We know something is wrong. What we don't know is what kind of equipment is in this vehicle. You will need a scan tool to check and verify some info
I do not believe this is something you can handle without the right test equipment..

 

A Hyundai dealer was contacted and told me it was the catalytic converter decarbonization process, normal Hyundai operation and the temperature of the catalytic converter was raised by about 600°C during this process.

 

Diesels require a "Regeneration" process to burn off accumulated soot in the DPF system.
When this takes place while driving , you hardly even notice it. If a" regen" is required and the vehicle is stationary usually the RPM goes up and stays there for a few minutes. I don't believe this is what is happening.
Is the DEF fluid up to the full level in the DEF tank?
Did you check what it has to say regarding diesel engine maintenance and operation in your owner's manual?

 

my car does not has def fluid.
but after car stop for while process regen end and car become normal.
My question, can i use dpf cleaner or diesel cleaner without any problem or worry about.

 

For your particular vehicle, I can't say for sure.
There is no way to prevent soot from forming and , I do not know of any additive to prevent that.

 

not for prevent. but as a normal service.

 

Everybody has different opinions and something you might check and that is what your owner's manual recommends. Some don't recommend additives .

A lot depends on where you reside and how your vehicle is used and if regular maintenance is performed.