Hello JP 님
Actually, ㄴ/는/은 + 데 is used more as the meaning of the adversative conjunction(but). It can be used to connect two clauses together while expresses "but".
이 음식은 맛있
는데 너무 매워.
This food is delicious
but too spicy.
갈건
데 좀 늦을거야.
I am coming
but I will be late a little.
-Grammar Point-
Verb stem + "-ㄴ / 은 / 는데"
I. A descriptive verb stem ending in a vowel + -ㄴ 데
1. 활발하다[hwalbalhada]: "to be lively, to be active, to be full of life"
활발하 + -ㄴ 데 ---> 활발한데...[hwalbalhande]: "(He) is full of life...(but) " - Indicating a different idea
2. 이다[ida]: "to be"
학생이다[haksaeng-ida]: "to be a student"
학생이 + -ㄴ 데 ---> 학생인데[haksaeng-inde]: "(I) am a student"
II. A descriptive verb stem root ending in a consonant + -은데
1. 좋다[jota]: "to be good"
좋[jo] + 은데 ---> 좋은데[joeunde]: "It's good...(but it's too expensive)"
2. 귀찮다[gwichanta]: "to be annoying"
귀찮 + -은데 ---> 귀찮은데[gwichan-eunde]: "(It) is annoying…(but it should be done by tonight)"
III. A verb stem (action verbs, and all verbs in forms other than the present tense) + -는데
1. 쉬다[swida]: "to rest"
쉬 + -는데 ---> 쉬는데[swineunde]: "
쉬는데… - (swineunde…) – [(She) is resting…]
2. 맛있다[masitda]: "to be delicious"
맛있 + -는데 ---> 맛있는데[masitneunde]: "It's delicious (but it has a lot of calorie)"
And some examples...
1. 새로 나온 엠피쓰리인데 별로야.
Sin-sangpuminde byeolroya.
It's a brand new MP3 but it's not nice.
2. 이 가방은 좋은데 너무 비싸.
I gabang-eun joeunde neomu bissa.
This bag is nice but it's too expensive.
3. 이 케이크 정말 맛있는데 칼로리가 너무 높아.
I keikeu jeongmal masitneunde kalroriga neomu nopa.
This cake is so delicious but has lots of calorie.