• 한국세라믹학회지
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• 제36권11호
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• pp.1243-1251
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• 1999

Densification behavior and microstructural evolution during the liquid-phase sintering of alumina-anorhite system were investigated as a function of MgO addition. When MgO component was added in either alumina or anorthite glass powder the aspect ratio of alumina grains decreased and concurrently the are of flat interface which was formed as a result of contact solid alumina gains rather increased. Consequently addition of MgO component in the Al2O3-amorthite system brought about suppression of the rearrangement of solid grains during the liquid phase sintering and then densification of specimens was also retarded.

• 헤리티지:역사와 과학
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• 제52권3호
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• pp.240-251
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• 2019

울산 하대고분에서 출토된 판상철부의 미세조직을 금속학적 방법으로 분석하여 제작기술을 살펴보았다. 또한 기존의 판상철부 연구자료와 비교 및 검토하여 판상철부에 적용된 다양한 제작기술을 파악하였다. 울산 하대고분 44호 목곽묘에서 나란히 배열된 상태로 출토된 판상철부 10점을 과학적으로 분석한 결과, 판상철부의 제작기술 체계를 '(1) 순철-형태 가공, (2) 순철-형태 가공-침탄, (3) 순철-형태 가공-침탄-탈탄' 세 가지 유형으로 분류할 수 있었다. 판상철부는 모두 단조에 의해 제작되었고, 순철을 소재로 두드려 형태를 만들었다. 특히 다수의 판상철부는 형태 가공 후 침탄 처리를 통해 재질을 강화시켰는데, 이는 중간 소재 또는 화폐로 통용됨으로써 당시 제철산업의 근간을 이루었던 철강 제품인 것으로 보인다. 한편 형태 가공이나 침탄 이후에는 담금질이 실시되지 않았다는 공통점을 가진다. 순철을 소재로 제작한 판상철부의 미세조직에는 불순 개재물이 다량 포함되어 있고, 비금속 개재물을 성분 분석한 결과, 유리상과 뷔스타이트가 함께 혼재한 철재(鐵滓)의 특징을 보여주므로 제련 공정에서 저온환원법이 적용되었을 가능성이 크다.

• Structural Engineering and Mechanics
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• 제73권6호
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• pp.715-724
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• 2020

The influence on flexural strength of Glass/Epoxy laminated composite curved panels of different geometries (cylindrical, spherical, elliptical, hyperboloid and flat) due to inclusion of nano cenosphere filler examined in this research article. The deflection responses of the hybrid structure are evaluated numerically using the isoparametric finite element technique and modelled mathematically via higher-order displacement structural kinematics. To predict the deflection values, a customised in-house computer code in MATLAB environment is prepared using the higher-order isoparametric formulation. Subsequently, the numerical model validity has been established by comparing with those of available benchmark solution including the convergence characteristics of the finite element solution. Further, a few cenosphere filled hybrid composite are prepared for different volume fractions for the experimental purpose, to review the propose model accuracy. The experimental deflection values are compared with the finite element solutions, where the experimental elastic properties are adopted for the computation. Finally, the effect of different variable design dependent parameter and the percentages of nano cenosphere including the geometrical shapes obtained via a set of numerical experimentation.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.231-236
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• 2004

The area of flat glass panel displays such as LCD (Liquid crystal display) and PDP (Plasma display panel) has been increased more than 2 $\times$ 2 m$^2$ for productivity improvement. However, such a large panel area incurs large panel deflection during panel transfer using robots or AGV (Automated guided vehicle) systems. Therefore, electronic industries are making an effort to find an alternative transfer system for the large glass panels with small deflection. The air conveyor with porous pads is one plausible solution, but it becomes expensive because the large porous pads cost much and air consumption increases as the panel area increases. In this work, a simple air slit levitating conveyor was devised to lower the equipment cost and to reduce the air consumption of system. The air flow model between the LCD glass panel and conveyor was constructed and its validity was verified by experiments. To minimize the air consumption, the conveyor dimensions were optimized, and the air consumptions between the air conveyors with the air slit and that with the porous pad were compared.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1998년도 추계학술대회 논문집
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• pp.53-56
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• 1998

Electroluminescent(EL) devices based on organic materials have been of great interest due to their possible applications for large-area flat-panel displays, where they are attractive because of their capability of multicolor emission, and low operation voltage. In this study, glass substrate/ITO/Eu(TTA)$_3$(Phen)/Al(A), glass substrate/ITO/TPD/Eu(TTA)$_3$(p-hen)/Al(B) and glass substrate/ITO/TPD/Eu(TTA)$_3$(phen)/AlQ$_3$/Al(C) structures were fabricated by vacuum evaporation method. where aromatic diamine(TPD) was used as a hole transporting material, Eu(TTA)$_3$(phen) as an emitting material. and tris(8-hydroxyquinoline)Aluminum(AlQ$_3$) as an electron transporting layer. Electroluminescent(EL) and I-V characteristics of Eu(TTA)$_3$(Phen) with a various thickness were investigated. This structure shows the red EL spectrum, which is almost the same as the PL spectrum of Eu(TTA)$_3$(phen). I-V characteristics of this structure show that turn-on voltage was 9V and current density was 0.01A/$\textrm{cm}^2$ at a dc operation voltage of 9V. Electrical transporting phenomena of these structures was explained using the trapped- charge-limited current model with I-V characteristics.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 춘계학술대회 논문집
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• pp.963-966
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• 2000

Plasma display panel (PDP) is a type of flat panel display utilizing the light emission that is produced by gas discharge. Barrier Ribs of PDP separating each sub-pixel prevents optical and electrical crosstalk from adjacent sub-pixels. Mold for forming barrier ribs has been newly researched to overcome the disadvantages of conventional manufacturing process such as screen printing, sand-blasting and photosensitive glass methods. Mold for PDP barrier ribs have stripes of micro grooves transferring stripes of glass-material wall. In this paper. Stripes of grooves of which width 48 um, depth 124um, pitch 274um was acquired by machining the material of WC with dicing saw blade. Maximum roughness of the bottom and sidewall of the grooves was respectively 120 nm, 287 nm. Maximum tilt angle caused by difference between upper-most width and lower-most width was 2$^{\circ}$. Maximum Radius of curvature of bottom was 7.75 ${\mu}{\textrm}{m}$. This results meets the specification for barrier ribs of 50 inch XGA PDP. Forming the glass paste will be followed by using mold in the near future.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2005년도 International Meeting on Information Displayvol.I
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• pp.583-588
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• 2005

Indium tin oxide (ITO) is a commonly used conducting transparent oxide film (CTO) used in flat panel display applications. Direct write laser ablation is sometimes employed for ITO patterning and it is important that the substrate material and remaining ITO be affected as little as possible by the laser ablation. In this investigation, femtosecond laser ablation of ITO was studied to identify laser processing parameters which cleanly ablated ITO with a minimum of damage to a glass substrate and surrounding ITO. The Ti:Sapphire chirp pulse amplified femtosecond laser used for the experiments had a wavelength of 775nm and produced pulses with a duration of 150fs at a rate of 2 kHz. Ablation was carried out at a sufficiently high panel scanning speed that single ablation spots could be studied. The pulse energy was adjusted to determine feasible spot diameters and depths which could be ablated into the ITO without damaging the glass substrate. Next, ablation of lines without glass damage was also demonstrated. Experiments were also performed with a high repetition rate (100kHz) femtosecond laser.

• 한국전기전자재료학회논문지
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• 제11권10호
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• pp.871-877
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• 1998

Electroluminescent(EL) devices based on organic materials have been of great interest due to their possible applications for large-area flat-panel displays, where they are attractive because of their capability of multicolor emission, and low operation voltage. In this study, glass substrate/ITO/Eu(TTA)$_3$(phen)/Al, glass substrate/ITO/Eu(TTA)$_3$(phen)/Al and glass substrate/ITO/Eu(TTA)$_3$(phen)/AlQ$_3$/Al structures were fabricated by vacuum evaporation method, where aromatic diamine(TPD) was used as a hole transporting material, Eu(TTA)$_3$(phen) as an emitting material, and Tris(8-hydroxyquinoline) aluminu-m(AlQ$_3$) as an electron transporting layer. Electrolumescent(EL) and I-V characteristics of Eu(TTA)$_3$-(-phen) were investigated. These structures show the red EL spectra, which are almost the same at the PL spectrum of Eu(TTA)$_3$(phen). I-V characteristics of this structure show that turn-on voltage was 9V and current density was 0.01A/㎤ at a operation voltage of 9V. Electrical transporting phenomena of these structures were explained using the trapped-charge-limited current model with I-V characteristics.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1998년도 춘계학술대회 논문집
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• pp.317-320
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• 1998

Electroluminescent(EL) devices based on organic materials have been of great interest due to their possible applications for large-area flat-panel displays, where they are attractive because of their capability of multicolor emission, and low operation voltage. In this study, glass substrate/ITO/Eu(TTA)$_3$(Phen)/Al(A), glass substrate/ITO/TPD/Eu(TTA)$_3$(phen)/Al(B) aNd glass substrate/ITO/TPD/Eu(TTA)$_3$(Phen)/A1Q$_3$/Al (C) structures were fabricated by vacuum evaporation method, where aromatic diamine(TPD) was used as a hole transporting material, Eu(TTA)$_3$(phen) as an emitting material, and tris(8-hydroxyquinoline) Aluminum (AlQ$_3$) as an electron transporting layer. Etectroluminescent(EL) and I-V characteristics of Eu(TTA)$_3$(phen) with a various thickness were investigated. This structure shows the red EL spectrum, which is almost the same as the PL spectrum of Eu(TTA)$_3$(phen). I-V characteristics of this structure show that turn-on voltage was 9V and current density was 0.01A/㎤ at a dc operation voltage of 9V. Electrical transporting phenomena of these structures was explained using the trapped-charge-limited current model with I-V characteristics.

• Electronic Materials Letters
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• 제14권6호
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• pp.749-754
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• 2018

Previous studies have reported on the mechanical robustness and chemical stability of flexible amorphous indium gallium zinc oxide (a-IGZO) thin-film transistors (TFTs) on plastic substrates both in flat and curved states. In this study, we investigate how the polyimide (PI) substrate affects hydrogen concentration in the a-IGZO layer, which subsequently influences the device performance and stability under bias-temperature-stress. Hydrogen increases the carrier concentration in the active layer, but it also electrically deactivates intrinsic defects depending on its concentration. The influence of hydrogen varies between the TFTs fabricated on a glass substrate to those on a PI substrate. Hydrogen concentration is 5% lower in devices on a PI substrate after annealing, which increases the hysteresis characteristics from 0.22 to 0.55 V and also the threshold voltage shift under positive bias temperature stress by 2 ${\times}$ compared to the devices on a glass substrate. Hence, the analysis and control of hydrogen flux is crucial to maintaining good device performance and stability of a-IGZO TFTs.