• Tribology and Lubricants
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• v.37 no.1
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• pp.14-24
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• 2021

This study shows the effect of the thermal boundary condition around the tilting pad journal bearing on the static and dynamic characteristics of the bearing through a high-precision numerical model. In many cases, it is very difficult to predict or measure the exact thermal boundary conditions around bearings at the operating site of a turbomachine, not even in a laboratory. The purpose of this study is not to predict the thermal boundary conditions around the bearing, but to find out how the performance of the bearing changes under different thermal boundary conditions. Lubricating oil, bearing pads and shafts were modeled in three dimensions using the finite element method, and the heat transfer between these three elements and the resulting thermal deformation were considered. The Generalized Reynolds equation and three-dimensional energy equation that can take into account the viscosity change in the direction of the film thickness are connected and analyzed by the relationship between viscosity and temperature. The numerical model was written in in-house code using MATLAB, and a parallel processing algorithm was used to improve the analysis speed. Constant temperature and convection temperature conditions are used as the thermal boundary conditions. Notably, the conditions around the bearing pad, rather than the temperature boundary conditions around the shaft, have a greater influence on the performance changes of the bearing.

• Transactions of Materials Processing
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• v.31 no.5
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• pp.290-295
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• 2022

Recently, the use of high-tech ceramic parts in functional electronic parts, automobile parts and semiconductor equipment parts is increasing. These ceramics materials are required to have high reproducibility, reliability, large size and complex shapes. The researchers initiated the work to develop a new shaping method called gel casting, which allows high performance ceramic materials with a complex shape to be produced. The manufacturing process parameters of gel casting include uniform mixing of the initiator, bubble removal, and slip injection. In this study, we analyzed the dispersion and gelation characteristics according to the change in the additive content of the alumina slurry in the gel casting process. The alumina slurry for gel casting was prepared by mixing a solvent, a monomer and a dispersant through a ball mill. Alumina powder and a gelation initiator were added to the mixed solution, and ball milling was performed for 24 hours. A viscosity of 6,435 cps and a stable zeta potential value were obtained under the conditions of alumina powder content of 55 vol% and dispersant 2.0 wt%. After curing for 12 hours by adding aps 0.1wt%, TEMED 0.2wt%, and Monomer 3, 5wt%, it was possible to separate from the molding cup, confirming that the gelation was completed.

• Food Science of Animal Resources
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• v.43 no.6
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• pp.1031-1043
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• 2023

The purpose of this study was to investigate the functional properties of salt-soluble proteins obtained from Protaetia brevitarsis (PB) and Tenebrio molitor (TM) larvae, the interaction between these proteins and pork myofibrillar protein (MP) in a gel system. The gel properties of salt-soluble protein extracts showed that the PB had a higher viscosity than the TM protein. However, the TM protein had higher gel strength compared with the PB protein. The gelation characteristics of the pork MP gel systems added with lyophilized insect salt-soluble protein powder showed to decrease slightly viscosity compared with MP alone. Adding the TM or PB protein powder did not affect the pork MP's hydrophobicity and sulfhydryl group levels. Furthermore, the protein bands of the MP did not change with the type or amount of insect salt-soluble protein. The cooking yields of the pork MP gels containing PB or TM protein powder were higher than those without insect protein. Regardless of the type of insect salt-soluble protein added, the pork MP's gel strength decreased. Furthermore, as the level of insect powder increased, the surface protein structure became rough and porous. The results demonstrated that proteins extracted from PB and TM larvae interfered with the gelation of pork MP in a gel system.

• Journal of Energy Engineering
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• v.23 no.3
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• pp.125-131
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• 2014

In order to increase landfill gas (LFG) production with food waste leachate, this study was confirmed to be acidogenetic conditions for landfill site injection. Thereby, it was conducted for acidogenetic treatments to determine the decrease in viscosity and VFA production. After acidogenesis treatments, solubility of food waste leachate increased approximately 15%, and as a result, UASB and CSTR were similar by reactor type using the change of retention time. Based on the result of the change in viscosity by reactor type, efficiency of UASB showed approximately 11.38% of higher decrease in viscosity as $76.95{\pm}3.27%$ vs. CSTR. Also, VFA production showed the higher increase of 2.01 times (UASB) and 1.76 times (CSTR) respectively at the point of increasing retention time from 3 to 5 days. From the above results, efficiency of UASB in a reactor was relatively higher because large molecular lead to longer retention time than small molecular due to having screen effect in the fixed media.

• Korean Chemical Engineering Research
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• v.47 no.4
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• pp.459-464
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• 2009

Gas-liquid mass transfer characteristics were investigated in pressurized three-phase slurry bubble columns with variation of column diameter. Effects of gas velocity, operating pressure, liquid viscosity, solid content in the slurry phase and column diameter on the gas-liquid volumetric mass transfer coefficient($k_La$) were determined. The effects of operating variables on the mass transfer coefficient tended to change with variation of column diameter. The mass transfer coefficient increased with increasing gas velocity or operating pressure but decreased with increasing column diameter, liquid viscosity or solid concentration in the slurry phase. The increase trend of $k_La$ value with increasing gas velocity and the decrease trend of $k_La$ value with increasing liquid viscosity, tended to decrease gradually with increasing column diameter. However, the effects of operating pressure and solid concentration in the slurry phase on the $k_La$ value did not change considerably with variation of column diameter. The values of $k_La$ were well correlated with operating variables with in this experimental conditions as $k_La=0.02D^{-0.26}U_G^{0.28}P^{0.43}{\mu}_L^{-0.04}S_c^{-0.35}$.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.29 no.5
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• pp.681-688
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• 1996

To investigate the effort of drying methods on the physicochemical properties of agar, gel strength, viscosity, melting and setting point, and phase transition by differential scanning calorimetery (DSC) during its heating were determined. In addition the structural differences of agar powder by scanning electron microscope (SEM) was examined. The most shortest onset temperature of gel strength increase was extruding method among any other methods. Viscosity of agar with hot air method, 400.00 cps at $45^{\circ}C$, was markedly increased, but with spraying and extruding ones were little change. The melting and setting point, and the temperature for maximum endothermic and enthalpy for agar with extruding one, $80.01^{\circ}C,\;36.05^{\circ}C\;and\;61.72^{\circ}C,\;0.73\;cal/g$, respectively, were lowest among the drying ones. But in the case of reheating after gelling, there were little change in all methods. Observing the surface structure of agar with SEM, extruding method showed the most unstable with absorptive property.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.8
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• pp.5124-5130
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• 2014

Dilution of the contrast agent by analyzing the change in the signal intensity during MR angiography in accordance with the viscosity and osmotic pressure minimizes the side effects, and improves the image quality. The contrast agent molarity changes by the dilution of the contrast agent in the blood, as it is injected, which leads to a change in signal intensity. Based on this principle, a phantom was prepared and experiments were performed. After the phantom experiment, a clinical experiment was conducted using the results of the phantom experiment. From November 2013 to January 2014, a group of patients were classified into diluted contrast agent (30 persons) and undiluted (30 persons), and the signal intensity of the cerebral vessels was compared. The signal intensity of the phantom according to the molarity of the contrast agent increased sharply from 0.0125 mmol, reached a peak at 20 mmol, and achieved equilibrium from 200 mmol. Based on the study results, the signal intensity of the blood vessels in the brain through were compared in a clinical experiment. All the brain vessels in the imaging range with diluting a high content of the gadolinium contrast agent showed high signal intensity. This result supports the phantom experiment and means that using the 500mmol diluted contrast agent is better than using 1000mmol undiluted contrast agent because it is easier to approach the 20mmol level needed to achieve the highest signal intensity. This study has significance in that it can minimize the high viscosity and osmotic pressure, which can cause side effects and improve the image quality using the method of the dilution rate.

• Journal of the Korean Society of Food Culture
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• v.28 no.6
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• pp.664-673
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• 2013

This study was conducted to investigate the physicochemical properties of mung bean starch and the quality characteristics of mung bean starch gels supplemented with gelatin and isolated soy protein (0, 2, 5%) during storage at $5^{\circ}C$ for 0, 24, 48, and 72 hours. The swelling power of mung bean starch supplemented with gelatin did not significantly change, whereas those supplemented with isolated soy protein (ISP) significantly increased. The solubility of mung bean starch supplemented with gelatin and ISP, however, significantly increased with increasing concentration. In addition, the soluble amylose and soluble carbohydrate of mung bean starch supplemented with gelatin and ISP significantly decreased with increasing concentration. In terms of pasting properties measured by the Rapid Visco Analyzer (RVA), the pasting temperature of mung bean starch supplemented with gelatin and ISP was not significantly different, whereas peak viscosity, minimum viscosity, final viscosity, breakdown, and consistency decreased. DSC thermograms showed that the onset temperature of mung bean starch supplemented with gelatin and ISP did not significantly change, whereas the enthalpy increased with the addition of 5% ISP. The lightness (L) and redness (a) of mung bean starch gels supplemented with gelatin, ISP, and without additives increased during cold storage, whereas the yellowness (b) decreased. The addition of gelatin and ISP suppressed changes in L, a and b of mung bean starch gel during cold storage. Synereses of mung bean starch gel supplemented with gelatin and ISP was lower than that without additives, with the addition of gelatin suppressing synereses more than ISP. The addition of gelatin and ISP also suppressed increases in hardness, chewiness, and gumminess of mung bean starch gels during cold storage. In the sensory evaluation, the addition of gelatin and ISP suppressed increases in hardness and brittleness of mung bean starch gels during cold storage. The addition of 2%, 5% gelatin and 2% ISP also suppressed a decrease in the overall acceptability of mung bean starch gels during 24-48 hr cold storage. Thus, the addition of 2-5% gelatin and 2% ISP to mung bean starch is appropriate for suppressing the quality deterioration of 24-48 hr cold-stored mung bean starch gels.

• Composites Research
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• v.20 no.1
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• pp.23-31
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• 2007

In order to improve the mechanical properties of jute fiber/polypropylene(PP) composites, the property change with the addition of a coupling agent, maleic anhydride polypropylene(MAPP) was examined experimentally. The maleated coupler acts as an intermediate to chemically connect the polar nature of the fiber and non-polar nature of the polyolefin polymer resin. Furthermore, the decrease in viscosity of the resin which results from the melting point reduction by the MAPP, leads to an increase of contact area with the fiber interface. We discussed the improvement of the PP composite blend of the maleated coupler with the 80mm jute long fiber mat in conjunction with the change of physical parameters in the thermoplastic resin. We confirmed the extent of contribution to the mechanical physical enhancement by using the following parameters: melting flow index(MI) and viscosity, contact angle, thickness of the composite, interfacial shear strength and morphology observation etc. Especially it was observed that the MI and viscosity, MAPP mixture had a very strong relationship with the tensile and flexural strength and modulus, and interfacial shear strength(IFSS).

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2785-2790
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• 2007

This study presents an impedance method of in-vitro characterization of the thrombotic potential of whole blood. Whole blood samples of 0.2 cc were put into a micro-cell with embedded three electrodes immediately after venepuncture at $37^{\circ}C$. Anti-coagulated blood samples were also collected for hematocrit and blood viscosity analyses. The rate of change of electron flow was measured, which indicates the inverse of the thrombotic potential. A sudden decrease in the rate of change of electron flow was observed at a time equal to approximately 110 seconds. This sudden decrease was significantly delayed in anti-coagulated samples. After the sudden decrease, the rate continued to decrease, reaching a minimum value in unadulterated samples while the change in the rate in the anti-coagulated ones was found rather moderate. Based on these preliminary findings, the present method may be of used as a new tool for the diagnosis of the thrombotic potential of whole blood.