I work at Samsung SDS. Since it was founded in 1985, we have ranked No.1 in the ICT (Information & Communication Technology) of domestic industry. 
=> Correct Sentence

Under the globalization policy, we are expended our business into Middle East and South America. As a system engineer, I develop and maintain e-bidding system at Public Procurement Service that is located in Dunsandong, downtown of Daejeon.
=> Under the globalization policy, we are have expended our business into the Middle East and South America. As a system engineer, I develop and maintain e-bidding system at Public Procurement Service that is located in Dunsandong, downtown of Daejeon. 

As one of the best ICT Service Providers, we provide System development and maintenance services to all industries.
=> Correct Sentence

In particular, I work at Public Services Department to provide the services to government offices. 
=> Correct Sentence

So, instead of having our seats at the headquarters or a local office, we move company to company by project that we work at. Our goal is to provide the service with System error for 24/7 to satisfy our clients.
=> Correct Sentence

[Comment]

Hi Daniel!
You did well in explaining your company's services. You stated the important details people should know when introducing a company. As an employee, it is a must that you know things about your company: the foundation, employees, services and so on. With that, you will be able to share what you can offer to the company.  You can be more productive by being aware of what you should do as part of it. I can say that you work for such a big and a successful company because it is known worldwide. 

Have a great day!

-T. Sandy- ^_^