• Transactions on Electrical and Electronic Materials
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• v.15 no.2
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• pp.73-76
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• 2014

$Pt/Al_2O_3/La_2Si_5O_x/SiO_2/Si$ charge trap memory capacitors were prepared, in which the $La_2Si_5O_x$ film was used as the charge trapping layer, and the effects of post annealing atmospheres ($NH_3$ and $N_2$) on their memory characteristics were investigated. $La_2O_3$ nanocrystallites, as the storage nodes, precipitated from the amorphous $La_2Si_5O_x$ film during rapid thermal annealing. The $NH_3$ annealed memory capacitor showed higher charge storage performances than either the capacitor without annealing or the capacitor annealed in $N_2$. The memory characteristics were enhanced because more nitrogen was incorporated at the $La_2Si_5O_x/SiO_2$ interface and interfacial reaction was suppressed after the $NH_3$ annealing treatment.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2010.04a
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• pp.67-67
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• 2010

이미지를 이용한 도공층 구조 분석은 도공층의 실제 Morphology를 분석하여 평가하는 방법으로서 최근 세밀한 도공층 구조 분석을 위해 이 방법에 대한 많은 연구가 진행되고 있다. 특히 이러한 방법은 수은압입법(Mercury intrusion)이나 질소흡착법 (Nitrogen adsorption by BJH theory) 등과 같은 기존의 공극 특성 평가 방법과 달리 pore aspect ratio 및 orientation 등과 같은 공극 dimension을 평가할 수 있는 장점이 있다. 이러한 공극 dimension은 size distribution 및 porosity와 더불어 인쇄, 라미네이션 접착 등과 같은 Liquid interfacial 및 침투 측면에서 중요한 요소이기 때문에 이를 평가하기 위한 적합한 방법으로 인식되고 있다. 또, 원지 부분과 도공층 간의 경계를 명확하게 보여주고 Surface와 Cross-section 영역을 구분하여 평가 할 수 있어 더 명확한 평가를 가능하게 한다. 본 연구에서는 이미지 분석을 통해 도공액 구성 조건에 따른 도공층의 공극 구조 특성을 평가 하였고 일부 요소에 대해서는 수은 압입법과 비교 평가하여 이미지 분석법과의 상관성에 대해 고찰 하였다. 본 연구에서 사용된 FE (Field Emission)-SEM은 일반 SEM과 달리 전압에 의한 높은 전기장의 형성을 통해 저 가속 전압으로 이미지를 구현하는 장비로서 본 연구에서는 FE-SEM을 통해 도공층의 세밀한 Morphology와 공극 구조 이미지를 구현할 수 있었다.

• Journal of the Korean Society of Safety
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• v.19 no.4 s.68
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• pp.25-30
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• 2004

Unidirectional fiber-metal matrix composites have superior mechanical properties along the longitudinal direction. However, the applicability of continuous fiber reinforced MMCs is somewhat limited due to their relatively poor transverse properties. Therefore, the transverse properties of MMCs are significantly influenced by the properties of the fiber/matrix interface. In this study, the interfacial stress states of transversely loaded unidirectional fiber reinforced metal matrix composites investigated by using elastic-plastic finite element analysis. Different fiber volume fractions $(5-60\%)$ were studied numerically. The interface was treated as thin layer (with different properties) with a finite thickness between the fiber and the matrix. The fiber is modeled as transversely isotropic linear-elastic, and the matrix as isotropic elastic-plastic material. The analyses were based on a two-dimensional generalized plane strain model of a cross-section of an unidirectional composite by the ANSYS finite element analysis code.

• Structural Monitoring and Maintenance
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• v.7 no.3
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• pp.233-259
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• 2020

Using bonded fiber-reinforced polymer laminates for strengthening wooden structural members has been shown to be an effective and economical method. In this research, properties of suitable composite materials (sika wrap), adhesives and two ways of strengthening beams exposed to bending moment are presented. Passive or slack reinforcement is one way of strengthening. The most effective way of such a strengthening was to place reinforcement laminates in the stretched part of the wooden beam (lower part in our case), in order to investigate the effectiveness of externally bonding FRP to their soffits. The model is based on equilibrium and deformations compatibility requirements in and all parts of the strengthened beam, i.e., the wooden beam, the sika wrap composite plate and the adhesive layer. The theoretical predictions are compared with other existing solutions. This research is helpful for the understanding on mechanical behaviour of the interface and design of the composite-wooden hybrid structures. The results showed that the use of the new strengthening system enhances the performance of the wooden beam when compared with the traditional strengthening system.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.26 no.2
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• pp.67-73
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• 2016

The degradation behaviors of TiN coating layers under thermo-mechanical stress were investigated in terms of comparison of finite element analysis (FEA) and experimental data. The coating specimen was designed to quarter cylinder model, and the pulsed laser ablation was assumed as heat flux condition. The FEA results showed that heat accumulation at the center of the laser-ablated spot occurred and principle stress was concentrated at the lower region of the coating layer. The microstructural observation revealed that surface melting and decrease of the coating thickness occurred in the TiN/Inconel 617 and the interfacial cracks formed in the TiN/Si. The delamination was caused by the mechanical stress from the center to the outside of the ablated spot as the FEA results expected. It was considered that the improvement of the thermal shock resistance was attributed to higher thermal conductivity of Si wafer than that of Inconel 617.

• Journal of Magnetics
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• v.17 no.2
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• pp.96-99
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• 2012

The change of saturation magnetization in boronized low carbon microalloyed steels was investigated as a function of boronizing time. Specimens were boronized in an electrical resistance furnace for times ranging from 3 to 9 h at 1123 K. The metallurgical and magnetic properties of the specimens were investigated using optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD) and vibrating sample magnetometry (VSM). A boride layer with saw-tooth morphology consisting of FeB and $Fe_2B$ was observed on the surface, its thickness ranged from 63 ${\mu}m$ to 140 ${\mu}m$ depending on the boronizing time. XRD confirmed the presence of $Fe_2B$ and FeB on the surface. The saturation magnetization decreased with increasing boronizing time. This decrease was attributed to the increased thickness of the FeB and $Fe_2B$ phases. Cracks were observed at the FeB/$Fe_2B$ interfaces of the samples. The number of interfacial cracks increased with increasing boronizing time.

• Journal of the Korea Concrete Institute
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• v.17 no.3 s.87
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• pp.481-485
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• 2005

The present study examines the distribution of calcium hydroxide, unhydrated cement grain and porosity at the steel-concrete interface. The formation of calcium hydroxide has been confirmed by microscopic analysis using BSE images containing the ITZ between the steel and concrete. It was found that calcium hydroxide does not form a layer on the steel surface, different from the hypothesis that has been available in investigating the corrosion of steel in concrete, ranging from 5 to $10\%$ within the steel surface. Moreover, the high level of porosity at the ITZ was observed, accounting for $30\%$, which may reduce the buffering capacity of cement hydration products against a local fall in the pH. These findings may imply that the mole of ($Cl^-$) :($OH^-$) in pore solution as chloride threshold level lead to wrong judgement or to a wide range of values.

• JSTS:Journal of Semiconductor Technology and Science
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• v.3 no.1
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• pp.1-12
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• 2003

This paper describes a study on the abnormal behavior of the electrical characteristics of the (n)GaAs/Ti/Pt/Au Schottky contacts prepared by the two techniques of electron beam deposition and rf sputtering and after an annealing treatment. The samples were characterized by I-V and C-V measurements carried out over the temperature range of 150 - 350 K both in the as prepared state and after a 300 C, 30 min. anneal step. The variation of ideality factor with forward bias, the variation of ideality factor and barrier height with temperature and the difference between the capacitance barrier and current barrier show the presence of a thin interfacial oxide layer along with barrier height inhomogenieties at the metal/semiconductor interface. This barrier height inhomogeneity model also explains the lower barrier height for the sputtered samples to be due to the presence of low barrier height patches produced because of high plasma energy. After the annealing step the contacts prepared by electron beam have the highest typical current barrier height of 0.85 eV and capacitance barrier height of 0.86 eV whereas those prepared by sputtering (at the highest power studied) have the lowest typical current barrier height of 0.67 eV and capacitance barrier height of 0.78 eV.

• Transactions of the Korean Society of Mechanical Engineers
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• v.8 no.6
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• pp.536-543
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• 1984

Thermal structure of two-dimensional surface discharge of the heated water into a rectangular resesvoir is investigated by a laboratory simulation with a shallow open channel and a relatively large reservoir. Experimental study is focused on the nature of interfacial mixing between a flowing layer of the hot water and the underlying cold water. For various conditions, mean temperature field, surface velocity distribution and turbulent mixing process have been quantitatively observed. It is found that the Richardson number strongly affects the integral structure of the flow field, and the buoyancy plays a role to control the turbulent diffusion process.

• Journal of the Microelectronics and Packaging Society
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• v.5 no.1
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• pp.7-18
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• 1998

In the flip chip interconnection on organic substrates using eutectic Pb/Sn solder bumps highly reliable Under Bump Metallurgy (UBM) is required to maintain adhesion and solder wettability. Various UBM systems such as 1$\mu$m Al/0.2$\mu$m Pd/1$\mu$m Cu, laid under eutectic Pb/Sn solder were investigated with regard to their interfacial reactions and adhesion proper-ties. The effects of numbers of solder reflow and aging time on the growth of intermetallic compounds (IMCs) and on the solder ball shear strength were investigated. Good ball shear strength was obtained with 1$\mu$m Al/0.2$\mu$m Ti/5$\mu$m Cu and 1$\mu$m Al/0.2$\mu$m ni/1$\mu$m Cu even after 4 solder reflows or 7 day aging at 15$0^{\circ}C$. In contrast 1$\mu$m Al/0.2$\mu$m Ti/1$\mu$m Cu and 1$\mu$mAl/0.2$\mu$m Pd/1$\mu$m 쳐 show poor ball shear strength. The decrease of the shear strength was mainly due to the direct contact between solder and nonwettable metal such as Ti and Al resulting in a delamination. In this case thin 1$\mu$m Cu and 0.2$\mu$m Pd diffusion barrier layer were completely consumed by Cu-Sn and pd-Sn reaction.