• Journal of the Korean institute of surface engineering
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• 제24권2호
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• pp.103-113
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• 1991

Electroless Ni-Cu-P alloy plating of Al base hard disk was performed to investigate some properties according to the change of composition. It was found that the composition of Ni and Cu in deposits changed linearly with increasing the mole ratio of NiSO4.6H2O/CuSO4.5H2O. The increase in hardness by heat - treatment was confirmed to be associated with small size grained crystallization of the amorphous deposits. Acid resistance of all deposits layer. which had been heated up to 30$0^{\circ}C$, was found to be exellent when immersed in 1N-H2SO4 solution, and it showed more superior acid resistance with decreasing Cu content and with increasing P. The resistivity of the deposits heat treated became smaller at temperature more than 50$0^{\circ}C$, and it became largerly with increasing P content. Cu 44.1wt% alloy(C bath) showed the most superior non-magnetically stable characteristics after heat treatment. It was superiorly with higher temperature and with decreasing P content.

• Polymer(Korea)
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• 제29권1호
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• pp.91-95
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• 2005

The PVA hydrogels were prepared by the chemical and irradiation method to improve the heat resistance of these hydrogels at the high temperature. The physical properties such as the gel content, the degree of swelling and the gel strength for the synthesized hydrogels were examined. Gel content increased as the chemical reaction time and the irradiation dose increased, and gel content of the hydrogels were higher when the two-steps of chemical and irradiation method were used rather than only the chemical method. Gel strength increased as the chemical reaction time increased, and as the irradiation dose decreased. The hydrogels prepared by the chemical reaction for 5 hours and the two-steps had the heat resistance at the high temperature.

• Korean Journal of Food Science and Technology
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• 제51권5호
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• pp.452-458
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• 2019

The objective of this study was to investigate the physicochemical characteristics and antioxidant potential of garlic processed using different heat treatments conditions, which is an effective method for removing the unpleasant odor and taste of raw garlic. The pH and soluble solid content of raw garlic (pH 6.07, $7.7^{\circ}Bx$) were almost equal or slightly higher than that of processed garlic samples (pH 5.06-6.09, $7.1-7.4^{\circ}Bx$). The color of processed garlic was also significantly affected. The amounts of amino acids such as ${\gamma}$-amino-n-butyric acid and few essential amino acids also increased after the thermal treatment of garlic. The antioxidant potentials of red and black garlic were higher than that of raw garlic. The polyphenol content of processed garlic ($38.51-81.51{\mu}g$ gallic acid equivalent/g sample) was significantly higher than that of raw garlic ($30.66{\mu}g$ gallic acid equivalent/g sample). These results indicated that heat treatment for different durations under a controlled environment enhanced the nutritional and functional properties of garlic.

• Journal of the Korean Society for Heat Treatment
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• 제35권2호
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• pp.88-95
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• 2022

Titanium alloy for bio-medical applications have been developed to reduce the toxicity of alloying elements and avoid the stress-shielding effect which is caused by relatively high elastic modulus compared to bone. Ti-39Nb-6Zr (TNZ40) alloy of elastic modulus exhibits around 40 GPa in the case of beta single phase. However, the strength of this alloy is lower than the other types of titanium alloys. Many research found that adding oxygen to beta-titanium alloys is beneficial for improving the strength through solid solution strengthening. In this study, TNZ40 ingots with addition of O were prepared by an arc remelting process (Ti-39Nb-6Zr-0.16O (wt.%), Ti-39Nb-6Zr-0.26O (wt.%)). Thermo-mechanical processing (i.e., heat treatment, cold swaging and aging heat treatment) has been performed under various conditions. Therefore, the aim of this study is to investigate the effect of oxygen content and ω phase formation on microstructure and mechanical properties.

• Journal of Life Science
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• 제12권5호
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• pp.589-594
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• 2002

Changes in the content of volatile terpenoids were investigated with heat-treated carrot. As heat treatment temperature became higher, the amount of volatile terpenoids decreased significantly. According to heat-treatment period, the volatile terpenoids, a-pinene and total terpenoids, decreased drastically during the initial 30-minutes of heat treatment but the rate of decrease slowed down afterwards. When changes in the content of volatile terpenoids in carrot juice were investigated according to sterilization temperature and period, the content decreased quickly with higher sterilization temperature. According to sterilization period, the content of volatile terpenoids decreased drastically during the initial 20-minutes of sterilization but decreased gradually afterwards. The amount of total terpenoids decreased more when sterilization was done at 10$0^{\circ}C$ for 20 minutes compared to sterilization at 6$0^{\circ}C$ and 8$0^{\circ}C$ for 60 min. In order to reduce the amount of volatile terpenoids in carrot juice, sterilization at high temperature for a short period of time would be more effective compared with sterilization at low temperature for a long period of time.

• Proceedings of the Korea Concrete Institute Conference
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• 한국콘크리트학회 1994년도 봄 학술발표회 논문집
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• pp.209-214
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• 1994

The heat of hydration of cement causes the intemal temperature rise at early age, particulay in massive concrete structures. As the results of the temperature rise and restraint condition, the thermal stress amy induce cracks in concrete. The prediction of the thermal stress is very important in design and consturction slages in order to control the cracks in mass concrete. In this study, the temperature rise of high strength concrete due to the heat of hydration is investigated. Test variables are type and content of binder. As the results, the temperature rise is imcreased with increasing cement content. However, the increament is decreased in higher cement comtnet range. Fly ash is effictive in the reduction of hydration heat.

• New & Renewable Energy
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• 제3권4호
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• pp.38-46
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• 2007

In order to characterize the thermal conductivity and viscosity of grout materials used for backfilling ground heat exchangers, nine bentonite grouts and cement grouts being adapted in the United State have been considered in this study. The bentonite grouts indicate that the thermal conductivity and viscosity increase with the content of bentonite or filler (silica sand). In addition, material segregation can be observed when the viscosity of grout is relatively low. The saturated cement grouts appear to possess much higher thermal conductivity than the saturated bentonite grouts, and the reduction of thermal conductivity in the cement grouts after drying specimens is less than the case of the bentonite grouts. Maintaining the moisture content of grouts is a crucial factor in enhancing the efficiency of ground heat exchangers.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 추계학술대회 논문집
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• pp.529-532
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• 2007

In order to characterize the thermal conductivity and viscosity of grout materials used for backfilling ground heat exchangers, nine bentonite grouts and cement grouts being adapted in the United State have been considered in this study. The bentonite grouts indicate that the thermal conductivity and viscosity increase with the content of bentonite or filler (silica sand). In addition, material segregation can be observed when the viscosity of grout is relatively low. The saturated cement grouts appear to possess much higher thermal conductivity than the saturated bentonite grouts, and the reduction of thermal conductivity in the cement grouts after drying specimens is less than in case of the bentonite grouts. Maintaining the moisture content of grouts is a crucial factor in enhancing the efficiency of ground heat exchangers.

• Computers and Concrete
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• 제6권1호
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• pp.19-40
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• 2009

This paper describes the development of modified heat of hydration and maturity-strength models for concrete containing fly ash and slag. The modified models are developed based on laboratory and literature test results, which include different types of cement, fly ash, and slag. The new models consider cement type, water-to-cementitious material ratio (w/cm), mineral admixture, air content, and curing conditions. The results show that the modified models well predict heat evolution and compressive strength development of concrete made with different cementitious materials. Using the newly developed models, the sensitivity analysis was also performed to study the effect of each parameter on the hydration and strength development. The results illustrate that comparing with other parameters studied, w/cm, air content, fly ash, and slag replacement level have more significantly influence on concrete strength at both early and later age.

• Korean Journal of Food Science and Technology
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• 제30권6호
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• pp.1327-1332
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• 1998

The optimum thermal condition of retort Biji product was determined by heat penetration curve, aerobic bacteria count and sensory test. Retort Biji showed a simple logarithmic heating curve regardless of solid content. Heating time was a $26{\sim}27$ min until Fo value reached 9 min and the amount of microorganism in the Biji product sterilized for 26 min at $121^{\circ}C$ were decreased to $10^{-4}\;CFU/g$, indicating the safe range for retort product. The rate of heat penetration was reduced as solid content and size of product were increased, whereas sterilization temperature and initial temperature of product influenced the heat penetration curve. Sensory scare indicated that there was no significant difference in color, flavor, and appearance among different thermal processes. However, Biji product sterilized at $121^{\circ}C$ showed the highest score in overall preference value.