"Thanks for being so patient in explaining" => (이렇게) 힘들여 [열심히 / 자세히] 설명해 주셔서 감사합니다. (formal) => (이렇게) 힘들여 [열심히 / 자세히] 설명해 줘서 고마워(요). (informal) => 설명을 이렇게 열심히 해 주셔서 감사합니다 (emphasize "so patient", but not as natural as the others) * 이렇게: so; this much. * 힘들여(서): taking pains; patiently. * 열심히: eagerly; ardently; with passion. * 자세히: with detail; thoroughly. * 설명해 주다: explain to someone.