( ,1978 )( ,1978 )( ,1978 )( ,1978 )

44

4

4

433

3

3

4

2 3

3

2

4

12

111

0

1

2

3

4

5

(S40 )

0

10

20

30

40

50

60

70

80

90

0

1

2

3

4

5

6

7

0

5

10

15

20

25

30

cm/s

Vg/Vw 1/3.316cm/s > 12.9cm/s

54cm/s > 42.3cm/s

30mm

D

°

[ No.2][ No.1]