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Ch16-I044963.fm Page 75 Tuesday, August 1, 2006 9:08 PM
Tuesday, August
Page 75
9:08 PM
Ch16-I044963.fm
1, 2006
75 75
X200) was continuously measured using SWELL for 30 minutes, the drift of the output voltage did
not occur. Next, the circumference of the same concrete cylinder heated successively with an electric
heater was measured again using SWELL for 30 minutes. The output of SWELL reduced from 0 to
-0.2mm as the temperature of the concrete surface rose gradually from 28 to 36°C. It is supposed that
the amount of change in the output of SWELL is sufficiently small because the surface temperature of
the lower leg is around 32°C.

4. SWELLING DURING PROLONGED STANDING

Experiments were carried out to measure the swelling of the lower leg for ten male and three female
subjects, aged 21 to 24. The subjects were asked to keep standing without moving their legs and with
peg operations by their hands for 30 minutes. For control experiments, they were also asked to keep
sitting without doing anything for 30 minutes on the other day. Figure 2 shows typical changes in the
leg swelling for 30 minutes. The magnitudes of the swelling increase almost linearly. Thus SWELL
can continuously measure the leg swelling. The measured average magnitudes for thirteen subjects
were 3.0mm after standing for 30 minutes. In order to verify the result of the measurement with
SWELL, non-contact measurement using a digital camera was conducted[9]. The pictures were taken
from the right-hand side of the subjects. Two pictures taken before and after being swollen were
using image-processing
superimposed by manual operations Standing software in order to measure the increase
Magnitude of swelling mm 4 3 3 Sitting
5 5
^ ^
Standing
Sitting

"o
CD 2 2
-o 1

0 1
0 600 0 Time s 1200 s 1800
1800
8 0
Time s
Figure 2: Typical changes in the leg swelling (21 years old, male)
Swelling measured by SWELL mm 4
5
Standing
Standing
Sitting •
o Sitting
3
2
Spearman's
Rank-Order
•E 1 1 •Q » Spearman's Rank-Order 0.98
Correlation Coefficient:
Correlation Coefficient : 0.98
0
2
0 0 1 1 2 3 3 4 4 5 5
Swelling estimated
mm
by digital camera method
Swelling estimated by digital camera method mm
Figure 3: Correlation between the swelling estimated by digital camera method and the one
measured by SWELL (Maximum value after 30 min)