• 마이크로전자및패키징학회지
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• 제18권4호
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• pp.11-18
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• 2011

3차원 칩 적층 접합에 사용하기 위한 Cu-Cu 금속 저온 접합 공정을 위하여 접합 온도 및 플라즈마 표면 전처리에 따른 열 압착 접합을 수행 하였다. 4점굽힘시험과 CCD 카메라를 이용하여 Cu 접합부의 정량적인 계면접착에너지를 평가하였다. 접합 온도 $250^{\circ}C$, $300^{\circ}C$, $350^{\circ}C$에서 각각 $1.38{\pm}1.06$(상한값), $7.91{\pm}0.27$(하한값), $10.36{\pm}1.01$(하한값) $J/m^2$으로 접합온도 $300^{\circ}C$ 이상에서 계면접착에너지 5 $J/m^2$ 이상의 값을 얻었다. 접합 온도 $300^{\circ}C$ 이하 낮은 온도에서 접합하기 위해 Cu-Cu 열 압착 접합 전 Ar+$H_2$ 플라즈마로 $200^{\circ}C$에서 2분간 표면 전처리 후 $250^{\circ}C$ 조건에서 열 압착 접합할 경우 계면접착에너지 값이 $6.59${\pm}0.03$(하한값) $J/m^2$로 표면 전 처리하지 않은 시험편에 비해 접합 특성이 크게 증가 하였다.

• 한국의학물리학회:학술대회논문집
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• 한국의학물리학회 1999년도 Japanese Journal of Medical Physics
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• pp.299-300
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• 1999

• JSTS:Journal of Semiconductor Technology and Science
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• 제3권2호
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• pp.63-68
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• 2003

The DC and RF characteristics of $In_{0.5}Ga_{0.5}P/In_{0.22}Ga_{0.78}As/GaAs$ p-HEMTs with a gate oxide layer of various thicknesses ($50{\;}{\AA},{\;}300{\;}{\AA}$) were investigated and compared with those of a Schottky-gate p-HEMT without the gate oxide layer. A prominent improvement in the breakdown voltage characteristics were observed for a p-HEMT having a gate oxide layer, which was implemented by using a liquid phase oxidation technique. The on-state breakdown voltage of the p-HEMT having the oxide layer of $50{\;}{\AA}$was ~2.3 times greater than that of a Schottky-gate p-HEMT. However, the p-HEMT having the gate oxide layer of $300{\;}{\AA}$ suffered from a poor gate-control capability due to the drain induced barrier lowering (DIBL) resulting from the thick gate oxide inspite of the lower gate leakage current and the higher on-state breakdown voltage. The results for a primitive p-HEMT having the gate oxide layer without any optimization of the structure and the process indicate the potential of p-HEMT having the gate oxide layer for high-power applications.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 추계학술대회 논문집 전기물성,응용부문
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• pp.171-173
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• 2001

ZnO:Al transparent conductive thin films were prepared by facing targets sputtering system with a DC power supply using ZnO target containing 2wt% of $Al_2O_3$ and Zn metal target. Sputtering was carried out at substrate temperature of R.T. and $200^{\circ}C$ with a DC current of 0.6A, $O_2$ flow rate of $0.1{\sim}0.5$ and thickness $300{\sim}900nm$. ZnO:Al films showed a resistivity as low as $10^{-4}{\Omega}-cm$ and a transmittance above 85 % at wavelength 300 and 800nm.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.86-89
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• 2005

Design and estimation of a spindle system which was composed of grinding spindle and regulating spindle for the centerless grinding of ferrule was performed and prototypes of each spindle were manufactured. Loop stiffness of the spindle system was 130 N/${\mu}m$. Although the value was lower than the target value of 150 N/${\mu}m$, as there included 20% of the safety factor, it was enough to machine the ferrule. Rotational accuracies of each spindle were about 0.2${\mu}m$ at the primary speed of 2,300 rpm(grinding spindle) and 300 rpm(regulating spindle). Temperature rises at the same speed were about $4.4\;\~\;4.7^{\circ}C$ in the case of grinding spindle and $1.8^{\circ}C$in the case of regulating spindle, which were well agreed with the designed value. From these results, it was estimated that the prototype of spindle system had a enough performances for the centerless grinding machine to machine the ferrule.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2005년도 후기학술대회논문집
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• pp.212-213
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• 2005

The results of an experimental and analytical study of composite pressure hull on buckling pressure are presented for URN 300. We predicted the buckling and post buckling analysis of composite laminated cylindrical shell and panel under external compression by using ABAQUS/Standard[Ver 6.4]. To obtain nonlinear static equilibrium solutions for unstable problems, where the load-displacement response can exhibit the type of nonlinear buckling behavior, during periods of the response, the load and/or the displacement may decrease as the solution evolves, used the modified Riks method. Experiments were conducted to verify the validation of present analysis for cross-ply laminated shells. The shells considered in the study have four different lamination patterns, [${\pm}{\Theta}$/0/90]$_{14s}$,[${\pm}{\Theta}_{14}$/$0_{14}$/$90_{14}$],[${\pm}$45/0/90]$_{18s}$ and [/0/90]$_{18s}$. At the result of this study, the optimized ply orientation angle is $75^{\circ}$. The critical load from experiment is 69% of that of numerical analysis, because the fracture of matrix was generated before buckling. So URN 300 is not proper to use at the condition under high external pressure.

• 대한기계학회논문집A
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• 제30권10호
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• pp.1173-1178
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• 2006

In a primary reactor cooling system(RCS), a dissimilar weld zone exists between cast stainless steel(CF8M) in a pipe and low-alloy steel(SA508 cl.3) in a nozzle. Thermal aging is observed in CF8M as the RCS is exposed for a long period of time to a reactor operating temperature between 290 and $330^{\circ}C$, while no effect is observed in SA508 cl.3. The specimens are prepared by an artificially accelerated aging technique maintained for 300, 1800 and 3600 hrs at $430^{\circ}C$, respectively. The specimens for elastic-plastic fracture toughness tests are according to the process in the thermal notch is created in the heat affected zone(HAZ) of CF8M and deposited zone. From the experiments, the $J_{IC}$ value notched in HAZ of CF8M presented a rapid decrease up to 300 hours at $430^{\circ}C$ and slowly decreased according to the process in the thermal aging time. Also, the $J_{IC}$ value presented a lower value than that of the CF8M base metal. And, the $J_{IC}$ of the deposited zone presented the lowest value of all other cases.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 C
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• pp.2083-2085
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• 2000

우리나라의 전열추진기술 프로그램에 따라 8�V의$\square$ $\square kJ$ 커패시터 뱅크 모듈이 제작되고 있다. 한 �V의 모듈은 6개의 22kV, 50kJ 자체 고장복구 커패시터와 주 스위치로서 각 모듈에 하나씩의 RVU-43 스위치를 사용하였다. 또 각 모듈에는 요구되는 전류 파형의 폭을 얻기 위하여 $20\sim160\;\mu\;H$의 펄스 파워 인덕터를 사용하였고 3개의 병렬 크로우바 스택을 적용하였다. 여러 종류의 스위치가 검토되었으며 그 중에서 펄스 파워 싸이리스터보다 가격이 싸면서 전류영점에서 차단기능이 있는 RVU-43 스위치가 선정되었다. 선정된 스위치(정격 25kV, 200kA, 120 Coulomb)에 대하여 자기방전 전압, 최소 동작전압, 동작 지연시간, 역전류 차단성능, 스위치 손실에 관한 특성시험을 행하고 그 결과를 보고한다.

• Bulletin of the Korean Chemical Society
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• 제20권9호
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• pp.1061-1066
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• 1999

The adsorption of CO on W(111) surface in the range of adsorption temperature between 300 K and 1000 K has been studied using AES, LEED, and TDS in an UHV system. After CO saturation at 300 K, four desorption peaks are observed at temperatures (K) of about 400, 850, 1000, and 1100 in thermal desorption spectra, called as α, β1, β2, and β3 state, respectively. The state was attributed to molecular species of CO, which is well known. Because the CO in βstates (especially the β3 state) is still debated as to whether it is dissociative or non-dissociative, the β3 state is mainly discussed. By using the variation method of heating rate in the thermal desorption spectrometry, the desorption energy and pre-exponential factor for the β3 state are evaluated to be 280 kJ/mol and 1.5×10 12 s-1 , respectively. A lateral interaction energy of 5.7 kJ/mol can also be estimated by Bragg-Williams approximation. To interpret the thermal desorption spectra for the β3 state, moreover, those for the model of a first order and a second order desorption are simulated using quasi-chemical approximation. In this study, a model of lying-down CO species is proposed for the β3 state of CO adsorption.

• Tribology and Lubricants
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• 제31권6호
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• pp.308-315
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• 2015

In the tribological performance of materials, a textured surface reduces the friction coefficient and wear. This study investigates the effects of a pattern of 300 µm dimples in a hexagonal array on the tribological characteristics. Previous studies investigated 200 µm dimples by using a similar material and method. There are three frictional conditions based on the Stribeck curve: boundary friction, mixed friction, and fluid friction. In this experiment, we investigated the frictional characteristics by conducting frictional tests at sliding speeds ranging from 9.6 rpm to 143.3 rpm and a normal load ranging from 13.6 N to 92 N. We used a photolithography method to create dimples for surface texturing. We used five specimens with different dimple densities 10%, 15%, 20%, 25%, and 30% in this study. The dimple density on the surface area is one of the important factors affecting the friction characteristics. The duty number graph indicates a fully developed fluid friction regime. Fluid friction occurs at a velocity of 28.7-143.3 rpm. We observed the best performance at a dimple density of 10% and a dimple diameter of 300 µm in the hexagonal array, the lowest friction coefficient at 0.0037 with 9.6 rpm 9.6N load, and the maximum friction coefficient at 0.0267 with 143.3 rpm 92N load.