• 한국전기전자재료학회논문지
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• 제19권8호
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• pp.749-753
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• 2006

The $ZnGa_2O_4$ phosphor thick films were fabricated using a screen printing method on Si(100) substrates at various sintering temperatures. The XRD patterns show that the $ZnGa_2O_4$ thick films have a (311) main peak and a spinel structure with increasing sintering temperatures. The particle sizes of $ZnGa_2O_4$ phosphor were about 100 nm and the thickness of $ZnGa_2O_4$ thick film was $10{\mu}m$. The CL and PL properties of $ZnGa_2O_4$ showed main peak of 420nm and maximum intensity at the sintering temperature of $900^{\circ}C$. These results indicate that $ZnGa_2O_4$ phosphor thick films hold promise for displays such as plasma display panel and field emission display.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.1299-1302
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• 2004

A real object duplication system (RODS), including three dimensional (3D) scanner and solid freeform fabrication system (SFFS), is a device to make three-dimensional objects directly from the drawing or photo data. A Selective Multi-Laser Sintering (SMLS) process designed in this paper is by which computer images received using 3D scanner are built up from polymer powder on building room of large size using dual laser at industrial type SFF system. Using the process can rapidly produce real object duplication components of industrial type such as cylinder, engine block, chassis of automobile, etc. In this paper, the industrial type SFF system using SMLS process is manufactured and the system is satisfied with high precision and high speed processing technique. To research characteristics of each part for theindustrial type SFF system, a structure and thermal analysis and test of each part is carried out. Also, to achievement of high performance for industrial type SFF system, design and fabrication for the structure, heater, nitrogen supply, laser and control part are carried out.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.1347-1352
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• 2004

In this work, $TiO_{2}$ nanoparticles were synthesized using a $N_{2}-diluted$ hydrogen coflow diffusion flame. The effect of flame temperature on the crystalline structure and the size of formed nanoparticles was investigated. The maximum centerline temperature of the flame ranged from 1,920K for $H_{2}-only$ flame to 863K for 81% $N_{2}-diluted$ flame. When the temperature was higher than about 1,000K, the particle size was tend to increase due to the agglomeration and sintering among the primary particles. On the other hand, when the temperature was lower than 1,000K, the portion of anatase phase was greater than 80%.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2010년도 제39회 하계학술대회 초록집
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• pp.294-294
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• 2010

Over the last decade, dye-sensitized solar cell (DSSC) has attracted much attention due to the high solar-to-electricity conversion efficiency up to 10% as well as low cost compared with p-n junction photovoltaic devices. DSSC is composed of mesoporous TiO2 nanoparticle electrodes coated with photo-sensitized dye, the redox electrolyte and the metal counter electrode. The performances of DSSC are dependent on constituent materials and interface as well as device structure. Replacing the heavy glass substrate with plastic materials is crucial to enlarge DSSC applications for the competition with inorganic based thin film photovoltaic devices. One of the biggest problems with plastic substrates is their low-temperature tolerance, which makes sintering of the photoelectrode films impossible. Therefore, the most important step toward the low-temperature DSSC fabrication is how to enhance interparticle connection at the temperature lower than $150^{\circ}C$. In this talk, the key issues for high efficiency plastic solar cells will be discussed, and several strategies for the improvement of interconnection of nanoparticles and bendability will also be proposed.

• 한국세라믹학회지
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• 제34권8호
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• pp.834-842
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• 1997

Controlled Ca impurity implanted inner crack-like pore in the high purity alumina single crystal, sapphire, had been created by micro-fabrication technique, which includes ion implantation, photo-lithography, Ar ion milling, and hot press technique. The morphological change and the healing of cracklike pore in Ca doped high purity single crystal alumina, sapphire, during high temperature heat treatment in vacuum were observed using optical microscopy. The dot-like surface roughening was developed and hexagon like crystal appeared on inner surface of crack-like pore after heat treatment. Bar type crystals, probably CaO.6Al2O3, were observed on the inner surface after 1 hour heat treatment at 1, 50$0^{\circ}C$, but this bar type crystal disappeared after 1 hour heat treatment at 1, $600^{\circ}C$. This disappearance means that there should be a little increase of Ca solubility limit to alumina at this temperatures.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2011년도 춘계학술발표대회
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• pp.42.2-42.2
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• 2011

$TiO_2$ films were modified by adding a glass frit as a light scattering particle and applied to an anode electrode in dye-sensitized solar cells (DSSCs) to enhance the adhesion between $TiO_2$ and fluorine doped transparent oxide (FTO). Low melting point glass frits at contents of (3 to 7wt%) were added to the nano crystalline $TiO_2$ films. The light scattering properties, photovoltaic properties and microstructures of the photo electrodes were examined to determine the role of the low glass transition temperature ($T_g$) glass frit. Electrochemical impedance spectroscopy, Brunauer-Emmett-Teller method and scratch test were conducted to support the results. The DSSC with the $TiO_2$ film containing 3wt% low Tg glass frit showed optimal performance (5.1%, energy conversion efficiency) compared to the $TiO_2$-based one. The photocurrent density slightly decreased by adding 3wt% of the frit due to its large size and non conductivity. However, the decrease of current density followed by the decrease of electron transfer due to the large frit in $TiO_2$ electrode was compensated by the scattering effect, high surface area and reduced the electron transfer impedance at the electrolyte-dye-$TiO_2$ interface. The stability of the photo electrodes was improved by the frit, which chemically promoted the sintering of $TiO_2$ at relatively low temperature ($450^{\circ}C$).

• 한국세라믹학회지
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• 제36권8호
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• pp.813-819
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• 1999

Ion implantation, photo-lithography, Ar ion milling과 hot press 법을 이용한 micro-fabrication techrique을 사용하여 고순도 알루미나 단결정인 사파이어의 내부에, 조절된 Ca의 첨가량을 갖고 있는, crack과 비슷한 형태의 기공들을 형성시켰다. 이 bi-cryslal을 각각의 온도에서 열처리하여 Ca 이온이 고온에서 알루미나의 morphology와 hcaling에 미치는 영향을 관찰하였다. 열처리 온도가 올라감에 따라서 crack-like pore의 내부에 hcxagonal bridging ligaments가 생성되었는데, 열처리 온도와 Ca의 첨가량이 증가할수록 크기가 커지는 것을 관찰할 수 있었고, 생성된 hexagonal bndgmg ligaments는 열처리가 진행됨에 따라 서서히 커지면서 모서리가 둥글어지는 현상을 관찰할 수 있었다. Bicrystal 내부에 형성된 crack-like pore는 열처리가 진행되면서 edge regression. ligamcnt growth 및 flow의 3가지의 특징적인 형태로 진행되었다. 이때 edge regression은 상대적으로 저온에서부터 전체 crack-like pore에서 서서히 일어나기 시작하였으며, ligament growth는 일부 crack-like pore에서 진행되있으며, 대단히 빠른 속도로 crack healing이 진행됨을 추정할 수 있었다. Flow는 $1800^{\circ}C$ 이상의 고온에서 모든 crack-like pore에 걸쳐서 느리게 일어남을 알 수 있었다.

• 센서학회지
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• 제7권5호
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• pp.350-355
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• 1998

인쇄/소결 방법으로 광감도가 매우 큰 CdS다결정 후막을 만들고 이를 이용하여 광전도 셀을 제작하였다. 낱알 크기는 $4\;{\mu}m$ 정도였다. 광전도 셀은 불순물로 첨가한 $CuCl_2$ 양이 0.06 - 0.12 mg 정도이면 감도와 광전류와 암전류 비율이 각각 0.8과 $10^5$ 이상을 나타내었고 응답파장은 511 nm 였다. 또한 주파수 특성을 나타내는 응답시간은 오름시간과 감쇠시간이 각각 50과 20 ms 정도 이였으며 최대허용 소비전력은 80 mW 이상이었다. 이상과 같이 인쇄/소결 방법으로 제작된 광전도 셀은 CdS 1g당 $CuCl_2$ 양이 0.06-0.12 mg 정도 주입되면 센서로서 좋은 특성을 나타내었다.

• 한국세라믹학회지
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• 제36권9호
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• pp.887-892
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• 1999

The inner crack-like pore with controlled amount of Ca impurity in the high purity alumina single crystal sapphire had been created by micro-fabrication technique which includes ion implanation photo-lithography Ar ion milling and hot press technique. The crack-like pores in two-hour hot pressed specimen were extremely stable even after heat treating at 1,80$0^{\circ}C$ for 5 hours almost no healing was observed. But the crack-like pores in one-hour hot pressed specimen at 1,30$0^{\circ}C$ were healed by heat treatment and the amount of healing was increased with the heat treatment time and temperature and the amount of Ca addition. The edges of crack-like pore parallel to <1100> direction in (001) basal plane were stable but the edges normal to this direction in (00101) plane <1120> direction were unstable to facetting This means that the surface energy of alumina along the <1100> direction in (0001) basal plane in much lower than <1120> direction.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2006년도 6th International Meeting on Information Display
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• pp.910-912
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• 2006

Barrier ribs in plasma display panels (PDPs) function to maintain the discharge space between the glass plates as well as to prevent optical cross-talking. The barrier ribs currently employed are typically $300{\mu}m$ pitch, $110{\sim}120{\mu}m$ in height, with upper and lower widths of $50{\mu}m$ and $80{\mu}m$, respectively. It has been reported that barrier ribs can be fabricated by screen-printing, sand blasting, etching and photolithographic processes. In this study, photosensitive barrier rib pastes were formulated and systematically evaluated in terms of photolithographic process variables such as printing, drying, UV exposure, development and sintering. It was found that the use of UV absorbent, polymerization inhibitor and surfactant were very effective in controlling the width uniformity of barrier ribs in the photolithographic method of barrier rib patterning.