powerfulguy
Banned Member
A bostonian commented on the two professors' Nature article as follows.
The problematic experiment of professors Seung-heon Lee and Panseok Yang..
Lee‘s main argument is based on the SEM, EDS and XRD data taken from a 300 mesh (maximum size 85 micrometers) aluminum powder that was heated/melted at 1100oC in air and then quenched in water. His experiment does not simulate the real underwater explosion conditions at all.
Aluminized explosives are designed for the pre-added aluminum particles to react immediately and fully during explosion with the decomposition products of the explosive and pre-added oxidants, not with oxygen or water from the surrounding environment after explosion. Lee‘s premise upon which his criticism is based is false, making his criticisms invalid.
Yang criticized that the JIG‘s oxygen/aluminum X-ray intensity ratios are too high for the deposits to be identified as aluminum oxide. He ignores the fact that the deposits do not have to be aluminum oxide for JIG’s claim to be valid.
If the JIG‘s logic is followed, the only requirement is that they are the same material. Nanometric aluminum oxide particles could have changed in seawater. The JIGs claim is weak but valid if not proven otherwise. But his work was poorly conducted. For example, to detect soft X-rays of low-Z elements such as oxygen generated by an electron beam as in EDS the detector is operated in windowless mode. Because the detection efficiency deteriorates with time especially for soft X-rays due to the deposition of contaminants on the detector, the X-ray detection efficiency needs to be calibrated with standards for the elements of interest. It is not clearly stated in his report that the calibration was carried out. The comparison of uncalibrated X-ray intensity ratios determined with different instruments can be meaningless. The uncorrected intensity ratios determined for the same material in different laboratories can be quite different.
There is another related issue. Yang, like JIG, coated the samples with gold to reduce charging. It is not clear if and how Yang eliminated the effects of the absorption of X-rays by the gold layer which should be significant especially for light elements.
The oxygen/aluminum intensity ratio will decrease with increasing thickness of the gold layer. It is certain that the thicknesses of the gold layer on the samples analyzed by JIG and Yang are different. Yang‘s argument still may be valid but is not trelevant.
Various chemical and physical properties of the deposits need to be studied more comprehensively to answer the question of whether the deposits originated from the torpedo‘s aluminized explosive. The JIG does not appear to have strong scientific evidence that supports its conclusion at this time. But it is unfortunate that there is disproportionate media coverage of the criticisms by Lee and Yang, especially in South Korea. It is important to critically evaluate their claims.
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It has been concluded that the Cheonan sank due to a North Korean attack.
Jang-yup Hwang died a few days ago.
Associates of Hwang claimed that Hwang was disappointed with some people who did not believe joint investigation team's results which blamed North Korea for the Cheonan attack.
Professors Lee and Yang must be out of their minds.
How can they act in such a way while they call themselves professors.
Nowadays many people say that North Korea has changed a lot, but when if we take a look at the way North Korean sank the Cheonan, we can see that nothing has changed with them.
North Korea should acknowledge its wrongdoing and apologize to the South Korean government.