• Journal of Powder Materials
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• v.20 no.1
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• pp.43-47
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• 2013

The extraction of metallic pure vanadium powder from raw oxide has been tried by Mg-reduction. In first stage, $V_2O_5$ powders as initial raw material was reduced by hydrogen gas into $V_2O_3$ phase. $V_2O_3$ powder was reduced in next stage by magnesium gas at 1,073K for 24 hours. After reduction reaction, the MgO component mixed with reduced vanadium powder were dissolved and removed fully in 10% HCl solution for 5 hours at room temperature. The oxygen content and particle size of finally produced vanadium powders were 0.84 wt% and 1 ${\mu}m$, respectively

• Journal of Magnetics
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• v.11 no.3
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• pp.103-107
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• 2006

In grain oriented electrical steel process, hot band annealing has thought to be essential for obtaining good magnetic properties. New hot rolling method of heavy reduction in early hot rolling stage was applied to obtain good magnetic properties in GO process without hot band annealing. Hot rolling was carried out by varyinghot rolling reduction distribution along hot rolling pass. The heavy hot rolling reduction in rear stand improves the magnetic flux density in the case of no hot band annealing. The hot band specimens of the heavy reduction in front stand shows the elongated hot deformed microstructures in the center layer and strong {001}<110> texture.On the contrary, the heavily reduced specimens in rear stand shows the recrystallization in the center layer of hot band and strong {111}<112> and {110}<001> textures.

• Bulletin of the Korean Chemical Society
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• v.30 no.11
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• pp.2669-2674
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• 2009

Controlled reduction of silver alkylcarbamate complexes with hydrogen gas was investigated as a facile synthetic method for high concentrations of silver nanocolloids in organic solvent. Polyvinylpyrrolidone (PVP) was used to stabilize the silver colloids obtained from the chemical reduction. To determine optimum conditions for preparation of the stable and controlled silver colloids with the narrowest particle size and distribution, a large number of experiments were carried out involving variations in the concentrations of the silver 2-ethylhexylcarbamate (Ag-EHCB) complex, PVP, and 2-propanol. The initial colloid had a mean particle diameter between 5$\sim$50 nm, as measured by transmission electron microscopy, and exhibited a sharp absorption band in the UV region with a maximum size near 420 nm. After treatment with a reducing agent, the colloids were characterized by ultraviolet-visible spectroscopy, X-ray diffraction, and high-resolution transmission electron microscopy.

• Journal of Powder Materials
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• v.26 no.4
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• pp.340-344
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• 2019

Due to the rapid development of electricity, electronics, information communication, and biotechnology in recent years, studies are actively being conducted on nanopowders as it is required not only for high strengthening but also for high-function powder with electric, magnetic, and optical properties. Nonetheless, studies on nickel nanopowders are rare. In this study of the synthesis of nickel nanoparticles from $LiNiO_2$ (LNO), which is a cathode active material, we have synthesized the nanosized nickel powder by the liquid reduction process of $NiSO_4$ obtained through the leaching and purification of LNO. Moreover, we have studied the reduction reaction rate according to the temperature change of liquid phase reduction and the change of particle size as a function of NaOH addition amount using hydrazine monohydrate ($N_2H_4{\cdot}H_2O$) and NaOH.

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.8
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• pp.34-42
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• 1999

In late 1997, the portion of registered light-duty diesel vehicle was 25.3% and its emission rate was 17.1% in Korea. Especially, diesel particulate matters(DPM) and NOx are hazardous air pollutants to human health and environment in urban area. The reduction technologies of exhaust emissions from diesel engines are improvement of engine combustion, fuel quality and development of diesel exhaust after treatment , In this study , a light-duty diesel oxidation catalyst(DOC) that is one of the diesel exhaust after treatment was made for performance evaluation and the emission characteristics were tested on CVS-75 mode. And the analysis of the particle size distribution with scanning mobility particle 100, 67.6% and 66.7, 10.0% for Pt and Pt-V catalyst .And for Pt catalyst, the PM increased 7.8% because of increasing sulfate but Pt-V catalyst reduced the PM to 23.0% . Test results of particle size distribution showed that peak values of number and mass densities are respectively 100∼200nm their distribution trend independent of vehicle speed.

• Structural Engineering and Mechanics
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• v.89 no.4
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• pp.383-397
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• 2024

To improve the vibration control performance and applicability of traditional particle tuned mass damper (PTMD) and realize the significant characteristic of lightweight design, this study proposes a novel particle tuned mass inerter system (PTMIS) by introducing inerter system (IS) to the PTMD. In the study, the motion equation of single degree of freedom (SDOF) structure attached with PTMIS is established first, then the variation law of the system's vibration reduction performance (VRP) is discussed through parameter analysis, and it is compared with the PTMD to analyze its VRP advantages. Finally, its vibration reduction (VR) mechanism from the perspective of core control force and energy analysis is explored, and its cavity relative displacement from the application perspective is analyzed. The results show that the PTMIS can remarkably improve the vibration control effectiveness of the PTMD. The reason is that the inerter can store energy and transfer the energy to the cavity and particles, which further stimulates the interaction between the two parts, thereby improving the nonlinear energy consumption effectiveness. Also, the IS can amplify the damping element's energy dissipation efficiency. In addition, the PTMIS can effectively reduce the working stroke of the PTMD, and through the analysis of the lightweight characteristics of the PTMIS, it is found that its lightweight advantage can reach nearly 100%.

• Resources Recycling
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• v.14 no.1
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• pp.26-32
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• 2005

A study on the preparation of Ag fine particles was performed through a reduction reaction using ascorbic acids as a reductant, which is one of the indispensable processes for the recycling of silver-bearing wastes. Silver nitrate solution in the range of 10~120 mmole/l was used and Tamol NN8906 or PVP was also used as a dispersant in the preparation of Ag fine particles size analyze, SEM, and TEM to determine the particle size and morphology of them. As a result, the reduction reaction of silver ions with ascorbic acid reached equilibrium within 10 min. It was found that about 60% excess of ascorbic acid was required in order to reduce completely silver ions in the solution. The particle size distribution of Ag particles prepared through the reduction reaction showed typically biomodal or trimodal distribution. Especially, initial Ag concentration in the solution, the type and amount of dispersant added during the reduction reaction played an important role in determining the mean particle size of Ag particles.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.12 s.243
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• pp.1321-1328
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• 2005

The burning characteristics of interacting coal particles in a convective flow are numerically investigated at various Reynolds numbers. The transient combustion of 2-dimensionally arranged particles, both the fixed particle distances of 5 radii to 20 radii horizontally and 4 radii to 24 radii vertically, is studied. The results obtained from the present numerical analysis indicate that the transient flame configuration and retardation of particle temperature augmentation with the horizontal or vertical particle spacing substantially influence devolatilization process and carbon conversion ratio of interacting particles. Volatile release and carbon conversion ratio of the second particle with decreasing horizontal and vertical particle spacing decrease gradually, whereas those of the first particle with decreasing vertical particle spacing increase due to flow acceleration. When the vertical particle spacing is smaller than $6R_0$, volatile release and carbon conversion ratio of the second particle decrease due to reduction of flame penetration depth and interference of oxygen diffusion by the first particle.

• KCID journal
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• v.21 no.1
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• pp.99-108
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• 2014

This study investigated the effects of NPS(non point source) pollution reduction of sediment traps through field experiments. Various sizes of 4 sediment traps were applied in a upland field located in Gunwi and assessed the infiltration and storage effects as well as NPS pollution reduction effects of this technique. The characteristics of deposited soil in the sediment traps were also analyzed including distribution of particle size, soil texture, and chemical properties. The results showed that slightly different composition of soil particle size from each sediment trap with high proportion of 0.15mm and 0.25mm ranges of soil particle diameters, while the loamy sand is the main types of deposited soils in the sediment traps. Decreased NPS pollution were observed from the water quality analysis of the samples taken from the sediment traps. Further research need to be proceeded continuously to improve this technique in order to utilize on upland fields for management of agricultural NPS pollutions.

• Applied Chemistry for Engineering
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• v.23 no.1
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• pp.14-17
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• 2012

Submicron silver particles were synthesized by chemical reduction with various room temperature ionic liquids. The size and distribution of silver particles were significantly affected by the anion type of ionic liquids and this is mainly attributed to the different abilities of the anions to coordinate with the silver particle, leading to various coagulation of silver particles. Among ionic liquids, 1-butyl-3-methylimidazolium hexafluorophosphate was the most effective to synthesize submicron silver particles.