in the milk samples at 2-5 days and 12 weeks Nickel content of colostrum was 0.062ug/N and those of trnsitional matured milk were 0.22ug/N and 0.017ug/N, These determinations will provide the basic information on the variability of minerals and trace elements as lactation proceed and the comparison of the components between term and preterm milk.