• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.23 no.7 s.166
• /
• pp.1215-1222
• /
• 1999

It is advantageous to use an NDE method to assess the mechanical properties of materials since the conventional method is time-consuming and sometimes requires cutting of sample from the material/component. This paper shows that the ultrasonic and the Barkhausen noise(BHN) methods can be used to accurately characterize forged reactor vessels. The attenuation coefficient of the ultrasonic wave was changed with heat treatment temperature and condition[as-quenched, tempered, PWHT]. The RMS[root mean square] voltage of Barkhausen noise depended on heat treatment temperature and conditions. The fracture appearance transition temperature(FATT) can be predicted using nondestructive evaluation methods.

• Resources Recycling
• /
• v.12 no.2
• /
• pp.28-35
• /
• 2003

The powder utilization is the one of the best recycling methods for the waste tires. However, economic problem still exist. In order to overcome an economic problem the ground rubber particles are surface modified, which induced to the rubber particles that have good mechanical properties and higher compatibility. In this study, we investigated ultrasonic treatment and reduced rubber particle size. Results showed that sulfur cross-linkage network of the waste rubber is changed by the ultrasonic treatment.

• Journal of Life Science
• /
• v.9 no.3
• /
• pp.248-252
• /
• 1999

Effects of the ultrasonic treatment on plant represents antifeeding activity and chitin synthesis inhibition activity against diamondback moth (Plutella xylostella L.) by a leaf-dipping method at a concentration of 5,000ppm. Methanol extracts of leaves of the ultrasonic treatment on plant was sequentially partitioned with n-hexane, chloroform, ethlyacetate, butanol and water fractions, and bioassayed. Antifeeding activities were observed in n-hexane, chloroform and ethlyacetate fractions. N-hexane fraction has 94.6% of strongest antifeeding activity against P. xylostella. From the n-hexane sequentially partitioned showed H6 and H8 fractions of antifeeding activities against P. xylostella. And chitin synthesis inhibition activity against P. xylostella was obtained the methaol, n-hexane and water fractions.

• Journal of Energy Engineering
• /
• v.20 no.2
• /
• pp.84-89
• /
• 2011

In this study, individual(alkaline, ultrasonic) and combined(alkaline+ultrasonic) pretreatment effect on sewage sludge solubilization was investigated. COD solubilization rates increased with the dose of NaOH added: solubilization reached 27.6%. Additional alkaline agents did not increase solubilization further. Ultrasonic pretreatment achieved 33~39% solubilization when 140 W/L amplitude. In(alkaline(pre-treatment)+ultrasonic (after-treatment)) treatment, solubilization increased as the combined intensity in creased($70.4{\pm}9.4%$). SCOD rising rate(0.076) was achieved.

• Food Science of Animal Resources
• /
• v.25 no.2
• /
• pp.162-167
• /
• 2005

This study was carried out to investigate the effect of ultrasound treatment on the quality, amino acid and fatty acid composition of fried chicken meat The moisture content of raw chicken meat was higher than fried chicken meat, but the crude protein and fat were lower than those of fried chicken meat The moisture and crude fat of ultrasonic fried chicken meat were higher than those of control. The crude protein of breast meat was higher than leg meat, but the moisture and crude fat were lower than leg meat The ultrasonic treatment did not affect on calorie of the fried chicken meat The pH of leg meat was higher than breast meat, and the fried loss of breast meat was higher than leg meat Frying loss of the leg meat was higher than that of control when ultrasonic treated The Hunters $L^{\ast}$ value of ultrasonic treated breast meat was higher than control, but the leg meat were not significantly different between ultrasonic treatment and control. The $a^{\ast}$ value of leg meat was higher than breast meat, and $b^{\ast}$ value of breast meat was higher than leg meat And the $b^{\ast}$ value of ultrasonic treatment was higher than control. The glutamic acid and aspartic acid were major amino acids in chicken meat The palmitic acid $(C_{16:0})$ and oleic acid $(C_{18:1})$ by fried were decreased, and the linoleic acid $(C_{18:2})$ was increased But the fatty acid composition by ultrasonic treatment were not changed.

• Journal of the Korean Wood Science and Technology
• /
• v.32 no.3
• /
• pp.25-32
• /
• 2004

This research work explored physical and mechanical properties of impregnated sawdust boards from three softwood species (P, densifora, L. kaemferi, and P. koraiensis) with phenol-formaldehyde (PF) resin by various vacuum treatment methods of combining pressure, vacuum, and ultrasonic waves. Simultaneous vacuum and ultrasonic wave treatments with no pressure resulted in the greatest increase in resin content, density, dimensional changes (thickness and length), bending strength, and hardness of impregnated board. This result seemed to be attributed to the ultrasonic wave treatment.

• Journal of the Korean Society for Heat Treatment
• /
• v.12 no.2
• /
• pp.157-165
• /
• 1999

Grain size of steels is one of the most important parameters which influence yield strength and fracture toughness. Ultrasonic wave propagating in polycrystalline materials is mostly attenuated by scattering at grain boundary. Effect of ultrasonic attenuation on average ferrite grain size of carbon steels with tensile strength $40{\sim}60kgf/mm^2$ consisting of multi phases such as ferrite + pearlite and ferrite + pearlite + bainite was evaluated. The attenuation of these steels rapidly increased with average ferrite grain diameter. Average ferrite grain diameter ($D_{av}$, ${\mu}m$) could be expressed as $1.79+22.97*a^{1/2.03}$, where a is attenuation with unit of nepers/cm. From this study, it was confirmed that nondestructive ultrasonic method could be used in measuring average ferrite grain size indirectly.

• Textile Coloration and Finishing
• /
• v.14 no.6
• /
• pp.305-312
• /
• 2002

In order to give a silk-like touch to PET fabrics, the PET fabrics were treated with NaOH alkaline solution in various conditions. In alkaline treatment, the liquor flow type pilot weight reduction apparatus with magnetostrictive ultrasonic transducer was used for the study. The effects of ultrasonic application, treatment time and temperature at NaOH 4% and 6"A solution on the decomposition rate of PET fabrics. From the results of the decomposition rate of PET fabrics, the qualitative and quantitative analysis of oligomer after decomposition of PET fabrics carried out by the HPLC. On the other hand, the surface pore characteristics of decomposition PET fabrics measured by porosimetery. The pore characteristics on the surface of treated PET fiber depended on the decomposition rate and did not depend on the ultrasonic cavitation. The pore diameter of alkaline untreated PET fiber were 15A and those of treated PET fibers were 5~6$\AA$ at the maximum pore volume. The average pore sizes of fiber before and after treatment were 141 h and 160h, respectively. Total amount of oligomer of the untreated PET fibers were 1.70wt% and 67.7% of total oligomer occupied with PET cyclic trimer and PET cyclic tetramer. Total amount of oligomer of fiber with 26.9% and 48.0% of weight loss without ultrasonic application were 1.78wt% and 1.79wt%, respectively. Also total amount oligomer of fibers which were reduced 27.7% and 48.2% of weight loss with ultrasonic application were 1.74wt%. This result showed that the removal rate of oligomer in the process of alkaline hydrolysis with ultrasonic higher than that of without ultrasonic application.tion.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.34 no.6
• /
• pp.751-756
• /
• 2010

Ultrasonic nonlinearity is very sensitive to changes in material properties. This paper describes the study of the correlation between heat treatment and ultrasonic nonlinearity by taking nonlinear factors into consideration. A modified formula was proposed for ultrasonic velocity. This formula indicated that the changes occurring in nonlinearity during heat treatments cause changes in the ultrasonic velocity. The experimental results show that the relative nonlinearity parameters calculated from the modified ultrasonic velocities and the ratio of amplitudes of the second harmonic and fundamental wave are in good agreement. The experimental results prove that heat treatment can result in changes in material nonlinearity. Moreover, the relative nonlinearity parameter calculated from the modified velocity formula is has a large value. Since this parameter has high sensitivity to changes in nonlinearity, it can be used to represent the relative nonlinearity change calculated in this study by using the modified formula for ultrasonic velocity.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.37 no.3
• /
• pp.353-358
• /
• 2013

The ultrasonic characteristics of 2.25Cr-1Mo steel were investigated in relation to the isothermal heat treatment temperature and time. Charpy impact tests and hardness tests were conducted on individual specimens with three different heat treatment conditions. A pulse-echo method with longitudinal waves was used to measure the attenuation and velocity of ultrasonic waves. The FATT (fracture appearance transition temperature) increased with an increase in the isothermal heat treatment time, which implies that the toughness decreased. As the isothermal heat treatment time and temperature increased, the longitudinal wave velocity and ultrasonic attenuation coefficient were raised.