• Transactions on Electrical and Electronic Materials
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• 제11권4호
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• pp.186-189
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• 2010

Nano-sized MgO single crystal powders have recently been reported to emit ultraviolet by stimulation of electrons in a vacuum. In this study, nanocrystalline MgO powders were applied to a xenon plasma flat fluorescent lamp (FFL) for a liquid crystal display backlight to improve its emission efficiency through the extra ultraviolet from the nano-MgO crystals. For comparison, a MgO nano-thin film was applied directly on the phosphors inside a lamp panel through e-beam evaporation. Adding MgO nano-crystal powders to the phosphors improved the luminance and efficiency of FFLs by around 20% and MgO nano-crystal coverage of 40% of the phosphor provided the best FFL emission characteristics; however, application of MgO thin film to the phosphors degraded the emission characteristics, even compared to FFLs without MgO. This was due to insufficient ultraviolet stimulation of the phosphors and the crystallinity and low secondary electron coefficient of the MgO.

• 한국세라믹학회지
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• 제53권6호
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• pp.610-614
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• 2016

Tyranno SA (SiC-polycrystalline fiber, Ube Industries Ltd.) shows excellent heat-resistance up to $2000^{\circ}C$ with relatively high mechanical strength. This fiber is produced by the conversion process from a raw material (amorphous Si-Al-C-O fiber) into SiC-polycrystalline fiber at very high temperatures over $1500^{\circ}C$ in argon. In this conversion process, the degradation reaction of the amorphous Si-Al-C-O fiber accompanied by a release of CO gas for obtaining a stoichiometric composition and the subsequent sintering of the degraded fiber proceed. Furthermore, vaporization of gaseous SiO, phase transformation and active diffusion of the components of the Si-Al-C-O fiber competitively occur. Of these changes, vaporization of the gaseous SiO during the conversion process results in an abnormal SiC-grain growth and also leads to the non-stoichiometric composition. However, using a modified Si-Al-C-O fiber with an oxygen-rich surface, vaporization of the gaseous SiO was effectively prevented, and then consequently a nearly stoichiometric SiC composition could be obtained.

• E2M - 전기 전자와 첨단 소재
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• 제7권4호
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• pp.306-311
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• 1994

In this study, the influence of the powder sintering, the 2nd sinteiing and the grinding time on the Superconducting properties in the Bi(Pb)SiCaCuO Superconductor has been studied. From the analysis of SEM and XRD patterns, it was known that the sample prepared by the process of powder sintering has a porous microstructure with the critical temperature(Tc) below 77K, while the sample prepared by the 2nd sintering has a highly oriented microstructure with the Tc above 100K. The Critical Current Density(Jc) of the sample prepared by the 2nd sintering was better than the sample prepared by the process of powder sinteiing, but it's Jc, was low in practical use. Also, the effect of grinding time from 0[min] to 120[min] was investigated. As the grinding time is increased, the samples degraded from high-Tc phase to low-Tc phase and nonsuperconducting phases.

• 대한기계학회논문집A
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• 제21권6호
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• pp.971-980
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• 1997

This study is to investigate the stiffness degradation of a composite laminated panel including transverse matrix cracks subjected to bending and twisting moments. Micromechanics theory on the composite material is derived by introducing crack density. Iterative numerical scheme is developed to calculate the degraded composite stiffness which has nonlinear relation due to the crack density. The finite element method is used for structural analysis of the composite panel. Structural responses of the composite panel are examined for various laminated angles and crack density under the bending and twisting moments. Also, the effect of crack opening and closing is considered in the examination. It is realized that the matrix cracks may cause severe stiffness reduction and should be considered in the composite laminated panel.

• 한국추진공학회지
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• 제8권4호
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• pp.36-42
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• 2004

고성능 액체로켓엔진 연소기 개발을 위해 연소기 챔버 재료로 사용되는 크롬동 소재에 대해서 인장시험을 수행하고 재료 물성치를 확보하였다. 확보한 크롬동 재료 물성치를 이용하여 구조해석을 수행해서 재생냉각형 연소기 시편을 설계하였다. 설계한 시편을 연소기 챔버 제작 공정과 동일한 공정으로 제작 후 강도 시험을 수행하여 시편의 항복압력과 파손 압력을 얻을 수 있었다. 크롬동 소재는 브레이징 후에는 상당한 기계적 물성 저하가 있었고 구조 해석을 통해 예측한 항복 압력이 실제 시험한 결과와 거의 같게 나타났다. 강도 시험 결과에서는 유로 연결부가 유로부보다 먼저 항복과 파손이 일어났다.

• 반도체디스플레이기술학회지
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• 제9권4호
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• pp.25-29
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• 2010

We have investigated the effect of surface roughness of TCO substrate on the characteristics of OLED (organic light emitting diodes) devices. In order to control the surface roughness of AZO thin films, we have processed photo-lithography and reactive ion etching. The micro-size patterned mask was used, and the etching depth was controlled by changing etching time. The surface morphology of the AZO thin film was observed by FESEM and atomic force microscopy (AFM). And then, organic materials and cathode electrode were sequentially deposited on the AZO thin films. Device structure was AZO/${\alpha}$-NPD/DPVB/$Alq_3$/LiF/Al. The DPVB was used as a blue emitting material. The electrical characteristics such as current density vs. voltage and luminescence vs. voltage of OLED devices were measured by using spectrometer. The current vs. voltage and luminance vs. voltage characteristics were systematically degraded with increasing surface roughness. Furthermore, the retention test clearly presented that the reliability of OLED devices was directly influenced with the surface roughness, which could be interpreted in terms of the concentration of the electric field on the weak and thin organic layers caused by the poor step coverage.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2013년도 춘계 학술논문 발표대회
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• pp.313-314
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• 2013

The study carried out the experiment with presenting as the fundamental data for developing non-cement by using red mud generated in blast furnace slag and bauxite generated in the process of manufacturing the pig iron process of manufacturing Al(OH)₃/Al₂O from as the binding material using the accelerator of NaOH. After fixing the thing and the NaOH adding the blast furnace slag and NaOH 10, 20, 30 (%) with 10, 20, 30 (%) substituted the red mud in the blast furnace slag and the experimental method carried out the experiment. And it measured the flexural strength and compressive strength and took a photograph EDS analysis and SEM. Consequently, the compressive strength was improved as the addition rate of the NaOH was high and the compressive strength according to the replacement ratio of the red mud was degraded. This is determined that film of the blast furnace slag is destroyed and it makes the hydration reaction condition and the intensity is revealed.

• E2M - 전기 전자와 첨단 소재
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• 제8권6호
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• pp.727-736
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• 1995

This paper examines the characteristics and physical properties of the scaled MONOS nonvolatile memory device for low programming voltage EEPROM. The capacitor-type MONOS memory devices with the nitride thicknesses ranging from 41.angs. to 600.angs. have been fabricated. As a result, the 5V-programmable MONOS device has been obtained with a 20ms programming time by scaling the nitride thickness to 57.angs. with a tunneling oxide thickness of 19.angs. and a blocking oxide thickness of 20.angs.. Measurement results of the quasi-static C-V curves indicate, after 10$\^$6/ write/erase cycles, that the devices are degraded due to the increase of the silicon-tunneling oxide interface traps. The 10-year retention is impossible for the device with a nitride less than 129.angs.. However, the MONOS memory device with 10-year retentivity has been obtained by increasing the blocking oxide thickness to 47.angs.. Also, the memory traps such as the nitride bulk trap and the blocking oxide-nitride interface trap have been investigated by measuring the maximum flatband voltage shift and analyzing through the best fitting method.

• E2M - 전기 전자와 첨단 소재
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• 제10권1호
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• pp.33-38
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• 1997

The green emitting phosphors of the Field Emission Display(FED), Al codoped ZnGa$_{2}$O$_{4}$:Mn, were synthesized and sintered at high temperature. From X-ray diffraction measurements, it was confirmed that poly crystalline ZnGa$_{2}$O$_{4}$ and ZnAI$_{2}$O$_{4}$ solid solution coexist in Al codoped ZnGa$_{2}$O$_{4}$:Mn. Photoluminescence spectra of Al codoped ZnGa$_{2}$O$_{4}$:Mn show that the main peak position is shifted from 504 nm to 513 nm with the increase of Al concentration. The brightness was improved with the amount of Al dopant. It showed the maximum value at the doping level of 0.03 mole and then, it degraded rapidly. These results are due to the superposition of emission from . ZnGa$_{2}$O$_{4}$:Mn and ZnAI$_{2}$O$_{4}$:Mn.

• Transactions on Electrical and Electronic Materials
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• 제17권1호
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• pp.25-28
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• 2016

We investigate the effect of interface states on the endurance of a charge trap flash (CTF) NOR array using charge pumping methods. The endurance test was completed from one cell selected randomly from 128 bit cells, where the memory window value after 10² program/erase (P/E) cycles decreased slightly from 2.2 V to 1.7 V. However, the memory window closure abruptly accelerated after 10³ P/E cycles or more (i.e. 0.97 V or 0.7 V) due to a degraded programming speed. On the other hand, the interface trap density (Nit) gradually increased from 3.13×10¹¹ cm⁻² for the initial state to 4×10¹² cm⁻² for 10² P/E cycles. Over 10³ P/E cycles, the Nit increased dramatically from 5.51×10¹² cm⁻² for 10³ P/E cycles to 5.79×10¹² cm⁻² for 10⁴ P/E cycles due to tunnel oxide damages. These results show good correlation between the interface traps and endurance degradation of CTF devices in actual flash cell arrays.