I've said this earlier and will say it again; this is a basic form taught to white belt students. There really isn't a whole lot to work with as far as hidden applications. As a hapkidoist, I can redirect some of those movements to get a grapple here or a lock there, but the level of student for whom iljang is designed for would be far from ready to explore such things. Yijang isn't really any better, with the only substantive difference being a greater variety of targets. Even samjang, which incorporates open hand parrying and more than two shifts in stance, would be a poor choice; at this level the students are still learning to correctly execute those techniques. Taegeuk sajang would be a much better candidate for this. It contains a variety of open and closed hand offenses and defenses, a greater variety of kicks, and a greater variety of stances.