• Food Engineering Progress
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• v.13 no.1
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• pp.24-31
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• 2009

The structural and physicochemical properties of dried aloe vera gel by DIS (dewatering impregnation soaking) process under optimum conditions were investigated. FT-IR spectra for dried samples of DIS aloes showed the typical patterns of standard aloe polysaccharide, and surface structures by SEM (scanning electron microscopy) were similar to a gel-like structure. In case of physicochemical properties of dried aloe samples by DIS process, solubilities and swelling powers of control (not osmotic treated aloe), DIS (S) and DIS (G), samples treated by osmotic solution of 60% sucrose/0.25% NaCl and 50% glucose/0.5% NaCl, were 48.3-57.3% and 8.3-11.7%, respectively, showing no significant differences among samples, but swelling power of DIS (PEG), sample treated by using 50% polyethylene glycol as an osmotic agent was about 5 times higher that of control. Also, water holding capacities of control, DIS (S) and DIS (G) were similar to each other, but that of DIS (PEG) was about 5 times higher that of control. Oil holding capacities of control and DIS aloes maintained the 50.9-86.4% levels of water holding capacities showing no significant differences among samples. Rehydration ratio of DIS (PEG) aloes were significantly dependent on the temperature of rehydrated solvent (water), and rehydration ratio of not-fileted aloe was about two folds higher than that of fileted aloe.

• Journal of Biomedical Engineering Research
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• v.16 no.1
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• pp.9-16
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• 1995

Biodegradable poly (I ,4-butanediol succinate) (PBS) was synthesized from 1,4-butanediol and succinic anhydride. The glass transition temperature of poly (I, 4-butanediol succinate) was revealed at $73^{\circ}C$. The crystallization and cold crystallization of the polymers were investigated as a function of holding time in melt state, cooling rate. reheating, and molecular weight. Chain scission and/or cmsslinking did not occur in the melt state at var.ious holding times. Slower scanning rate can allow more times for nucleation, rearrangement, and packing of the polymer chain, so the onset temperature of crystallization from the melt was increased. PBS crystallized from the melt was found to have spherulitic structure. The degradation behavior of PBS was studied under basic conditions and with microorganisms using the modified ASTM method. In the basic solution. PBS lost up to 85% of its mass within two days. Based upon visual observation, the crystalline structure of films composed of larger molecular weight polymers retained their crystallinity longer than similar structures in low molecular weight samples.

• International Journal of Fluid Machinery and Systems
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• v.2 no.4
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• pp.334-345
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• 2009

Pumped storage power plants are playing a significant role in the contribution to the stabilization of an electrical grid, above all by stable operation and fast reaction to sudden load respectively frequency changes. Optimized efficiency and smooth running characteristics both in pump and turbine operation, improved stability for synchronization in turbine mode, load control in pump mode operation and also short reaction times may be achieved using adjustable speed power units. Such variable speed power plants are applicable for high variations of head (e.g. important for low head pump-turbine projects). Due to the rapid development of power semiconductors and frequency converter technology, feasible solutions can be provided even for large hydro power units. Suitable control strategies as well as clear design criteria contribute significantly to the optimal usage of the pump turbine and motor-generators. The SIMSEN tool for dynamic simulations has been used for comparative investigations of different configurations regarding the power converter topology, types of semiconductors and types of motor-generators including the coupling to the hydraulic system. A brief overview of the advantages & disadvantages of the different solutions can also be found in this paper. Using this approach, a customized solution minimizing cost and exploiting the maximum usage of the pump-turbine unit can be developed in the planning stage of new and modernization pump storage projects.

• Polymer(Korea)
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• v.27 no.6
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• pp.596-602
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• 2003

A Polymeric emulsifier was synthesized by solution polymerization with 2-ethylhexyl acrylate, n-butyl acrylate, and acrylic acid. A series of polymeric emulsifier have been used in the emulsion copolymerization of 2-ethylhexyl actryacrylate and n-butyl acrylate. The size of the synthesized latex particles was around 145 nm and its distribution was very narrow. Emulsion with polymeric emusifier showed no coagulum after 7 cycles of freeze-thaw test, while the emulsion with traditional emulsifier exhibited coagulum after 2 cycles. The adhesion tests showed that the initial tackiness and peel strength decreased as the molecular weight and acrylic acid content of polymeric emulsifier increased, whereas the holding power increased.

• Journal of the Korean Applied Science and Technology
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• v.10 no.2
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• pp.81-90
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• 1993

The Surfactants composed of acylated aterocollagen which is produced by the acylation of the side chain amino radicals of aterocollagen with an aliphatic acid having 12 to 18 carbon atoms will be discussed in this study. This condensation is done at moderate reaction temperature (<$25^{\circ}C$) in aqueous alkaline solution. The products of this reaction were identified by UV/VIS spectroscopy and infrared spectroscopy. For these compounds, surface active properties and physical properties including isoelectric point, Krafft point, surface tension, critical micelle concentration(cmc), foaming power, viscosity behaviour, water holding capacity, skin irritation and emulsifying power were measured respectively. The experimental results received that the products have a good emulsifying power, excellent water holding capacity while having low skin irritation. Thus, these derivatives will be expected to be used as an emulsifying agent for O/W type cosmetic emulsion.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.8 no.4
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• pp.208-212
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• 1975

The study was conducted to determine the optimum conditions for keeping quality of shucked sea mussel, Mytilus edulis, during marketing under commercial handling. As quality factors, water holding capacity, pH, VBN and TMA content were measured. Water holding capacity was obviously affected by salt content of the sea mussel meat. Water was released at the salinity above $2.8\%$ and absorbed below the value. In case of distilled water added instead salt solution, $23.3\%$ weight was gained. Absorbing or releasing water of sea mussel meat was also influenced by temperature showing either water gain or loss was greater at, $3^{\circ}C\;than\;25^{\circ}C$. Osmotic quilibrium by salt between meat and liquor was held within 4 hours. The pH value of fresh sea mussle marked 6.0 which is somewhat lower when compared with that of other shellfishes, and it gradually decreased to 5.0 during storage. VBN contents of fresh muscle and shell liquor were $2.1mg\%$ and $1mg\%$ respectively. The sour odour began to be detectable with $5.0mg\%$ of VBN content. TMA in the sea mussel was not detected.

• Korean Journal of Poultry Science
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• v.21 no.4
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• pp.277-284
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• 1994

The functional properties of mechanically deboned chicken meat(MDCM) from whole carcass, whole carcass without exsanguination, neck without skin, leg hone, and upper back and rib were studied. Also, the effects of adding different levels of gelatin and MDCM to the comminuted meats were investigated. Proximate composition values of MDCM ranged from 54.2 to 68.6% moisture, 14.5 to 19.7% protein, 12.3 to 30.1% fat, and 1.1 to 1.3% ash. The MDCM from leg hone had a higher content of fat, and a lower contents of moisture and protein. The MDCM from neck without skin tended to be opposite to the MDCM from leg hone. The total pigment and myoglobin levels were highest in MDCM from whole carcass without exsanguination such as 3.83 and 0.29 rng /g, and those from the other parts were 1.58~2.93 mg /g and 0. 17~0.31 mg /g, respectively. The emulsifying capacity and water holding capacity were highest in MDCM from neck without skin which contained lower levels of fat, collagen and hydroxyproline, but a higher level of salt soluble protein. The emulsifying capacity of comminuted meat decreased as gelatin content increased. The extractability of hydroxyproline from gelatin showed a higher solubility in acidic solution. The MDCM could he added up to 20% level without detrimentally affecting functional properties of comminuted meats although they had less water holding capacity and cooking loss as the proportion of MDCM increased.

• Korean Journal of Metals and Materials
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• v.49 no.12
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• pp.917-923
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• 2011

Dissolution and precipitation behaviors of complex carbonitrides in austenite of a V-Nb microalloyed steel were quantitatively examined through electrical resistivity measurement and transmission electron microscopy. The electrical resistivity increased with solution treatment temperature up to $1240^{\circ}C$ and then was saturated at $225n{\Omega}m$ for a holding time of 10 min. The electrical resistivity method was also used to quantitatively measure the isothermal precipitation kinetics of the complex carbonitrides in austenite. Nb-rich precipitates were observed in austenite at the early stages of precipitation, but Nb was replaced by V up to the equilibrium amount within the precipitates with further holding time. The time-temperature-precipitation diagram showed a C-type curve; nose temperature and its incubation time were $900^{\circ}C$ and 100 s, respectively.

• Korean Journal of Metals and Materials
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• v.47 no.4
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• pp.223-227
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• 2009

The precipitates, hardness, and tensile properties of Al-6.2Si-2.9Cu AC2B alloy were investigated with respect to solution treatment time at $500^{\circ}C$. $Al(Cu)-Al_2Cu$ eutectic, Si, ${\theta}-(Al_2Cu)$, and $Q-(Al_5Cu_2Mg_8Si_6)$ phases were observed in the as-cast specimen. With increasing the solution treatment time at $500^{\circ}C$, the $Al(Cu)-Al_2Cu$ eutectic and ${\theta}-(Al_2Cu)$ phases were gradually reduced and finally almost disappeared in 5 h. The mechanical properties, such as hardness, tensile strength, and elongation, were improved with solution treatment time until about 5 h due to the dissolution of the $Al_2Cu$ particles. With further holding time, the mechanical properties did not change much. The solution treated specimens for over 5 h at $500^{\circ}C$ exhibit almost the same tensile properties even after aging at $250^{\circ}C$ for 3.5 h. Accordingly, the optimal solution treatment condition of the Al-Si-Cu AC2B alloy is considered to be 5 h at $500^{\circ}C$.

• Journal of Korean Society of Steel Construction
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• v.26 no.4
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• pp.263-275
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• 2014

In this study, connection of steel reinforced concrete(SRC) column and composite beam which consists of H-section and U-section members were tested under cyclic loading. An essential point of the composite beam is the structural performance of welded joint between the H-section and the U-section members. To improve the structural performance of joint of two beam members, vertical stiffeners, trapezoidal stiffeners, and top bars were used. Five full-scaled specimens were designed to study the effect of a number of parameters on cyclic performance of connections such as H-section beam size($H-500{\times}200{\times}10{\times}16$, $H-600{\times}200{\times}11{\times}17$), the presence of stiffeners and top bars, and the presence of no weld access hole(WAH) method. Based on the test results, deformation capacity of the specimens with H-500 series beam and H-600 series beam were 4% and 3% rotation angle, which is the requirement for the Special Moment Frame and Intermediate Moment Frame(IMF), respectively. Test result showed that deformation capacity of connection with stiffeners and top bars is greater than that of connection without stiffeners and top bars. Finally, energy dissipation capacity and strain profile of specimens were summarized.