(Top) The Phagspa letters [k, t, p, s, l], and their Hangul counterparts, g, t, b, j, l [k, t, p, ts, l]. Note the lip on both [t]'s.
(Bottom) The derivation of Phagspa w, v, f from variants of the letter [h] plus a subscript [w], and the analogous composition of hangul w, v, f from variants of the letter [p] plus a circle. Although not reflected in this font, the original 蒙古字韻 Měnggǔ Zìyùn shows rounder bottoms for the v and f than for the w.
From en:Image:Phagspa-Hangul_comparison.png: (Top) The Phagspa letters [k, t, p, s, l], and their hangul derivatives, g, t, b, j, l [k, t, p, ts, l]. Note the lip on both [t]'s. (Bottom) The derivation of Phagspa w, v, f from variants of the letter