• 비파괴검사학회지
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• 제4권2호
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• pp.7-14
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• 1985

An experiment to investigate the rate of change of phase angle of eddy current output signal caused by outer surface defect of nonferromagnetic tube by variation of standard depth of penetration and variation of percent of tube wall penetration was carried out. The results of the experiment show that the phase angle of defect signal is increased with decreasing the standard depth of penetration or the depth of defect. The results also show that the phase angle is decreased with increasing the skin effect of eddy current, and that the resolution is decreased with decreasing the depth of defect.

• 한국막학회:학술대회논문집
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• 한국막학회 2004년도 Proceedings of the second conference of aseanian membrane society
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• pp.166-169
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• 2004

Microfiltration membranes were prepared from aromatic polyethersulfone (PES) polymer, using aprotic solvent (N-methyl-2-pyrrolidone, NMP) and non-solvent additive (2-methoxy ethanol, 2-ME) by the phase inversion co-process of the vapor-induced phase inversion (VIPI) and the nonsolvent-induced phase inversion (NIPI). According to the change of the additive amount, the solvent amount and the relative humidity, membrane characterization was studied. The non-solvent additive in casting solution played an important role in membrane morphology. During the vapor-induced phase inversion, the relative humidity led to water sorption on the surface of casting dope at which pore formation was generated. The prepared membranes were characterized by scanning electron microscope observations, measurements of capillary flow porometer and pure water flux (PWP). Also the thermodynamic and kinetic properties of membrane-forming system were studied through coagulation value, light transmittance and viscosity.

• 한국재료학회지
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• 제12권1호
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• pp.16-20
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• 2002

In this study, the 95W heavy alloys of 3/7, 5/5 and 7/3 of Ni/Fe ratio were sintered at the temperature range between 1420 and $1480^{\circ}C$ for 1h and their microstructures were discussed for an effect of the ${\mu}$-phase $(Fe_7W_6)$ on the microstructure. The ${\mu}$-phase was observed in the only 95W-1.5Ni-3.5Fe alloy of 3/7 and it is thought to be formed and grown from the surface of the W particle. The W particle was surrounded with the ${\mu}$-phase and there were only the W particles and this phase without Ni-Fe-W matrix at the most part. The ${\mu}$-phase changed the interphase structure in the alloy and the grain growth of the W was suppressed because of interrupting the solution-reprecipitation of the W. The W content in the matrix was considered to be lowered due to the interruption of the solution-reprecipitation and the formation of the ${\mu}$-phase in the .

• 한국의류산업학회지
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• 제16권2호
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• pp.326-332
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• 2014

To develop cool touch feeling fabrics for summer clothing material, it was manufactured several compositions of woven fabrics, having rayon multi-filament yarn (non-twisted) as warp and various kinds of yarn, such as viscose rayon multi-filament yarn (twisted), tencel$^{(R)}$ spun yarn, PET high absorbance quick dry filament yarn, and PET based rayon-like yarn, as weft. After preparing the fabrics, basic properties of the fabrics were investigated, such as air-permeability, tensile strength, absorption rate, drying rate, etc. Also, surface warm / cool sensations of the woven fabrics were assessed by Qmax Warm / Cool Touch Tester. It was observed that the fabrics composed of viscose rayon multi-filament yarn (warp) and PET high absorbance quick dry filament yarn (weft) showed excellent surface cool touch sensation-the highest Qmax value. This is because the fabric having flat shaped PET high absorbance quick dry filament shows the largest contact area with Qmax measuring plate. And, the fabric also showed superior high absorbance and quick dry property as expected. In addition, we treated phase change material (PCM) on the surface of the fabric composed of viscose rayon multi-filament yarn (warp) and PET high absorbance quick dry filament yarn(weft) to improve the cool touch feeling. However, the surface cool touch feeling was impaired by resin treated with PCM during the finishing process.

• 펄프종이기술
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• 제30권4호
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• pp.49-58
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• 1998

The SPM could image the most detailed microstructure of a sample in a wet and dry state by measuring the interaction between the atoms on the sample surface and the extremely sharp probe tip. The refined fibre exhibited large wrinkles formed by fibrillar bundles, the disintegrated fibres extensively showed “scale-like features”. By using the Non-Contact Atomic Force Microscopy (NC-AFM) and Contact Atomic Force Microscopy (C-AFM) including Phase Detection Microscopy (PDM) and Force Modulation Microscopy (FMM), it was possible to investigate surface topography, surface roughness and mechanical property (hardness or visco-elasticity) of fibre surface in detail. The PDM and FMM images showed that the disintegrated only fibre displayed uniform mechanical properties, whereas the refined one did not. The surface roughness of pulp fibres was higher in refined fibres than in disintegrated fibres due to the presence of external fibrils. These SPM images would be used to provide visual evidence of morphological change of a single fibre created during mechanical treatments such as refining, drying, calendering and so on.

• 반도체디스플레이기술학회지
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• 제2권2호
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• pp.1-4
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• 2003

We have developed a rotating compensator spectroscopic ellipsometer (RCSE). As the ellipsometry measures a change in the polarization state of a light wave upon non-normal reflection from surface, the degree of sensitivity is enhanced greatly through the detection of relative phase change. RCSE acquires additional information from the non-ideal surface of sample and operates over the photon energy range from 1.5 to 4.5 eV. We applied RCSE to measure the optical properties of films and the line-width of patterned PR films on crystalline silicon.

• 한국주조공학회지
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• 제37권6호
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• pp.199-206
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• 2017

In this study, the variations of microstructures and tensile properties of Ti-(44-54)at.%Al binary alloys were investigated. The heat-treated microstructure depended greatly on their solidification structure and annealing temperature. We measured the variations of volume fractions of primary and secondary lamellar structure as a function of the heat treatment temperature in a Ti-47at.%Al alloy. The variation of ductility as a function of Al content was in good agreement with the change of fracture mode in the tensile fracture surface. It can be inferred that the variations of yield stress and hardness of ${\gamma}$ phase in a single ${\gamma}$-phase field region are enhanced by anti-site defects created by deviations from the stoichiometric composition. In a Ti-47at.%Al alloy within the (${\alpha}_2+{\gamma}$) two-phase field, the yield stress tended to be the maximum at a near equal volume fraction of lamellar and ${\gamma}$ grains. The ductility depended sensitively on the overall grain size and Al content. The calculation of fracture strain using Chan's model indicated that the change of ductility as a function of annealing temperature was primarily determined by the variations in the overall grain size and lamellar volume fraction.

• Macromolecular Research
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• 제17권12호
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• pp.943-949
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• 2009

A highly dispersed W/O emulsion of silicone oil (cyclomethicone)/water system was prepared with a nonionic surfactant. The surface and interfacial tension between the oil and water were characterized in terms of the droplet size distribution and viscosity change of the emulsion. When the dispersed phase concentration was relatively high, the viscosity of the emulsion was rapidly increased and the droplet size of the emulsion was decreased. The rheological behavior of the emulsion system showed non-Newtonian and shear thinning phenomena depending upon the content of the dispersed phase. The droplet size of the emulsion was decreased with increasing surfactant content and water concentration. The relative viscosity of the emulsion was better predicted with the Choi-Schowalter model than with the Taylor model. The value of the complex modulus increased with increasing surfactant concentration. The linear viscoelastic region was expanded with a dispersed phase concentration. According to the change in the viscosity, the behavior was classified into three distinct regions: [I] linear viscoelastic, [II] partially viscoelastic, and [III] viscous. The creep/recovery behaviors in each region were characterized.

• 대한설비공학회지:설비저널
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• 제13권4호
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• pp.223-229
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• 1984

Experiments were performed for freezing of an initially superheated or nonsuperheated liquid phase in a cooled vertical tube. The liquid was placed in a copper tube whose surface maintained a uniform temperature during the data run and the freezing occurred in a copper tube. The phase change medium was n-odtadecane, a paraffin which freezes at about $61^{\circ}C$. Measurements were made which yielded information about the time dependence of the freezing front, of the amount of frozen mass, and of the various energy components extracted from the tube. The time-wise decay of the initial liquid superheat was also measured. Initial superheat of the liquid tends to moderately diminish the rozen mass and associated latent energy extraction at small times but has lit tie effect on these quantities at large tiems. Natural convection in the liquid Plays a modest role only at small times and disappears when the superheat decay to zero. Although the latent energy constitutes the largest contributor to the total extracted energy, the sensible energy components can make a significant contribution, especially at large tube wall subcoolings, large initial liquid superheating and short freezing time.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.424.1-424.1
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• 2014

Vanadium dioxide (VO2) is a strongly correlated oxide exhibiting a first-order metal-insulator transition (MIT) that is accompanied by a structural phase transition from a low temperature monoclinic phase to a high-temperature rutile phase. VO2 has attracted significant attention because of a variety of possible applications based on its ultrafast MIT. Interestingly, the transition nature of VO2 is significantly affected by stress due to doping and/or interaction with a substrate and/or surface tension as well as defects. Accordingly, there have been considerable efforts to understand the influences of such factors on the phase transition and the fundamental mechanisms behind the MIT behavior. Here, we present the influences of oxygen deficiency, hydrogen doping, and substrate-induced stress on MIT phenomena in single-crystalline VO2 nanobeams. Specifically, the work function and the electrical resistance of the VO2 nanobeams change with the compositional variation due to the oxygen-deficiency-related defects. In addition, the VO2 nanobeams during exposure to hydrogen gas exhibit the reduction of transition temperature and the complex phase inhomogenieties arising from both substrate-induced stress and the formation of the hydrogen doping-induced metallic rutile phase.