• 한국재료학회지
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• 제14권9호
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• pp.619-626
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• 2004

Pulsed metalorganic chemical vapor deposition (MOCVD) of conformal copper seed layers, for the electrodeposition Cu films, has been achieved by an alternating supply of a Cu(I) source and $H_2$ reactant at the deposition temperatures from 50 to $100^{\circ}C$. The Cu thickness increased proportionally to the number of cycles, and the growth rate was in the range from 3.5 to $8.2{\AA}/cycle$, showing the ability to control the nano-scale thickness. As-deposited films show highly smooth surfaces even for films thicker than 100 nm. In addition about a $90\%$ step coverage was obtained inside trenches, with an aspect ratio greater than 30:1. $H_2$, introduced as a reactant gas, can play an active role in achieving highly conformal coating, with increased grain sizes.

• 한국음향학회지
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• 제13권6호
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• pp.24-30
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• 1994

본 논문에서는 금속에서의 광음향신호를 분석하기 위해 CW $CO_{2}$ 레이저를 사용하여 광음향 신호검출 시스템을 구성하였으며 알루미늄, 탄소강 및 활동을 샘플로 선택하고 레이저 변조주파수, 록인앰프의 시정수를 변화시키면서 샘플의 종류 및 두께에 따른 수 nA정도의 광음향 신호를 검출하여 신호처리 기법에 의해 금속에서의 광음향 신호의 특성을 분석하였다. 실험결과 시정수를 조정하여 광음향 신호를 안정화시킬 수 있었고 광음향 신호는 금속고유의 열팽창계수에 대한 열용량에 비례하여 증가하고 샘플두께 및 변조주파수에 대하여 지수함수적으로 감소함을 확인하였다.

• 한국정보통신학회논문지
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• 제7권4호
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• pp.719-724
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• 2003

본 논문은 halo doping profile을 갖는 나노구조 LDD MOSFET의 문턱전압에 대하여 연구하였다. 소자의 크기는 일반화된 스켈링 이론을 사용하여 100nm 에서 40m까지 스켈링하였다. Van Dort Quantum Correction Model(QM) 모델을 정전계 스켈링 이론과 정전압 스켈링 이론에 적용하여 문턱전압을 조사하였으며, gate oxide 두께의 변화 따른 direct tunneling current를 조사하였다. 결과적으로 게이트 길이가 감소됨에 따라 문턱전압이 정전계 스켈링에서는 감소하고 정전압 스켈링에서는 증가함을 알았고 direct tunneling current는 gate oxide 두께가 감소함에 따라 증가됨을 알았다. 또한 채널 길이의 감소에 따른 MOSFET의 문턱전압에 대한 roll-off특성을 최소화하기 위하여 일반화된 스켈링에서 $\alpha$값은 거의 1 이여야 함을 알았다.

• 한국정밀공학회지
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• 제21권4호
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• pp.161-169
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• 2004

In this study, we investigated fatigue crack growth behavior of laser welded sheet metal due to a single overload. Fatigue specimens were made using butt joint of cold rolled sheet metal that was welded by $CO_2$ laser. The fatigue crack propagation tests were performed in such a way that fatigue loading was parallel to the weld line while crack propagation was perpendicular to the weld line. Single overload was applied when fatigue crack tip was arrived near the weld line. The distances between the crack tip and the weld line at which a single overload was applied were 6, 4 and 2mm. The effect of specimen thickness and overload ratio on the fatigue behavior was determined. The plastic zone size of crack tip due to the single overload was determined from the finite element analysis. For investigating fatigue crack growth behavior, we used different thickness specimen 0.9mm and 2.0mm, and variable overload ratio applied fatigue crack propagation test. Also we used finite element analysis for investigating the plastic zone size of crack tip when single overload applied

• Structural Engineering and Mechanics
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• 제67권6호
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• pp.565-578
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• 2018

This research article reported the nonlinear finite solutions of the nonlinear flexural strength and stress behaviour of nano sandwich graded structural shell panel under the combined thermomechanical loading. The nanotube sandwich structural model is derived mathematically using the higher-order displacement polynomial including the full geometrical nonlinear strain-displacement equations via Green-Lagrange relations. The face sheets of the sandwich panel are assumed to be carbon nanotube-reinforced polymer composite with temperature dependent material properties. Additionally, the numerical model included different types of nanotube distribution patterns for the sandwich face sheets for the sake of variable strength. The required equilibrium equation of the graded carbon nanotube sandwich structural panel is derived by minimizing the total potential energy expression. The energy expression is further solved to obtain the deflection values (linear and nonlinear) via the direct iterative method in conjunction with finite element steps. A computer code is prepared (MATLAB environment) based on the current higher-order nonlinear model for the numerical analysis purpose. The stability of the numerical solution and the validity are verified by comparing the published deflection and stress values. Finally, the nonlinear model is utilized to explore the deflection and the stresses of the nanotube-reinforced (volume fraction and distribution patterns of carbon nanotube) sandwich structure (different core to face thickness ratios) for the variable type of structural parameter (thickness ratio, aspect ratio, geometrical configurations, constraints at the edges and curvature ratio) and unlike temperature loading.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2018년도 춘계학술대회
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• pp.173-174
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• 2018

논문은 MOSFET와 JLFET로 구성된 3D 인버터의 inter-layer dielectric (ILD)의 두께에 따른 하층 게이트에 의한 전기적 상호작용을 비교하였다. MOSFET와 JLFET 모두 ILD의 두께가 100 nm에서 문턱전압의 변화량이 크지 않았지만 100 nm에서 문턱전압의 변화량이 크게 증가하였다. 특히 JLFET의 문턱전압의 변화량이 MOSFET보다 2배 정도 크게 변화하여 하층 게이트에 의한 전기적인 영향을 더 크게 받는다.

• Bulletin of the Korean Chemical Society
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• 제28권12호
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• pp.2481-2485
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• 2007

Spatially resolved, quantitative, non-destructive analysis using synchrotron x-ray reflectivity (XR) with subnano-scale resolution was successfully performed on the nanoporous organosilicate thin films for low dielectric applications. The structural information of porous thin films, which were prepared with polymethylsilsesquioxane and thermally labile 4-armed, star-shaped poly(ε-caprolactone) (PCL) composites, were characterized in terms of the laterally averaged electron density profile along with a film thickness as well as a total thickness. The thermal process used in this work caused to efficiently undergo sacrificial thermal degradation, generating closed nanopores in the film. The resultant nanoporous films became homogeneous, well-defined structure with a thin skin layer and low surface roughness. The average electron density of the calcined film reduced with increase of the initial porogen loading, and finally leaded to corresponding porosity ranged from 0 to 22.8% over the porogen loading range of 0-30 wt%. In addition to XR analysis, the surface and the inner structures of films are investigated and discussed with atomic force and scanning electron microscopy images.

• 한국기계가공학회지
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• 제7권2호
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• pp.60-65
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• 2008

The high-technology industries including a semi-conductor and an information communication need an ultra-precision technology from the technological points of view. Nano technology based on an ultra-precision technology is being studied to overcome the delicate technology that may occur in the semi-conductor fields. Then, the transferring equipment with high resolution and long displacement becomes an important technology. The goal of this study is to analyze the displacement magnification mechanism driven by piezoelectric actuator which has high resolution and fast response characteristics using flexure hinge with the merits of soft displacement, negligible back-lash and stick-slip, and no-lubrication. The analyses to reduce the magnification losses occurred during the magnification process are performed using ANSYS software based on FEM. The five design variables such as arm thickness, thickness of hinge, radius of hinge, length of input side at the 1st lever and magnification ratio of 1st lever are optimized to induce the maximum magnification ratio using Taguchi method.

• 전기학회논문지
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• 제57권5호
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• pp.803-807
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• 2008

A making process of DSC(dye sensitized solar cell) was presented. In general, Photo electrodes of DSC was made by using colloid paste of nano $TiO_2$ and processing of Doctor-blade printing and high temperature sintering for porous structure. These methods lead to cracks on $TiO_2$ surface and ununiform of $TiO_2$ thickness. This phenomenon is one factor that makes low efficiency to cells. After $TiO_2$ printing on TCO glass, a physical vibration was adapted for reducing ununiform of $TiO_2$ thickness. And a thermal treatment at low temperature(under $75^{\circ}C$) was adapted for reducing cracks on $TiO_2$ surface. In this paper, we have designed and manufactured an ultrasonic circuit (100W, frequency and duty variable) and a thermal equipment. Then, we have optimized forcing time, frequency and duty of ultrasonic irradiation and thermal heating for surface treatment of photo-electrode of DSC. In I-V characteristic test of DSC, ultrasonic and thermal treated DSC shows 19% improved its efficiency against monolithic DSC. And it shows stability of light-harvesting from drastically change of light irradiation test.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2010년도 제39회 하계학술대회 초록집
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• pp.132-132
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• 2010

In the nano-scale Si processing, patterning processes based on multilevel resist structures becoming more critical due to continuously decreasing resist thickness and feature size. In particular, highly selective etching of the first dielectric layer with resist patterns are great importance. In this work, process window for the infinitely high etch selectivity of silicon oxynitride (SiON) layers and silicon nitride (Si3N4) with EUV resist was investigated during etching of SiON/EUV resist and Si3N4/EUV resist in a CH2F2/N2/Ar dual-frequency superimposed capacitive coupled plasma (DFS-CCP) by varying the process parameters, such as the CH2F2 and N2 flow ratio and low-frequency source power (PLF). It was found that the CH2F2/N2 flow ratio was found to play a critical role in determining the process window for ultra high etch selectivity, due to the differences in change of the degree of polymerization on SiON, Si3N4, and EUV resist. Control of N2 flow ratio gave the possibility of obtaining the ultra high etch selectivity by keeping the steady-state hydrofluorocarbon layer thickness thin on the SiON and Si3N4 surface due to effective formation of HCN etch by-products and, in turn, in continuous SiON and Si3N4 etching, while the hydrofluorocarbon layer is deposited on the EUV resist surface.