In order to obtain the fundamental data for the marine ranch, this paper was carried out to investigate cortisol variation in blood according to adapted time in the measurement of auditory threshold. The groups were adapted at the experimental tanks for 0.5, 1, 3 and 6 hours, respectively. At the results, cortisol concentration had a deep connection with adapted time. In particular, cortisol concentration in the experimental group of 1 hour was significantly increased, whereas others showed no difference comparing with the control group. When classical conditioning method with the sound coupled with a delayed electric shock was given after the adapted time of 1 hour and 6 hours, the rate of the conditioning completion for 6 hours was higher than that of 1 hour. Therefore, this suggests that the sufficient adapted time was required for the accurate auditory threshold.

NiAl based ODS (Oxide Dispersion Strengthened) intermetallic alloys have been produced by mechanical alloying (MA) process and consolidated by hot extrusion. Subsequent thermomechanical treatments have been applied to induce secondary recrystallization in an attempt to improve creep resistance in this material. The creep behavior of secondary recrystallized MA NiAl has been investigated and compared with those of as-extruded condition. Minimum creep rate were shown to be approximately two orders of magnitude lower than that in as-extruded condition. The improvement in creep resistance is believed due to the grain coarsening, restricting of dispersoid coarsening as well as increase in grain aspect ratio. Creep threshold stress behavior, below which no measurable creep rate can be detected, has been discussed on the basis of particle-dislocation interaction theory. The threshold stress becomes negligible after secondary recrystallization in MA NiAl, presumably due to dispersoid coarsening and a decrease in grain boundary area during secondary recrystallization.