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DDPO₄ 와 ODPO₄ SAM 코팅의 나노 응착 및 마찰 특성 연구
윤의성(Eui-Sung Yoon),양승호(Seung Ho Yang),공호성(Hosung Kong),Andrei Ya Grigoriev 한국트라이볼로지학회 2002 한국트라이볼로지학회 학술대회 Vol.35 No.-
Nano adhesion between SPM (scanning probe microscope) tips and DDPO₄ (dodecylphosphoric acid ester) and ODPO₄ (octadecylphosphoric acid ester) SAM (self-assembled monolayer) was experimentally studied. Tests were performed to measure the nano adhesion and friction in both AFM(atomic force microscope) and LFM(lateral force microscope) modes with the applied normal load. DDPO₄ and ODPO₄ SAM were formed on TiMe and TiOx surfaces. TiMe and TiOx were coated on the Si wafer by ion sputtering. Adhesion and friction of DDPO₄ and ODPO₄ SAM surfaces were compared with those of OTS (octadecyltrichlorosilane) SAM and DLC surfaces. DDPO₄ and ODPO₄ SAM converted the TiMe and TiOx surfaces to be hydrophobic. When the surface was hydrophobic, the adhesion and friction forces were found lower than those of bare surfaces. Work of adhesion was also discussed to explain how the surface was converted into hydrophobic. Results also showed that tribological characteristics of DDPO₄ and ODPO₄ SAM had good properties in the adhesion, friction, wetting angle and work of adhesion. DDPO₄ and ODPO₄ SAM could be one of the candidates for the bio-MEMS elements.
Eui-Sung Yoon(윤의성),R.Arvind Shingh,Hung-Gu Han,Hosung Kong 한국트라이볼로지학회 2004 한국트라이볼로지학회 학술대회 Vol.39 No.-
Nano/micro-scale studies on friction properties were conducted on Si (100) and three self-assembled monolayers (SAMs) (PFOTC, DMDM, DPDM) coated on Si-wafer by chemical vapor deposition technique. Experiments were conducted at ambient temperature (24±1℃) and humidity (45±5%). Nano-friction was evaluated using Atomic Force Microscopy (AFM) in the range of 0-40nN normal loads. In both Si-wafer and SAMs, friction increased linearly as a function of applied normal load. Results showed that friction was affected by the inherent adhesion in Si-wafer, and in the case of SAMs the physical/chemical structures had a major influence. Coefficient of friction of these test samples was also evaluated at the micro-scale using a micro-tribotester. It was observed that SAMs had superior frictional property due to their low interfacial energies. In order to study of the effect of contact area on friction coefficient at the micro-scale, friction was measured for Si-wafer and DPDM against Soda Lime balls (Duke Scientific Corporation) of different radii (0.25 ㎜, 0.5 ㎜ and 1 ㎜) at different applied normal loads (1500, 3000 and 4800μN). Results showed that Si-wafer had higher friction coefficient than DPDM. Furthermore, unlike that in the case of DPDM, friction was severely influenced by wear in the case of Si-wafer. SEM evidences showed that solid-solid adhesion to be the wear mechanism in Si-wafer.
표면형상이 젖음각과 마이크로/나노 트라이볼로지 특성에 미치는 영향
윤의성(Eui-Sung Yoon),오현진(Hyun-Jin Oh),양승호(Seung Ho Yang),공호성(Hosung Kong) 한국트라이볼로지학회 2002 한국트라이볼로지학회 학술대회 Vol.35 No.-
Effect of surface topography on the water wetting nature and micro/nano tribological characteristics of Si-wafer and PTFE was experimentally studied. The ion beam treatment was performed with a hollow cathode ion gun in different argon ion dose conditions in a vacuum chamber to change the surface topography. Micro/nano tribological characteristics, water wetting angles and roughness were measured with a micro tribo tester, SPM (scanning prove microscope), contact anglemeter and profilometer, respectively. Results showed that surface roughness increased with the argon ion dose. The water wetting angle of the ion beam treated samples also increased with the ion dose. Results also showed that micro-adhesion and micro-friction depend on the wetting characteristics of the PTFE samples. However, nano-tribological characteristics showed little dependence on the wetting angles. The water wetting characteristics of modified PTFE samples were discussed in terms of the surface topographic characteristics.
암모니아처리 볏짚급여시 , 사료섭취량 , 영양적 가치 및 제1위내 성상에 미치는 영향
윤칠석,최의성,오태광 이남형,김창원,김춘수 ( Chil Surk Yoon,Eui Sung Choi,Tae Kwang Oh,Nam Hyung Lee,Chang Won Kim,Chun Su Kim ) 한국축산학회 1983 한국축산학회지 Vol.25 No.6
This experiment was conducted to determine the effect of ammonia treated rice straw on nutritive value and rumen characteristics. Rice straw was treated with aqueous NH₄OH to supply 40g NH₃ Kg^(-1) straw dry matter. The reaction time with ammonia was 6 weeks at room temperature. The results are as follows: Crude protein content increased more than 2 times by treatment, and the NDF content was decreased about 4.7%. The effect of ammoniation was the important factor in enhancing IVDMD. Ammoniation resulted in the significant improvements in intake, digestbility and nutritional quality. Improvements in nitrogen and sulfur retention was significant with treated straw. Also, Molar proportions of acetate increased (P$lt;.01) and butyrate decreased (P$lt;.01) with ammoniation. In conclusion, ammoniation is a simple and effective method of improving the feeding value of rice straw.
윤의성(Eui-Sung Yoon),R. Arvind Singh,공호성(Hosung Kong) 한국트라이볼로지학회 2005 한국트라이볼로지학회지 (Tribol. Lubr.) Vol.21 No.5
Nano/micro friction with the contact area was studied on Si-wafer (100) and diamond-like carbon (DLC) film. Borosilicate balls of radii 0.32 ㎛, 0.5 ㎛, 1.25 ㎛ and 2.5 ㎛ mounted on the top of AFM tip (NPS) were used for nano-scale contact and Soda Lime glass balls of radii 0.25 mm, 0.5 mm, 1 mm were used for micro-scale contact. At nano-scale, the friction between ball and surface was measured with the applied normal load using an atomic force microscope (AFM), and at micro scale it was measured using ball-on flat type micro-tribotester. All the experiments were conducted at controlled conditions of temperature (24±1℃) and humidity (45±5%). Friction was measured as a function of applied normal load in the range of 0-160 nN at nano scale and in the range of 1000 μN, 1500 μN, 3000 μN and 4800 μN at micro scale. Results showed that the friction at nano scale increased with the applied normal load and ball size for both kinds of samples. Similar behavior of friction with the applied normal load and ball size was observed for Si-wafer at micro scale. However, for DLC friction decreased with the ball size. This difference of in behavior of friction in DLC nano- and micro-scale was attribute to the difference in the operating mechanisms. The evidence of the operating mechanisms at micro-scale were observed using scanning electron microscope (SEM). At micro-scale, solid-solid adhesion was dominant in Silicon-wafer, while plowing in DLC. Contrary to the nano scale that shows almost a wear-less situation, wear was prominent at micro-scale. At nano- and micro-scale, effect of contact area on the friction was discussed with the different applied normal load and ball size.