Expert backs Cheonan finding

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Expert backs Cheonan finding

A professor on Monday backed one piece of key evidence cited by an investigation team as proof that North Korea was responsible for the deadly sinking of the South Korean warship Cheonan, as opponents continued to raise doubts about results of the probe.

A South Korean-led multinational team concluded in May that a North Korean torpedo sank the Cheonan in March, citing “overwhelming evidence” that includes a torpedo fragment marked with “No. 1” in North Korean style that was retrieved from the site of the sinking.

Investigators said the marking proved that the torpedo came from the North.

Skeptics have cast doubt about the evidence, arguing that the writing in blue ink inside the propulsion part of the torpedo would have melted from the intense heat of the explosion.

Song Tae-ho, professor of mechanical engineering at Korea Advanced Institute of Science and Technology, rebutted claims that the ink would have burned off, because the heat of the explosion apparently cooled rapidly underwater.

“Under any extreme circumstances, the temperature at the propulsion part would have risen to 20 degrees Celsius [68 degrees Fahrenheit] at most,” Song told reporters at a press conference at the Ministry of National Defense. “So there is no possibility that the handwritten mark could have been damaged by the heat of the blast,” said Song, an expert in heat transfer, citing the results of his experiments.

Song said his press conference wasn't commissioned by the defense ministry and that he worked independently.

Last month, two South Korean-born U.S. scientists, including Lee Seung-hun, a physics professor at the University of Virginia, held a press conference in Tokyo and raised doubts over the handwritten mark.

Song said the argument by the U.S.-based scientists was probably based on “incorrect factors” in their experiment that “ignored a basic theory of heat transfer.”

The investigation team cited a so-called “bubble jet effect,” a powerful water pillar created when a torpedo explodes, as the cause that split the Cheonan in two, killing 46 sailors.

Song claimed that the temperature on the surface of the propulsion part at the time of the blast was believed to have risen up to 604 degrees Celsius, but cooled down to 28 degrees Celsius within 0.1 seconds of the explosion.

“Let me assume that fire is set on one side of a piece of plasterboard. Within such a short period of time, the heat wouldn't be transferred to the other side of the board,” Song said.

“Because the handwritten mark was put inside the propulsion part, I think the heat of the explosion didn't damage it,” the professor said.

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