• The Journal of Natural Sciences
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• v.5 no.1
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• pp.77-86
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• 1992

By cation-exchange-reaction long-chain organic cationic tensides can be intercalated in the montmorillonite layer space, and thus intercalations-complexes of montmorillonite with different properties of materials can be obtained. Such intercalations-complexes are finding strong technical appliances in many areas and are also used very often as model-systems for studying behaviors of materials. Therefore in this research intercalations-complexes of montmorillonite with organic cationic tensides ad model-systems were synthesized and their behabiors under various different conditions were studied.

• Journal of the Korean Ceramic Society
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• v.54 no.3
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• pp.249-256
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• 2017

We design Ge-Al multilayer assemblies as anode materials for Li-ion batteries, in which Ge and Al thin films are alternately deposited by a radio sputtering method. By sandwiching Ge layers between Al layer, the cyclability, rate capability, and capacity of Ge are improved significantly. The success of the Ge-Al multilayer is attributed to the Al films. To maintain the integrity of electrical contact, Al acts as an elastic layer, which can expand or shrink with the Ge film upon lithiation or delithiation. In addition, the presence of the Al film on the surface can prevent direct contact of Ge and electrolyte, thereby reducing the growth of a SEI layer. Importantly, with high electrical and ionic conductivities, the Al film provides efficient electrical and ionic routes for electrons and Li-ions to access the Ge film, promoting a high specific capacity and high rate capability for Ge.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2011.05a
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• pp.42-43
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• 2011

Improvement of the photovoltaic efficiency via exposure of organic solar cells to solvent-vapor at room temperature is reported. Carbon disulfide ($CS_2$) vapor treatment can induce Poly(3-hexylthiophene) (P3HT) self-organization into ordered structure leading to enhanced hole transport and light absorption. The power conversion efficiency (PCE) of the organic solar cells can be increased from 0.89 to 1.67% by solvent-vapor treatment.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.165-166
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• 2006

Nb-Ti alloys were hydrogenated to prepare fine and contamination-free powders. Cracks were introduced in the alloys when they were annealed at 1473 K and cooled in a hydrogen atmosphere. The fragments produced by hydrogen-induced cracking are brittle and the friability enhanced with the Ti content of the alloy, which is beneficial for further refinement of particle size. We also demonstrate that Nb-Ti powders with the average particle size less than 1 m can be produced by ball milling at a temperature lower than 203 K. Furthermore, hydrogen-free powders can then be obtained by annealing above the temperature corresponding to hydrogen desorption from Nb solid solution.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.625-626
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• 2006

In the present study, the focus is on the synthesis of nanosized WC powder by the chemical vapor condensation proces. The synthesized W-C system powder by the CVC process shows W2C, W, WO3 phases and can not shows WC phase. After recarburization heat treatment under mixture gas atmosphere of argon and hydrogen gases, the synthesized W-C system powder fully transformed to the pure WC. The synthesized WC powder after recarburization heat treatment has an average particle size of 20 nm. The nano-sized WC powder can be prepared by the combination of the CVC process and heat treatment methods.

• Applied Microscopy
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• v.45 no.3
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• pp.131-134
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• 2015

Here we show how by processing energy dispersive X-ray spectrometry (EDS) data obtained using highly sensitive, new generation EDS detectors in the AZtec LayerProbe software we can obtain data of sufficiently high quality to non-destructively measure the number of layers in two-dimensional (2D) $MoS_2$ and $MoS_2/WSe_2$ and thereby enable the characterization of working devices based on 2D materials. We compare the thickness measurements with EDS to results from atomic force microscopy measurements. We also show how we can use electron backscatter diffraction (EBSD) to address fabrication challenges of 2D materials. Results from EBSD analysis of individual flakes of exfoliated $MoS_2$ obtained using the Nordlys Nano detector are shown to aid a better understanding of the exfoliation process which is still widely used to produce 2D materials for research purposes.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.624-627
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• 2000

The shielding effectiveness of materials is determined by measuring the ratio of the incident electromagnetic power which passes through the material under test. To measure the shielding effectiveness materials made by conductive polymer, the flanged coaxial transmission-line holder based in ASTM D4935-89, was fabricated. This apparatus has dynamic range between 95dB and 120dB in frequency range of 50Mhz-2Ghz. Furthermore, this system can be utilized to measure the shielding effectiveness of materials produced by conductive polymer and can be adapted for shielding materials design.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.05a
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• pp.547-550
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• 2008

Precipitation characteristics of the Fe-36Ni based high strength Invar alloy for power transmission wire was investigated in this study. High strength can be obtained in this alloy through precipitation hardening and strain hardening by cold working. $FactSage{(R)}$ in this study, revealing that equilibrium phases which can be formed are two kind of MC-type precipitates and MoC carbide. The latter stoichiometric carbide was expected to be formed at relatively lower temperature $770^{\circ}C$. High strength above 1000MPa and 40% of elongation were obtained at room temperature in both cases.

• Journal of the Korean Society for Nondestructive Testing
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• v.12 no.3
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• pp.33-39
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• 1992

This paper presents a summary of the immersion ultrasonic test to analyze the quality of diffusion bonding parts. The most important property of diffusion bonding parts is bonding strength, and that can be obtained by shear test. By comparing among data obtained by ultrasonic test(C-Scan) and those by shear test (bonding strength), these data are shown to be in good relation. Therefore ultrasonic C-Scan test result can be used successfully in quantitative quality control for diffusion bonded parts.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.04a
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• pp.188-189
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• 2022

With the development of nano-reinforcement technology, TiO₂ nanomaterials have received widespread attention as one of the additives without pozzolanic reaction, which can be used to improve the mechanical properties of cement-based materials. Meanwhile, with the development of additive manufacturing technology or known as 3D printing technology, its application in the construction field has also got noticed. Therefore, in this work, the effect of three sizes of TiO₂ on the compressive strength of hardened cement-based materials fabricated by binder jetting 3d printing was evaluated. According to the results, the TiO₂ particles with larger sizes can provide better reinforcement to the hardened cement due to its more significant filling effect.