• Design & Manufacturing
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• v.18 no.3
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• pp.37-43
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• 2024

With the development of technology in the electrical and electronic field, research on heat dissipation materials that can efficiently emit and control heat to solve the heat generation problem is being actively conducted. Since heat dissipation materials require electrical insulation and thermal conductivity, the polymer composite material was manufactured by mixing chemically stable silicone resins and ceramic fillers, and thermal conductivity and mechanical properties were observed. At the same filling amount, the larger the particle size and the higher the high thermal conductivity filler was added, the higher the thermal conductivity was, mechanical properties were confirmed to have higher tensile strength and elongation as the particles were smaller and the tissue was denser. After selecting materials in consideration of thermal conductivity and mechanical properties, an appropriate mixing ratio is considered important.

• Clean Technology
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• v.28 no.4
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• pp.278-284
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• 2022

This study presents an excellent planar heater based on low-dimensional composites. By optimizing the ratio of 1D carbon nanotubes (CNT) and 2D MXene (Ti₃C₂T_X), it is possible to create a planar heater that has superior electrical conductivity and high heat generation characteristics. Low-dimensional composites were prepared by mixing CNT paste and MXene solution with eco-friendly waterborne polyurethane (WPU). In order to find the optimal mixing ratio for the MXene-CNT-WPU composites, samples with MXene to CNT weight ratios of 3:1, 1:1, 1:3, 1:7, and 1:14 were investigated. In addition to these different weight ratios, 5 wt% WPU was equally applied to each sample. It was confirmed that the higher the weight ratio of CNT, the lower the sheet resistance and the higher the heating temperature. In particular, when the MXene-CNT-WPU planar heater was fabricated by mixing MXene and CNT at a weight ratio of 1:7 and 1:14, the heating temperature was higher than the heating temperature of a CNT-WPU planar heater. These characteristics are due to the optimized mixture of the 1D materials (CNT) and the 2D materials (MXene) causing the formation of a flat surface and a dense network structure. The low-dimensional composites manufactured with the optimized mixing ratios found in this study are expected to be applied in flexible electronic devices.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.6
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• pp.751-757
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• 2011

Subminiature devices such as Lab-on-a-chip and p-TAS(Micro Total Analysis System) have been intensively studied in biotechnology and chemistry, In many cases, a micromixer was widely used to mix different solutions for synthesizing novel materials. However, in microfluidic system, there is generally a laminar flow under very small Reynolds number so it is difficult to mix each solution perfectly. To settle this problem, we propose a new mixing mechanism which generates a horizontal and vertical multi-mixing (HVM) flow for effective mixing within a short mixing section. We evaluated the proposed mechanism using CFD analysis, and the results showed that the HVM mechanism had a relative high-effectiveness comparing to the existing methods.

• Journal of the Korean Ceramic Society
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• v.42 no.4
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• pp.276-281
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• 2005

$LiNi_{1-y}M_{y}O_{2}(M=Zn^{2+},\;Al^{3+},\;and\;Ti^{4+},\;0.000\{\le}y{\le}0.100)$ were synthesized by the combustion method by calcining in $O_{2}$ stream at $750^{\circ}C$ for 36 h. XRD analyses, observation by FE-SEM and measurement of the variation of discharge capacity with the number of cycles were carried out. The composition $LiNi_{0.99}M_{0.01}O_{2}(M=Zn^{2+},\;Al^{3+},\;and\;Ti^{4+})$ of all the compositions showed relatively good electrochemical properties. $LiNi_{0.99}M_{0.01}O_{2}$ exhibited poor crystallinity and $LiNi_{0.99}M_{0.01}O_{2}$ showed the cation mixing of large fraction. $LiNi_{0.99}M_{0.01}O_{2}$ with improved cycling performance showed good crystallinity and the cation mixing of small fraction.

• Proceedings of the Materials Research Society of Korea Conference
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• 1998.08a
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• pp.146.2-146
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• 1998

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.03a
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• pp.57-57
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• 2003

• Proceedings of the Materials Research Society of Korea Conference
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• 1992.05a
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• pp.145-145
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• 1992

• Proceedings of the Materials Research Society of Korea Conference
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• 1992.05a
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• pp.45-45
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• 1992

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.3
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• pp.8-13
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• 2018

Zirconium potassium perchlorate(ZPP) is an igniter composed of potassium perchlorate as an oxidizing agent and zirconium as a fuel with a Viton binder. ZPP has been used to provide an ignition source in the aerospace, propulsion, and automotive industries. This study investigates the manufacturing process and characteristics of ZPP, such performance and shape/calorimetry/pressure characteristics with respect to pyrotechnic mechanical device(PMD). During the production of ZPP, the mixing process was designed to produce uniform particle size and shape by mixing the raw materials at high speed.

• Journal of Powder Materials
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• v.25 no.6
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• pp.487-493
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• 2018

The impact of different mixing methods and sintering temperatures on the microstructure and piezoelectric properties of PZNN-PZT ceramics is investigated. To improve the sinterability and piezoelectric properties of these ceramics, the composition of $0.13Pb((Zn_{0.8}Ni_{0.2})_{1/3}Nb_{2/3})O_3-0.87Pb(Zr_{0.5}Ti_{0.5})O_3$ (PZNN-PZT) containing a Pb-based relaxor component is selected. Two methods are used to create the powder for the PZNN-PZT ceramics. The first involves blending all source powders at once, followed by calcination. The second involves the preferential creation of columbite as a precursor, by reacting NiO with $Nb_2O_5$ powder. Subsequently, PZNN-PZT powder can be prepared by mixing the columbite powder, PbO, and other components, followed by an additional calcination step. All the PZNN-PZT powder samples in this study show a nearly-pure perovskite phase. High-density PZNN-PZT ceramics can be fabricated using powders prepared by a two-step calcination process, with the addition of 0.3 wt% MnO2 at even relatively low sintering temperatures from $800^{\circ}C$ to $1000^{\circ}C$. The grain size of the ceramics at sintering temperatures above $900^{\circ}C$ is increased to approximately $3{\mu}m$. The optimized PZNN-PZT piezoelectric ceramics show a piezoelectric constant ($d_{33}$) of 360 pC/N, an electromechanical coupling factor ($k_p$) of 0.61, and a quality factor ($Q_m$) of 275.