What is used in the production of dubu (Korean tofu)? Tofu, in Korea, is known as 'dubu'. This product is very similar to (possibly exactly the same as) the Japanese counterpart. 

What is used in the process of making authentic dubu?

A quick internet search has failed to give me any results for making dubu, but there are plenty for tofu. These recipes usually require soya beans, water and Epsom salt/lemon juice. I'd be interested to know if the Korean process is the same.
As far as I know, Korean and Japanese tofu are effectively identical in taste and preparation: my Japanese wife, who is generally quite particular about her ingredients, happily buys Korean brands from a Korean grocery for her Japanese cooking.

If you're dead set on making your own, in both countries the key ingredient for curdling is nigari (Japanese) aka 간수 gansu (Korean), basically magnesium chloride.  Epsom salts are magnesium sulfate, so close but not the same thing; lemon juice is out of the question (for one thing, neither countries had lemons until recently!).

When experimenting, bear in mind that both countries use several different styles of tofu.  "Standard" tofu/dubu is momen-dofu in Japan, but Korean soft tofu (sundubu) is even softer than Japanese kinugoshi-tofu and more akin to a rare Japanese type called oboro-tofu.