• IEIE Transactions on Smart Processing and Computing
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• 제4권5호
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• pp.318-323
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• 2015

We present a new way to create a thermally stable, highly strained germanium (Ge) optical resonator using a novel Ge-on-dual-insulators substrate. Instead of using a conventional way to undercut the oxide layer of a Ge-on-single-insulator substrate for inducing tensile strain in germanium, we use thin aluminum oxide as a sacrificial layer. By eliminating the air gap underneath the active germanium layer, we achieve an optically insulating, thermally conductive, and highly strained Ge resonator structure that is critical for a practical germanium laser. Using Raman spectroscopy and photoluminescence experiments, we prove that the novel geometry of our Ge resonator structure provides a significant improvement in thermal stability while maintaining good optical confinement.

• 한국태양에너지학회 논문집
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• 제32권4호
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• pp.43-50
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• 2012

Metal-metal oxide (M-M oxide) cermet solar selective coatings with a double cermet layer film structure were deposited on the Al-deposited glass substrate by using a directed current (DC) magnetron sputtering technology. M oxide (CrO and ZrO) was used as the ceramic component in the cermets, and Cr and Zr used as the metallic components. In addition, black Cr (Cr-$Cr_2O_3$ cermet) solar selective coatings were deposited on the Ni-plated Cu substrate by using a electroplating method for comparison. The thermal stability tests were carried out for performance evaluation of solar coatings. Reflectance measurements were used to evaluate both solar absorptance(${\alpha}$) and thermal emittance (${\epsilon}$) of the solar coatings before and after thermal testing by using a spectrometer. Optical properties of optimized cermet solar coatings were ${\alpha}{\simeq}0.94-0.96$ and ${\epsilon}{\simeq}0.1$ ($100^{\circ}C$). The results of thermal stability test of M-M oxide solar coatings showed that the Cr-CrO cermet solar selective coatings were more stable than the Zr-ZrO cermet selective coatings at temperature of both $400^{\circ}C$ in air and $450^{\circ}C$ in vacuum. The black Cr solar selective coatings were degraded in air at temperature of $400^{\circ}C$. The main optical degradation modes of these coatings were diffusion of metal atoms, and oxidation.

• Bulletin of the Korean Chemical Society
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• 제16권4호
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• pp.326-331
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• 1995

Poly(enaryloxynitriles) containing Schiff bases were prepared from p-bis(1-chloro-2,2-dicyanovinyl)benzene (2) and various aromatic diols having Schiff base moiety by interfacial polymerization. The chemical structure of the polymers was confirmed through synthesis of their corresponding model compounds. All the polymers were soluble in polar aprotic solvents and their brittle films were cast from DMF solution. They showed a large exotherm around 340 ℃ attributable to the chemical change of dicyanovinyl group. Especially, curing of azomethine group was observed to occur at 390 ℃ by differential scanning calorimetry. According to the thermogravimetric analyses, they exhibited excellent thermal stability with 60-90% residual weight at 500 ℃ in nitrogen.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.1047-1050
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• 2009

The two approaches to improve the stability of oxide TFTs are described. First approach is the optimization of device architecture including MIS structure and passivation layer using conventional InGaZnO semiconductor channel layer. Second approach is to develop the new kinds of oxide semiconductor materials, which is very robust and stable against the gate bias stress and thermal stress.

• 한국결정성장학회지
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• 제8권4호
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• pp.660-666
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• 1998

Li-GFICs, Li-PCICs의 intercalation 과정에 있어서 구조, 화합물의 에너지 상태, 열적 분해 특성, 전기적 성질에 미치는 영향에 대하여 토론하였다. X-선 회절 분석에 의하면 Li-CFICs는 주로 2 stage가 형성되었고 Li-PCICs는 1 stage와 2 stage가 주된 회절선으로 타나났다. Li-AGIC의 경우 지배적으로 1 stage의 구조가 나타났지만 순수한 1 stage의 화합물은 얻을 수가 없었지만 인조 흑연의 구조적 특성 때문으로 예상할 수 있다. 화합물의 에너지 상태를 측정한 결과 여러 가지 탄소물질의 층간 삽입 성질이 이들의 구조와 관련이 있으므로 Li-AGCIs와 Li-GFICs가 에너지적으로 가장 안정한 상태를 보이고 있다. 따라서 Li-CICs중 이들 두가지 화합물은 에너지 저장재로써 적합성을 제시할 수 있다. Li-GFICs에 대하여 열분해에 의한 분석을 한 결과 $300^{\circ}C$에서와 $400^{\circ}C$ 부근에서 강한 발열반응을 보이고 있다. Li-AGIC에 대하여 열적 변이가 일어나는 동안에 열적 안정성과 리튬의 발산 과정을 살펴본 결과, 각각의 온도에서 화합물은 완전한 deintercalation이 일어나지 않고 고온에서도 고차 stage가 유지되었다. 충전 방전특성을 알아본 결과 흑연섬유를 적극물질로 사용하였을 경우 비교적 안정성을 보였고 특성이 우수하게 나타났음을 알 수 있다.

• 펄프종이기술
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• 제44권1호
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• pp.1-9
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• 2012

In this study, 5 solvent soluble polymers were treated on Hanji. Mechanical properties, morphology and oxidation index with thermal aging were measured on the aged Hanji, dewaxed Hanji and polymer treated Hanji. Synthetic polymers(such as polylactic acid, polybutylene succinate, polystyrene) treated Hanji had higher strength and thermal stability than cellulose derivatives(such as cellulose nitrate and cellulose acetate) treated Hanji. Polymer treated Hanji showed a little bit of color change. The oxidation index of PS treated Hanji did not increase with thermal aging because it did not have a carboxyl group in chemical structure. Finally, polystyrene was found to be the most efficient method for strengthening the dewaxed Hanji. The best aging safety and thermal stability were obtained at the polystyrene 3% solution.

• 한국결정성장학회지
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• 제29권1호
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• pp.19-23
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• 2019

The PMMA (polymethyl methacrylate)/clay nanocomposites were synthesized by in situ radical polymerizations with different clay contents (3 and 7 wt%) using microwave heating. The nanostructure, optical, and thermal properties of the synthesized PMMA/clay nanocomposites were measured by XRD, TEM, AFM, UV-vis, and TGA. It was found that the intercalated- or exfoliated structure of PMMA/clay nanocomposites was strongly dependent on the content of clay. Thus, the imposition of microwave-assisted polymerization facilitated a delamination process of layered silicates to achieve exfoliation state of interlayer distance. The PMMA/3 wt% C10A nanocomposite with well-dispersed and exfoliated clay nano-layers showed the good optical transparency similar to pure PMMA in this study. The thermal decomposition rates of the PMMA/clay nanocomposites become to be lower compared to that of the pure PMMA, indicating the intercalated- or exfoliated inorganic silicate has high thermal stability. A possible reason is that the thermally segmental motion of PMMA polymer into inorganic silicate interlayer spacing has increased the thermal stability of the PMMA/clay nanocomposites.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.204.2-204.2
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• 2014

Among various metal oxides, ZrO2 is of particular interests and has received widespread attention thanks to its ideal mechanical and chemical stability. As a cheap metal, Ag nanoparticles are also widely used as catalysts in ethylene epoxidation and methanol oxidation. However, the nature of Ag-ZrO2 interfaces is still unknown. In this work, the growth, interfacial interaction and thermal stability of Ag nanoparticles on ZrO2(111) film surfaces were studied by low-energy electron diffraction (LEED), synchrotron radiation photoemission spectroscopy (SRPES), and X-ray photoelectron spectroscopy (XPS). The ZrO2(111) films were epitaxially grown on Pt(111). Three-dimensional (3D) growth model of Ag on the ZrO2(111) surface at 300 K was observed with a density of ${\sim}2.0{\times}1012particles/cm2$. The binding energy of Ag 3d shifts to low BE from very low to high Ag coverages by 0.5 eV. The Auger parameters shows the primary contribution to the Ag core level BE shift is final state effect, indicating a very weak interaction between Ag clusters and ZrO2(111) film. Thermal stability experiments demonstrate that Ag particles underwent serious sintering before they desorb from the zirconia film surface. In addition, large Ag particles have stronger ability of inhibiting sintering.

• 한국수소및신에너지학회논문집
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• 제30권2호
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• pp.128-135
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• 2019

In this study, the mesoporous $SiO_2$ (5, 10, or 15 wt%) was incorporated into the polybenzimidazole matrix in order to improve the proton conduction as well as physiochemical properties of composite membrane. The chemical structure of mesoporous $SiO_2$ and crystallinity of as-prepared membranes were analyzed by Fourier-transform infrared (FT-IR) spectroscopy and X-ray diffraction (XRD) analysis, respectively. The thermal stability of the pristine $X_1Y_9$ and composite membranes were evaluated by thermogravimetric analyzer (TGA). On other side, the physical and chemical properties of the pristine $X_1Y_9$ and composite membranes were also determined by acid uptake and oxidative stability tests, respectively. With the incorporation of 15 wt% $SiO_2$, the composite membrane exhibits the higher proton conductivity that may be applicable for non-humidified high temperature fuel cell applications.

• 환경영향평가
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• 제32권6호
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• pp.473-487
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• 2023

1970~1980년대 준공된 우리나라의 다목적댐 저수지에는 발전방류를 위한 고정식 취수구가 심층에 설치되어 있어 일부 댐 하류에서는 냉수 방류에 의한 농작물 냉해, 안개 일수 증가 등의 문제점이 제기된 바 있다. 본 연구에서는 고정식 취수구를 통해 심층 취수가 이루어지고 있는 합천호를 대상으로 취수 수심이 저수지의 수온 성층 구조와 방류 수온에 미치는 영향을 분석하였다. 3차원 수리수질모형인 AEM3D를 이용하여 합천호의 연직 수온 분포를 재현하고 계절별 수온성층 구조를 분석하였으며, 수문 조건에 따른 수온성층 변화를 비교 분석하기 위하여 풍수해와 갈수해를 대상으로 모델링 하였다. 또한 취수심 변경 시나리오를 적용함으로써 취수 수심이 수온성층 구조에 미치는 영향을 분석하였다. 모의 결과 심층 취수를 표층 취수로 변경할 경우 수온약층의 형성 위치가 풍수해 6.5 m, 갈수해 6.8 m 감소하여 더 얕은 수심에 형성될 것으로 분석되었다. 또한 수체 안정도 지수인 Schmidt Stability Index (SSI)와 Buoyancy frequency (N²)가 증가하여 수온성층 강도가 증가하는 것으로 나타났다. 표층 취수시 연평균 방류수온이 풍수해 3.5℃, 갈수해 5.0℃ 증가하여 하류하천의 영향은 감소하나, 호내의 저수온층 수체적과 수온성층 강도가 증가하므로 추후 수질관리를 위해 취수심을 댐 운영의 주요인자로 고려해야 할 것으로 판단된다.