• Proceedings of the Korean Magnestics Society Conference
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• 2016.05a
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• pp.136-136
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• 2016

• Proceedings of the Korean Magnestics Society Conference
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• 2014.11a
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• pp.127-127
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• 2014

• 한국초전도학회:학술대회논문집
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• v.13
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• pp.7-7
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• 2003

• Korean Journal of Metals and Materials
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• v.50 no.11
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• pp.861-866
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• 2012

A dense nanostructured TiN-AlN composite was prepared from high-energy ball milled TiN-AlN mixture powders by pulsed current activated sintering (PCAS). A highly dense TiN-AlN bulk composite was obtained within 2 minutes at $1500^{\circ}C$ with the simultaneous application of 80 MPa pressure and pulsed current. The fine crystalline structure of the TiN-AlN mixture, which was obtained by high-energy milling, was effectively maintained during PCAS and resulted in the enhancement of the mechanical properties. The micro hardness and fracture toughness of TiN-AlN composite were $1780kg/mm^2$ and $5MPa.m^{1/2}$, respectively. The mechanical properties were higher than monolithic AlN or TiN.

• Journal of Powder Materials
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• v.12 no.6 s.53
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• pp.387-392
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• 2005

The p-type semiconductor $Bi_2Te_3-Sb_2Te_3$ thermoelectric materials were fabricated by melting, milling and sintering process and their thermoelectric properties were characterized. The compound materials were ball-milled with milling time and the powders were sintered by spark plasma sintering process. The ball milled powders had equiaxial shape and approedmately $1\~3{\mu}m$ in size. The figure of meritz of sintered thermoelectric materials decreased with milling time because of lowered electrical resistivity. The thermoelectric properties of $Bi_2Te_3-Sb_2Te_3$ materials have been discussed in terms of electrical property with ball mill process.

• Korean Journal of Materials Research
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• v.16 no.2
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• pp.116-122
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• 2006

The effects of milling time in argon and hydrogen atmospheres on the hydrogen sorption speed of a getter alloy, $Zr_{57}V_{36}Fe_{7}$, was studied. The hydrogen sorption speed of milled alloys was evaluated at room temperature. In argon, as the oxygen content increased with milling time, the hydrogen sorption speed decreased accordingly. In hydrogen, on the other hand, the oxygen content decreased at first with milling time but started increasing after 5 hrs of milling time. Similar to the case of argon, however, the hydrogen sorption speed changed exactly in the opposite direction with the oxygen content, exhibiting the maximum rate at 5 hrs. These results suggest that in both atmospheres the hydrogen sorption speeds are inversely related with the oxygen contents.

• Journal of Powder Materials
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• v.3 no.4
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• pp.233-245
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• 1996

Nanocrystalline materials, with a grain size of typically <100 nm, are a new class of materials with properties vastly different from and often superior to those of the conventional coarse-grained materials. These materials can be synthesized by a number of different techniques and the grain size, morphology, and composition can be controlled by controlling the process parameters. In comparison to the coarse-grained materials, nanocrystalline materials show higher strength and hardness, enhanced diffusivity, improved ductility/toughness, reduced, density, reduced elastic modulus, higher electrical resistivity, increased specific heat, higher coefficient of thermal expansion, lower thermal conductivity, and superior soft and hard magnetic properties. Limited quantities of these materials are presently produced and marketed in the US, Canada, and elsewhere. Applications for these materials are being actively explored. The present article discusses the synthesis, structure, thermal stability, properties, and potential application of nanocrystalline materials.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2004.11a
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• pp.33-33
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• 2004

• Journal of Korean Elementary Science Education
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• v.23 no.4
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• pp.305-317
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• 2004

The learning materials in elementary school science textbooks should include all kinds of materials being used by both teachers and students in the science teaching. The major purpose of this research is to analysis textbooks and teacher's guidebooks prepared for the science teaching of 3-6 grade students. To clarify this research, we listed whole of the learning materials of science teaching for each grade and counted numbers being used for whole of the lessons of science. And according to the characteristics and the methods of its preparation of materials, the types of learning materials can be divided into 10 categories such as teaching equipments for science, test materials, consumables, audio-visual aids, teaching equipments in general, collecting' recycling materials, field studies' collected data, breeding' cultivation materials, manufacture materials, and etc. At the result of this research, the 7th national science curriculum needs total 844 items of learning materials for science education. They could be separated into ten types of categories such as 159 items of teaching equipments for science, 65 items of test materials, 116 items of consumables, 198 items of audio-visual aids, 64 items teaching equipments in general, 31 items of collecting' recycling materials, 38 items of field studies (collecting) materials, 17 items of breeding-cultivation materials, 58 items of manufacturing materials, 105 items of other materials. And we found out that there were 332 items of materials for the 3rd grade, 303 items for the 4th grade, 324 items for the 5th grade, and 254 items for the 6th grade. The result of this research could be useful for classroom activities for science teaching.

• Journal of the Korean Ceramic Society
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• v.46 no.5
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• pp.441-446
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• 2009

Dense crack-free yttria film with 10 $\mu m$ thickness was prepared on aluminum by aerosol deposition. X-ray diffraction pattern on the film showed that it contained the same crystalline phase as the raw powder. Transmission electron microscopy revealed a nanostructured yttria film with grains smaller than 100 nm. Tensile adhesion strength between the film and aluminum substrate was 57.8 $\pm$ 6.3MPa. According to the etching test with $CF_4-O_2$ plasma, the etching rate of the yttria film was 1/100 that of quartz, 1/10 that of sintered alumina and comparable to that of sintered yttria.