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탐침형 정보저장 기술을 위한 실리콘 탐침의 나노 마멸 특성에 관한 연구
이용하(Y. H. Lee),정구현(K. H. Chung),김대은(D. E. Kim),유진규(J. G. Yoo),홍승범(S. B. Hong) 한국정밀공학회 2004 한국정밀공학회 학술발표대회 논문집 Vol.2004 No.10월
The reliability issue of the probe tip/recording media interface is one of the most crucial concerns in the Atomic Force Microscope (AFM)-based recording technology. In this work, the tribological characteristics of the probe/media interface were investigated by performing wear tests using an AFM. The ranges of applied normal load and sliding velocity for the wear test were 10 to 50nN and 2 to 20㎛/s respectively. The damage of the probe tip was quantitatively as well as qualitatively characterized by Field Emission Scanning Probe Microscope (FESEM) analysis and calculated based on Archard’s wear equation. It was shown that the wear coefficient of the probe tip was in the order of 10?⁴ ~10?³, and significant contamination at the end of the probe tip was observed. Thus in order to implement the AFM-based recording technology, tribological optimization of the probe/media interface must be achieved.
플라즈마 화학기상 증착법에 의해 증착된 B이 첨가된 ZnO 박막의 전기적 특성
최준영(J. Y. Choi),조해석(H. S. Cho),김영진(Y. J. Kim),이용의(Y. E. Lee),김형준(H. J. Kim) 한국진공학회(ASCT) 1995 Applied Science and Convergence Technology Vol.4 No.1
본 연구에서는 투명 전극으로의 응용을 목적으로 PECVD법에 의해 증착된 B이 첨가된 ZnO 박막의 전기 및 광학적 특성을 살펴보았다. B을 첨가하지 않은 ZnO 박막은 비저항이 수 Ω-㎝ 정도의 값을 가지고 있었으며 시간에 따른 비저항의 변화가 컸으나, 2% B₂H_6을 5~16 sccm의 유량 범위에서 첨가한 경우에는 5~9×10^(-2) Ω-㎝의 비저항을 가지고 시간 경과에 따른 비저항의 변화가 아주 작은 ZnO 박막을 얻을 수 있었다. Van der Pauw법에 의한 Hall 계수의 측정 결과에 의하면, B을 첨가하지 않은 ZnO 박막의 전자 농도는 10^(17)/㎤정도였으나 B을 첨가함으로써 최고 10^(20)/㎤까지 증가하였다. 그러나 B이 첨가되기 전에는 박막의 전하 나르게 이동도가 4 ㎠/Vㆍsec이었으나, B 첨가에 의해 0.7 ㎠/Vㆍsec 이하로 감소하였다. B을 첨가한 경우와 첨가하지 않은 경우의 ZnO 박막은 모두 가시광선영역에서 90% 이상의 광투과율을 가지고 있었으며, B을 첨가한 경우는 전자농도가 증가함에 따라 광학적 밴드 갭이 3.3eV로 부터 3.55 eV로 증가하는 거동을 보였다. We investigated the electrical and optical properties of B-doped ZnO films deposited by plasma enhanced chemical vapor deposition (PECVD) using DEZ, N₂O, and B₂H_6 for the application of transparent conducting electrodes. The resistivity range of undoped ZnO films was a few Ω-㎝, but that of B-doped ZnO films was 5~9×10^(-2) Ω㎝. Hall measurement using the van der Pauw method showed that the carrier concentrations of ZnO films increased from 10^(17)/㎤ for undoped films to 1.2×10^(20)/㎤ with increasing B₂H_6 flow rate, while the carrier mobility decreased from 4 ㎠/Vㆍsec to 0.7 ㎠/Vㆍsec. The transmittance within visible region was nearly 90% for both undoped and B-doped ZnO films and the optical band gap of the films increased from 3.3 eV to 3.55 eV as the flow rate of B₂H_6 increased.
한은영,류인철,이용무,구영,한수부,최상묵,신지연,양승민,정종평,Han, E.Y.,Rhyu, I.C.,Lee, Y.M.,Ku, Y.,Han, S.B.,Choi, S.M.,Shin, J.Y.,Yang, S.M.,Chung, C.P. 대한치주과학회 2001 Journal of Periodontal & Implant Science Vol.31 No.3
The purpose of this study is to determine if a relationship exists among osteoporosis, alveolar bone density and periodontal disease in postmenopausal osteoporotic women and postmenopausal healthy women. Twenty-two women were evaluated for this study. They were attending the postmenopausal clinic, Seoul National University Hospital and generally healthy except osteoporosis. They had experienced menopause not less than one year when we began to examine them. Bone densities of lumbar area(L2-L4) was determined by DEXA(LUNAR-expert Co,. U.S.A). We diagnosed osteoporosis when T-score was below -2.5 and healthy state when T-score was over -1. Osteoporotic(10 female), not hormone-treated group and healthy control group(12 female) were asked for their age, menopausal age, menopausal period and the number of remaining teeth and examined clinically for plaque index(PI), gingival index(GI), clinical attachment loss(CAL) on their 6 Ramfjord index teeth. Intraoral radiographs were taken in maxillary anterior zone. All films were equally exposed and developed. Each films was digitized and analysed using image processing software, Scion image. Alveolar bone regions of interest were selected and Intensity of each pixel was quantized in the array ranging from 0(white) to 255(black). The two groups were comparable with respect age, menopausal age, menopausal period and number of remaining teeth. The osteoporotic women had significantly lower alveolar bone density than controls in maxilla. But no significant difference was found with respect clinical attachment loss, plaque index and gingival index. Supported by the Ministry of Public Health and Welfare, Korea (HMP-00-CH-10-0009).
Sol-Gel Process를 이용한 SiO<sub>2</sub>/TiO<sub>2</sub> 복합 미립자의 합성
구상만,이동현,류창석,이용은,Koo, S.M.,Lee, D.H.,Ryu, C.S.,Lee, Y.E. 한국공업화학회 1997 공업화학 Vol.8 No.2
응집이 없는 단분산의 $SiO_2/TiO_2$ 복합 미립자를 얻기 위하여 $TiO_2$seed가 분산되어 있는 에탄올 수용액과 TEOS (Tetraethyl Orthosilicate)를 에탄올에 녹인 용액을 혼합하여 $TiO_2$ 주위에서 TEOS가 가수분해 및 축합 반응이 일어나도록 유도하여 복합 미분말을 제조하였다. 촉매로 암모니아를 사용하였고, 반응온도는 실온이었다. 반응변수는 TEOS의 농도, 암모니아의 농도, $TiO_2$ seed의 크기 및 양이었다. 응집이 없는 복합 미립자를 얻기 위한 최적조건은 [TEOS]=0.3M, [$NH_4OH$]=0.7M, $TiO_2$ seed의 크기가 200~300 nm이었고, 이때 $0.8{\sim}0.9{\mu}m$의 입자크기를 갖는 복합입자를 얻을 수 있었다. Monodisperse, spherical $SiO_2/TiO_2$ composite fine powders were prepared by modified Sol-Gel process which $TiO_2$ fine Powders was used as a seed particles for condensation of TEOS (Tetraethyl Orthosilicate). The reaction was carried out under $N_2$ atmosphere at ambient temperature using $NH_3$ as a catalyst. Ethanol was used as a solvent. Drying process was carried out with vacuum trap which cooled by liquid $N_2$. The reaction variables were the concentration of TEOS, the concentration of ammonia, the size of $TiO_2$ seed and molar ratio of $SiO_2/TiO_2$. The optimum condition for the preparation of $SiO_2/TiO_2$ composite fine powders without agglomeration was [TEOS]=0.3M, [$NH_3$]=0.7M, size of $SiO_2/TiO_2$ seed = 200~300nm.
Sol - Gel process 를 이용한 SiO2 / TiO2 복합 미립자의 합성
구상만,이동현,류창석,이용은 ( S . M . Koo,D . H . Lee,C . S . Ryu,Y . E . Lee ) 한국공업화학회 1997 공업화학 Vol.8 No.2
응집이 없는 단분산의 SiO₂/TiO₂ 복합 미립자를 얻기 위하여 TiO₂ seed가 분산되어 있는 에탄올 수용액과 TEOS(Tetraethyl Orthosilicate)를 에탄올에 녹인 용액을 혼합하여 TiO₂ 주위에서 TEOS가 가수분해 및 축합 반응이 일어나도록 유도하여 복합 미분말을 제조하였다. 촉매로 암모니아를 사용하였고, 반응온도는 실온이었다 반응변수는 TEOS의 농도, 암모니아의 농도, TiO₂ seed의 크기 및 양이었다. 응집이 없는 복합 미립자를 얻기 위한 최적조건은 [TEOS]=0.3M, [NH₄OH]=0.7M, TiO₂seed의 크기가 200∼300 nm이었고, 이때 0.8∼0.9㎛의 입자크기를 갖는 복합입자를 얻을 수 있었다. Monodisperse, spherical SiO₂/TiO₂ composite fine powders were prepared by modified Sol-Gel process which TiO₂ fine powders was used as a seed particles for condensation of TEOS (Tetraethyl Orthosilicate). The reaction was carried out under N₂ atmophere at ambient temperature using NH₃ as a catalyst. Ethanol was used as a solvent. Drying process was carried out with vacuum trap which cooled by liquid N₂. The reaction variables were the concentration of TEOS, the concentration of ammonia, the size of TiO₂ seed and molar ratio of SiO₂/TiO₂. The optimum condition for the preparation of SiO₂/TiO₂ composite fine powders without agglomeration was [TEOS]=0.3M, [NH₃]=0.7M, size of TiO₂ seed = 200∼300nm.