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과학동아 1990년 04호
결과값을 %로 표시하기 위해서 /Range Format 메뉴를 호출한 다음 Percent를 선택한다. 그러면 Percent 표시를 할 범위를 지정하기 위해서Enter range to format: C19..C19라는 메시지가 나타나는데 →키를 네번 눌러 G19를 범위의 끝 위치로 한 다음 ↵키를 누른다.(그림 3)을 보면 숫자들이 천의 자리에 콤마를 가지고 ...
superconductive at unexpectedly high temperatures. Superconductivity meant the ability to conduct a current with 100 percent efficiency, with zero loss in heat.Thus, a mixture of oxides of the metals cobalt, manganese, titanium and niobium could be superconductive at temperatures as high as 122K(151 Celsius degrees below zero). That is very cold, colder than Antarctica at its coldest, but it ...
at Wayne State University in Detroit and found to be super-diamonds indeed. The carbon-12 diamonds can conduct heat 50 percent better than ordinary diamonds can, and they can withstand 10 times the intensity of radiation. What was thought to have been the ultimate has been beaten!Unfortunately, carbon-12 diamonds are even more expensive than diamonds ordinarily are, so they probably will not ...
too low to be economically smelted by human beings.When the bacteria have gnawed away at the mineral for a while, 10 percent of the cobalt content can be easily dissolved out, So far, the people at the Idaho National Engineering Laboratory have made this work only on small-scale, but there's no reason it can't be made into a large-scale technique eventually.The United States Gold Corporation ...
much more gravitational force than that. There is "dark matter," of whose nature we know nothing, that may make up 90 percent or more of all matter in the universe. However, even allowing for that, it doesn't seem possible that the universe could have been created in its present shape by gravity alone--yet there is nothing else to work with. That is the dilemma that astronomers now face.But ...
of water would reduce the cosmic ray radiation to the point that the risk of cancer would be increased by only 2 percent over that on Earth.This protection, however, might be inadequate in the case of a sudden solar flare.On top of all this there might be serious consequences of long-term exposure to zero gravity, such as steady bone demineralization and muscle atrophy. We can imagine ...
contained 30 percent oxygen, rather than 20 percent as it does today. This seems unlikely on its face. With 30 percent oxygen, any forest fire started by lightning would sweep a continent. Sure enough, further examination showed that the report was mistaken.One more case. The great supernova of 1987 in the Greater Magellanic Cloud produced a neutron star that spun at a rate of 2,000 times a ...
the cluster, the more that extra mass has to be.A number of astronomers feel that the missing mass may make up 90 percent of the total mass of the Universe. This makes it all the more frustrating that we can't detect it and don't know the nature of it.Is there anything the mass can do that might give us a hint of exactly where it is? In theory, there is.As long age as 1916, Albert Einstein, ...
결과값을 %로 표시하기 위해서 /Range Format 메뉴를 호출한 다음 Percent를 선택한다. 그러면 Percent 표시를 할 범위를 지정하기 위해서Enter range to format: C19..C19라는 메시지가 나타나는데 →키를 네번 눌러 G19를 범위의 끝 위치로 한 다음 ↵키를 누른다.(그림 3)을 보면 숫자들이 천의 자리에 콤마를 가지고 ...
wealth, and with many problems more immediate than an earthquake that may or may not come for long time.Some 80 percent of the 290 million people at risk in the year 2000 will live in developing nations that are simply not going to have the means to keep all their millions in safe structures. Even the United States may not be able to keep pace with structural deterioration, if our deficit ...
bacteria.)The amount of carbon dioxide in the atmosphere before our present industrial age began was about 0.027 percent. That's very little but it was enough to keep the plant world growing and to keep the Earth reasonably warm.However, the amount of carbon dioxide in the atmosphere has been rising sreadily. By 1958 carbon dioxide made up 0.030 percent- and still going up. That increase ...