Main video: Video of several tree forms, include multi-axis: (Korean dialogue with some English subtitles)
What, are they just learning about espaliered trees now? This technique has been around for decades, at least. UBCBG's food garden has had espaliered apple and pear trees since the first time I went there over 40 years ago.
Yes, I looked for photos, only found one, but I did do a posting six years ago with the interpretive sign. https://forums.botanicalgarden.ubc.ca/threads/june-2017-in-the-garden.90953/#post-356535 Maybe the point is that the technique is getting more popular in commercial orchards.
Here's an article on the development in Korea: Tree branches grow and stretch into the sky?… Development of flat apple cultivation method. So is this somehow different than espalier or is it just one form of it?
This is a form of espaliering, which has limitless variations. UBCBG used to have an espaliered tree spelling out UBC, although I haven't seen it recently.