• Journal of Astronomy and Space Sciences
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• v.19 no.4
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• pp.319-326
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• 2002

Laboratory tests have been carried out for investigation of the spectroscopic characteristics at visible wavelength of 12 common satellite materials used in satellite bus and payload. The obtained spectral data show that the materials can be classified and identified since their spectral features and albedos distinctly differ among them. It is suggested that the result of the laboratory tests for the satellite materials can be used for the predictions of material types, material composition ratios, sizes, and masses in comparison with the spectral data obtained from observations of new satellites or space debris.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07a
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• pp.340-343
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• 2004

The phase transition between amorphous and crystalline states in chalcogenide semiconductor films can controlled by electric pulses or pulsed laser hem: hence some chalcogenide semiconductor films can be applied to electrically write/erase nonvolatile memory devices, where the low conductive amorphous state and the high conductive crystalline state are assigned to binary states. This letters researched into the characteristic of phase change transition in differential Chalcogenide thin films materials. The electrode used Al and experimented on 100nm, 300nm, 500nm respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07a
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• pp.377-380
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• 2004

The phase transition between amorphous and crystalline states in chalcogenide semiconductor films can controlled by electric pulses or pulsed laser beam; hence some chalcogenide semiconductor films can be applied to electrically write/erase nonvolatile memory devices, where the low conductive amorphous state and the high conductive crystalline state are assigned to binary states. GeSbTe(GST), AsSbTe(AST), SeSbTe(SST) used to phase change materials by appling electrical pulses. Thickness of ternary chalcogenide thin films have about 100nm. Upper and lower electrode were made of Al. It is compared with I-V characteristics after impress the variable pulses.

• Journal of Powder Materials
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• v.27 no.6
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• pp.449-457
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• 2020

Iron and copper are practically immiscible in the equilibrium state, even though their atomic radii are similar. As non-equilibrium solid solutions, the metastable Fe-Cu alloys can be synthesized using special methods, such as rapid quenching, vapor deposition, sputtering, ion-beam mixing, and mechanical alloying. The complexity of these methods (multiple steps, low productivity, high cost, and non-eco-friendliness) is a hinderance for their industrial applications. Electrical explosion of wire (EEW) is a well-known and effective method for the synthesis of metallic and alloy nanoparticles, and fabrication using the EEW is a simple and economic process. Therefore, it can be potentially employed to circumvent this problem. In this work, we propose the synthesis of Fe-Cu nanoparticles using EEW in a suitable solution. The powder shape, size distribution, and alloying state are analyzed and discussed according to the conditions of the EEW.

• Textile Coloration and Finishing
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• v.27 no.3
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• pp.194-201
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• 2015

Cotton and silk fabrics were dyed with Houttuynia cordata extract using aqueous ethanol solution and the dyeing and post-treatment conditions were optimized to impart antimicrobial activity to the fabrics. The dried Houttuynia cordata can be extracted at $80^{\circ}C$ for 3 hours using an aqueous ethanol solution containing 70%(w/w) ethanol. For the highest color yields. Both cotton and silk fabrics can be dyed at $100^{\circ}C$ for 60min with 10g/L of NaCl under pH 4. Silk fabrics can be dyed to higher K/S than cotton fabrics. The color fastness properties of the dyed fabrics were good when either citric acid crosslinking or aluminum alum mordanting was carried out as a post treatment. The dyed silk and cotton fabrics with the post treatments showed excellent antimicrobial activity against both Staphylococcus aureus and Klebsiella pneumoniae.

• Nuclear Engineering and Technology
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• v.53 no.5
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• pp.1593-1601
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• 2021

Oxide dispersion strengthening (ODS) tungsten alloys are highly desirable in irradiation applications. However, how to improve the properties of ODS-tungsten alloys efficiently has been worth studying for a long time. Here we report a nanostructuring approach that achieves W-La₂O₃ alloy with a high level of flexural strength and Vickers hardness at room temperature, which have the maximum value of 581 MPa and 703 Hv, respectively. This method named solution combustion synthesis (SCS) can generate 30 nm coating structures W-La₂O₃ composite powders by using Keggin-type structural polyoxometalates as raw materials in a fast and low-cost process. The composite powder can be fabricated to W-La₂O₃ alloy with an optimal microstructure of submicrometric W grains coexisting with nanometric oxide particles in the grain interior, and a stability interface structure of grain boundaries (GBs) by forming transition zones. The method can be used to prepare new ODS alloys with excellent properties in the future.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2002.05a
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• pp.181-183
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• 2002

The accurate permeability for preform is critical to model and design the impregnation of fluid resin in the composite manufacturing process. In this study, the in-plane and transverse permeability for a woven fabric are predicted numerically through the coupled flow model which combines microscopic with macroscopic flow. The microscopic and macroscopic flow which are flows within the micro-unit and macro-unit cell, respectively, are calculated by using 3-D CVFEM(control volume finite element method). To avoid checker-board pressure field and improve the efficiency on numerical computation, A new interpolation function for velocity is proposed on the basis of analytic solutions. The permeability of plain woven fabric is measured through unidirectional flow experiment and compared with the permeability calculated numerically. Based on the good agreement of the results, the relationships between the permeability and the structures of preform such as the fiber volume fraction and stacking effect can be understood. The reverse and the simple stacking are taken in account. Unlike past literatures, this study is based on more realistic unit cell and the improved prediction of permeability can be achieved. It is observed that in-plane flow is more dominant than transverse flow in the real flow through preform and the stacking effect of multi-layered preform is negligible. Consequently, the proposed coupled flow model can be applied to modeling of real composite materials processing.

• Journal of Engineering Education Research
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• v.26 no.1
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• pp.3-11
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• 2023

The purpose of this study is to develop Raspberry Pi-based CanSat instruction materials for liberal arts classes to be used in university space education. The educational satellite simulation program is developed by applying the ADDIE program consisting of analysis, design, development, execution, and evaluation of 15 lessons per semester. The usefulness of the instruction materials is evaluated by a validity test of a total of 6 experts. The proposed materials are applied to 100 college students from various majors. To analyze the impact on creative problem-solving ability, a questionnaire is conducted before and after class, and as a result, it is confirmed that there is a significant improvement in all areas after class. The class satisfaction survey is conducted for a total of 10 questions, and the average score is 4.41 out of 5, which is high. In conclusion, the proposed instruction materials make it possible to achieve successful space education using Raspberry Pi and improve creative problem-solving ability in universities.

• The Korean Journal of Nuclear Medicine Technology
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• v.27 no.1
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• pp.23-28
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• 2023

Carbon materials are widely used in many areas of our lives. A fiber having a carbon content of 90% or more obtained by heating an organic fiber precursor is referred to as a "carbon fiber". Carbon fibers are currently used in the medical market to manufacture radiation transmission device parts, artificial joints, and medical aids, as many developments have been made to utilize carbon fibers' characteristics such as light weight, radiation permeability, biocompatibility, high strength, high heat resistance, thermal conductivity, and electrical conductivity. In order to maintain body temperature and increase immunity in long-lasting nuclear medical examination and treatment through the idea of convergence of carbon materials and radiation technology, the quality of medical services can be improved by utilizing carbon materials. We should be aware of the domestic carbon-based medical device industry and make efforts to contribute to the development of medical devices. As a radiation expert, we should try to use our skills and experience to find items that can be fused with medical devices to develop various nuclear medical examination fields and radiographic examination fields that can be widely applied. We should actively engage in future technology development and carbon material research to strengthen the global competitiveness of the domestic medical device industry and improve the quality of medical services.

• Carbon letters
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• v.15 no.2
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• pp.89-104
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• 2014

Materials with appropriate surface roughness and low surface energy can form superhydrophobic surfaces, displaying water contact angles greater than $150^{\circ}$. Superhydrophobic carbon-based materials are particularly interesting due to their exceptional physicochemical properties. This review discusses the various techniques used to produce superhydrophobic carbon-based materials such as carbon fibers, carbon nanotubes, graphene, amorphous carbons, etc. Recent advances in emerging fields such as energy, environmental remediation, and thermal management in relation to these materials are also discussed.