In korean, consonants are divided into three categories of articulation or coarticulation, one of them is called Tenseness.
In korean orthography, tensed consonants are written with a reduplicated consonant sign. In IPA orthography, they are written with a pair of vertical parallel lines at the bottom of the letter:
P”ㅃ T”ㄸ Tɕ” ㅉ K” ㄲ
There is an article on Tenseness in Wikipedia, but it is on the Tenseness of vowels, nethertheless it is describing the articulatory way of production well: widened mouth, less open, uplift tongue.
How about the Tenseness of consonants, what exactly is happening inside the the mouth and beyond, what is happening in the articulatory system in order to create them?