Abstract
This report treats problems on the following items.
1. The mathematical definition of butt swell.
From the BEHRE's stem curve, I define that the butt swell is the separating prom from the straight line,
x/y=a+bx,
where x=h/H', y=d/D.
2. The butt swell height.
According as dbh become larger the butt swell height become higher, but its standard devistion is about 40cm.
3. The effect of butt swell in breast height.
According as dbh become larger the increasing quantity of diameter owing to the butt swell increases.
4. The effect of butt swell in volume-diameter relation.
According as the butt swell become larger the form factor become smaller, but its relation is non significance. Therefore, I think that the breast height is the best measuring height of diameter.
