• 마이크로전자및패키징학회지
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• 제11권2호
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• pp.1-9
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• 2004

[ $BaTiO_3$ ]분말의 양과 에폭시/$BaTiO_3$ 복합 내장형 커패시터 필름의 유전상수와의 관계를 살펴보고 이에 대해 고찰하였다. 이를 위해 $BaTiO_3$ 분말의 함량에 따른 에폭시/$BaTiO_3$ 복합 내장형 커패시터 필름의 밀도 변화와 필름의 표면 및 단면 모습을 관찰하였다. 또한 $BaTiO_3$ 분말의 함량을 높이기 위한 여러 가지 bimodal 조합에 따른 에폭시/$BaTiO_3$ 복합 내장형 커패시터 필름의 유전상수 변화를 관찰하였다. 단일 입자를 이용한 unimodal의 경우 유전상수가 가장 높게 측정된 $S_4$ 분말을 이용하여 얻을 수 있었던 유전상수의 최대값은 약 60 이었다. 최대값보다 과량의 $BaTiO_3$ 분말을 첨가하였을 경우, 에폭시/$BaTiO_3$ 복합 내장형 커패시터 필름의 유전상수가 감소하는데, 이는 과량의 분말을 수용하기 위해 생성된 기공에 의한 것이었다. Bimodal 조합의 경우 가장 큰 분말과 가장 작은 분말의 조합인 $S_5+C_1$ 조합이 $75\;vol\%$의 가장 많은 양의 분말을 넣어 가장 높은 유전상수 90 을 얻는데 성공하였다.

• 폴리머
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• 제38권2호
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• pp.199-204
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• 2014

본 연구는 2-ethylhexyl acrylate와 2-hydroxyethyl acrylate 기본구조에 isobornyl acrylate와 tetrahydrofurfuryl acrylate(THFA)의 조성비를 변화시키면서 광중합된 4원 공중합체를 합성한 후 가교제로 1,6-hexanediol diacrylate가 혼합된 시럽을 제조하였다. 합성한 시럽에 UV-광원을 조사시켜 점착제를 제조한 후 점착특성과 광학특성을 고찰하였으며 시럽의 기본물성인 고형분, 점도, 및 분자량 분석도 수행하였다. THFA의 함량이 증가할수록 시럽의 분자량은 감소하였으나 고형분은 반대로 증가하였다. 점착제의 박리강도는 THFA의 함량에 따른 반비례관계를 나타내고 점착제의 표면에너지는 비례관계를 나타내었다. 또한 모든 점착제에서 92% 이상의 광투과도와 1.0%이하의 haze값, 그리고 1.0 이하의 색차계값을 보여주었다.

• 한국염색가공학회지
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• 제28권2호
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• pp.101-108
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• 2016

Polypropylene(PP)/multiwalled carbon nanotubes(MWCNT) nanocomposites films and PP/poly(vinyl alcohol)/CNT nanocomposites films were prepared through melt mixing method by the extruder. The PP/CNT nanocomposites films, which contain CNT of a variable content, were prepared for the first time and research on a appropriate content of the CNT on the PP/CNT nanocomposites films was conducted. The effects of take-up speed of the extruder on the mechanical and chemical properties of the PP/CNT and PP/PVA/CNT nanocomposites film were studied. Field emission scanning electron microscope(FE-SEM) was used to examine the surface morphology and the DSC measurement and tensile test were conducted. It was found that the properties decreased when take-up speed was increased.

• Applied Microscopy
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• 제24권3호
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• pp.87-93
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• 1994

In order to elucidate the machinability of lead brass, orthogonal machining experiment was conducted in SEM(Scanning Electron Microscope) equipped with a micro-machining device at a cutting speed of $7{\mu}m/s$ for brass containing 0.2 to 3wt% Pb. The microfactors (i.e., shear angle, contact length between chip and tool) were determined by in-situ observations. Machinability of brass containing lead is discussed in terms of the microfactors and the cutting resistant force tested by lathe cutting. The dynamic behavior of the chip formation of lead brass during the machining process was examined: The chips of lead brass form as a shear angle type. The shear angle increases with the content of lead in (6:4) brass. The pronounced effect of lead on the contact length between chip and tool was observed above 1% Pb. The cutting resistant force tested by lathe decreases remarkably with the lead content in brass. The observed microfactors are in close relation to the tested resistant force in macromachining.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1991년도 추계학술대회 논문집 학회본부
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• pp.299-303
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• 1991

A lamp heated LPCVD equipment has been made. Wafer is heated by an array of fifteen tungsten halogen lamps above the front side of a wafer and pyrometer views the back side of the wafer through $CaF_2$ window. Reactor which consisits of a quartz window and a water cooled-stainless steel plate can be evacuated to $5{\times}10^{-3}$ torr with a rotary vane pump. By pyrolysis of $SiH_4$ at about $600^{\circ}C$, polysilicon has been formed on the silicon dioxide film. The measured results show that thickness nonuniformity is 15% and temperature nonuniformity is 1.1%. Because activation energy of pyrolysis of $SiH_4$ is very high, about 1.8eV, small temperature variation will induce large thickness nonuniformity. The main cause of temperature nonuniformity is unsymmetry of lamp power and an unbalanced cooling structure. Charls & Evans' SIMS result shows that the oxygen content in the deposited polysilicon is comparable to that of silicon substrate but carbon content is ten times higher.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 Proceedings ICPE 01 2001 International Conference on Power Electronics
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• pp.708-712
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• 2001

A new phase-shifted parallel-input/series-output (PI SO) dual inductor-fed push-pull converter for high-power step­up applications is proposed. This converter is operated at a constant duty cycle and employs an auxiliary circuit to control the output voltage with a phase-shift between the two modules. It features a voltage conversion characteristic which is linear to changes in the control input, and high step-up ratio with a greatly reduced switch turn-off stress resulting in a significant increase in the converter efficiency. It also shows a low ripple content and low root-mean-square (RMS) current in the output capacitor. The operational principle is analyzed and a comparative analysis with the conventional pulse-width-modulated (PWM) PISO dual inductor-fed push-pull converter is presented. A 50kHz, 800W, 350Vdc prototype with an input of 20-32Vdc has also been constructed to validate the proposed converter. The proposed converter compares favorably with the conventional counterpart and is considered well suited to high-power step-up applications.

• Carbon letters
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• 제8권3호
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• pp.177-183
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• 2007

[ $TiO_2$ ]ACF composites were prepared by the electrochemical method with Titanium (IV) n-butoxide (TNB) electrolyte under different electrochemical operation time. The BET surface area for $TiO_2$/ACF composites decrease with the increase of electrochemical operation time. There is a single crystal structure which is anatase in all of the samples from the data of XRD. The SEM micrphotographs of $TiO_2$/ACF composites show that the $TiO_2$ particles were well mixed with the ACF. There are O and P with strong C and Ti peaks in all samples from EDX results, and it also shows that a decrease of the C content with a increasing of Ti content with increasing of the electrochemical operation time in the over all composites. DSC cures show that the exothermic peak of all composites at $560^{\circ}C$ represents the transformation heat of amorphous parts to anatase phase and the discontinuous grain growth of the transformed anatase particles. Finally, the excellent photoactivity of $TiO_2$/ACF composites (especially, ACFT10) could be attributed that the decrease of concentration of MB can be concluded to be much faster for the adsorption by ACF than for photocatalytic decomposition by $TiO_2$.

• Journal of Electrical Engineering and information Science
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• 제1권2호
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• pp.134-144
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• 1996

In this paper, we propose a new access method, called the HG-tree, to support indexing and retrieval by image content in large image databases. Image content is represented by a point in a multidimensional feature space. The types of queries considered are the range query and the nearest-neighbor query, both in a multidimensional space. Our goals are twofold: increasing the storage utilization and decreasing the area covered by the directory regions of the index tree. The high storage utilization and the small directory area reduce the number of nodes that have to be touched during the query processing. The first goal is achieved by absorbing splitting if possible, and when splitting is necessary, converting two nodes to three. The second goal is achieved by maintaining the area occupied by the directory region minimally on the directory nodes. We note that there is a trade-off between the two design goals, but the HG-tree is so flexible that it can control the trade-off. We present the design of our access method and associated algorithms. In addition, we report the results of a series of tests, comparing the proposed access method with the buddy-tree, which is one of the most successful point access methods for a multidimensional space. The results show the superiority of our method.

• 한국재료학회지
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• 제18권9호
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• pp.470-474
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• 2008

Composites of gadolinium-doped ceria/magnesia(CGO/MgO) were synthesized and characterized for the electrolytes of intermediate temperature solid oxide fuel cells. XRD and SEM results revealed that composite electrolytes consisted of their own phases after sintering at $1400^{\circ}C$ without noticeable solid solution of Mg into CGO. As the MgO content increased, the total electrical conductivity decreased, which might be attributed to the decrease of grain boundary conductivity, possibly due to the lowering of the continuity of the CGO grains and blocking effects of the insulating MgO phase. The space charge effect may not be a significant factor to affect the electrical conductivity of the CGO/MgO composites.

• 한국콘텐츠학회:학술대회논문집
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• 한국콘텐츠학회 2012년도 춘계 종합학술대회 논문집
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• pp.323-324
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• 2012

유아기는 인간의 삶은 중요한 영향을 준다. 이러한 유아들을 위해 교육법과 교육소재들이 있다. 교육소재는 교육법이 추구하는 인간상을 위해 교육적인 내용과 간접경험을 제공한다. 본 논문은 교육소재를 개발하여 경험을 제공하고 발상력과 창의력을 키운다.