My name is Jinsu Kim.
=> Correct Sentence 

I work at Public Development Department of Samsung SDS.
=> I work at the Public Development Department of Samsung SDS. 

Since 2012, I have worked on Korea ON-line E-Procurement System(KONEPS) project of Public Procurement Service(PPS) in Daejeon.
=> Correct Sentence 

It’s a part of my job to maintain the KONEPS system.
=> Correct Sentence 

In particular, I process requests of the client, PPS, to change the system’s database models, which includes its design.
=> Correct Sentence 

Before joining Samsung SDS, I studied Information & Telecommunication toward my Bachelor's degree at ChungBuk National University to develop my strong interest in Information Technology (IT). 
=> Correct Sentence 

So, I enjoy working as a system engineer.
=> Correct Sentence 

[Comment]

Hello Daniel!

Fantastic! You introduced yourself with the important information you need to indicate. How you introduce youself will leave a lasting impression to your reader. Introducing youself in an interesting way will help people remember you. Sometimes, the information you should say depends on what they ask from you, so make sure to be mindful about it. 

Take Care!

-T. Sandy-