• Journal of the Korean Society of Safety
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• v.29 no.4
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• pp.28-33
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• 2014

Recently, the actuator worked by the driving recovery-force of the thermo elastic martensitic transformation of shape memory alloys(SMA) has been studied. This paper presents a study on the fatigue life of shape memory alloy (SMA) actuators undergoing thermally induced martensitic phase transformation under various stress levels. shape memory recoverable stress and strain of Ti-44.5at.%Ni-8at.%Cu alloys were by means of constant temperature tensile tests. Differential scanning calorimetry (DSC) was employed in order to investigate the transformation characteristics of the alloy before the tests. the results were summarized as follows. The martensite inducing stress incerased with the increasing of the Cu-contents. The fatigue life decreased with the increasing of the test load and the Cu-content. The data acquired will be very useful during the design process of an SMA NiTiCu element as a functional part of an actuator.

• Korean Journal of Food Science and Technology
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• v.29 no.5
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• pp.939-946
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• 1997

Effects of moisture content on the gelatinization and recrystallization of non-waxy and waxy rice starch gels were investigated by differential scanning calorimetry (DSC). The recrystallization rates of the starch gels containing various moisture contents $(40{\sim}70%)$ were analyzed by Avrami equation. The waxy rice starch had higher gelatinization temperature and enthalpy than non-waxy one. The highest degrees of recrystallization in both rice starch gels stored at $4^{\circ}C$ were shown at 40%, and recrystallizations above 80% moisture content were not found. The degree of recrystallization of waxy one was higher than that of non-waxy one in the range of 40 to 60% moisture content. The Avrami exponents (n) of both rice starch gels were near to 1.0 and the time constant (1/k) was increased with increasing moisture content in the range of 40 to 70% moisture content. The recrystallization rate of waxy rice starch gel was slower than that of non-waxy one. The recrystallization of rice starch gels could be explained by the change of ice melting enthalpy during storage. The Wg's, represented the maximum practical amount of plasticizing water, were about 29.9% and 28.2% for non-waxy and waxy rice starch gels, respectively.

• Journal of the Korean Society of Food Science and Nutrition
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• v.28 no.1
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• pp.1-8
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• 1999

Starch was isolated from nine Korean sweet potato varieties(Shinmi, Seangmi, Yulmi, Shinyulmi, Sunmi, Jeungmi, Mokpo 26, Mokpo 29, and Mokpo 30) and analysed in its physicochemical properties in comparison with a commercial sweet potato starch(Kumokanyu) imported from China. Protein content in the isolated starch was highest(1.1%) in Mokpo 29 and lowest(0.3%) in Kumokanyu, whereas lipid content was equally less than 0.2%. Pasting analysis by Rapid Viscoanalyser(RVA) showed that Yulmi starch had the lowest pasting temperature(70.2oC) whereas Kumokanyu did the highest one (74.3oC). Under a differential scanning calorimetry(DSC), however, Kumokanyu showed the lowest onset temperature(61.8oC) and enthalpy(42.0 J/g) for crystal melting. Shinyulmi showed the highest peak viscosity of the starch paste, but shear thinning was significant like commercial potato starch. Kumokanyu, however, displayed the least peak visicosity but good shear stability. With the starch gels prepared at 4oC, Mokpo 29 showed the highest hardness, whereas Shinyulmi did the lowest one. Against repeated freeze thawing treatments, the starch gel of Kumokanyu was most stable, and among the Korean varieties, Yulmi, Shinyulmi, Jeungmi and Mokpo 26 had good stability. According to the chain distribution analysis, Shinyulmi and Mokpo 29 consisted of larger quanitites of shorter amylopectin chains than Kumokanyu, potato and corn starches.

• Korean journal of food and cookery science
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• v.5 no.2
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• pp.43-50
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• 1989

Physicochemical properties on defatted potato starches, Irish Cobbler and Dejima, were investigated. The average diameter of the Irish Cobbler and Dejima starch were $22.5-29.8\mu\textrm{m}$, and both the starches had birefringence. Irish Cobbler starch was lower than that of Dejima starch in water binding capacity, swelling power and solubility. Relative crystallinity of both the starches was decreased after defatted. The blue value of Irich Cobbvler and Dejima starch was measured 0.37 and 0.35 respectively Transmittnace of 0.1% starch suspensions was higher on defatted starch than on untreated starch. Differential Scanning Calorimetry of untreated potato starch showeed higher gelatinization temperature in Irish Cobbler starch than in Dejiam starch. The gelatinization enthalpy of untreated starch was higher in Irisch Cobbler starch than in Dejima starch, but, after defatted, it was decreased.