• Applied Microscopy
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• 제45권3호
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• pp.170-176
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• 2015

In this work, various electron microscopy and analysis techniques were used to investigate the microstructural evolution of a 9% Cr tempered martensite ferritic (TMF) steel T91 upon ultrasonic nanocrystalline surface modification (UNSM) treatment. The micro-dimpled surface was analyzed by scanning electron microscopy. The characteristics of plastic deformation and gradient microstructure of the UNSM treated specimens were clearly revealed by crystal orientation mapping of electron backscatter diffraction (EBSD), with flexible use of the inverse pole figure, image quality, and grain boundary misorientation images. Transmission electron microscope (TEM) observation of the specimens at different depths showed the formation of dislocations, dense dislocation walls, subgrains, and grains in the lower, middle, upper, and top layers of the treated specimens. Refinement of the $M_{23}C_6$ precipitates was also observed, the size and the number density of which were found to decrease as depth from the top surface decreased. The complex microstructure and microstructural evolution of the TMF steel samples upon the UNSM treatment were well-characterized by combined use of EBSD and TEM techniques.

• 한국진공학회지
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• 제4권S2호
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• pp.95-99
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• 1995

keV ion beam irradiatin for surface modification and thin film growth have been discussed. keV ion beam irradiation in reactive gas environment has been developed for improving wettability of polymer, and for enhancing adhesion to metal film, and adventages of the method have been reviewed. An epitaxial Cu film on Si(100) substrate has been grown by ionized cluster beam and changes of crystallinity and surface roughness have been discussed. Stoichiometric $SnO_2$ films on Si(100) and glass have been grown by a hybrid ion beam Deposition(2 metal ion sources+1 gas ion source), and nonstoichiometric $SnO_2$ films are controlled by various deposition conditions in the HIB. Surface modification for polymer by kev ion irradiation have been developed. Wetting angle of water to PC has been changed from 68 degree to 49 degree with $Ar^+$ irradiation and to 8 degree with $Ar^+$ irradiation and the oxygen environment. Change of surface phenomena in a keV ion beam and characteristics of the grown films are suggested.

• 한국항만학회지
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• 제9권2호
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• pp.25-38
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• 1995

The wind generated circulation model describes the phenomenon based on the following physical assumptions: a) As the horizontal dimension of the flow domain is several orders of magnitude larger than vertical dimension, nearly horizontal flow is realistic. b) The time taken for circulation to develop may effect on the flow domain of the earth's rotation, the contribution of the Coriolis force. c) A flow domain of large dimension results in quite large Reynolds number and the Reynolds stresses are approximated by the turbulent mean velocity gradient. d) The circulation is forced by the shear stresses on the water surface exercised by the wind. Modification made to the depth average approximation of the convective terms and the bed shear stress terms by adopting a certain distribution of current over the depth and laboratory measurements for the bed shear expression. Modification circulation patterns, energy evolution and surface profile gave the significant differences comparing with the classical model results. The modified model results in higher free surface gradients balancing both the free surface shear and the bed shear and consequently to higher surface profiles along the coast.

• 멤브레인
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• 제33권1호
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• pp.1-12
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• 2023

본 총설은 소수성 불소수지계 분리막의 표면 개질에 대한 개론으로 다양한 표면 개질 방법 및 그 연구 결과를 중점적으로 서술하였다. PTFE로 대표되는 불소수지계 고분자 분리막은 막 증류, 유수 분리, 기체 분리를 포함한 다양한 막 분리 공정에서 사용되어왔다. PTFE 막은 내화학성, 내열성, 높은 기계적 강도와 같은 뛰어난 물성에도 불구하고 소수성 표면 특성으로 인해 기술 적용의 확장에 제한적이다. 친수성 향상을 위해 습식 화학법, 친수성 고분자 코팅, 플라즈마 처리, 조사, 원자층 증착과 같은 다양한 PTFE 표면 개질 방법을 이용하며 이를 통해 불소수지계 분리막의 응용분야가 확장될 수 있다.

• 한국재료학회지
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• 제34권4호
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• pp.194-201
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• 2024

In this study, the surfaces of two gold nanoparticles of different shapes were modified with hexadecyltrimethylammonium bromide (CTAB) and used for contact lenses. The polymer was based on 2-hydroxyethyl methacrylate (HEMA), and spherical and sea urchin-shaped gold nanoparticles were used as additives. CTAB was used to modify the surface of the sea urchin-shaped gold nanoparticles. To analyze the physical properties of the prepared contact lens, optical transmittance, refractive index, water content, contact angle, and atomic force microscope (AFM) were measured and evaluated. The results showed the nanoparticles did not significantly affect optical transmittance, refractive index, or water content of the lens, and tensile strength increased according to the ratio of the additive. The addition of the sea urchin-shaped nanoparticles resulted in lower wettability compared with the spherical nanoparticles, but somewhat superior tensile strength. In addition, it was found that the wettability of the lens was improved when the surface-modified sea urchin-shaped gold nanoparticles were added. The types of gold nanoparticles and surface modification methods used in this study are considered to have great potential for use in ophthalmic materials.

• Journal of Periodontal and Implant Science
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• 제41권6호
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• pp.263-272
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• 2011

A number of surface modification techniques using immobilization of biofunctional molecules of Titanium (Ti) for dental implants as well as surface properties of Ti and Ti alloys have been developed. The method using passive surface oxide film on titanium takes advantage of the fact that the surface film on Ti consists mainly of amorphous or low-crystalline and nonstoichiometric $TiO_2$. In another method, the reconstruction of passive films, calcium phosphate naturally forms on Ti and its alloys, which is characteristic of Ti. A third method uses the surface active hydroxyl group. The oxide surface immediately reacts with water molecules and hydroxyl groups are formed. The hydroxyl groups dissociate in aqueous solutions and show acidic and basic properties. Several additional methods are also possible, including surface modification techniques, immobilization of poly(ethylene glycol), and immobilization of biomolecules such as bone morphogenetic protein, peptide, collagen, hydrogel, and gelatin.

• 한국염색가공학회지
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• 제19권1호
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• pp.45-52
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• 2007

Polyacrylonitrile(PAN) fiber was treated with low-temperature plasmas of argon and oxygen for surface modification, and its surface chemical structure and morphology were examined by a field emission scanning electron microscope(FESEM) and a Fourier-transform infrared microspectroscopy(IMS). The argon-plasma treatment caused the only mechanical effect by sputtering of ion bombardment, whereas the oxygen plasma brought about a chemical effect on the PAN fiber surface. The experimental evidences strongly suggested that cyclization of nitrile group and crosslinking were likely to occur in the oxygen-plasma treatment. On the other hand, with the argon-plasma treatment, numerous my pits resulted in ranging from several tens to hundreds nanometers in radius. The plasma sensitivity of functional groups such as C-H, $C{\equiv}N$, and O-C=O groups in the PAN fiber was dependent on their chemical nature of bonding in the oxygen-plasma, in which the ester group was the most sensitive to the plasma. Vacuum-ultraviolet(VUV) radiation emitted during plasma treatment played no substantial role to alter the surface morphology.

• 한국레이저가공학회지
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• 제13권3호
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• pp.13-18
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• 2010

In this paper, polyimide (PI) surface was modified by UV Laser with a low laser fluence and investigated changes of surface geometry and chemical characteristics by SEM (scanning electron microscope), X-ray diffraction (XRD), XPS (x-ray photoelectron spectroscopy) and the measurements of contact angle of water. PI surface was peeled off and modified with microstructure fabrications by photochemical ablation over the laser fluence of 50 mJ/cm2. As laser fluence increased, delamination of PI surface was occurred largely and strongly. In chemical characteristics, the O/C and N/C atomic ratios increased and contact angle decreased from $80^{\circ}$ to $40^{\circ}$.

• 한국가스학회지
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• 제4권1호
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• pp.33-39
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• 2000

긴 표면균열을 갖는 알루미늄합금(A5083)의 평판을 사용하여, 균열관통후의 응력확대계수를 검토하였다. 짧은 표면균열의 관통후에 제안된 식에 의하여 긴 표면균열 관통시의 평가는 균열종횡비가 적을수록 오차가 크게 되므로, 진전거동을 정확하게 평가하기 위해서는 수정이 필요하였다. 따라서 긴 표면균열 관통시의 종횡비를 고려하여, 응력확대계수의 평가식을 수정함으로써 관통후 고정도의 해석이 가능하였다.

• 대한의용생체공학회:의공학회지
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• 제10권1호
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• pp.43-52
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• 1989

We modified polymer surfaces, polyethylene, polystyrene and polyester, to improve cellcompatibility. For surface modification of the polymers, we used various surface treatment methods; physicochemical oxidation methods such as plasma discharge, corona discharge, sulfuric acid and chloric acid treatments, and biological methods such as adsorption of plasma protein and fibronectin onto the polymer surfaces. The treated polymer surfaces were characterized by electron spectroscopy for chemical analysis ( ESCA ). The physicochemically treated polymers showed different surface chemical structures depending on the treated methods. The sulfuric acid-treated surfaces showed greater carboxyl groups than those of plasma- or corona- treated surfaces, while the chloric acid-treated one showed high density of hydroxyl group on the surface. By the biological treatments, the surfaces were uniformly coated with proteins. The fibronectin adsorbed on the surface seems to have unique properties for cell binding.