• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.10a
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• pp.504-507
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• 2002

Glass fiber reinforced PET (Poly-Ethylene-Terephthalate) matrix composite was manufactured by rapid press consolidation technique as functions of temperature, pressure and time in pre-heating, consolidation and solidification stages. The optimal manufacturing conditions for this composite were discussed based on the void content, tensile, interlaminar shear, and impact properties. A tensile test was attempted to investigate the mechanical properties of the composite. It is found that the level of crystallinity and microstructure affects on the tensile properties substantially.

• Tunnel and Underground Space
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• v.23 no.3
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• pp.212-218
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• 2013

Tuff specimens were thermally treated with predetermined temperatures of 200, 400 and $600^{\circ}C$ to construct specimens simulating weathered tuff rocks. Specific gravity, absorption ratio, elastic wave velocity, uniaxial compressive strength, Brazilian tensile strength, Young's modulus, Poisson's ratio and slake-durability index were measured for pre-heated specimens. Heating of rock specimens entailed the degradation of material properties except for slake-durability index. It was found that correlations among P-wave velocity, uniaxial compressive strength, Brazilian tensile strength, Young's modulus and absorption ratio are high. Regression equations which use the P-wave velocity as an independent variable were presented to evaluate uniaxial compressive strength, Brazilian tensile strength, Young's modulus and absorption ratio.

• Journal of Environmental Science International
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• v.28 no.11
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• pp.927-933
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• 2019

A lipid-enriched strain of Botryococcus braunii (UTEX 572) was cultivated in a semi-batch aeration tank to enhance biomass as well as to develop intracellular lipids and fatty acids. A 30 day period of incubation produced 1.39 g/L of biomass and 0.31 g/L of total lipids in the biomass. The grown biomass was pre-treated using several methods to extract the total lipid content efficiently: ultrasonication was found to yield the highest percentage of lipids-namely 19.8% per biomass. Direct heating of biomass in an autoclave also showed better performance than when using only conventional solvent extraction. To enhance the biomass harvest and lipid extraction efficiency, coagulation and flocculation steps were added to the extraction process. It is noteworthy that not only the solvent type but also the solvent/biomass ratio greatly affected efficiency. In addition, the moisture content of the harvested(wet) biomass affected the efficiency significantly. This study elucidated the need for future research on optimizing this extraction process.

• Archives of Pharmacal Research
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• v.22 no.3
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• pp.294-299
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• 1999

Precolumn orthophthaldehyde (OPA) labeling method of sphingoid bases, sphingosine and sphinganine, was investigated to obtain high fluorescent detectability. In order to improve the fluorescent yield, we investigated the optimal solubility of sphingoid bases for five pre-incubation solvents by incorporating the heating procedure before OPA derivatization. The pre-incubation in ethanol prominently increased the fluorescent peak height of OPA derivative for each sphingoid bases in high performance liquid chromatography. About tenfold increase of detectability was archived by pre-incubating lipid extracts pellets in ethanol at $60^{\circ}C$ for 30 min. Optimal derivatization was performed in 30 min at ambient temperature and the fluorescent intensity of OPA derivative was stable for two weeks at $4^{\circ}C$. The detection limit of sphingosine was 0.1 pmol as injected amount. This method was applied to the determination of cellular sphingosine and sphinganine in various human lung cancer cells. This OPA procedure was prospective to be useful for quantitating the amount of sphingoid bases in other cancer cells.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 1996.11a
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• pp.137-144
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• 1996

The kinetic coefficients far decomposition of the cured phenol resin (SC-1008) using a modified Arrhenius relationship have been determined from thermogavimetric analyses (TGA). The kinetic parameters were determined by multiple heating rate technique developed by Freideman and Henderson. Weight loss (decomposition) and weight loss rate (decomposition rate)were measured and recorded for three heating rates; $5^{\circ}C$/min ,$10^{\circ}C$/min, and $20^{\circ}C$/min. Relatively good agreement was obtained between measured and calculated decomposition as a function of temperature. By separating the reaction, the reaction order and pre exponential factor become empirical parameters which provide a "best fit" of the data. However, this method yields an extremely accurate reproduction of the thermograms over a wide range of heating rates. This is the desired result for kinetic parameters used in thermal models.al models.

• Journal of Environmental Science International
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• v.23 no.7
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• pp.1367-1373
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• 2014

This study was conducted to evaluate the effects of heating hatching eggs on the number of day-old chicks, egg temperature and egg weight during extended storage, and to provide basic information for improving hatchability to livestock producers. Eggs (Hy-line) were subjected to the following treatments: "control": eggs were maintained in an incubator after storage for 8 days; "T1": eggs were preheated for 8 hours at $23.9^{\circ}C$ after storage for 8 days in a hatchery; "T2": eggs were initially heated for 8 hours at $37.8^{\circ}C$ in an incubator and then preheated for 8 hours at $23.9^{\circ}C$ in a hatchery after storage for 8 days. The results were as follows: First, at the end of the experiment, the total number of day-old chicks was higher in T1, followed by T2 and then the control. This indicated that chick hatchability may be improved when eggs are preheated. Second, compared with the control, the number of day-old female chicks was expected to be higher in treatments with pre-heating; however, the results indicated the opposite effect. Third, as storage time lengthened, the factor that influenced preheating (the main effect and interactions) was not egg weight but egg temperature measured in the upper, middle and bottom parts of incubator. The temperatures recorded in all treatments ranged from 37.97 to $38.40^{\circ}C$ in the upper parts of incubator, 37.80 to $38.26^{\circ}C$ in the middle parts of incubator, and 37.94 to $38.59^{\circ}C$ in the bottom parts of incubator over storage. In conclusion, preheating was very effective in improving hatchability, and egg temperature was the main factor affecting preheating and hatchability.

• 한국지구물리탐사학회:학술대회논문집
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• 2003.11a
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• pp.244-251
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• 2003

A two-dimensional BEM code, $FRACOD^{2D}$, was applied to simulate fracture initiation and propagation processes in a rock pillar during an in situ heater test of a rock pillar planned at the $\"{A}sp\"{o}$ Underground Rock laboratory of SKB, in Southern Sweden. To take the advantage of conventional BEM for simulating fracturing processes, but without efforts for domain integral transformation, a hybrid approach is developed to simulate the fracturing processes in rock pillar under coupled thermo-mechanical loading. The code FRACOD was used for simulating the fracture initiation and propagation processes with its boundary tractions reflecting the effects of the initial and redistributed thermomechanical stresses in the domain of interest at multiple excavation and heating steps were produced by a special algorithm of stress inversion, based on resultant thermo-mechanical stress fields at each excavation and heat loading step by a FEM code without considering fracturing processes. This hybrid approach can take the advantages of both types of numerical methods and avoids their shortcomings for fracturing process simulation and domain effects, respectively. In this paper, we present the hybrid approach for the stress, displacements, and fracturing processes at sequential excavation and heating steps of the in situ heater test as a predictive modelling, the formulation of the fracturing models and the predictive results. Two sections of borehole depth, 0.5 m and 1.5 m below the tunnel floor are considered. The pillar area is modelled with the FRACOD and the stress field produced by excavation and heating is transferred with corresponding boundary stresses. From the modelling results, the degree of fracturing and damage are evaluated for 120 days of heating. Dominated shear fracturing in the vicinity of the central pillar was observed from the models at both sections, but spalled area appears to be limited. Based on the modelling results, a sensitivity study for the effect of pre-existing fractures in the vicinity of the holes is also conducted, and the initiation and evolution of EDZ around the deposition holes are investigated using this particular numerical technique.

• Culinary science and hospitality research
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• v.20 no.2
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• pp.54-64
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• 2014

In order to enhance the firmness of retorted onion, long time, low temperature blanching(LTLT) in calcium solution was conducted. Pre-heating onion in calcium solution significantly improved its texture after high temperature sterilization as compared to conventional blanching alone. The improvement of the firmness by the LTLT blanching is related to the formation of strongly cross-linkages between carboxyl groups and divalent cations($Ca^{2+}$) by the action of pectin methy-lesterase(PME) in onion. A maximum firmness of retorted onion was obtained at the condition of pre-heating at $70^{\circ}C$ for 120min in 0.5%calcium solution. This result supports that the activity of PME and the content of bonded calcium in onion were highest at $70^{\circ}C$. Additionally, the reaction of alkali calcium with various divalent cations such as $Mg^{2+}$ provided a function to hydrolyze pectin molecules, resulting in firmer retorted onion in various calcium agents. Further investigation should be carried out to determine the optimal condition for prevention of tissue softening of various retorted vegetables.

• Journal of the Korean Ceramic Society
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• v.42 no.6 s.277
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• pp.437-442
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• 2005

We fabricated BSCCO-2212 (2212) bulk superconductor by melt casting process, and evaluated the dependence of the critical properties on the temperature and cooling .ate of mold and the pouring methods of melt. It was observed that the critical current (Ic) of 2212 was significantly dependent on the pre-heating temperature of the mold. At the pre-heating temperature of $500^{\circ}C$ followed by air cooling condition, Ic of 48 A at 77 K was obtained which was higher than others processed at different temperatures. In addition, the Ic improved to 132 A when tilt casting method was applied. The improved Ic is probably due to the fact that the tilt casting reduced a turbulent flow of the melt during casting causing less porosity and more homogeneous microsructure. Critical temperature was measured to be 87-89 K after the first heat treatment and it improved to 90-91 K when subsequently heat treated at $650^{\circ}C$ in a nitrogen atmosphere. This improvement was considered to be due to an optimization of the oxygen content in the range of 8.16-8.2.

• Polymer(Korea)
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• v.29 no.2
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• pp.211-215
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• 2005

Stabilization process is absolutely necessary to convert the precursor fibers into chemically, physically, thermally and structurally stable carbon fibers. Especially, it is critically important for rayon fibers experiencing severe weight loss and thermal shrinkage occurring at the stabilization stage below $400^{\circ}C$. The stabilization of rayon fibers strongly depends not only on stabilization temperature but also on heating rate, chemical pre-treatment, atmosphere, and so on. In the present study, the weight loss, fiber diameter change occurred in the furnace during the stabilization process for rayon fibers produced with various heating rates and in the absence and presence of phosphorous-based flame retardants and the thermal stability of the stabilized fibers were investigated. The result indicates that the weight, diameter and thermal stability of the rayon fibers are significantly affected by the type and amount of the flame retardant used. It is also suggested that the pre-treatment of rayon fibers with a concentration lower than $3\;vol\%$ of phosphoric acid is most desirable for further carbonization process of stabilized rayon fibers.