1,721,147 research outputs found
양의 전하를 가지는 마이셀과 음의 전하를 가지는 polyelectrolytes의 복합체
No full text학위논문(박사) - 한국과학기술원 : 물리학과, 2009.2, [ vii, 37 p. ]The adsorption of materials onto the surface of soft matter is of special interest in view of its relevance to biological system. It has been considered that electrostatic interaction and hydrophobic interaction play an important role in adsorption of materials and deformation of the surface of soft matter. 1. I have used small angle neutron scattering(SANS) to study the complex is dependent on the charge ratio, Z of cationic surfactant to polyelectrolyte. For 1/Z>0.5, the complexes is well-soluble in aqueous solution and have a necklace-like shape. The higher the polyelectrolyte concentration is, the shorter the length of a complex becomes. And, for 1/Z>12.5, complexes have spherical shape. The spherical form of micelle is maintained while the structure of complex is not. Ionic strength and conductance, however, increases with increasing the concentration of polyelectrolyte in solution. Here, the persistence length of polyelectrolyte is determined by the ionic strength, which is a key factor for bring together micelles. Moreover, the addition of simple salt induces to form a spherical complex at the concentration of polyelectrolyte formed necklace-like complex. Therefore, the persistence length of polyelectrolyte plays an important role in the complex shape-change. 2. I have perform the neutron and x-ray reflectivity for getting detail information about the structural change of lipid membranes by adsorption and penetration of MG and T-1249. the insertion of hydrophobic materials make the local order of hydrocarbon tails loose. And the fluidity of lipid membranes controls the insertion of materials.한국과학기술원 : 물리학과
Study on characteristics of filamentary and glow discharges generated at atmospheric dielectric barrier discharge
No full text학위논문(석사) - 한국과학기술원 : 물리학과, 2002.2, [ [ii], 57 p. ]DBD를 위한 실험장치를 설계 및 제작을 하였다. 이 장치의 한쪽 전극을 투명한 전극을 사용하여 CCD를 이용하여 플라즈마의 상태를 관찰하였고, 이를 동시에 측정한 전기적 신호와 비교하였다. 측정한 전기적 신호로부터 각 상태에서 여러 플라즈마 특성을 계산하였다. 이로부터 FD와 APGD 사이에 명백한 차이점을 관찰하였고, FD에서 APGD로의 전이가 불연속적으로 일어나는 것을 관찰하였다.
또한 Ar, He, 그리고 He과 O2의 혼합기체에서 방전을 하였으며, 방전기체에 따른 방전특성의 차이를 관찰하였다. 그리고, 주파수의 변화와 유전체 사이 간격의 변화에 따른 Paschen curve의 변화를 관찰하였다.한국과학기술원 : 물리학과
Adaptive Integral Super-Twisting Sliding Mode Control for Uncertain Stochastic Systems
No full textIn this paper, we consider the adaptive integral super-twisting sliding mode control problem for stochastic systems with bounded uncertainties and state-multiplicative stochastic (Brownian) noise. We first introduce an integral-type sliding surface. Then, we develop the adaptive super-twisting controller which guarantees the reachability to the specified sliding surface in finite time. We also characterize a sufficient condition for stochastic stability of sliding motion in terms of a linear matrix inequality. Hence, the proposed controller first guarantees the finite-time convergence to the sliding surface and then achieves the stochastic stability of the closed-loop system in the predefined sliding surface under bounded uncertainties. Two simulation results are presented to illustrate the theoretical results and the effectiveness of the proposed control method
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Effect of nonionic surfactants on the electrorheology of emulsions
Full text linkIn this study, we consider the effect of nonionic surfactants on the rheological responses of emulsion systems under the action of a uniform dc electric field. The model emulsions consist of a less conducting dispersed phase and a more conducting continuous phase. When the shear flow is weak, the positive viscosity effect is produced due to the formation of chain-like morphology. The nonionic surfactants used here generate two distinctively different effects. Specifically, first, the steric hindrance induced by the surfactant molecules renders the structure unstable, and thereby reduces the degree of positive viscosity effect. Secondly, the presence of surfactant molecules also prevents the rotation of the dispersed droplets by anchoring across the interface or by decreasing the size of dispersed phase. The second effect suppresses the negative viscosity effect
Holographic fabrication of three-dimensional nanostructures for microfluidic passive mixing
No full textIn this study, we incorporated mixing units of three-dimensional (3D) interconnected pore network inside microfluidic channels by combining single prism holographic lithography and photolithography. 3D pore network structures were generated by the interference of four laser beams generated by a truncated triangular pyramidal prism. The levelling between the 3D porous structures and the channel walls was greatly improved by employing supercritical drying, which induced negligible internal capillary stresses and reduced substantially anisotropic volume shrinkage of 3D structures. Also, complete sealing of the microfluidic chips was achieved by attaching flexible PDMS cover substrates. Overall mixing performance of the systems with completely sealed mixing units was 84% greater than that obtained without such mixers. Splitting and recombination of flows in the 3D interconnected pore structures enhanced the mixing efficiency by decreasing the diffusion path and increasing the surface contact between two liquid streams. Because the flow splitting and recombination was developed through the 3D interconnected pore network, high mixing efficiency (> 0.60) was achieved at low Reynolds numbers (Re < 0.05) and Peclet numbers in the regime of Pe < 1.4 x 10(3).This work was supported by a grant from the Creative Research
Initiative Program of the MOST/KOSEF for ‘‘Complementary
Hybridization of Optical and Fluidic Devices for Integrated
Optofluidic Systems.’’ The authors also appreciated partial
support from the Brain Korea 21 Program. JHM thanks the
support by the Sogang University Research Grant of 2008 and
the Manpower Development Program for Energy & Resources
supported by the Ministry of Knowledge and Economy (MKE)
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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