Haedong Gumdo is art that uses Jin Gum (real sword).
The use of Jin Gum is limited to adult black belts only. During whole practice with other people, we use Mokum (wooden sword) or Jukdo (bamboo sword). Minors can use a Gagum (a practice sword which does not have sharpened blade) for their exercise instead of Mokum.
Nevertheless, adults black belts can use a real sword for their practice in a safe place.

Besides this practice use, another use of Jin Gum is for cutting object practice.

Cutting objects

Paper
Paper is widely used material for cutting practice starting from beginner's level (White belt level). Students of all levels before black belt uses wooden sword for paper cutting - 1 paper to 5 papers. Adults black belts can practice paper cutting using real sword.

Cucumber
Minor student who has a Gagum (a practice sword) can use his or her Gagum for cucumber cutting as they cannot use a real sword. Cucumber cutting practice can be started from the 1st Dan (degree) of black belt.

Bamboo
The 1st Dan of black belt (adult) starts cutting practice with one bamboo cutting. However, as is is not easy to get fresh bamboo in Canada, we hardly practice this one.

Sheaf of straw
Along with bamboo, a sheaf or sheaves of straw are main material for cutting practice in Korea. Bur for the same reason as bamboo, we do not use sheaves of straw.

Techniques for cut
You start cutting practice from a single cut of the object. In accordance with your level, you then learn multiple cuts of one object.
After you have enough experience and techniques in single and multiple cuts, you can practice cuttings of multiple objects combined with single and multiple cuts.
High level black belts also exercise cutting of moving objects.