• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.578-580
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• 2008

Blue-emitting $CaAl_2Si_2O_8:Eu^{2+}(CAS:Eu^{2+})$ phosphor, prepared by solid-state reaction, is described in this paper. We researched the effect of boron ion substitution in the host materials. The phase and luminescent properties were investigated using the powder X-ray diffraction(XRD) and photoluminescence(PL) spectra.

• Proceedings of the Korean Magnestics Society Conference
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• 2003.12a
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• pp.86-86
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• 2003

• Proceedings of the Korean Magnestics Society Conference
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• 2014.05a
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• pp.87-87
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• 2014

• 한국전기화학회:학술대회논문집
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• 2004.04a
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• pp.33-33
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• 2004

• Proceedings of the Korean Magnestics Society Conference
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• 2015.11a
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• pp.148-148
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• 2015

• International Journal of Advanced Culture Technology
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• v.8 no.2
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• pp.165-175
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• 2020

The purpose of this study is to examine whether the visual materials presented in the science textbooks coincide with those visual materials that are preferred the most by students. After analyzing the visual materials presented in the unit "Molecular Motion and Change of State" of science textbooks for the first grade of middle school, questionnaires by teaching-learning process are made. Thereafter, students are requested to select those types of visual materials that were preferred by them by process and describe their reasons for the selection. According to the results of the survey of students' perception, students at the high science achievement level prefer those visual materials that were presented conceptually and implicatively, while students at the low science achievement level prefer concrete and detailed visual materials. Except for the learning motivation process, the proportion of non-preferred visual materials is higher in the remaining processes and those visual materials that were presented in the science textbooks are much different from those visual materials that were preferred by students.

• Journal of Powder Materials
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• v.31 no.2
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• pp.137-145
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• 2024

In order to predict the process window of laser powder bed fusion (LPBF) for printing metallic components, the calculation of volumetric energy density (VED) has been widely calculated for controlling process parameters. However, because it is assumed that the process parameters contribute equally to heat input, the VED still has limitation for predicting the process window of LPBF-processed materials. In this study, an explainable machine learning (xML) approach was adopted to predict and understand the contribution of each process parameter to defect evolution in Ti alloys in the LPBF process. Various ML models were trained, and the Shapley additive explanation method was adopted to quantify the importance of each process parameter. This study can offer effective guidelines for fine-tuning process parameters to fabricate high-quality products using LPBF.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.547-548
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• 2006

The main object of this research was to examine the effect of sintering conditions on the microstructure of tungsten heavy alloys and how the resulting modification of the microstructure can be used to optimize their mechanical properties. Alloys composed of 88%, 93% and 95% wt. of tungsten and the balance is Ni: Fe in the ratio of 7:3 were sintered at different temperatures for different sintering holding times in hydrogen atmosphere. It was shown that the mechanical properties of the alloys, and especially their ductility, are harmed when tungsten grains are contiguous.

• Journal of the Korean Physical Society
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• v.73 no.9
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• pp.1279-1282
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• 2018

This paper reports the deposition of a metal line using a multilayer stack and laser-induced forward transfer (LIFT) using a low cost continuous wave blue laser with a wavelength of 450 nm. The donor structure was composed of a light-to-heat (LTH) layer, a release layer, and a transfer layer in series. Amorphous silicon as the LTH layer absorbs photon energy and converts it to heat. A release layer was melted so that a silver transfer layer would be transferred to the receiver substrate. The transferred silver layer showed reasonable physical and electrical characteristics. A low cost fine linewidth metal layer could be achieved using this modified LIFT technique and blue laser.

• Carbon letters
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• v.16 no.4
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• pp.223-232
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• 2015

This review presents current progress in the preparation methods of liquid crystalline nano-carbon materials and the liquid crystalline spinning method for producing nano-carbon fibers. In particular, we focus on the fabrication of liquid crystalline carbon nanotubes by spinning from superacids, and the continuous production of macroscopic fiber from liquid crystalline graphene oxide.