Kim Kwang Sop, doctor of chemical engineering at a university in the U.S., in his paper said that the joint team for investigation into the case of the "Cheonan" warship sinking made erroneous analysis of aluminum adsorptive and failed to prove the story about the warship sinking by "torpedo No. 1".

Presenting his paper to the south Korean Ministry of Defense, he demanded it correct the story concerning "torpedo No.1."

An Su Myong, doctor of electric and computer engineering and submarine specialist of Berkeley University in the U.S., expressed his doubt about the result produced by the joint investigation team.

He said the team drew a conclusion that the warship was sent to the bottom being torpedoed by the north's submarine boat and accused the team of having failed to prove its possibility.

If a mine is not to blame for the explosion, the case is same with torpedo in light of the speed of water stream, tide difference, the depth of water, fog and other conditions in the waters near Paekryong Island at that time, he said, adding:

The joint investigation team said the warship was cut into two pieces by shock generated by the explosion of torpedo under the warship.

The "Cheonan" warship was 10 meters in width and torpedo speed is 15.3 meters per second.

This means that torpedo can stay under the warship only for about 0.6 seconds.

If the investigation team's assertion is true, the torpedo might have exploded at that very interval at the exact point where the team said the incident happened.

In view of the actual conditions of the West Sea of Korea, the attack capacity of submarine boat and torpedo's sound signal processing for detecting targets, the probability can be considered close to 0.0000001 per cent.