• 한국세라믹학회지
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• 제48권5호
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• pp.348-353
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• 2011

By gel-casting, the silicon-polymer green bodies were prepared for silicon nitride ceramics, sintered by microwave gas phase reaction. Considering the viscosity and the idle time of slurries, we decided the operational conditions of related processes, and the optimum concentrations of raw materials powders, organic monomers, cross-linker, dispersant, initiator, and catalyst. So we could get the machinable green bodies, having about 50 MPa of bending strength without cracks by selecting drying conditions carefully.

• 한국세라믹학회지
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• 제24권6호
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• pp.561-571
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• 1987

In case of glass ceramics and powder preparation from the metalakoxide solutions, metalakoxide solutions with a various species of alkoxy groups have unique characteristics. Therefore, in this study, the mixing ability of homogeneous sol, gel morphology and physical properties of gels were investigated by the changes in terms of the different four alkoxy groups, CH3-, C2H5-, i-C3H7-n-C4H9-, along with the catalyst for the purpose of the observation about the homogenous transition range from sol to gel. As a result, when the fixed condition was mol ratio of H2O/Si(OR)4=2.0 and variables were batch composition and addition amount of catalyst, the characteristics of Tetra-normal-Butoxysilane and Tetra-iso-propoxysilane systems had very narrow sol-gel conversion region than Tetramethoxysilane and Tetraethoxysilane system. And silicon-alkoxide, systems having narrow sol-gel conversion region were enlarged by addition of catalyst. In viewpoint of the weight loss of gel produced by hydrolysis of silicon alkoxide systems with different four alkoxy groups, the amounts of weight loss of gel containing large molecular alkoxy groups were much more than those of small molecular alkoxy group.

• 한국방사선학회논문지
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• 제13권7호
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• pp.909-916
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• 2019

구강 및 두경부 암의 방사선치료 시 치료 범위에 피부를 포함하는 경우가 많으며 이때 볼루스의 사용이 빈번해진다. 특히 턱 부분의 요철로 인하여 환자의 적용 시 선량 불확실성을 제공한다. 본 연구에서는 3D Printing을 이용하여 Gel 볼루스와 Poly lactic acid(PLA), Silicon을 적용한 환자 맞춤형 볼루스를 제작하여 물성 특성을 확인하고, 제작된 볼루스와 치료계획의 불일치성을 확인하며, 실제 방사선 선량 전달시 발생하는 선량불확실성을 측정하였다. 그 결과 일반적인 요철 부위에는 PLA 재질의 볼루스가 안정적이며, 요철이 심하거나 환자의 체형이 자주 바뀔 수 있는 환자의 경우 Silicon 재질의 볼루스가 유용할 것으로 사료된다.

• 한국결정성장학회지
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• 제5권4호
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• pp.332-342
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• 1995

실리콘 알콕사이드 용액의 졸-겔 전이에 있어서 반응조건에 중요한 영향을 미치는 인자에 대하여 Raman 분광분석을 기초로 해서 고찰해 보았다. 촉매의 종류, 용매, 건조제어용 화학첨가제 및 물의 양과 같은 여러 가지 인자가 졸-겔 과정에 있어 전이메카니즘에 영향을 주었다.

• 한국세라믹학회:학술대회논문집
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• 한국세라믹학회 2000년도 춘계총회,특별강연,심포지움,연구발표회
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• pp.46.2-46.2
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• 2000

• The Plant Pathology Journal
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• 제28권2호
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• pp.164-171
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• 2012

Rice blast disease caused by Magnaporthe grisea (Hebert) Barr [teleomorph] is one of the most devastating diseases in rice plantation areas. Silicon is considered as a useful element for a large variety of plants. Rice variety MR219 was grown in the glasshouse to investigate the function of silicon in conferring resistance against blast. Silica gel was applied to soil while sodium silicate was used as foliar spray at the rates of 0, 60, 120, 180 g/5 kg soil and 0, 1, 2, 3 ml/l respectively. The treatments were arranged in a completely randomized design. Disease severity and silicon content of leaves were compared between the non-amended controls and rice plants receiving the different rates and sources of silicon. Silicon at all rates of application significantly (${\alpha}$ = 0.05) reduced the severity of disease with highest reduction (75%) recorded in treatments receiving 120 g of silica gel. SEM/EDX observations demonstrated a significant difference in weight concentration of silicon in silica cells on the leaf epidermis between silicon treated (25.79%) and non treated plants (7.87%) indicating that Si-fertilization resulted in higher deposition of Si in silica cells in comparison with non-treated plants. Application of silicon also led to a significant increase in Si contents of leaves. Contrast procedures indicated higher efficiency of silica gel in comparison to sodium silicate in almost all parameters assessed. The results suggest that mitigated levels of disease were associated with silicification and fortification of leaf epidermal cells through silicon fertilization.

• 마이크로전자및패키징학회지
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• 제19권3호
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• pp.63-69
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• 2012

Adhesion and mechanical reliability of silicon/epoxy/polyimide interfaces are critical issues for flexible electronics. Bonds between these interfaces are mainly hydrogen bonds, so their adhesion is weaker than cohesive fracture toughness and vulnerable to moisture. In order to enhance adhesion and suppress moisture-assisted debonding, UV/Ozone treatment and innovative sol-gel derived hybrid layers were applied to silicon/epoxy/polyimide interfaces. The fracture energy and subcritical crack growth rate were measured by using a double cantilever beam (DCB) fracture mechanics test. Results showed that UV/Ozone treatment increased the adhesion, but was not effective for improving reliability against humidity. However, by applying sol-gel derived hybrid layers, adhesion increase as well as suppresion of moisture-assisted cracking were achieved.

• Transactions on Electrical and Electronic Materials
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• 제2권2호
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• pp.32-36
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• 2001

A new solid source for low temperature diffusion into silicon was developed. The source wafer consists of an “active” compound, which is sol-gel prepared phosphosilicate glass-ceramics containing 56% P$_2$O$\sub$5/, embedded in a skeletal foam-like, inert substrate. Phosphorus diffusion from the new solid sources at low temperatures (800-875$^{\circ}C$) produced reprodecible sheet resistances and shallow junctions. From a series of one hour doping runs, the life time of the phosphosilicate source was determined to be over 40 hours. The effective diffusion coefficient of phosphorus into silicon and the corresponding activation energy at 850$^{\circ}C$ were determined to be 7.5${\times}$10$\^$-15/ $\textrm{cm}^2$/sec and ∼3.9 eV, respectively.

• 한국세라믹학회지
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• 제48권5호
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• pp.354-359
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• 2011

Silicon nitride ceramics were prepared by microwave gas phase reaction sintering. By this method higher density specimens were obtained for short time and at low temperature, compared than ones by conventional pressureless sintering, even though sintering behaviors showed same trend, the relative density of sintered body inverse-exponentially increases with sintering temperature and/or holding time. And grain size of ${\beta}$-phase of the microwave sintered body is bigger than one of the conventional pressureless sintered one. Also they showed good bending strengths and thermal shock resistances.

• 한국재료학회지
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• 제23권4호
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• pp.246-249
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• 2013

Nano-sized ${\beta}$-SiC nanoparticles were synthesized combined with a sol-gel process and a carbothermal process. TEOS and carbon black were used as starting materials for the silicon source and carbon source, respectively. $SiO_2$ nanoparticles were synthesized using a sol-gel technique (Stober process) combined with hydrolysis and condensation. The size of the particles could be controlled by manipulating the relative rates of the hydrolysis and condensation reactions of tetraethyl orthosilicate (TEOS) within the micro-emulsion. The average particle size and morphology of synthesized silicon dioxide was about 100nm and spherical, respectively. The average particles size and morphology of the used carbon black powders was about 20nm and spherical, respectively. The molar ratio of silicon dioxide and carbon black was fixed to 1:3 in the preparation of each combination. $SiO_2$ and carbon black powders were mixed in ethanol and ball-milled for 12 h. After mixing, the slurries were dried at $80^{\circ}C$ in an oven. The dried powder mixtures were placed in alumina crucibles and synthesized in a tube furnace at $1400{\sim}1500^{\circ}C$ for 4 h with a heating rate of $10^{\circ}C$/min under flowing Ar gas (160 cc/min) and furnace cooling down to room temperature. SiC nanoparticles were characterized by XRD, TEM, and SAED. The XRD results showed that high purity beta silicon carbide with excellent crystallinity was synthesized. TEM revealed that the powders are spherical shape nanoparticles with diameters ranging from 15 to 30 nm with a narrow distribution.