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

• Progress in Superconductivity and Cryogenics
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• v.4 no.2
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• pp.16-20
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• 2002

Bi-axially textured Ni tapes for YBCO coated conductors were Prepared by cold rolling and heat treatment of Ni Powder compacts. The Ni powder used in this study was 5 urn in particle size and 99.99 % in purity. The process of this study consists of filling of hi powder into a rubber mold, cold-isostatically Pressing and sintering of the powder compacts at 110$0^{\circ}C$ for 6h in 96 % Ar - 4 % H$_2$ atmosphere. The sintered compacts were cold rolled with a 5 % step reduction ratio into a 100 micron-thick tapes and then heat-treated at 100$0^{\circ}C$ for various time periods. The (200) texture of Ni tape was successfully developed through the recrystallization heat treatment of the cold rolled Ni tapes. At 100$0^{\circ}C$, the degree of texture of the heat-treated Ni tapes seems not to be significantly affected by the heat-treatment time. The short heat treatment of S min was sufficient to develop the complete (200) cube texture. The degree of in-Plane and out-of-plane texture of the prepared Ni tapes was 8-10$^{\circ}$. The heat treated Ni tapes consisted of equiaxed grains with a size 50-70 microns. and the AFM sol-face roughness was as smooth as 3 nm.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2004.06a
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• pp.268-277
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• 2004

process (ACP), electrochemical properties of high heat-generating alkali and alkali earth oxides in molten salt were measured and the behavior of those elements were analyzed. The reduction potentials of Cs, Sr, and Ba in a molten LiCl-$Li_2O$ system were more cathodic than that of Li and closely located one another. Thus, it is expected that the alkali and alkali earth would not hinder the reaction mechanism which is via lithium reduction. Alkali and alkali earth metals are likely to recycle into molten salt when the process is operated beyond metal reduction potentials and the effect of electric current on the mass transport is also determined by measuring the metal concentrations in the molten salt phase at different current conditions.

• Transactions of the Korean Society of Automotive Engineers
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• v.25 no.1
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• pp.111-115
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• 2017

This forged piston is proposed with a lighter weight and higher durability than a gravity casting piston for gasoline engines. However, a forged piston is very difficult to develop and mass-produce due to lack of basic technologies such as design, material and forging technique. First, we benchmarked existing forged pistons according to database design parameters. Second, we evaluated two solidification processes, continuous casting and spray forming, to produce heat-resistant alloy billets for forging. The spray forming process gives better mechanical properties at all temperatures, particularly at elevated temperatures except when poor formability is present. We used DEFORM simulation to determine the optimum process condition with billet from spray forming and successfully commercialized it with LF Sonata HEV.

• Proceedings of the IEEK Conference
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• 2002.06b
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• pp.193-196
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• 2002

This paper presents the improvement of the boron penetration and the reverse short channel effect (RSCE) in the 130nm W/WNx/Poly-Si dual gate PMOSFET for a high performance embedded DRAM. In order to suppress the boron penetration, we studied a range in the process heat budget. It has shown that the process heat budget reduction results in suppression of the boron penetration. To suppress the RSCE, we experimented with the halo (large tilt implantation of the same type of impurities as those in the device well) implant condition near the source/drain. It has shown that the low angle of the halo implant results in the suppression of the RSCE. The experiment was supported from two-dimensional(2-D) simulation, TSUPREM4 and MEDICI.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.14 no.5
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• pp.113-119
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• 2015

The technical development of electric vehicles has been actively proceeding because of the reduction of oil resources and need for eco-friendly vehicle technology. In particular, an electronic control unit is an important element in the technology of electric vehicles due to the motor drive system. This paper concerns an experimental study on the thermal analysis of the steering control ECU structure for an electric vehicle. The ECU unit is designed for eight heat sinks for the thermal analysis of the ECU structure. The thermal analysis characteristics of the ECU structure are evaluated by the temperature distribution, heat flow, von Mises stress, total translation, and external surface temperature measurement of the ECU unit.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.6 no.4
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• pp.86-91
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• 2007

The heat generated by the brake system of vehicles results in reduction of friction force on the brake surface and vibration when breaking. These problems play essential part in break's performance. To solve these problems, extensive research has been conducted such as drilling cooling holes on the brake pud, accommodating ventilated holes and etc. In this study, we suggest the compression of brake in circumferential direction in order to improve its cooling performance. And we analyzed comparing temperature distribution which is generated accomplishing heat analysis at each disc.

• Journal of Ceramic Processing Research
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• v.13 no.spc1
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• pp.110-113
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• 2012

Ge-S and Li-Ge-S powders were synthesized via solution-based process in order to employ chalcogenide-based solid electrolyte for use in Li secondary batteries. GeCl4 and thioacetamide in combination result in Ge-S powders of which major crystalline phase becomes GeS2 where the tetragonal and orthorhombic phases coexist after heat treatment. A chemical treatment using NaOH brings about the reduction of chlorine in the powders obtained. However, the heat treatment at 300 ℃ is more effective in minimizing the chlorine content. When lithium chloride is used as the precursor of Li ions, the LiCl powders are agglomerated with an inhomogeneous distribution. When Li2S is used, the Li-Ge-S powders are distributed more uniformly and the orthorhombic GeS2 phase dominates in the powders.

• International Journal of Air-Conditioning and Refrigeration
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• v.17 no.1
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• pp.32-36
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• 2009

The ice storage system uses water for low temperature latent heat storage. However, a refrigerator capacity is increased and COP is decreased due to supercooling of water in the course of phase change from solid to liquid. This study investigates the cooling characteristics of the TMA-water clathrate compound including TMA (Tri-methyl-amine, $(CH_3)_3N$) of $20{\sim}25wt%$ as a low temperature latent heat storage material. The results showed that the phase change temperature and the specific heat is increased and the supercooling degree is decreased as the weight concentration of TMA increased. Especially, the clathrate compound containing TMA 25 wt% has the average phase change tempera ture of $5.8^{\circ}C$, the supercooling degree of $8.0^{\circ}C$ and the specific heat of 3.499 kJ/kgK in the cooling process. This can lead to reduction of operation time of refrigerator in low temperature latent heat storage system and efficiency improvement of refrigerator COP and overall system. Therefore, energy saving and improvement of utilization efficiency are expected.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.7 no.4
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• pp.62-67
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• 2008

In this research, we developed a pilot wire-drawing machine as well as wire end-pointing roller. Using these machines, we performed a pilot wire-drawing test at different coating material and lubricant when the reduction ratio is 10 %. To inversely compute the friction coefficient between the coating layer of wire and the surface of die for a specific lubricant, we carried out a series of three dimensional finite element analysis. Results show that the drawing force is varied with the coating material of wire at the same reduction ratio and lubricant. It is noted that the frictional coefficient in drawing is dependent on the coupled property of coating material and lubricant, indicating the best coating material for a given lubricant.