Well, there's a couple different things that factor into any accent. These include things such as pitch, intonation, pronunciation, and rate of speech. I mean rate of speech within a sentence, as well as overall, though that's more of a matter of sounding natural as opposed to having an accent. For example, some vowel sounds should be held a bit longer than the way the same vowel is pronounced in another word. So there's a lot of different little things that contribute to having an accent. Your pronunciation seems pretty good to me! I think it's more of a matter of intonation. Listen and practice! Ask for feedback. Ask people for their own recordings of the same sentences. Write little arrows or dashes above Korean text to notate the intonation for yourself. Try children's audiobooks. Pay attention to what is being said, the context, the mood, the tone, etc of the text and audio. Try and pick out patterns. Listen to words in isolation. Listen to the same words used in several other common sentences and structures. Your pronunciation of 공부 sounded a bit odd to me, but I'm not a native. I see you have two "natural" results for that recording as well :)

Also, shadow and mimic what you hear. Like a baby babbling away after his or her parent. For more on this concept (as well as a product, but the point was the information), visit this website: http://www.mimicmethod.com/ There is also an accompanying YouTube channel that goes with it.

안녕하세요, Kai :) Hi, Kai :) Kai의 발음은 나쁘지 않습니다. I think your pronunciation is not bad. 한국사람들이 알아듣기에 아무런 문제가 없어요. I believe all Koreans can understand what you said. 계속 연습하면 훨씬 나아질 것입니다. The more you practice the better you will be. 다만, 한국노래나 버라이어티 TV 프로그램을 보기보다는, 뉴스나 한국어 교재에 있는 MP3를 듣는 것이 더 좋겠다는 생각입니다. :) I think you'd better listen Korean news, radio or MP3 recordings rather than Korean songs or TV programs. Good luck! :)

http://www.italki.com/question/301202 I wrote about general language learning and Korean in particular.

Check the comments on my answer :)