• Proceedings of the KIEE Conference
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• 2003.07c
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• pp.1424-1426
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• 2003

PMN-PZT 적충형 세라믹 액츄에이터 소자를 제작한후 그 열화 특성을 조사하였다. 액츄에이터는 tape casting 방법으로 green sheet를 제작한후, screen printing방법을 이용하여 전극형상을 만들고, lamination과 cutting공정을 통하여 소자를 제작하였다. 작된 소자의 구조적인 특성을 분석하기 위하여 X-ray diffractometer를 사용하였으며, Doppler effect를 사용하는 laser vibrometer를 이용하여 전압에 따른 변위량을 측정하였다. 제작된 소자의 열화 특성을 알아보기 위하여 60 Hz의 triangular 교류 파형을 적충형 세라믹 액츄에이터에 인가하여 열화전과 후의 P-E hysteresis loop의 변화를 살펴보았으며, unipolar AC 전압을 지속적으로 인가하여 소자를 depling 시킴으로써 열화현상을 관찰하였다. 파단면에 대한 SEM 분석을 통하여 소자의 파괴 메카니즘을 알아 보도록 하였다. 이로부터 전기적, 기계적 열화가 소자의 동작에 미치는 영향에 대해서 알아 보았다.

• Proceedings of the Korea Multimedia Society Conference
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• 2003.05b
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• pp.464-467
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• 2003

본 논문에서는 체적 데이터에 대한 효율적인 볼륨 랜더링을 수행하기 위해서, 기존의 광선 추적 기법에 광선 보간을 통해 광선을 추적하는 기법인 IRCF를 제안한다. IRCF 과정은 이웃 화소에 대해 광선추적을 통해서 얻은 불투명도의 정보를 이용하여 보간한 위치에서 새롭게 광선추적을 해가는 방식이다 기존의 광선 추적 랜더링의 경우 고화질의 영상을 얻지만, Volume Rendering Operations의 계샨량이 많아 랜더링 속도가 떨어져 현재 개선된 랜더링 기법들이 많이 제안되고 있는 실정이다. 본 논문은 다른 각도로의 접근하고자 하여 제안한 IRCF 과정을 통해 Volume Rendering Operations의 계샨량을 최대한 줄여 랜더링 속도를 높이고 기존 방식의 고화질 영상에 가깝게 결과를 얻을 수가 있었다. 또한, 본 논문에서는 기존의 광선 추적 기법에서 표현하는 일반적인 회전, 절단, 불투명 등 제어 효과들을 제안한 기법을 통해 비교 분석한다.

• Journal of the Korean Society for Heat Treatment
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• v.34 no.6
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• pp.281-286
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• 2021

Arc ion plating (AIP), laser cladding, and nitriding are methods that can prevent mold damage or repair and create cracks and breakages on the die surface. The dissolution and soldering behavior of coated SKD61 by using arc ion plating, laser cladding, and nitriding was investigated. The structure of the coating was investigated as a function of deposition conditions by X-ray diffraction and the crystallographic orientation was determined using the texture factor. The TiAlN film deposited with AIP showed excellent corrosion resistance in the molten aluminum alloy at 680℃. In this paper, we have detailed the corrosion and mass loss phenomena associated with these steel-cast metal interactions.

• Journal of Environmental Science International
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• v.33 no.5
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• pp.297-304
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• 2024

PM (Particulate Matters) was collected from a bag filter dust collector at an aluminum foundries, and its physicochemical properties were investigated using particle size analyzer and scanning electron microscopy with energy dispersive X-ray spectrometer (SEM/EDS). The median volume diameter of the particles passing through the pretreatment dust collector of the cyclone was approximately 10 ㎛. The cyclone pretreatment dust collector was shown to significantly reduce the throughput of large particles with a particle size of 100 ㎛ or more. The chemical composition of the particles showed a high Al content, and trace amounts of Mg, Si, and Zn were detected.

• Conservation Science in Museum
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• v.24
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• pp.17-36
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• 2020

This paper describes the consevation treatment of eleven bigyeokjincheolloe bomb shells that were excavated from the Joseon-period local government office and fortress of Mujang-hyeon (present-day Mujang-myeon) in Gochang in 2018. It also provides information on the production method of the shells revealed through CT scanning, gamma-ray transmission imaging, and metallographic analysis. In preparation for the special exhibition "Bigyeokjincheolloe" at the Jinju National Museum in 2019 (July 16 to August 25), contaminants were removed from the shells and their surface was reinforced during the first phase of conservation treatment. Furthermore, the closures for the shells were identified for the first time. Regarding the production of the shells, the CT scanning and gamma-ray transmission imaging identified many blowholes in the interior of the body and the use of a chaplet on the side of one shell. The side of the body proved to be relatively thinner than the top and bottom. The traces of a hole for pouring molten metal into the center of the bottom indicates that molten metal was indeed emptied into the inverted body. In the metallographic analysis of two of the bodies and one lid, cementite and pearlite structures were identified on the body, indicating that it was made by casting. The presence of the ferrite structure with a partial distribution of the pearlite along with non-metallic inclusion in the lid suggested that the lid was made by forging.

• Journal of Korea Foundry Society
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• v.24 no.1
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• pp.40-44
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• 2004

The influence of Pd and Ag additions on the thermal stability, the glass forming ability (GFA) and mechanical property of $Zr_{55}Al_{10}Cu_{20}Ni_{10}Pb_{(5-x)}Ag_x$ (x = $0{\sim}5at%$) alloys obtained by melt spun and injection casting method have been investigated by using of X-ray diffraction, thermal analysis (DTA, DSC) and micro-Vickers hardness(Hv) testing. The thermal properties of melt-spun $Zr_{55}Al_{10}Cu_{20}Ni_{10}Pb_{(5-x)}Ag_x$ (x = $0{\sim}5at%$) alloys exhibit a supercooled liquid region(${\Delta}T_x$) exceeding 91 K before crystallization. The largest ${\Delta}T_x$ reaches as large as 126 K for the $Zr_{55}Al_{10}Cu_{20}Ni_{10}Pb_5$ alloy. The reduced glass transition temperature, $T_{rg}$ increased with increasing Ag content. The largest $T_{rg}$ is obtained for the $Zr_{55}Al_{10}Cu_{10}Ni_{10}Ag_5$ alloy. The $Zr_{55}Al_{10}Cu_{10}Ni_{10}Ag_5$ bulk amorphous alloy rod with 3 mm in diameter was fabricated by injection casting. Hv increased with increasing Ag content and the largest value was obtained for the $Zr_{55}Al_{10}Cu_{10}Ni_{10}Ag_5$ bulk amorphous alloy.

• Polymer(Korea)
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• v.39 no.1
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• pp.40-45
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• 2015

Simple poor-cosolvent casting was used to surface treat biodegradable elastic poly(L-lactide-co-${\varepsilon}$-caprolactone) (PLCL; 50:50) copolymer films that presented lotus-leaf-like structures. We evaluated whether the lotus-leaflike-structured PLCL (L-PLCL) films could be used as a biomaterial for artificial vascular grafts. The surface morphology, hydrophobicity, and antithrombotic efficiency of the films were examined while immersed in platelet-rich plasma (PRP) using scanning electron microscopy (SEM) and a contact angle meter. The recovery and crystallinity of the films were measured using a tensile-strength testing machine and an X-ray diffractometer, respectively. The solvent containing acetic acid, as a poor co-solvent, and methylene chloride mixed in a 1:2 ratio produced an optimal PLCL film with a water contact angle of approximately $124^{\circ}$. Furthermore, the surface of the L-PLCL films immersed in PRP showed a lower rate of platelet adhesion (<10%) than that of the surface of an untreated PLCL film immersed in PRP.

• Journal of Technologic Dentistry
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• v.28 no.1
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• pp.27-41
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• 2006

The physical property and phase transformation in a commercial dental casting high gold alloy was investigated as a function of ageing temperature and time using microvickers hardness tester, X-ray diffraction, optical and electron microscopy and EPMA analyser. 1. With increasing ageing time, the hardness of solution-treated gold alloys increased slowly at the initial stage of ageing treatment at an ageing temperature of $300{\sim}400^{\circ}C$, and it reached a maximum value of hardness at the medium stage. Finally, it decreased gradually during further ageing. The maximum value of hardness at was similar with that of the conventional materials and suitable for using as the crown & bridge. 2. During isothermal ageing at a temperature range of $300{\sim}400^{\circ}C$, three phases consisting of the Au-rich ${\alpha}_1$phase with a face-centered cubic structure, the Pt3Zn ${\alpha}_2$phase with an ordered AuCu3(L12) type(f.c.c.) and the Pt-rich ${\alpha}_3$phase with face-centered cubic structure in solution-treated gold alloys were transformed into different three phases consisting of the ${\alpha}_1$phase, the ${\alpha}_3$phase and the PtZn $\beta$phase with an ordered AuCu I(L10) type. 3. The hardening of gold alloys was attributed to the lattice strains of the matrix resulting from the transformation of the ${\alpha}_2$phase to the $\beta$phase. 4. The softening of gold alloys during over-ageing was attributed to the coarsening of the nodules consisting of the $\beta$phase and ${\alpha}_1$matrix.

• Journal of Korea Foundry Society
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• v.30 no.6
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• pp.231-234
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• 2010

The effect of $C_2Cl_6$ for preventing to the surface oxidation and ignition of molten Mg alloy was studied with metallographic analysis, X-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy. The alloy used for this study was AM100A Mg casting alloy with high strength. In order to investigate the surface protective characteristic of this molten alloy by $C_2Cl_6$ addition, we added them into molten AM100A alloy at $700^{\circ}C$ and then the melts were slowly cooled under a protective atmosphere of air containing Ar gas and $C_2Cl_6$ flux addition. The result found that the surface oxidation and ignition reaction of molten AM100A Mg alloy by adding $C_2Cl_6$ flux was more slowly occurred than that of the only a protective atmosphere of containing Ar gas with increasing time. This result was due to a dense protective film formed containing $MgCl_2$ on surface of molten Mg alloy during casting and solidification. The $MgCl_2$ was formed by a reaction of $C_2Cl_6$ with molten Mg.

• Polymer(Korea)
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• v.33 no.4
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• pp.313-318
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• 2009

Copolyimides were synthesized from bis (3-aminophenyl) sulfone (APS) and 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) containing a fluorine substituent ($-CF_3$) with different mole ratios of 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride (DSDA) containing a sulfone group (-$SO_2$-). The PI films were obtained from poly (amic acid) (PAA) by solution casting through thermal imidization on a glass plate. Wide-angle X-ray diffraction (XRD), scanning electron microscopy (FE-SEM), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), universal tensile machine (UTM) measurements, and UV-Vis spectrometry were used to assess thermo-mechanical properties, morphology, and optical transparency. Thermal properties and optical transparency decreased with increasing DSDA mole fraction. In contrast, mechanical properties increased with increasing DSDA mole fraction. As compared to conventional PI films, however, the PI copolymer films in this work were found to exhibit better optical transparency.