• Proceedings of the KSME Conference
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• 2003.11a
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• pp.424-429
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• 2003

Hot gas path components, which are made of nickel based superalloys, are subject to periodic replacement due to degradation of thermomechanical properties that might bring catastrophic failure during normal operation of gas turbine units. In order to rejuvenate the metallurgical condition of the serviced components, heat treating techniques such as solution annealing and aging heat treatments have widely been employed. However, the effectiveness of those typical heat treatments is not apparent enough in terms of quantitative grounds. On the other hand the demand of the rejuvenation heat treatment and hot isostatic pressing (HIP) have constantly been raised by the end users. Therefore it is necessary to verify how the typical heat treating techniques affect to the aged and degraded material. As the result of experimental work in this study, GTD-111 and GTD-222 Ni-based superalloys were collected and analyzed quantitatively through microscopic observation, microhardness evaluation and creep test.

• Journal of the Korean Society for Heat Treatment
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• v.18 no.4
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• pp.223-228
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• 2005

Tube hydroforming provides a number of advantages over conventional stamping process, including fewer secondary operation, weight reduction, assembly simplification, adaptability to forming of complex structural components and improved structural strength and stiffness. It can produce wide range of products such as subframe, engine cradle, and exhaust manifold. In this study, the effect of the heat treatment conditions such as post seam annealing (PSA) and bright annealing (BA) on the ovality and hydro-formability of steel tubes has been investigated. Hydroformabilities have been estimated by the bulging heights obtained at various processing parameters such as internal pressure, axial feeding and heat treatment conditions. The ovality and forming height are strongly influenced by material properties after heat treatments.

• Asian-Australasian Journal of Animal Sciences
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• v.27 no.10
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• pp.1513-1520
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• 2014

The present aim was to investigate the effects of traditional Chinese medicine prescriptions (TCM) on body temperature, blood physiological parameters, nutrient apparent digestibility and growth performance of beef cattle under heat stress conditions. Twenty-seven beef cattle were randomly divided into three groups as following; i) high temperature control (HTC), ii) traditional Chinese medicine prescriptions I+high temperature (TCM I) and iii) traditional Chinese medicine prescriptions II+high temperature (TCM II) (n = 9 per group). The results showed that the mean body temperature declined in TCM II treatment (p<0.05). Serum $T_3$ and $T_4$ levels with TCM I and TCM II treatments elevated (p<0.05), and serum cortisol levels of TCM I treatments decreased (p<0.05), compared with the HTC group. Total protein, albumin, globulin in TCM II treatments elevated and blood urea nitrogen levels of both TCM treatments increased, but glucose levels of both TCM treatments decreased, compared with the HTC group (p<0.05). The apparent digestibility of organic matter and crude protein with TCM I treatment increased, and the apparent digestibility of acid detergent fiber elevated in both TCM treatments (p<0.05). Average daily feed intake was not different among three groups, however average daily gain increased and the feed:gain ratio decreased with both TCM treatments, compared with the HTC group (p<0.05). The present results suggest that dietary supplementation with TCM I or TCM II improves growth performance of heat stressed beef cattle by relieving heat stress responses and increasing nutrient apparent digestibility.

• Journal of the Korean Society for Heat Treatment
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• v.16 no.6
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• pp.349-355
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• 2003

• Korean Journal of Food Science and Technology
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• v.18 no.6
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• pp.437-442
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• 1986

Physicochemical properties of chestnut starch, which was adjusted at 14, 18, 21 and 24% moisture and heated for 16 hr at $100^{\circ}C$, were investigated. The cystallinity, swelling power and solubility of the starch were decreased upon heat-moisture treatments. The swelling power of the heat-moisture treated starch showed an inverse relation with moisture levels, while the solubility showed opposite trend. The swelling power and the solubility of both raw and heat-moisture treated starches held a liner relationship. The. water binding capacity of the starch was drastically increased upon heat-moisture treatments. Amylograms revealed that the heat-moisture treated starches had higher initial pasting temperature and lower viscosity than untreated starch. No peak viscosity was observed for the heat treated starches above 21% moisture. The minimum moisture contents for gelatinization of raw and heat-moisture (18%) treated starches were 45 and 40%, respectively. The gelatinization temperature of raw and heat-moisture (18%) treated starches was $65^{\circ}C$.

• Journal of the Korean Society for Heat Treatment
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• v.13 no.5
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• pp.369-372
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• 2000

• Journal of the Korean Society for Heat Treatment
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• v.11 no.1
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• pp.27-34
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• 1998

Effects of different heat treatments on microstructure and damping capacity of Cu-55%Mn alloy were investigated to find an optimum heat treatment condition for a maximum damping capacity. The alloy showed the high level of damping capacity in case of the aging at 375 and $400^{\circ}C$. This is ascribed to the FCC${\rightarrow}$FCT martensitic transformation and microstructural changes from mottled to tweed band type. The damping capacity had a maximum value of 0.33 in logarithmic decrement when the alloy was aged at $375^{\circ}C$ for 14 hours followed by 20 times of thermal cycling between room temperature and $250^{\circ}C$. The refinement of tweed structure by thermal cycling is thought to be responsible for the highest damping capacity.

• Journal of the Korean Society for Heat Treatment
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• v.17 no.3
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• pp.146-150
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• 2004

Because of the social needs for energy saving and the rigid environmental regulation, the development of light materials and new economical manufacturing technologies have been actively investigated. Recently, the hydroforming of high strength aluminum tube has attracted great interest due to its good strength-to-weight ratio, which could play an important role in lightweighting of automobile. However, the limited formability of high strength aluminum alloys is considered to hinder the active application of the hydroforming process. In this paper, the hydroformability of aluminum tubes with different heat treatments was investigated as the basic research of the hydroforming process for the high strength aluminum tubes.

• Korean Journal of Materials Research
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• v.24 no.6
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• pp.285-292
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• 2014

Commercial activated-carbon used as the electrode material of an electric double-layer capacitor (EDLC) was posttreated with various acids and alkalis to increase its capacitance. The carbon samples prepared were then heat-treated in order to control the amount of acidic functional groups formed by the acid treatments. Coin-type EDLC cells with two symmetric carbon electrodes were assembled using the prepared carbon materials and an organic electrolyte. The electrochemical performance of the EDLC was measured by galvanostatic charge-discharge, cyclic voltammetry, and electrochemical impedance spectroscopy. Among the various activated carbons, the carbon electrodes (CSsb800) prepared by the treatments of coconutshell-based carbon activated with NaOH and $H_3BO_5$, and then heat treated at $800^{\circ}C$ under a flow of nitrogen gas, showed relatively good electrochemical performance. Although the specific-surface-area of the carbon-electrode material ($1,096m^2/g$) was less than that of pristine activated-carbon ($1,122m^2/g$), the meso-pore volume increased after the combined chemical and heat treatments. The specific capacitance of the EDLC increased from 59.6 to 74.8 F/g (26%) after those post treatments. The equivalent series resistance of EDLC using CSsb800 as electrode was much lower than that of EDLC using pristine activated carbon. Therefore, CSsb800 exhibited superior electrochemical performance at high scan rates due to its low internal resistance.

• Food Science and Preservation
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• v.21 no.6
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• pp.776-783
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• 2014

Kimchi cabbages were cut ($3{\times}3cm$), and were pre-heat treated at $40^{\circ}C$, and their physicochemical qualities and browning degrees were investigated during 8 weeks storage at $5^{\circ}C$. The Cut kimchi cabbages were treated at $40^{\circ}C$ (1~8 hrs) and their protein bands profiles were determined by sodium dodecyl sulfate polyacrylamide electrophoresis (SDS-PAGE). The 60, 39, 33, and 12 kDa bands considered heat shock proteins (HSPs) were expressed in the cut kimchi cabbage, and the 4-hr pre-heat treatment (HS 4) exhibited the strongest band ratio. The weight ratios and titratable acidities of the pre-heat treated cut kimchi cabbages were not changed so much after 8 weeks storage at $5^{\circ}C$, and the soluble solid contents of HS 4 decreased less than that of any other treatments. The browning degree of HS 4 after 8 week storage was also shown to be the least among the treatments. The polyphenol oxidase (PPO) activities of all treatments slightly rose during the over all storage period, in contrast with the decrease of total phenolic contents. The expression of HSPs was identified in the pre-heat treated cut kimchi cabbages, and HS 4 exhibited the best quality and appearance after 8 weeks storage at $5^{\circ}C$.