• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
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• pp.254-255
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• 2012

Interest in nano-crystalline silicon (nc-Si) thin films has been growing because of their favorable processing conditions for certain electronic devices. In particular, there has been an increase in the use of nc-Si thin films in photovoltaics for large solar cell panels and in thin film transistors for large flat panel displays. One of the most important material properties for these device applications is the macroscopic charge-carrier mobility. Hydrogenated amorphous silicon (a-Si:H) or nc-Si is a basic material in thin film transistors (TFTs). However, a-Si:H based devices have low carrier mobility and bias instability due to their metastable properties. The large number of trap sites and incomplete hydrogen passivation of a-Si:H film produce limited carrier transport. The basic electrical properties, including the carrier mobility and stability, of nc-Si TFTs might be superior to those of a-Si:H thin film. However, typical nc-Si thin films tend to have mobilities similar to a-Si films, although changes in the processing conditions can enhance the mobility. In polycrystalline silicon (poly-Si) thin films, the performance of the devices is strongly influenced by the boundaries between neighboring crystalline grains. These grain boundaries limit the conductance of macroscopic regions comprised of multiple grains. In much of the work on poly-Si thin films, it was shown that the performance of TFTs was largely determined by the number and location of the grain boundaries within the channel. Hence, efforts were made to reduce the total number of grain boundaries by increasing the average grain size. However, even a small number of grain boundaries can significantly reduce the macroscopic charge carrier mobility. The nano-crystalline or polymorphous-Si development for TFT and solar cells have been employed to compensate for disadvantage inherent to a-Si and micro-crystalline silicon (${\mu}$-Si). Recently, a novel process for deposition of nano-crystralline silicon (nc-Si) thin films at room temperature was developed using neutral beam assisted chemical vapor deposition (NBaCVD) with a neutral particle beam (NPB) source, which controls the energy of incident neutral particles in the range of 1~300 eV in order to enhance the atomic activation and crystalline of thin films at room temperature. In previous our experiments, we verified favorable properties of nc-Si thin films for certain electronic devices. During the formation of the nc-Si thin films by the NBaCVD with various process conditions, NPB energy directly controlled by the reflector bias and effectively increased crystal fraction (~80%) by uniformly distributed nc grains with 3~10 nm size. The more resent work on nc-Si thin film transistors (TFT) was done. We identified the performance of nc-Si TFT active channeal layers. The dependence of the performance of nc-Si TFT on the primary process parameters is explored. Raman, FT-IR and transmission electron microscope (TEM) were used to study the microstructures and the crystalline volume fraction of nc-Si films. The electric properties were investigated on Cr/SiO2/nc-Si metal-oxide-semiconductor (MOS) capacitors.

• 대한금속재료학회지
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• 제48권3호
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• pp.248-255
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• 2010

The effect of various alloying elements and melt treatment on the microstructural control of Al-Sn metallic bearing alloy was investigated. The thickness of tin film crystallized around primary aluminum decreased with the addition of 5% Cu in Al-Sn alloy, with tin particles being reduced in size by intervening the Ostwald ripening. With the addition of Si in Al-10%Sn alloy, the tin particles were crystallized with eutectic silicon, resulting in uniform distribution of tin particles. With the addition of Cu and Si in Al-Sn alloy, both the tensile strength and yield strength increased, with the increasing rate of yield strength being less than that of tensile strength. Although the Al-10%Sn-7%Si alloy has similar tensile strength compared with Al-10%Sn-5%Cu, the former showed superior abrasion resistance, resulting from preventing the tin particles from movement to the abrasion surface.

• 대한방사선방어학회:학술대회논문집
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• 대한방사선방어학회 2011년도 춘계 학술발표회 및 심포지엄
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• pp.80-81
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• 2011

• 펄프종이기술
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• 제40권5호
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• pp.1-10
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• 2008

Synthetic mineral microparticles (SMM) is a patented system which has been developed to promote drainage of water and retention of fine particles during papermaking. It is shown in patents that the SMM system can have advantages in both of drainage and retention, compared with montmorillonite (bentonite), which is one of the most popular materials presently used in this kind of application. Turbidity and gravity drainage time were measured using a Britt-Jar test with representative SMM formulations, in order to confirm the efficacy of SMM covering a wide range of compositions and discover effects of some key variables that have the potential to lead to unexpected advantages in terms of the effectiveness of the microparticles, when used in combination with a cationic polyacrylamide treatment of papermaking furnish. An iron silicate showed highest retention performance, as well as suitably fast drainage time relative to other metal silicate and bentonite. Zinc silicate improved retention and drainage. SMM synthesized from aluminum sulfate ($Al_2(SO_4){_3}$) did not show a benefit in retention and drainage, relative to bentonite. SMM synthesized from aluminum chloride ($AlCl_3$) performed better in drainage and retention than bentonite when the Al/Si ratios were 0.76 and 1.00. It was found that when the Al/Si ratio and neutralization are considered, pH variation due to the change of Al/Si ratio can be a key factor to control the size of primary metal silicate particles and the degree of coagulation of the primary particles.

• 산업진흥연구
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• 제1권2호
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• pp.1-6
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• 2016

본 연구에서는 고장력강판(SPFH590)을 이용하여 1차 일반전단가공의 클리어런스가 2차 셰이빙 공정에 미치는 영향에 대하여 실험을 통하여 고찰하였다. 실험 결과 일반전단가공의 클리어런스 15%의 경우에서는 셰이빙에 의해 파단면이 완전하게 제거되지 못하여 일부 잔존하였으며, 일반전단가공 10%로 전단한 제품의 셰이빙 가공에 의한 전단면의 크기가 넓게 되는 것을 알 수 있었다. 일반전단가공 10%로 하고, 셰이빙 클리어런스 2%의 경우에는 93%의 전단면이 발생하였으며, 클리어런스 3%에서는 87%의 전단면이 발생하는 것으로 나타났다.

• 한국재료학회지
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• 제28권1호
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• pp.6-11
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• 2018

There are various manufacturing processes for pure $SiO_2$ that is used as abrasives, chemicals, filters, and glasses, and in metallurgy and optical industries. In the optical fiber industry, to produce $SiO_2$ preform, $SiCl_4$ is utilized as a raw material. However, the combustion reaction of $SiCl_4$ has caused critical environmental issues, such as ozone deficiency by chlorine compounds, the greenhouse effect by carbon dioxide and corrosive gas such as hydrochloric acid. Thus, finding an alternative source that does not have those environmental issues is important for the future. Octamethylcyclotetrasiloxane (OMCTS or D4) as a chlorine free source is recently promising candidate for the $SiO_2$ preform formation. In this study, we first conducted a vaporizer design to vaporize the OMCTS. The vaporizer for the OMCTS vaporization was produced on the basis of the results of the vaporizer design. The size of the primary particle of the $SiO_2$ formed by OMCTS was less than 100 nm. X-ray diffraction patterns of the $SiO_2$ indicated an amorphous phase. Fourier-transform infrared spectroscopy analysis revealed the Si-O-Si bond without the -OH group.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 하계학술대회 논문집
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• pp.917-920
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• 2001

Effects of addition of manganese and final reduction on segregation behavior of sulfur and final mangetic induction during final annealing have been investigated in the 300 ppm sulfur-contained 3% silicon-iron alloy strips with or without manganese. At the same concentration of sulfur, lower final reduction is favorable for final Goss texture. This is because the probability that the initial Goss grains survive under the highly segregated sulfur atmosphere and grow selectively within the segregated sulfur-free time range becomes higher. In the case of 3% silicon-iron with manganese, much lower magnetic induction was obtained, although the weak final reduction of 30% is given to the alloy, comparative to the 40%. This is because MnS particles acted as an reducer in the primary grain size.

• Applied Microscopy
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• 제52권
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• pp.12.1-12.8
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• 2022

The microstructure of diatom frustules found in mud sediments along the coast of Boryeong- city, South Korea, was observed using a scanning electron microscopy (SEM), and the constituent elements of diatoms were analyzed using energy-dispersive X-ray spectroscopy (EDS). Diatom frustules and clay minerals were present in the SEM images of the mud powder. High-magnification SEM images revealed that the surface of the frustules contained identically shaped circular pores, measuring 1 ㎛ in diameter, arranged at regular intervals. This study revealed that the diatom shell fragments in the mud powder ranged in size from 3 to 30 ㎛, with an average thickness of approximately 2.5 ㎛. The elements Si, Al, Fe, K, Na, Mg, and Ti were detected while analyzing the frustule constituents, with Si being the primary component with the highest content.

• 열처리공학회지
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• 제10권4호
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• pp.246-254
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• 1997

The 6.5wt %Si-Fe alloy sheets were made by the twin roll process. The magnetic properties and microstructures of sheets annealed in the sulfur atmosphere were studied. In the as-prepared sheet, non-oriented columnar grains about $10{\mu}m$ in diameter were observed, which grew from the surface to the inner part of the sheet. When the annealing temperature was around $700^{\circ}C$, the primary recrystallization was formed around the middle part of the sheet thickness, and the grain size increased with increasing annealing temperature. At the annealing temperature of $900^{\circ}C$, the grain size became $30{\sim}40{\mu}m$. Around the annealing temperature, the motive force of the grain growth is the grain boundary energy. However, above $1000^{\circ}C$ the surface energy played an important role in the observed grain growth. When the sheet were annealed at $1200^{\circ}C$, the grains whose (100) planes were paralled to the thin plate surface grew, and all sheet surfaces were covered with these grains after 1 hour annealing. This phenomenon is called tertiary recrystallization. A difference in surface energy between (100) and (110) surfaces provides a driving force for growth of tertiary grains. The coercive force was 0.27 mOe and the AC core loss $W_{12/50}$ was 0.38w/kg for the 6.5wt%Si-Fe alloy.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2001년도 춘계학술대회 논문집
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• pp.381-384
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• 2001

The combined stirring method to uniform distribution of particle is consisted of two strring force both electro-magnetic stirring generated from induction heating and mechanical stirring with graphite stirrer. PMMC billets were fabricated with the volume fractions ranged from 0% to 20% and particle sizes ranged from 14$\mu\textrm{m}$ to 25$\mu\textrm{m}$. It is important to control the size of primary ${\alpha}$-AI solid particles because it could become the cause of the particle pushing or capture phenomena from the fact that secondary dendrite arm spacing size depends on the cooling rate during the solidification in hypoeutectic AI-Si alloy.