• Journal of Mechanical Science and Technology
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• v.15 no.11
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• pp.1463-1471
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• 2001

The Kachanov and Rabotnov (K-R) creep damage model was interpreted and applied to type 316LN and HT-9 stainless steels. Seven creep constants of the model, A, B, $textsc{k}$, m, λ, ${\gamma}$, and q were determine d for type 316LN stainless steel. In order to quantify a damage parameter, the cavity was interruptedly traced during creep for measuring cavity area to be reflected into the damage equation. For type 316LN stainless steel, λ= $\varepsilon$R/$\varepsilon$* and λf=$\varepsilon$/$\varepsilon$R were 3.1 and increased with creep strain. The creep curve with λ=3.1 depleted well the experimental data to the full lifetime and its damage curve showed a good agreement when r=24. However for the HT-9 stainless steel, the values of λ and λf were different as λ=6.2 and λf=8.5, and their K-R creep curves did not agree with the experimental data. This mismatch in the HT-9 steel was due to the ductile fracture by softening of materials rather than the brittle fracture by cavity growth. The differences of the values in the above steels were attributed to creep ductilities at the secondary and the tertiary creep stages.

• Korean Journal of Community Nutrition
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• v.2 no.2
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• pp.179-186
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• 1997

A new bioelectrical impedance method has been developed and evaluated. The electrodes; were made of stainless steel and electrical interfaces were created by an upright subject gripping hand electrodes and stepping onto foot electrodes. Eight tactile electrodes were in contact with surfaces of both hands and feet; thumb, palm and fingers, front sole, and rear sole. Automatic on-off switches were used to change current pathways and to measure voltage differences for target segments. Segmental body resistances and whole body resistance(RWHOLE)were measured in 60 healthy subjects. Segmental resistances of right arm(RRA), left arm(RLA), trunk(RT), right leg(RRL) and left leg(RLL)were310.0$\pm$61.6$\Omega$, 316.9$\pm$64.6$\Omega$, 25.1$\pm$3.4$\Omega$, 236.8$\pm$31.2$\Omega$ and 237.6$\pm$30.4$\Omega$, respectively. Individual segmental impedance indexes(Ht2/RRA, Ht2/RT, and Ht2 /RLA) were closely related to lean body mass(LBM)as measured by densitometry ranged from r=0.925 to 0.960. Ht2/(RRA+RT+RLA) predicted LBM slightly better(r=0.969) than the traditional index, Ht2/RWHOLE(r=0.964), supporting the accuracy of the segmental measurement. A multiple regression equation utilizing Ht2/RRA, Ht2/RT and Ht2/RRL predicted LBM with r=0.971. Ht2/RRA term of the regression contributed to more than 40$\%$ of the LBM prediction, indicating that lean mass of arm represented whole body LBM more closely than other body segments. The new bioimpedance method was characterized by upright posture, eight tactile electrodes, segmental measurements and utilization of electronic switches in comparison with the traditional method. The measurement with this new method was extremely reproducible, quick and easy to use.

• Journal of Acupuncture Research
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• v.17 no.2
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• pp.231-246
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• 2000

Acupuncture has been used for treatment of numerous diseases, especially for pain control in the oriental culture. However, the mechanism of pain control by acupuncture was not clear so far. The present study was examined that the effects of electro-acupuncture (EA) applied to the acu-point of extra-segmental area on modulation of formalin induced pain in Sprague - Dawley rats. In order to apply EA to acu-points in the plantar area of right fore paws, a pair of teflon - coated stainless steel wires were implanted in HT 7 (shin-mun) and PC 7 (dae-neong) 5 days before behavioral test. A behavioral test was performed by means of video camera after injection of 5% formalin ($50{\mu}l$) into the lateral plantar region of left hind paw. EA was delivered by a constant current stimulator at 4~5 mA, 2 ms, and 10 Hz for 30 min. The electromyographic activities were recorded in the biceps femoris muscle under chloral hydrate anesthesia. Test stimuli with 1~9mA were applied to the sural nerve territory including the medial portion of the 4th toe and the lateral portion of the 5th toe. Behavioral responses including favoring, flinching and bitting were occured in the biphasic pattern, such as the lst phase (0~5 min) and the 2nd phase (20~45 min) after formalin injection. However, EA (4~5 mA, 2 ms, 10 Hz) significantly inhibited Che behavioral responses. EMG activities of flexor reflex had a latency of 100~300 ms and thresholds of test stimuli for EMG were 4~5 mA in normal rats. Injection of formalin decreased threshold of test stimuli and increased EMG activities for 2hrs after injection. However, EA significantly inhibited EMG activities of flexor reflex increased by formalin and recovered EMG evoked thresholds. These results suggest that contralateral extra-segmental EA inhibits the first and second phases of formalin induced pain but their mechanism be needed to examine additionally.