Hello. For me, those words feel like this. 유쾌하다 cheerful ,pleasant and amusing. To describe someone's nature or evaluating some kind of jokes or writings. 쾌적하다 in a good hygiene. Mostly, use this word to describe some places which have good ventilation system(or big windows) so that the air is fresh. Or you can say the air(or wind) is 쾌적. 쾌활하다 almost similar to 명랑하다. But more energetic than 명랑하다. 명랑하다 cheerful. This word goes well with bright young kids. 경쾌하다 quick , light and cheerful. To describe someone's steps or fast and rytmical music. 불쾌하다 unpleasant. Amost similar to '기분 나쁘다’ 활달하다 active and energetic. Almost similar to 활발하다 발랄하다 someone's behavior or facial expression are bright and lively. 적극적이다 active. Agressive(in positive way) To achieve something, someone will act as ‘적극적’ 활달하다 활기차다 활발하다 are very similar verbs. But usually 활달하다 and 활발하다 are for describing behavior, while 활기차다 can express someone's state. 친근하다 familiar 친하다 intimate, close to someone(not a physical distance) Keep going!:)