| hardness |
The resistance to surface indentation usually measured by the depth of penetration (or arbitrary units related to the depth of penetration) of a blunt point under a given load using a particular instrument according to a prescribed procedure.
출처: www.fibreglast.com/contentpages-glossary+of+terms+...
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| hardness |
The hardness of water is equal to the concentration of dissolved calcium and magnesium ions. Usually expressed as ppm of (CaCO 3 ).
출처: www.howtobrew.com/glossary.html
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| hardening |
The hardening of steel is accomplished by heating the metal to cherry red and quickly quenching it in brine, water, or oil, depending on the alloy or application.
출처: faculty.uwstout.edu/hunts/art415002/glossary.shtml
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| hard water |
Water which has a high concentration of dissolved minerals and solids.
출처: www.aquahobby.com/articles/e_glossary.php
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| hard water |
Natural water containing impurities in various proportions. Traditional hardness is a measure of calcium or dissolved solids in a solution, measured in parts per million. Hard water generally ranges from 100 to 250 ppm.
출처: www.alpha-plumbing.com/plumbing-terminology-h.htm
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