• Korean Journal of Materials Research
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• v.8 no.9
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• pp.849-855
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• 1998

The purpose of this study was performed to compare to the characteristics (microstructure, phase change and hardness, erosion rate) of HVOF sprayed coatings with 20wt% NiCr claded and 7wt%NiCr mixed $\textrm{Cr}_{3}\textrm{C}_{2}$ powder. In the case of the 20wt% NiCr claded $\textrm{Cr}_{3}\textrm{C}_{2}$ powder, microstructural feature showed that the primary $\textrm{Cr}_{3}\textrm{C}_{2}$ was remained in the coating but was barely remained in the mixed $\textrm{Cr}_{3}\textrm{C}_{2}$ coating. As a results of XRD analysis, both 20wt%NiCr claded and 7wt% NiCr mixed $\textrm{Cr}_{3}\textrm{C}_{2}$ powder was decomposed during spraying but the degree of decomposition of the 20wt%NiCr claded was lower than 7wt%NiCr mixed $\textrm{Cr}_{3}\textrm{C}_{2}$ powder. After spraying the mixed powder for microhardness was higher than claded $\textrm{Cr}_{3}\textrm{C}_{2}$ powder and which was increased up to $\textrm{Hv}_{300}$= 1665 after heat treatment to $1000^{\circ}C$. however. 20wt%NiCr claded $\textrm{Cr}_{3}\textrm{C}_{2}$ became to decrease at $600^{\circ}C$ which was the maximum.

• Asian-Australasian Journal of Animal Sciences
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• v.18 no.2
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• pp.282-295
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• 2005

The processing of dietary lipids can be distinguished in several sequential steps, including their emulsification, hydrolysis and micellization, before they are absorbed by the enterocytes. Emulsification of lipids starts in the stomach and is mediated by physical forces and favoured by the partial lipolysis of the dietary lipids due to the activity of gastric lipase. The process of lipid digestion continues in the duodenum where pancreatic triacylglycerol lipase (PTL) releases 50 to 70% of dietary fatty acids. Bile salts at low concentrations stimulate PTL activity, but higher concentrations inhibit PTL activity. Pancreatic triacylglycerol lipase activity is regulated by colipase, that interacts with bile salts and PTL and can release bile salt mediated PTL inhibition. Without colipase, PTL is unable to hydrolyse fatty acids from dietary triacylglycerols, resulting in fat malabsorption with severe consequences on bioavailability of dietary lipids and fat-soluble vitamins. Furthermore, carboxyl ester lipase, a pancreatic enzyme that is bile salt-stimulated and displays wide substrate reactivities, is involved in lipid digestion. The products of lipolysis are removed from the water-oil interface by incorporation into mixed micelles that are formed spontaneously by the interaction of bile salts. Monoacylglycerols and phospholipids enhance the ability of bile salts to form mixed micelles. Formation of mixed micelles is necessary to move the non-polar lipids across the unstirred water layer adjacent to the mucosal cells, thereby facilitating absorption.

• Journal of applied mathematics & informatics
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• v.26 no.1_2
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• pp.161-176
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• 2008

The effect of variable viscosity on MHD mixed convection Hiemenz flow over a thermally stratified porous wedge plate has been studied in the presence of suction or injection. The wall of the wedge is embedded in a uniform Darcian porous medium in order to allow for possible fluid wall suction or injection and has a power-law variation of the wall temperature. An approximate numerical solution for the steady laminar boundary-layer flow over a wall of the wedge in the presence of thermal diffusion has been obtained by solving the governing equations using numerical technique. The fluid is assumed to be viscous and incompressible. Numerical calculations are carried out for different values of dimensionless parameters and an analysis of the results obtained shows that the flow field is influenced appreciably by the magnetic effect, variable viscosity, thermal stratification and suction / injection at wall surface. Effects of these major parameters on the transport behaviors are investigated methodically and typical results are illustrated to reveal the tendency of the solutions. Comparisons with previously published works are performed and excellent agreement between the results is obtained.

• Membrane and Water Treatment
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• v.7 no.4
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• pp.367-375
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• 2016

Although the bucky paper (BP) made from carbon nanotubes (CNTs) possesses beneficial characteristics of hydrophobic nature and high porosity for membrane distillation (MD) application, weak mechanical strength of BP has often prevented the stable operation. This study aims to fabricate the BP with high mechanical strength to improve its MD performance. The strategy was to increase the purity level of CNTs with an assumption that purer CNTs would increase the Van der Waals attraction, leading to the improvement of mechanical strength of BP. According to this study results, the purification of CNT does not necessarily enhance the mechanical strength of BP. The BP made from purer CNTs demonstrated a high flux ($142kg/m^2{\cdot}h$) even at low ${\Delta}T$ ($50^{\circ}C$ and $20^{\circ}C$) during the experiments of direct contact membrane distillation (DCMD). However, the operation was not stable because a crack quickly formed. Then, a support layer of AAO (anodic aluminum oxide) filter paper was introduced to reinforce the mechanical strength of BP. The support reinforcement was able to increase the mechanical strength, but wetting occurred. Therefore, the mixed matrix membrane (PSf-CNT) using CNTs as filler to polysulphone was fabricated. The DCMD operation with the PSf-CNT membrane was stable, although the flux was low ($6.1kg/m^2{\cdot}h$). This result suggests that the mixed matrix membrane could be more beneficial for the stable DCMD operation than the BP.

• Journal of Hydrogen and New Energy
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• v.20 no.4
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• pp.265-273
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• 2009

Proton Exchange Membrane Fuel Cell (PEMFC) has low operating temperature and high efficiency. And PEMFC consists of many components as bipolar plate, gas diffusion layer, membrane etc.. Flow-field in bipolar plate roles path for transporting reactants to membrane. Therefore a design of flow-field has an effect on PEMFC's performance. In this study, Computational Fluid Dynamics (CFD) simulations were performed for comparing mixed multiple serpentine (MMS) flow-field and multiple serpentine (MS) flow-field. And we studied an effect according to change mixing region design in MMS flow-field. Finally the applicability of results is verified by performing CFD simulation about fixed MMS flow-field which is combined good designs.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.04b
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• pp.37-38
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• 2009

SiC power device possesses attractive features, such as high breakdown voltage, high-speed switching capability, and high temperature operation. In general, device design has a significant effect on the switching characteristics. It is known that in SiC power MOSFET, the JFET region width is one of the most important parameters. In this paper, we demonstrated that the switching performance of DMOSFET is dependent on the with width of the JFET region by using 2-D Mixed-mode simulations. The 4H-SiC DMOSFETs with a JFET region designed to block 800 V were optimized for minimum loss by adjusting the parameters of the n JFET region, CSL, and n-drift layer. It has been found that the JFET region reduces specific on-resistance and therefore the switching characteristics depend on the JFET region.

• Textile Coloration and Finishing
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• v.27 no.3
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• pp.219-227
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• 2015

This study aims to propose a method to reduce hair damage after investigating the following: the factors which vary depending on hair treatment conditions; the degree of hair damage in the bleached sample; and an analysis of the effects of a perm on wave formation. To determine the effects of these treatment types, hair bleach was mixed with the hair treatment, and hair damage and formation of permanent waves were examined. Using a scanning electron microscope, in addition, morphological changes were analyzed and the following results were obtained: After mixing natural powder(2.5g) and hair cream(2.5g) and bleaching the mixture, it was compared to the scale structure of untreated hair. When 5g of natural powder was mixed and bleached, a clear layer was observed among cuticle scales, showing the effects of hair treatment. Therefore, this confirms that the effects of hair treatment were most notable when grain powder was mixed with hair cream. Once hair is damaged, it is almost impossible to regain its original state. When chemical agents are used, therefore, it is important to consider the possible hair damage they cause.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.9
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• pp.737-740
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• 2009

SiC power device possesses attractive features, such as high breakdown voltage, high-speed switching capability, and high temperature operation. In general, device design has a significant effect on the switching characteristics, In this paper, we demonstrated that the switching performance of DMOSFETs are dependent on the with Channel length ($L_{channel}$) and Current Spreading Layer thickness ($T_{CSL}$) by using 2-D Mixed-mode simulations. The 4H-SiC DMOSFETs with a JFET region designed to block 800 V were optimized for minimum loss by adjusting the parameters of the JFET region, CSL, and epilayer. It is found that improvement of switching speed in 4H-SiC DMOSFETs is essential to reduce the gate-source capacitance and channel resistance. Therefore, accurate modeling of the operating conditions are essential for the optimizatin of superior switching performance.

• Journal of the Korean institute of surface engineering
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• v.36 no.6
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• pp.491-499
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• 2003

Copper-based leadframe sheets were oxidized in a hot alkaline solution to form brown-oxide layer on the surface and molded with epoxy molding compound (EMC). The brown-oxide-coated leadframe/EMC joints were machined to form sandwiched double-cantilever beam (SDCB) specimens and sandwiched Brazil-nut (SBN) specimens for the purpose of measuring the fracture toughness of leadframe/EMC interfaces. The SDCB and the SBN specimens were designed to measure the fracture toughness of the leadframe/EMC interfaces under nearly mode-I loading and mixed-mode (mode I ＋ mode II) loading conditions, respectively. Fracture surfaces were analyzed by various equipment such as glancing-angle XRD, SEM, AES, EDS and AFM to elucidate failure path. Results showed that failure occurred irregularly in the SDCB specimens, and oxidation time of 2 minutes divided the types of irregular failures into two classes. The failure in the SBN specimens was quite different from that in the SDCB specimens. The failure path in the SBN specimens was not dependent on the phase angle as well as the distance from tips of pre-cracks.

• Journal of the Korea Safety Management & Science
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• v.2 no.2
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• pp.95-108
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• 2000

Electrochemical charateristics of activated carbon fiber cloth(ACFC) electrode were studied with propylene carbonate(PC), ${\gamma}$-butyrolactone(GBL) and N,N-dimethyl-formamide(DMF) as a solvent and tetraethylammoniumtetrafluoroborate(TEABF$_4$), tetraethylammoniumhexafluorophosphate(TEABF$_{6}$), tetrabutylammoniumtetrafluoroborate(TBABF$_4$) and tetrabutylammonium hexafluorophosphate(TBAPF$_6$) as an electrolytes(active material). The concentrations of electrolytes were in the range of 0.2~1.2 N, the volume ratios of PC and DMF as a mixed solvent system, were 90：10, 80：20, 70：30, 60：40, 50：50, and 40：60 vol%. Electrochemical characteristics such as electric conductivity, internal resistance, and electric capacitance of fabricated unit cells were measured after the moisture of activated material was removed with molecular sieve. Electrochemical characteristics were better in mixed solvents system than in mono solvent system. The mono solvent system of 1.0 N electrolyte of GBL/TEABF$_4$ with activated carbon cloth electrodes showed better result but the mixed solvent system with PC and DMF/TEABF$_4$(50：50 vol%) and the concentration of 1.0 N electrolyte showed the best characteristics. Internal resistance was 3.47 $\Omega$ and specific capacitance was 19.1 F/g respectively.y.