A major part of every Martial Art is breathing technique. Good breathing will give you force and energy on one side, but on the other side will not tell a potential attacker when you are out of balance and injurable.
Breathing in the Martial arts is with the diaphragm, e.g. the breathing will be initialized by the stomach, as opposed to breathing with the breast as often seen on untrained people. The inhalation is through the nose, the exhalation through the mouth. Through lifting the abdomen, the diaphragm will be pulled down and initializes the inhalation. The exhalation is vice versa.
Very often in different Martial Arts you find a loud exhalation. This is a good way for beginners to focus on their breathing and for learning the correct breathing rhythm. But experienced students should use this loud exhalation during breathing excercises only. During sparring or a real fight this is no good idea, as an opponent could use this as a hint for best time to attack. During inhalation no fast response is possible, also a hit has more effect. So during sparring the exhalation should be unhearable, but nonetheless correctly and forcefully.
A very forceful breathing technique is the Kihap, a loud cry. It is important that the Kihap is from the stomach not your vocal chord. Often you could find students (even high graduated) who use their vocal chord too much for Kihap. This is not very good for your vocal chord and even not very effectful. A correctly done Kihap could have the following effects: