This process is common to every pattern of yaksok kyorugi of Taekwondo. It should be settled who is attacker and who is defender. In this photos, the right person is attacker and the left defender.

The attacker moves first. He shifts from Junbi to Apkubi Arae Makgi. Here, the attacker should follow the ways of Samjae. It means he should not draw back, but drop his hip down bending his knee.

And the attacker yells with his motion. It signs that he is ready for atttack. Then, the defender get ready for defence. It means he thinks how he will move. He then yells, which signs he is ready for defence.

Refer to "Understanding the attacker's motion".

Pattern 7 is the following. The counter attack is Ap chagi.

The attacker shifts from Arae Makgi to Apkubi momtong jireugi with one step forward. Then the defender drops down, and step aside to the left with his right hand push the attackers punch away slightly, and then kick the last rib of the attacker with his right foot.

In this practice, you should get the sense of good distance for your Ap-chagi. And remember, you should kick in low pose. Don't stand up while kicking or before kick.