• 한국재료학회지
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• 제14권6호
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• pp.443-450
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• 2004

Parylene polymer thin film shows excellent homogeneous coverage chracteristics when it was deposited onto very complex three dimensional solid matters, such as deep hole and micro crack. The parylene deposition process can be conducted at room temperature although most of chemical vapor deposition processes request relatively high processing temperature. Therefore, the parylene coating process does not induce any thermal problems. Parylene thin film is transparent and has extremly high chemical stability. For example, it shows high chemical stability with high reactive chemical solutions such as strong acid, strong alkali and acetone. The bio-stability of this material gives good chances to use for a packaging of biomedical devices and electronic devices such as display. In this review article, principle of deposition process, properties and application fields of parylene polymer thin film are introduced.

• Applied Microscopy
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• 제25권1호
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• pp.130-138
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• 1995

TEM specimen preparation methods have been examined to characterize Cu oxide particles in the polyimide film. Polyimide films were prepared by coating polyamic acid onto Cu films which had been deposited on TEM-mask and glass substrates and Cu foil, followed by thermal curing. In case of TEM-mask, direct observation was possible without further preparation. In other cases, TEM specimen were made by separating polyimide film from the substrate. Polyimide films were removed from glass and Cu foil by dissolving glass in HF solution and Cu foil in $H_{2}SO_{4}$ solution. TEM-mask observation confirms that fine $Cu_{2}O$ particles precipitate in the polyimide as a result of reaction of polyamic acid with Cu. However $Cu_{2}O$ particle reacts with HF and $H_{2}SO_{4}$ solution during dissolving the substrate and interpretation could be misled. It is concluded characterization of $Cu_{2}O$ particle in polyimide using TEM-mask is better than other methods.

• 센서학회지
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• 제21권3호
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• pp.167-171
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• 2012

Ag- and Pd-loaded $SnO_2$ nanowire network sensors were prepared by the growth of $SnO_2$ nanowires via thermal evaporation, the coating of slurry containing $SnO_2$ nanowires, and dropping of a droplet containing Ag or Pd nanoparticles, and subsequent heat treatment. All the pristine, Pd-loaded and Ag-loaded $SnO_2$ nanowire networks showed the selective detection of $C_2H_5OH$ with low cross-responses to CO, $H_2$, $C_3H_8$, and $NH_3$. However, the relative gas responses and gas selectivity depended closely on the catalyst loading. The loading of Pd enhanced the responses($R_a/R_g$: $R_a$: resistance in air, $R_g$: resistance in gas) to CO and $H_2$ significantly, while it slightly deteriorated the response to $C_2H_5OH$. In contrast, a 3.1-fold enhancement was observed in the response to 100 ppm $C_2H_5OH$ by loading of Ag onto $SnO_2$ nanowire networks. The role of Ag catalysts in the highly sensitive and selective detection of $C_2H_5OH$ is discussed.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 추계학술대회 논문집 Vol.15
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• pp.47-50
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• 2002

ZnO nanowires were coated conformally with aluminum oxide ($Al_{2}O_{3}$) material by atomic layer deposition (ALD). The ZnO nanowires were first synthesized on a Si (100) substrate at $1380^{\circ}C$ from ball-milled ZnO powders by a thermal evaporation procedure with an argon carrier gas without any catalysts; the length and diameter of these ZnO nanowires are $20\sim30{\mu}m$ and $50{\sim}200$ nm, respectively. $Al_{2}O_{3}$ films were then deposited on these ZnO nanowires by ALD at a substrate temperature of $300^{\circ}C$ using trimethylaluminum (TMA) and distilled water ($H_{2}O$). Transmission electron microscopy (TEM) images of the deposited ZnO nanowires revealed that 40nm-thick $Al_{2}O_{3}$ cylindrical shells surround the ZnO nanowires.

• 대한조선학회논문집
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• 제44권6호
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• pp.627-634
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• 2007

A bonded plate or a coated part can be debonded by external impact or thermal expansion. To analyse adhesive strength, the blister test is generally adopted. In this paper, a blister test is modelled theoretically and then the stability and bifurcation of the blister are studied under several different cases. The blister is simplified to consist of a pure bending plate attached elastically to the rigid substrate. Expression of the energy release rate is obtained as a form of an explicit function for a circular-type blister or tunnel-type blister grown by controlling the internal pressure or internal volume. Stability and bifurcation are also studied in the frame of the quasi-static evolution. The study shows that the circular- type blister propagates with the first mode of bifurcation and that the tunnel-type blister propagates with a regular wave. It is proved that the waves have the same form on two side lines of the tunnel and that the wave length can be obtained. When the internal pressure is controlled, the blister is unstable, but when the internal volume is controlled, it is stable.

• 반도체디스플레이기술학회지
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• 제5권3호
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• pp.5-10
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• 2006

This paper investigates cutting qualities after laser dicing and predicts the problems that can be generated by laser dicing. And through 3 point bending test, die strength is measured and the die strength after laser dicing is compared with the die strength after mechanical sawing. Laser dicing is chiefly considered as an alternative to overcome the defects of mechanical sawing such as chipping on the surface and crack on the back side. Laser micromachining is based on the thermal ablation and evaporation mechanism. As a result of laser dicing experiments, debris on the surface of wafer is observed. To eliminate the debris and protect the surface, an experiment is done using a water soluble coating material and ultrasonic. The consequence is that most of debris is removed. But there are some residues around the cutting line. Unlike mechanical sawing, chipping on the surface and crack on the back side is not observed. The cross section of cutting line by laser dicing is rough as compared with that by mechanical sawing. But micro crack can not be seen. Micro crack reduces die strength. To measure this, 3 point bending test is done. The die strength after laser dicing decreases to a half of the die strength after mechanical sawing. This means that die cracking during package assembly can occur.

• 접착 및 계면
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• 제18권4호
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• pp.159-165
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• 2017

본 연구에서는 반응성 희석제로 사용되는 BA의 함량에 따른 자외선 경화형 폴리우레탄 아크릴레이트 수지를 제조하여 수지의 열적 기계적 성질, 접착강도, 굴곡성을 확인하였다. BA의 함량이 40% 이상으로 증가할수록 Polyol의 Tg와 아크릴 수지의 Tg가 분리되어 나타난 것을 DSC로 통해 확인하였다. 또한 BA의 함량이 증가할수록 아크릴 수지의 낮은 기계적인 물성이 주도적으로 발현되어 인장강도와 신장률, 접착강도가 감소하는 것으로 나타났다. 굴곡성을 평가한 결과 BA의 함량이 40%인 경우 경도가 낮으면서 다른 수지에 비해 Tm이 낮아 굴곡성이 우수한 것으로 나타났다.

• 한국대기환경학회지
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• 제12권4호
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• pp.421-428
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• 1996

In this study, in order to make up its draw-back in Cu-ZSM-5 catalytic system, some of transition metals or alkaline earth metals were cocation-exchanged in Cu-ZSM-5. Among various cocation-ion-exchanged ZSM-5 catalysts, Mg/Cu-ZSM-5 has been found the most active and durable in NOx reduction even at high oxygen content as well as at the presence of water vapor. The role of Mg in ZSM-5 is supposed to prevent the dealumination of aluminum ions in super-cage even at harsh hydro-thermal conditions, and also it seems to stabilize the Cu ions in the structure. In order to prepare commercially available catalysts, Mg/Cu-ZSM-5 catalysts were wash-coated on the surface of honeycomb type monolith, and tested in terms of catalytic activities. As a result, it was found that the catalyst prepared bt the wash-coating showed satisfactorily high NOx conversion for the practical use in SCR process.

• 한국분말재료학회지
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• 제17권3호
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• pp.230-234
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• 2010

Homogenous silica-coated $CoFe_2O_4$ samples with controlled silica thickness were synthesized by the reverse microemulsion method. First, 7 nm size cobalt ferrite nanoparticles were prepared by thermal decomposition methods. Hydrophobic cobalt ferrites were coated with controlled $SiO_2$ using polyoxyethylene(5)nonylphenylether (Igepal) as a surfactant, $NH_4OH$ and tetraethyl orthosilicate (TEOS). The well controlled thickness of the silica shell was found to depend on the reaction time and the amount of surfactant used during production. Thick shell was prepared by increasing reaction time and small amount of surfactant.

• Journal of Electrochemical Science and Technology
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• 제2권1호
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• pp.51-56
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• 2011

We develop a new nonwoven composite separator for a safer lithium-ion battery, which is based on coating of silica ($SiO_2$) colloidal particles/styrene-butadiene rubber (SBR) binder to a poly(ethylene terephthalate) (PET) nonwoven support. The $SiO_2$ particles are interconnected by the SBR binder and closely packed in the nonwoven composite separator, which thus allows for the development of unusual porous structure, i.e. highly-connected interstitial voids formed between the $SiO_2$ particles. The PET nonwoven serves as a mechanical support that contributes to suppressing thermal shrinkage of the nonwoven composite separator. The $SiO_2$/SBR content in the nonwoven composite separators plays an important role in determining their separator properties. Porous structure, air permeability, and electrolyte wettability of the nonwoven composite separators, in comparison to a commercialized polyethylene (PE) separator, are elucidated as a function of the $SiO_2$/SBR content. Based on this understanding of the nonwoven composite separators, the effect of $SiO_2$/SBR content on the electrochemical performances such as self-discharge, discharge capacity, and discharge C-rate capability of cells assembled with the nonwoven composite separators is investigated.